Monolayers and multilayers of mesogen-substituted acetylene monomers and polymers

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Material Information

Title:
Monolayers and multilayers of mesogen-substituted acetylene monomers and polymers
Physical Description:
xii, 175 leaves : ill. ; 29 cm.
Language:
English
Creator:
Roberts, Marion Joseph
Publication Date:

Subjects

Subjects / Keywords:
Thin films, Multilayered   ( lcsh )
Acetylene compounds   ( lcsh )
Polymers   ( lcsh )
Chemistry thesis, Ph. D
Dissertations, Academic -- Chemistry -- UF
Genre:
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1995.
Bibliography:
Includes bibliographical references (leaves 166-174).
Statement of Responsibility:
by Marion Joseph Roberts.
General Note:
Typescript.
General Note:
Vita.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 002046065
oclc - 33410395
notis - AKN3995
System ID:
AA00002046:00001

Full Text












MONOLAYERS


AND


MULTILAYERS
MONOMERS


OF MESOGEN-SUBSTITUTED
AND POLYMERS


ACETYLENE


MARION


JOSEPH


ROBERTS


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
nfl' mlut TTTrT lTTYDoTimv fl L' LTlflTZT1rA TKT TAnnTmTr T crTTrTrTT Tr r mam















ACKNOWLEDGMENTS


Every


scientific


researcher


owes


a great


debt


those


who


have


preceded


him


author


no exception


this


rule.


author


personally


acknowledge


support


and


opportunities


provided


research


advisor,


. Duran.


Also


encouragement


example


Karl


S6derholm


Dr. Katherine


Williams


helped


provide


impetus


toward


pursuit


an advanced


degree.


Perhaps


a little


or committees


author


unorthodox


must


thank


thank


institutions


Graduate


selection


committee


providing


this


chance


to continue


education.


Also


College


Work


Study


Program


allowed


author


a chance


demonstrate


potential


as a future


scientist


while


still


an undergraduate.


pooling


resources


Reynolds,


Dr. George


Dr. Randy


Butler


Duran


Ken


create


Wagener,


what


John


called


polymer


group'


been


a great


help


that


only


provides


access


equipment


which


might


otherwise


unavailable


also


brings


about


new


interactions


between


researchers.


r~ ~~~~~~~~~~~ ~ ~ ~ ~ ~ -I fl tir -a La-npr ..~ L.


nrr n I nm r rrr


~nltnA r.l


-A--


lr `1 n


L


*< /








laboratory;


namely


. Huanchun


Zhou,


Willie


Rettig,


Mathias


Naumann,


Dr. J6rg


Adams


and


Dr. Thomas


Servay


Each


provided


invaluable


advice


encouragement


During


four


months


while


author


was


working


NASA


Lewis


Research


Center


, Dr


Mike


Meador


provided


close


advisement


Lewi


Research


Center


, Dr. Kathy


Chuang


Dr. Jim


Kinder,


Schiemann


were


helpful


The


advice


gratefully


support


acknowl


edged.


. Radi


Awartani


an important


Farchan


way,


Labs


Dr. Jacques


Le Moigne


interpretation


data


changed


model


developed


Chapter


Three


undergraduate


students,


Elli


Teer


Watson,


Shen


have


worked


with


author


years


Their


energy


willingness


learn


(and


sometimes


teach)


have


been


a great


help


Among


fellow


graduate


students


special


acknowledgment


owed


now


Dr. Angie


Thibodeaux


Dr. Rigoberto '


Gobet


Advincula


Angie


was


always


expert


on anything


which


author


could


turn


good


advice.


The


author


now


Dr. Advincula


worked


closely


on much


work


reported


in Chapter


this


dissertation.


Finally,


important


acknowledge


financial


material


support


from


NASA


Lewi


Research


Center


, KSV


Instrument


Numeri


Company


Software


, NanoFilm


Company,


Technologies


Instrument


Company,


Company


Visual


and

















TABLE


ACKNOWLEDGMENTS


OF CONTENTS


S a a S S S S a a S S a S S


LIST


OF FIGURES


a a S SS S S S a v,'


ABSTRACT


S S S S S S S a a S S S S S a S S S xl


CHAPTERS


INTRODUCTION


S S a a S S S S S S S 5 S1


rview
yacety
gmuir-
ymers
Blod
uble D
ethy
ncipal


* .
ene
lod
rom
ett
riv
yle
Obj


and NL
gett-Ku
Pre-or
-Kuhn F
atives
ne .
ectives


*
0
h
i
i
o


* S S S S S S S a a a a a
* S S S S S S a S a a S S
n Technique . .
ented Monomers in Langmuir
ims .
f Polyphenylene-


this
this


ertation


15
15


. 17
. 18


LANGMUIR AND LANGMUIR-BLODGETT-KUHN
OGEN SUBSTITUTED ACETYLENE MONOMERS


FILMS


* S 20


Introduction
Langmui
Polymer
Fi
Experimental
Synthes
un'
Synthes
ph
Synthes
do
tr
Langmui
Dac-^n1 41-0 rsnA^/


r Techniqu
ization of
1ms .


* I1


. .
of
cyn
of
yla
of
can
eth
Blo
F'N'


a
4-
oat
4-
cet
2-
oxy
yls
dge
or.,


* a a S S S S a S 2t
a 2
e . . .. 2
Langmuir-Blodgett-Kuhn
. . 2
* 2 f


drox
, II
'-ol
ene,
0-(4
thyl
ylac
-Kuh


biphenyl-4'
S . .


-biphenyl-4-i
IV .
'-ol-bipheny.
)-anthryl)-
etylene, VII
n Experiment:


an


(11--


oxy


0
5

6
7


. 28
)-n
30


l-4-oxy)

5 39
s . 47
Art


Sol


Pri


P


Daae


w


d(









Conclusion


. a . . *69


3 PROPERTIES
ETHYNYLENE IN


OF SOLUBLE DERIVATIVE
LANGMUIR FILMS .


S OF POLYPHENYLENE-
S . 73


Introduction


a a C S C S S S C S S


etical
Monola
Cellul
imenta
Spectr
Trough
Format
Brewst
Epiflu'
Image
ts and
Langmu
h
e
Langmu


Co
er
r
M
sc
Se
on


hydr


me
et
Langmui
an
Langmui
hy
PY
PP
Topolog
Cellula
Energet
Future Work


CONCLUSIONS


h
y


Knsi
s o
Net
[eth
opy
htup
Sof
Ang
sce
ces
scu
Fill
oxy
nyl
Fil]
oxyl
oxy:
nylu
Fil]
PP1


- -


Fl
rox
idi
PYR
of
Ne
cs


d
f
w
o


erations . . 7
Rigid-Rod Polymers . 7
works . 7
ds 8
* . 8
* . . 8
a Cellular Network . 8
e Microscope .. 8
ce Trough . . 8
ing . . 8
sion . . . 8


opert
canox
, PEH
opert
canox
ylene
, PPE


ie
y)
U
ie
y)
-e
HU


Behavior


Pol
etho


s


s


Poly(


(2-(11-
yphenylene-


. 89


-5-
thynylene-pyridine-


Mixtures


Im Properties of Poly(
yundecanoxy ) phenylene-
nium bromide-ethynylen
I . S S C .


the PPEHU C
twork Dynami
of Cell Coal


llular
s .
science


PEHU


,5-di(11-
thynylene-
),


Network
. .


a C S a C C C a C C C


C 4 C S S S C a a S S S S S C


REFERENCE


LIST


BIOGRAPHICAL


* S C C S a a C a C C C S C S S


SKETCH


C C S S S C C S S S C S C C S


Theor


Exper






Resul


-(11-


I I I 1









LIST


OF FIGURES


Figure


Polyacetylene
double and


consi
single


sts of
bonds.


alternating


carbon


Figure


Langmuir


film


balance


with


an insoluble


monolayer


molecules


under


compare


ssion.


Figure


1-3.


Structures


multilayers.


and


Z-type


LBK


SP 5 5 5 a S S S S10


Figure


2-1.


ogen-sub


stituted


amphiphilic


compounds


studied


with


Langmuir


-Blodgett


technique.


. P S S . 21


Figure


2-2.


Proton


NMR


compound


ODd3.


S. .G29


Figure


Synthetic


scheme


used


mesogen-


substituted


phenylac


etylene.


S. 31


Figure


2-4.


Proton


NMR


IV in


tetrahydrofuran-d4.


. 38


Figure


2-5.


Synthetic


scheme


anthrylacetylene.


mesogen-substituted
.39


Figure


2-6.


Proton


NMR


CDCl3.


Figure


2-7.


Isotherm


. a . 51


Figure


2-8.


Isotherm


% II


mixture


mole


and


* a a . 54


Figure


2-9.


UV spectrum


film


1+11


on a hydrophobic


mixture


quartz


an LBK


plate


. 56


Figure


Isotherm


27 C.


Figure


-11.


Isotherms


V and


VI at


Figure


Hysteresis


exhibited


compress


compr


V during
session c


ycle.


Figure


2-13.


Isotherm


IV at 23


Figure


2-14.


Isotherm


c.4 n. *.


'I


C, -.L


S
-~ - -


- ~ I -


. . 46


S . 60


. 66


S68


Y,


I at


*








Figure


3-2.


Possible topological changes occurring during
coarsening of a cellular network. Cell
coalescence is a third such change. .


Figure


3-3.


UV absorbance
This spectra
Marc Moroni.


of PEHU in THF
was obtained


solution.
by


Figure


3-4.


UV absorbance
film cast on
obtained by


spectra of PEHU
quartz. This
Marc Moroni. .


in a thin
spectra wa


solid


Figure


3-5.


UV absorbance spectra of
film during compression
0.45 nm2/repeat unit


PEHU in
between


a Langmuir
0.2 and


Figure


Figure


3-6.


3-7.


Isotherm
25C.


Hysteresis
sweeps at


surface


of PEHU
25C.


potential


isotherm


PEHU


during


Figure


3-8.


PEHU'
unit


s effective
decreases


absorbance per
with compression


repeat
at 25C.


.94


Figure


3-9.


Isotherm of
coexisten
specific
The boxes
morpholog
the isoth
monolayer
The morph
only on d


PPEHU


at
on
etw
B,
e c
ing
=MC
in


The


serve
e das
sent
ondin
essio
, bla
and


ecompress


phase


at
ed 1
he o
poi
of
k=ME
are


the
ines.
observed
nts on
the
phase)
seen


monolayer.


.a


Figure


3-10.


UV excitation spectra of a
PPEHU on quartz (emission
500 nm). . .


cast film
monitored


. 98


Figure


Figure


3-11.


3-12.


UV excitation
solution of
456 nm) .


UV-Visible
chloroform


spectra of
PPEHU (Emis


emission spectra
solution. .


a chloroform
sion monitored


PPEHU


Figure


3-13.


UV-Vi
nacst


sible
film


emission s
rfn nilarl-7


;pectra


PPEHU


96








Figure


3-15.


Temperature


dependence


PPEHU


isotherms.


Figure


3-16.


Typical


boundary


liquid-expanded/liquid-conden


coexis
films


tence


envelope


long-chain


seen


fatty


ed phase
Langmuir


acids


alcohols.


S . . .104


Figure


3-17.


ective


dipole


moment


PPEHU


air-water


erface.


. . 105


Figure


3-18.


Lever


rule


plot


phase


coex


stence


region


of PPEHU


at 25


Figure


3-19.


Idealized


picture


orientation


the
PPEHU


side-chain


phases.


Figure


3-20.


Hysteresis
speed of
unit/min)


of PPEHU a
2 mm/min (0
SThe plot


.0084
shows


2 and a barrier
nm2/repeat
the difference


surface


pressure


between


compares
within


sion


decompression


biphasic


sweeps


region.


Figure


3-21.


Relative


total


reflectivity


calculated


from


BAM


compress


images


PPEHU


ion/decompres


sion


during
cycle


one


* 115


Figure


Figure


3-22.


3-23.


Domain
phase


Domains o
LC phase
holding


of MC phase
t 0.45 nm2


Dispersed
and 25 C.


MC phase


minutes
0.45 nm2


dispersed


compare


ssing
C.


and
* S S S S


Figure


3-24.


Cellular


network


aged


at 0.35


nm2/repeat


25C


Figure


Figure


Figure


3-25.


3-26.


3-28.


Cellular ne
nm2/repeat


itwork
and ;


Cellular network
nm /repeat and :


Mosaic


decompre
strip is


BAM


ssion


PPEHU


aged


0.45


250C


PPEHU


images


aged


PPEHU


to 0.62 nm2


x 400


after


at 25C


Each


S. 122










Figure


3-30.


Dendrites


PPEHU
analy


formed


below


zer


in plan


during come
nm2/repeat
e). Image


>ression


and
size


15C
is


of
(no
1200


x 800


Figure


3-31.


Birefringent


film


below


(analyzer


regions
0.60 nm2


in PPEHU
/repeat ai


to usual


Langmuir
3 15C


polarization


refl


1200


ected
x 800


beam)


Image


size


Figure


3-32.


Epifluorescence


microscope


image


PPEHU


0.60


nm2/repeat


25C.


Figure


3-33.


therms


PPEHU


pure


compared
component


mixture


isotherm


PEHU
of


and
each


23C.


Figure


3-34.


BAM


image
PPEHU


molar


mN/m


mixture


23C


of PEHU


Image


size


1200


x 800


Figure


3 -35.


BAM


image


PPEHU


1200


mixture


1 mN/m
x 800 u


of PEHU
Image


size


Figure


3-36.


Comparison o
1:1 mixture


pure


monolayer
of PEHU an
components


stability
PPEHU, a
10 mN/m a


each


..... .. .. .. 133


Figure


3-37.


Isotherm


surface


5C.


potential


PPYPYRI


Figure


3-38.


BAM


image


PPYPYRI


spread


1200


air/water
um x 800


interface


Image


size


Figure


3-39.


BAM


0.7


image
5 nm2


of PPYPYRI


25C


during
Image s


compreE
ize is


ssion
1200


x 800


Figure


3-40.


BAM image
0.40 nm2


PPYPYRI
25C.


under
Image


compares


size


sion
1200


x 800


TI, .a


-mnarr nf


V A yAan nnra e 4 a n"


?-d "I


RBM


~llr; nn


PVDVPT








Figure


3-42.


BAM


image c
1.0 nm2


PPYPYRI


during


Image


decompression


size


1200


x 800


S. 137


Figure


3-43.


BAM


image c
1.7 nm2


PPYPYRI


during


Image


decompression


size


1200


x 800


138


Figure


3-44.


Lewis


' la


0.65


w plot for
nm /repeat


PPEHU


cellular


network


25C.


Figure


3-45.


Perimeter


network


law plot for PPEHU
at 0.65 nm2/repeat <


cellular


25C


Figure


-46.


Von


Neumann


s Law


plot.


S. 146


Figure


Figure


-47.


3-48.


Variation
relative


Section


cell growth


phase


exponent


with


fraction


of a ruptured


cell edge.















Abstract


of Dissertation


Presented


Graduate


School


:he University
Requirements f


of Florida


Partial


Degree


Doctor


Fulfillment


Philosophy


MONOLAYERS


AND


MULTILAYERS


OF MESOGEN-SUBSTITUTED


ACETYLENE


MONOMERS


Marion


AND


Joseph


POLYMERS


Roberts


May


1995


Chairperson


: Randolph


Duran


Major


Department


: Chemi


stry


With


view


toward


improving


knowledge


properties


organic


mole


cules


monomolecular


films,


general


class


mesogen-sub


stituted


acetylene


compounds


was


chosen


study.


Such


compounds


potentially


find


application


as both


nonlinear


optical


electrically-


conducting


materials


Monolayer


properties


were


discovered


through


surface


analytical


method


such


Brewster


angle


microscopy,


epifluorescence


microscopy,


in situ


ultraviolet


spectroscopy,


surface


potentiometry.


Langmuir-Blodgett-Kuhn


(LBK)


technique


was


used


study


monolayer


properties


a series


stituted


acetylene


monomers.


Preliminary


work


with


substituted


liquid


crystalline


monoacetylenes


phenylacetylenes








phenylacetylene


monomer,


4-(4'


-ol-biphenyl-4-decanoxy)-


phenylacetylene,


with


improved


reactivity


thin


solid


films


was


achieved.


In addition,


a new


substituted


anthrylacetylene


, 2-(10-(4'


-ol-biphenyl


-4-oxy)


dodecanoxymethyl)-anthryl)-trimethyls


ilylacetylene,


was


synthesized.


LBK


was


also


used


produce


monomolecular


films


phenylene


acetylene


rigid-rod


polymers


poly(2-(11-


hydroxyundecanoxy)-5-methoxyphenylene-e


thynylene),


poly(


-hydroxyundecanoxy)


-5-methoxyphenylene-ethynylene-


pyridine-ethynylene),


poly(


,5-di(11-hydroxyundecanoxy)


phenylene-ethynylene-pyridinium


bromide-ethynylene).


air-water


interface,


form microscopic

simple processing


polymer


network


procedure.


morphologies


The


were


after


properties


observed


treatment


one


polymer


network


s network

dynamics.


was


studied


A model


detail,


including


nanoscale


orientation


polymer


within


estimating


its

line


network

tension


is proposed.


between


new


phases


method

based o


observation


of cell


coalescence


presented.















CHAPTER


INTRODUCTION


typical


- the


in vi


sible


class-one
chemical


evolution


are


, metallurgical,


and


trends


electronic


production
performance
volume of m


ever


with


-more-


inve


erials


efficient


stment


unit


sati


of ever-l


function


sfyingly


ess


formed


effective


weight and
or performed


. ephemeraliza


tion


- accomplish


hed


within


ever-i


ess


increments


time


- le.


acce


lera tion.


This


ess


overall


known


Ephemerali


everything


inexorably


sumtotally


zation


with


omni weighabl e


me taphysi


- R


. Buckmin


trends
nothing


"progr


toward


physical


of intell
ster Full


trending


ess


an ultimate


, which


mas


tered


more


ephemeral


with


zation


doing
trend


ect.


er


Critical


Path


1981,


page


Overview


world


s population


continue


increase,


consumption


of available


resources


will


also


necess


arily


increase


ess


more


efficient


means


are


found


adopted.


more


obvious


successes


found


construction


ectronic


mechanic


micro-devi


ces


from


crys


talline


silicon.


limit


minituration


will


soon


reached


electronic


devices.


Thus,


there


growing


interest


in optical-based


devi


ces


Materials


which


alter


omni weigh tl


ess











devices.


In addition,


techniques


shaping


these


new


materials


into


working


devices


will


be needed.


invention


laser


provided


a source


high


intensity,


coherent,


directed


light.


Soon


after


came


discovery


that


materials


can


alter


intense


laser


light


doubling


or tripling


frequency


light.


These


special


materials


are


called


nonlinear


optical


materials


because


way


they


alter


wavelength


intense


light.


important


note


that


light


must


intense


to double


order


or triple


a nonlinear


light


optical


frequency,


(NLO)


material


otherwise


NLO


material


does


affect


exiting


light


frequency.


Thus,


possible


induce


NLO


effects


using


normal


light


sources.


first


NLO


effects


were


observed


in inorganic


materials


such


as quartz.


In general,


inorganic


materials


allow


researcher


much


flexibility


making


new


materials

effects i


with


esired


n organic


improvements


in the


properties.


materials


figures


opened


The

the


of merit


scovery


further


NLO


materials.


organic


material


which


been


found


have


best


efficiency


tripling


light


frequency


is polyacetylene.


-r n


3 %TT f


Dn 1 rt~nnCrtlhnn











planar


conformation,


PA chain


enshrouded


delocalized


cloud


of n-electrons.


When


PA is exposed


electric


field,


such


as that


laser


light,


electron


density


displaced


molecule


becomes


polarized


along


main


polymer


chain


The polarization


induced


oscillating


electric


laser


light


may


described


equation,


P1%o


+ &2


Y3
+ --E
6


where


field-dependent


dipole


moment


molecule


intrinsic


dipole


moment


molecule;


coefficients


are


linear


polari


ability,


first


hyperpolari


ability,


second


hyperpolarizability,


respectively,


molecule.


Each


three


coeffici


ents


is a measure


of how


responsive


molecule


polariz


force


electric


field.


In weak


electric


fields


the displacement


electron


density


is proportional


electric


field


strength.


plot


dipole


moment


versus


electric


field


strength


gives


straight


line


with


a slope


electric


field


strength


increases


to magnitudes


which


are


only


accessible


with


laser


light,


nonlinear


contributions


such


as P


+(XE



































Figure


1-1. Polyacetylene


consists
double a


alternating


single


carbon


bonds


In substituted


polyacetylenes


which


have


an electron


accepting


group


one


end


chain


and


an electron


donating


group


opposite


end,


polarization


occurs


more


one


direction


along


chain


than


other.


The


coefficient,


thus


frequency


a measure


molecule


light


this


s potential


passing


polarization


ability


through


asymmetry


double


In polyacetylenes











changed


molecule


s polarization.


This


important


such


functions


as optical


switching,


which


use


one


light


beam


to alter


path


of a second


beam


changing


refractive


index


material


4In addition


optimization


of NLO


response


at a molecular


level,


res


earcher


must


also


strive


arrange


molecules


material


so that


summe


d NLO


response


maximized.


Thus


macroscopic


polarization,


+ X(2)E2


which


given


+ 1)E


becomes


quantity


of interest.


To a first


approximation


it is


possible


bulk


medium


infer


from


nonlinear


those


optical


individual


properties


molecules.


Thus,


molecules'


influences


ultimate


material


likewise,


affects


For


example,


with


polyacetylene


been


shown


that


third


order


NLO


response


increased


ordering


polymer


chains


such


that


planarity


each


main


chain


maintained.


Furthermore,


interchain


alignment


polymer


also


affects


nonlinear


response


material.


Langmuir-Blodgett


films,


third


order


hyperpolarizability


can


written5


= O.Ny


p=Xrl, E


I\










number


molecules


per


unit


volume


effect


side


chains


on the


main


chain


conformation


can


vary


depending


their


bulkiness


presence


of inter


-side


chain


interactions


Lanamuir-Blodaett


-Kuhn


Technique


Langmuir-Blodgett-Kuhn


technique


one


method


which


organic


material


process


to achieve


such


ordering


molecul


LBK


utili


zes


orienting


properties


an interface


between


phases


Typically,


phases


are


air


and


water


other


system


have


been


exploit


ed such


air-mercury


Desirabl


properties


include


high


interfacial


tension,


inertness


and


that


materials


to be processed


interface


should


insolubl


subphase.


A commonly


studied


material


stearic


acid


Stearic


acid


an amphiphilic


molecule,


that


a hydrophilic


headgroup


-COOH)


a hydrophobic


tail


(-C17H3)


Thus


in a monolayer


, stearic


acid


average


oriented


with


headgroup


immersed


water


tailgroup


outs


water


apparatus


used


perform


LBK


technique


Langmuir


film


balance


(Figure


The experimental


quantities


which


are


readily


accessible


with


Langmuir


, it










difference


between


surface


tension


pure


solvent


that


film-covered


surface


Surface


tension


defined


as surface


free


energy


per


unit


area


boundary


between


solvent


above


Surface


tension


units


energy


area


or force


length.


Boundaries


between


dimensional


pha


ses


within


Langmuir


monolayers


analog


line


lead

the s


free


line


surface


energy


tension


tension


unit


which

Line


is a one

energy is


length


dimensional


defined


boundary


between


domains


dimen


sional


ases.


Line


tension


units


energy


per


length


or force.


The


first


experiment


performed


with


Langmuir


film


technique


usually


isothermal


surface


pressure


versus


area


diagram


isothermm).


Molecules


are


spread


water


surface


laterally


compressed


with


mechanical


barriers


while


isotherm


surface


can


give


pressure


important


area


information


are


such


recorded.


as the


compressibility


monolayer


also


cross


sectional


area


molecules


within


close-packed


monolayer.


This


method


was


actually


used


determine


diameter


buckminsterfullerene


a few


years


ago.


A second


experiment


in which


usually


performed


monolayer


hysteresis


is subjected


repeated


experiment,

compression











third


type


isobaric


experiment


creep


experiment.


monolayer


monolayer


stability


stability


determined


maintaining


a constant


surface


pressure


while


recording


change


area


over


time.


Wilhelmy balance


monolayer


moving barrier


1111111111111111111111


-subh


side view


Figure


1 -2.


monolayer


Langmuir
molecules


film


under


balance


with


an insoluble


compression.


LBK


films


are


result


sequentially


depositing


monolayers


on a solid


supporting


surface


such


as a glass


slide


To clarify


definition


terms


introduced


here,


a Langmuir


film


refers


an insoluble


monolayer


air-water


solid


interfa


substrate.


ce.


With


An LBK


LBK


film


technique,


is supported


a suitable


on a


substrate


/---


lllIiiilllllllllllll111111











silylated).


During


experiment,


an indication


quality


transfer


deposition


ratio


given


is defined


transfer


area


ratio.


of monolayer


removed


from


water


surface


divided


area


state


coated


monolayer.


this


way,


multilayered


thin


film


is created


one


layer


a time


supporting


substrate.


combination


Layers


materials


may

which


one


are


amenable


material


transfer


growing


film.


the layers


are


laid


down


each


time


substrate


moves


across


phase


boundary,


then


deposition


Y-type


(Figure


1-3).


also


possible


have


deposition


occur


only


when


substrate


enters


subphase


depending


(X-type)


monolayer


leaves


material,


(Z-type),


substrate,


subphase,


surface


pressure


When


the desired


film


thickn


ess


is achieved,


subjected


film


further


on its


supporting


processing


other


substrate


may


techniques


and/or


evaluated


wide


variety


analytical


methods


available


thin


films.


11,12


Oftentimes,


uniformity


fluidity


Langmuir


film


gives


a good


indication


quality


resulting


technique.


researchers


For


have


this


worked


reason,


find


among


ways


others,


image


many


Langmuir






















Figure
and Z-


St


type


LBK


ructures of
multilayers


microscopy


technique


13, 14,15,16,17


This


technique


allowed


first


time


study


morphological


changes


material


adsorbed


interface


in real


time.


The


technique


suffers


somewhat


material


of interest


fluorescent


because


introduction


of a probe


material


with


suitable


compatibility


then


necessary


A second


more


recently


developed


imaging


technique


Brewster


angle


microscopy


BAM.


18, 19, 20


an improvement


over


epifluorescensce


microscopy


extent


that


probe


molecules


are


necessary.


other


hand,


early


BAM


systems


suffer


from


lower


resolution


rm2)


and


image


quality.


Image


quality


lost


through


ever-present


interference


fringes


which


are


result


using


coherent


light


illuminate


interface.


Neverthel


ess


information


gained


useful


finding the


best


conditions


O--t-(


O ---
1=1t











course,


many


other


surface


analytical


techniques


besides


microscopy


have


been


exploited


to learn


more


about


behavior


molecules


air/water


interface.


For


example,


monitoring


surface


potential


changes


during


Langmuir


film


compression


can


give


a clue


orientation


of dipoles


interface.


The


method


measuring


surface


potential


values


reported


dissertation


was


vibrating


electrode


method.


this


method,


there


one


electrode


beneath


water


surface


other


electrode


above


water


surface


upper


electrode


moved


with


respect


water


surface


resulting


change


capacitance


gap


leads


current


flow


an external


circuit.


The


magnitude


current


is proportional


potential


difference


across


gap.


A potentiometer


circuit


used


find


voltages


necessary


prevent


current


flow.


an actual


measurement,


potential


clean


water


surface


potential


interface


zero


caused


change


molecules


recorded


surface


introduced


effective


dipole


molecules


Langmuir


film


may


estimated


using


equation,


4nia.











where


effective


dipole


film,


AV is


measured


surface


potential,





mean


molecular


area.


The


molecules


water


are


preferentially


oriented


water


surface


introduction


film-forming


molecules


alters


that


structure.


Rearrangement


this


structure


water


surface


changes


contribution


surface


potential


an unknown


degree.


Thus


care


must


taken


interpretation


surface


potential


data.


Another


surface


analytical


technique


situ


spectroscopy


Langmuir


film.


The


apparatus


consists


a xenon


arc


lamp


source


with


a quartz


fiber


optic


cable


piping


light


collected


through


a mirror


water


resting


on the


surface.


light


bottom


trough


focused


onto


of a second


quartz


fiber


optic


cable


suspended


above


water


surface.


This


second


fiber


optic


cable


carries


light


to a diffraction


grating


which


precisely


aligned


that


each


wavelength


strikes


separate


diode


generated


in a diode


each


diode


array.


are


The


processed


screte


give


voltages


a reading


corresponding


intensity


each


wavelength.


actual


experiment,


range


of intensities


from


clean


water


surface


are


subtracted


from


intensities


with











Scientific


interest


in LBK


films


arises


from


possibility


of constructing


designed


molecular


architectures


which


allow


study


physical


phenomena


on a molecular


level


Practical


interest


arises


from


continuous


trend


of size


reduction


electronic


devices,


which


calls


new


materials


processing


techniques.


Macroscopic


properties


organic


solids


are


closely


related


their


microstructure.


LBK


films


often


possess


highly


crys


talline


lamellar


structure


with


domains


diameter


between


micrometers.


Shear


forces


occurring


during


monolayer


deposition


can


deform


domains


induce


a highly


anisotropic


morphology


In principle


stances


which


form


stable


monolayers


contain


isolated


or conjugated


double


triple


bonds


or epoxide


moieties


can


polymerized


LBK


films


upon


high


energy


radiation.


However


monomers


containing


vinyl


groups


were


found


ess


suit


than


monomer

group,


containing


because


during


larger


butadiene


polymerization


or diacetylene


a mismatch


arises


between


packing


hydrocarbon


chains


polymer


formed


chain


situ.


containing


23 Thus


rather


, phase


short


transitions


vinyl


are


repeat


induced


unit


which


are


often


accompanied


incomplete


conversion










probably


due


to relatively


poor


contacts


between


individual


domains.


Further


research


on LBK


films


directed


towards


better


morphological


control


improved


thermal


mechanical


stability.


approach


change


molecular


archite


cture.


Results


with


polymeric


LB films


based


on polyimides


maleic


anhydride


copolymers,


polyglutamates


a-helix


form,


polyphthalocyaninatosiloxanes


are


quite


promising.


Molecules


which


are


amphiphilic


are


usually


always


best


suited


processing


LBK


technique


Besides


usual


amphiphiles,


molecules


completely


different


structures


such


as porphyrins,


phthalocyanines,


oligothiophenes


, polycyclic


aromatic


quinones,


a variety


of polymers


form


stable


monolayers


LBK


films


A second


experimental


tactic


been


conditions.


more


improve


suitable


processing


shaping


troughs


might


also


help


improve


morphological


quality


Also,


various


annealing,


thermal


treatments,


compare


ssion


schemes


have


been


discussed


Unfortunately,


present,


there


tool


organizing


microstructures


within


layer


plane


a specific


interlayer


alignment


of molecular


domains


possible


either


incorporation











multilayer


film


with


each


layer


having


multiple


domains,


film


could


heated


transition


temperature


between


the c

liquid


rystalline


crystalline


liquid


state


crystalline

molecules


(LC

are


state.


less


ordered


are


still


quite


highly


aligned.


Also


while


LC state,


domains


in each


layer


increase


in size


through


normal


coarsening


process


ses


or the


direction


alignment


when


changed


film


using


cooled


electric


back


or magnetic


crystalline


fields.


state,


each


layer


can


have


fewer


but


larger


domains.


This


type


processing


LBK


films


been


demonstrated


using


preformed


LC side


chain


polymers


Several


excellent


reviews


diverse


materials


that


have


been


studied


with


LBK


may


found


9,31,32


use


preformed


polymers


preparation


LBK


films


been


discussed


along


with


recent


dev


elopments


different


classes


of polymers


LBK


multilayers


their


outstanding


properties


highlighted.


Polymers


from


Pre-oriented


Kuhn


Monomers


in Langmuir-Blodgett-


Films


Highly


obtained


ordered


using


crys


tals


solid-state


macromolecules


polymerization


can


LBK


films.


-; ni-t 1 al-inn i a


C -a4-A


4- p 1*


nn l~~mnr:


nL: mrll


1 110


I


1 ~










propagation,


termination


processes


an LBK


film.


central


problem


solid-state


polymerization


associated


with


chain


propagation


which


hybridization


atoms


involved


changes


during


reaction,


example,


acetylene


polymerization.


34 In such


reactions,


van


der


Waals


contact


distances


change


covalent


bond


distances.


Thus


there


is necessarily


a change


in lattice


distances


during


polymerization;


neverthel


ess


, fully


crystalline


polydiacetylene


been


obtained


in a solid


state


reaction.


Highly


ordered


films


of polydiacetylene


are


obtained


either


air/water


interface


or on solid


supports.


37,38


Chemically


adsorbed


monolayers


of substituted


monoacetylenes


have


been


polymerized


using


catalysts


or high


energy


also

crys


electron


been


tallin


beam


polymerized

e metal pro


irradiation.


in solid


violates


Monoacetylenes


crystals.


are


converted


have


example,

gamma


irradiation


amorphous


metal


polypropiolates


Propargylamine


in a tetrachlorocadmate


layer


complex


was


polymeri


gamma


irradiation.


41 Some


questions


that


have


been


answered


these


studies


remain.


The


polymer


repeat


structure


could


be criti


cally


dependent


on the


substituent


terminal


acetylene


and


details










associated


unknown


with


initiation


present,


are


propagation,


important


which

the q


are


questionss


explored


this


thesis


effect


stituent


on the


terminal


acetylene


studying


LB films


alkylactylenes


arylacetylenes.


Soluble


Derivatives


of Polvyphenvlene-ethvnvylene


Rigid


polymers


with


a linear


conjugated


backbone


built


up by


para-linked


arylene


units


are


interesting


compounds


due


their


unique


properties


concerning


heat


stability


photoconductivity.


Rod-like


polymers


can


organized


form


LB films


reasons


related


stiffn


ess


their


backbone.


Stable


monolayers


are


formed


polymers


polar


which


functional


exhibit


groups


groups


with


Generally


or very


, the


transfer


small


these


materials


poor43


therefore


ese


materials


were


considered


suited


formation


of multilayers.


overcome


this


problem,


rod-like


polymers


surrounded


conformationally


crystallization


objects


mobile


were


govern


side


developed


a great


chains


prevent


On a 2D plane,


extent


shape


efficiency


packing


objects


are


forced


together


pressure.


example


when


equal-sized


disks


pack


together


in a plane,










increased.


Extreme


aspect


ratios


seen


in rigid


rods


or hard


needles


are


predicted


lead


most


efficient


packing


also


Thus


anisotropy


, soluble


within


plane


polyphenylene-ethynylenes


offer


potential


obtain


well


defined


layered


structures


LBK


films


PrinciDal


Obiectives


this


Dissertation


overall


objective


this


dissertation


description


behavior


mesogen


stituted


acetylene


monomers

interface


such


and

and


films.


polymers


in monolayer


as multilayer


Fundamental


films


knowledge


films


including


gained


air/water

formation


would


include


effect


of balancing


hydrophilic


hydrophobic


tendencies


a mol


ecule


more


complex


than


classical


fatty


packing


from


acids


and

ese


or lipids.


thus

new m


The


ultimate


olecules


was


molecular


stability

explored.


shape


monolayers


In Chapter


on the


formed

the


work


takes


challenge


preorienting


monomers


well-ordered


arrays


prior


attempting


polymerization


with


hope


that


order


would


preserved


resulting


polymer.


New


knowledge


gained


with


regard


acetylenic


monomers


includes


processing


acetylene


monomer


into











acetylenic


monomer


was


synthesized


which


approaches


more


closely


goal


solid


state


polymerization


these


materials.


The

approach.


work

The


reported


materials


Chapter


are


takes


pre-formed


a different


poly(phenylene-


acetylene)


polymers


so que


stions


about


reactivity


are


mute.


materials


are


variation


well-known


hairy-rod


polymers


with


regard


their


Langmuir


film-forming


properties.


comparisons


shape


with


these


theoretical


rigid-rod


models


molecules


of needles


leads


on a 2D


plane.


These


polymers


differ


from


previously


studied


rigid-


polymers


that


alkyl


side


chains


which


give


these


polymers


their


solubility


are


terminated


with


a hydroxy


group.


Thus


Langmuir


films


gain


stability


only


from


packing


adsorption


polymers


water


but


surface.


also


This


through


strong


difference


leads


non-classical


phase


behavior.


New


knowledge


gained


with


regard


poly(phenylene-acetylene)s


includes


detailed


description


two-dimensional


phase


behavior


these


materials.


microscale


description


This


description


morphology


includes


phase


nanoscale


intra-


only


separation


and


also


intermolecular


arrangement.















CHAPTER


LANGMUIR


AND


LANGMUIR-BLODGETT


FILMS


OF MESOGEN


SUBSTITUTED


ACETYLENE


MONOMERS


Introduction


Toward


ultimate


goal


developing


polymeric


materials


with


high


electrical


conductivity


high


third


order


nonlinear


optical


property


this


work


focused


primarily


on a cl


ass


of substituted


acetylenes


which


might


exhibit


liquid


crys


talline


behavior


while


same


time


possess


amphiphilic


character


(Figure


known


that


are


both


improved


conductivity


when


nonlinear


polyacetylene


optical


is highly


properties


ordered.


Since


discov


electrical


conductivity


polyacetylene,


this


class


of compounds


become


subject


intense


res


earch


activity


subsequent


discovery


nonlinear


optical


properties"


acetylenes


created


additional


interest.


Polyacetylenes


are


characterized


a consequence


e.g.


large


having


extended


molecular


highly


- electron


hyperpolari


displacable


systems


ability


electron


High


clouds,


nonlinear


properties


are


dependent


on not


only


extended












0
O

I
O ^^^OH


0


,0-OH


III


O0o0


'0 -0


VI I


Figure
studied


Mesogen-sub


with


stituted


amphiphilic


Langmuir-Blodgett-Kuhn


compounds


technique


IV


Oo-OH


_


~-











Liquid


crystals


are


used


as display


devices


in which


function


comes


from


ability


liquid


crystalline


molecules


to self


organize.


51 The


use


of liquid


crystals


making


Langmuir-Blodgett-Kuhn


films


a step


towards


better


morphological


control


The


Langmuir-


Blodgett-Kuhn


technique


offers


potentially


greater


control


over


molecular


orientation


inter-molecular


packing


which


could


lead


creation


new


types


thin-film


devices


Previous


attempts


at polymerization


alkyl


substituted


monoacetylenes


catalysts


in solution


have


been


mostly


unsuccessful


54.55


other


hand,


solid


state


polymerization


monoacetylenes


been


achieved


gamma


irradiation


some


cases


56, 57


failed


in another.


58 Yet,


general,


a successful


solid


state


polymerization


can


lead


highly


ordered


polymer


59 In


this


work,


an approach


solid


state


polymerization,


utilizing


amphiphilic


mesogen-


subs


tituted


acetylenes,


was


tried.


Such


compounds


are


amenable


manipulation


using


the Langmuir-Blodgett-Kuhn


technique


monomer,


into


a two-dimensional


incorporated


monolayer


monolayer,


60,61


would


ideal


polymerize


yield


high


molecular


weight,


highly


ordered


substituted


polyac


etylenes.


een


shown


that


conductivity


in polyacetylene











monomers


essence,


monomers).


prior


to polymerization


"locking-in"


First,


pred


liquid


(the


determined


polymerization,


geometry


crystallinity


monomer


should


be such


that


acetylene


group


present


on each


molecule


would


be positioned


as near


ideal


polymerization


as possible.


Second,


amphiphilic


character


monomer


is exploit


create


two-


dimensional


films


using


Langmuir-Blodgett-Kuhn


technique.


In other


words,


liquid


crystallinity


influences


plane


orientation


monolayer


monomers


while


normal


Langmuir-Blodgett-Kuhn


technique


determines


orientation


monomers


within


plane.


The


repeat


unit


length


acetylene


units


joined


in cisoid


conformation


range


63 This


distance


between


acetylene


groups


would


optimal


polymerization.


For


a usual


head


tail


polymerization


acetylene


groups


should


a 120


angle


with


ax carbon


of each


acetylene


within


carbon


of its


neighbor.


This


a reasonable


geometry


expect


from


Y-type


LBK


deposition


because


tilt


angle


monomers


often


range


from


normal.


Previous


work


with


liquid


crystalline


substituted











Le Moigne


coworkers


have


synthesized


a number


liquid


crystalline


substituted


monoacetylenes


polymerized


a few


these


acetylenes


in solution


using


Ziegler-Natta


cataly


(albeit


eld)


Zhang


Blumstein r

crystalline


research


group


stituted


has

monoa


synthesized

cetylenes (


several


for


liquid


example,


compound


also


had


little


success


with


polymerization66


conventional


techniques.


compounds


listed


in Figure


represent


variations


basic


theme.


Preliminary


work


showed


that


I when


mixed


with


processible


Langmuir


films.


Compound


desirable


properties


one


molecule.


phenyl


Compound


ring


IV is


introduced


variation


next


on compound


acetylene


III.


group


reasons.


First,


conjugation


between


phenyl


ring


acetylene


group


will


increase


wave


length


peak


sorbance.


Thus


be possible


to initiate


radical


polymerization


using


UV irradiation


or by


heating


instead


more


drastic


gamma


irradiation.


Secondly,


phenyl


group


was


introduced


this


position


so that


phenyl


group


would


serve


limit


distance


interdigitation


between


LB layers


(assuming


Y-type


deposition).


Compounds


are


also


phenyla


cetylenes


like


IV but


they


have










conformations


main


chain


whereas


presence


spacer


between


main


chain


mesogen


favor


helical


conformations.


other


67 The


compounds


series


this


study,


V and


also


that


differ


most


from


hydrophilic


part


molecule


includes


acetylene


group


(which


a significant


dipole).


Within


series


, V and


length


hydrophobic


tail


was


varied


study


on film


properties.


Compound


VII


an extention


strategy


that


anthracene


moves


maximum


absorbance


peak


still


longer


wavelengths,


indeed,


unsub


tituted


9-ethynylanthracene


been


reported


"spontaneously"'


anthracene


polymerize.


ring


68 The


allows


substitution


to strongly


pattern


affect


conformation


polymer


main


chain


possibly


leading


ribbon-like


conformation.


Anthracene


is also


stable


while


carrying


a -2


charge


Thus


polyethynylanthracene


would


an interesting


polymer


with


regard


ability


maintain


charge


separations.


Such


charge


separations


are


element


photorefractive


nonlinear


optical


materials.


Lanamuir


Technicrue


One


goal


this


work


been


to explore


possibility


polymerizing


arylacetylene


compounds


through










caused


polymerization


shrinkage


because


computer


controlled


pressure


apparatus


on the


can


monolayer


maintain


a constant


compensate


lateral


this


shrinkage.


These


experiments


required


apparatus


purging


atmosphere


around


trough


with


inert


gas,


such


as Ar


eliminate


problems


free-radical


scavenging


03 attack


monomers


on any


are


polymerizing


pre-oriented


acetylene.


prior


fact


polymerization


that


may


lead


a more


ordered


polymer


configuration.


This


been


observed,


instance,


case


3-alkyl


pyrroles,


where


a very


high


degree


of 2


substitution


erved


Langmuir


film


polymerization


The


polymer


film


may


then


transferred


a solid


support


or a solution


further


characterization.


Polymerization


Lanamuir-Blodaett-Kuhn


Films


Monolayers


monomers


were


transferred


a solid


substrate


example


, a quartz


plate


produce


Langmuir-


Blodgett-Kuhn


capability


films


.The


dipping


computer


a quartz


controlled


plate


through


system


monolayer


while


same


time


maintaining


same


amount


lateral


compression


monolayer


moving


barrier.


number


monolayers


may


built


quartz


plate










with


compounds


suggested


that


possible


polymerize


this


class


of compounds


with


gamma


irradiation


Using


Langmuir-Blodgett-Kuhn


technique,


two-


dimensional


monolayers


these


compounds


made


Monolayer


monolayer


, the


acetylene


monomer


can


built


on a solid


state


into


a multilayer


microstructure.


In order


solid


state


polymerization


possible,


intermolecular


geometry


acetylene


functional


groups


mus


t fall


within


ecise


constraints.


Thus,


realistically


is necessary


first


show


that


such


compounds


can


indeed


processed


into


LBK


multilayers.


Once


LBK


multilayers


are


made,


then


the molecular


structure


can


undertaken


to achieve


required


intermolecular


geometry.


However,


correct


geometry


between


acetylene


functional


groups


does


guarantee


that


polymerization


will


take


place


Experimental


Compound


group


was


synthesized


University


Lowell,


Zhang


sachu


Blumstein


setts


Compound


was


synth


esized


ster


Ringsdorf


group


Univer


sity


of Mainz


, Germany


Compounds


V and


were


synthesized


Advincula


Duran


group


"fine- tuning"











proton


carbon-13


nuclear


magnetic


resonance


spectroscopy


NMR.


was


The


performed


Fourier


using


transform


a General


infrared


Electric


spectra


QE-300


were


obtained


using


a Biolab


FTIR


fitted


with


diffuse


reflectance


attachment.


Mass


spectroscopy


were


performed


Maria


Ospina


of Dr


. David


Powell


University


Florida.


Melting


points


were


obtained


using


bath


melting


point


apparatus.


Synthesis


4-hydroxy


biphenvl-4


'-(11-undecvnoate).


4-hydroxy


biphenyl-4


'-(11-undecynoate),


, was


synthesized


mmol


using


10-undecynoic


the following

acid (Farchan


procedure.


mmol


A solution

biphenol


(Aldrich),


mmol


p-toluene


sulfonic


acid


was


made


a minimum


pyridine


placed


round


bottom


neck


flask


under


purge.


Stirring


continuously,


a solution


15 mmol


1,3-


dicyclohexylcarbodiimide


(DCC,


Aldrich)


in 5


ml dry


pyridine


was


added


dropwise


over


minute


period.


After


DCC


solution


was


added,


reaction


solution


remained


clear


yellow-orange


in color.


Three


minutes


after


DCC


was


added


white


crystals


urea


began


to precipitate.


After


6 days,


urea


stals


were


filtered


washed

























Figure 2-2. Proton NMR of compound III in CDCdl.


product


added


mixture

give a


chloroform


n acidic


phase.


reading


Enough


paper.


5M HC1

The


phases


were


separated


another


5M HCI


was


added


chloroform


phase.


The


chloroform


phase


was


washed


twice


more


with


50 ml portions


5M HCI


followed


washings


with


with


50 ml of deionized


portions


saturated


water


NaHCO3.


then


The


washings


chloroform


phase


was


left


overnight


dry


over


anhydrous


Na2S04.


The


chloroform


solution


was


filtered


again


and


then


rotavapped


give


off-white


crys


tals.


Thin


layer


chromatography


was


used


determine


that


best solvent


system


separation


product


mixture


was


01-101


thyl


acetate;


TLC


product


mixture


showed


four


spots.


spots


with


lowest


values


corresponded











mixture


was


dissolved


again


in a minimum


CHCl3:EtAc


separation


column.


NMR


on a silica


in CDCl3


gel

the


(100-200

purified


mesh) ca

product


hromatography


(Figure


gave


.4 d,


and 7


The


peaks


from


ppm


are


aromatic


protons


biphenyl


moiety.


peak


chloroform


peak.


Synthesis of 4-C(4'-ol-biphenyl-4-decanoxy)-phenylacetylene.
Iv


overall


synthetic


scheme


synthesis


this


mesogen-sub


stituted


phenylacetylene


shown


in Figure


2-3.


Synthesis


of 4-(10-hvdroxvldecanoxv)-iodobenzene.


reaction


was


up by


transferring


ml of


toluene


a 500


3-neck


roundbottom


flask


fitted


with


a reflux


condenser


under


The


next


reagents


added


were


tetra(n-butyl)ammonium


bromide


followed


iodophenol.


this


point,


organic


phase


light


hint


purple


color


while


aqueous


phase


was


clear.


final


reach


tant


added


reaction


flask


was


reflux,


10-chlorodecanol.


final


ml portion


After


hours


10-chlorodecanol


was














O-R-OH


HO-R-Cl


Phase


Transfer


= C0H20


O-R-O-Ts


HO -4-*-O'Na+


EtOH


t-butyl-Me2SiCl


SiMe,
i 3


----SiMe3


Pd(PPh3)2Cl2
Cul, P(Ph)3


O-SiMe2-


nIlI


XII


But4NF


-R-O


I- -


-SiMeg+










reflux,


organic


phase


clear


golden


yellow.


The


reaction


was


stopped


turning


heat


and


transferring


reaction


solution


a separatory


funnel


with


chloroform.


The organic


phase


was


washed


with


ml portion


of deioni


water,


portions


weight


KOH


solution,


ml portions


of saturated


NH4Cl


solution,


finally


with


ml of


deionized


water.


The


organic


phase


was


dried


over


MgS04


filtered.


solvent


was


removed


under


reduced


pressure


with


a rotary


evaporator.


clear


yellow


so obtained


slowly

of IX


solidifies

or 95%. El


to a white


mental


waxy


analysis


solid.


Yield


found


was


iodine


(calculated


7%),


carbon


.2%),


hydrogen


7%).


Proton


NMR


in CDC13


product


shows


, alkyl);


alkyl);


alcohol


proton);


methylene


protons


OH);


methylene


protons


ar a


arylether);


aromatic);


aromati


Synthesis


Tosvlate


4-(10-hvdroxvldecanoxv)-


iodobenz


ene.


Three


grams


4-(10-hydroxyldecanoxy)-iodobenzene,


were


dissolved


50 ml of


pyridine


cooled










was


wrapped


with


parafilm


and


flask


was


kept


refrigerator


< 50C)


24 hours.


reaction


mixture


was


initially


clear


yellow


became


darker


in color


(sometimes


becoming


clear


red)


over


time


with


precipitation


clear


long


needle-like


crystals.


The


reaction


mixture


was


poured


while


into


a 600


stirring


with


ml beaker


filled


a magnetic


stir


with


water


bar.


reaction


mixture


white


was


milky


crystals


white


tosylate


water.


would


Sometime


precipitate


this


point


crystals


were


then


filtered


dried


dessicator.


Other


times


crystals


did


cipitate


this


point


diethyl


so the


ether.


reaction


ether


mixture

solution


was

was


extracted

extracted


twice

twice


with

with


HCl: H20


remove


pyridine,


then


washed


with


deionized


water


and


dried


with


anhydrous


Mg2SO4.


The


ether


was


then


removed


using


a rotary


evaporator


room


temperature.


important


tosylate


below


room


temperature


until


ready


use.


This


procedure


yields


pure


white


crystals


tosylate,


Proton


NMR


in CDC1


shows


peaks


starting


material


(except


alcoholic


proton),


plus


characteristic


methyl


peak


ppm


tosylate


The


FTIR


also


shows


a band


1355


Cm-'


due


asymetric










Synthesis
XI


4-(10-(4-Iodophenoxy)decanoxy)


biphenvl-4


This


reaction


was


up by


dissolving


equivalent)


of NaOH


with


50 ml of


pure


ethanol


a 250


three-neck


round-bottom


flask


fitt


ed with


a reflux


condenser


under


a slight


itive


pressure


of dry


gas.


After


NaOH


dissolved,


of 4,4


-biphenol


was


added


reaction


mixture


was


heated


to a light


reflux.


reaction


mixture


anion.


a clear


After


lime


green


minutes,


color


grams


biphenolate


was


added.


reaction


proceeds


, white


solids


prec


ipitate


and


green


tint


solution


becomes


colorless.


After


to 8 hours


reaction


time,


heat


was


removed


reaction


mixture


was


allowed


solids


formed


slowly


were


cool


room


filtered


temperature.


recrystallized


The

with


white

ethyl


acetate.


product


yield


grams


small


pure-white


crystal


The


melting


point


was


154-156


The


range


of melting


an indication


product


purity.


product


was


soluble


in tetrahydrofuran


or pyridine.


The


proton


NMR


in pyridine-d5


product


shows


peaks


alkyl)


methylene


protons


a to


arylether


linkage);


methyl


ene


protons


other


arylether


linkage);


, aryl


OH proton);


F


I












Synthesis


4-(10-(4-Iodophenoxy)


decanoxy)biphenyl-4


butyldimethylsilanol), XII


This


reaction


was


up by


sso


living


4-(10-


(4-Iodophenoxy)


decanoxy)biphenyl


-4'-ol,


tetrahydrofuran


a 250


round


bottom


flask


under


positive


pressure


of dry


gas.


Next,


equivalents)


imidazole


was


added


reaction


flask


followed


.2 equivalents


butyldimethyl


silylchloride.


reaction


mixture


was


stirred


with


a magnetic


stirrer


room


temperature


hours.


Progress


reaction


indicated


precipitation


fine


white


crystals


imidazoleHCl.


product


is obtained


filtering


imidazol e Cl


crystals


removing


solvent


using


a rotary


evaporator.


This


procedure


yield


ed 3


product


presence


protecting


group


seen


proton


nmr


CDC1


3 by


strong


peaks


at 0


ppm


presence


silyl


protecting


group


(Note


: The


starting


material


sparingly


soluble


CDCl


protected


material


moderately


soluble


allows


a good


nmr


obtained).


Synthesis
IX


4-(4


-ol-biphenyl-4-decanoxy) -henylacetylene.











fitted


with


a dry


condenser


and


magnetic


stir


bar.


The


reaction


was


run


under


a slight


positive


pressure


of dry


catalyst,


di(triph


enylphosphine)palladium


dichloride


cocatalysts,


triphenylphosphine


were


trans


ferred


amount


mg catalyst


(nominal


would


equivalents


XII)


(nominal


would


0.02


equivalents


to XII)


3 (nominal


would


0.08


equivalents


to XII)


with


a minimum


of dry


THF


reaction


flask.


Next,


ml of


trimethylsilylacetylene


(nominal


would


equivalents


XII)


was


tran


sferred


using


then


a syringe


through


through


a septum


a septum


into


from


reaction


stock


flask.


bottle


The


and


reaction


mixture


was


allowed


stir


room


temperature


minutes


before


a heating


mantle


controlled


a Variac


was


used


heat


reaction


mixture


to a gentle


reflux.


reaction

yellow w


mixture


ith


slowly


suspended


turned


white


from


solids


ear


to clear


through clear

yellow with


sus


pended


black


solids


during


24 hour


reaction


time.


After


24 hour,


reaction


flask


was


removed


from


heating

solvent


mantle


was


removed


allowed

with a


cool


rotary


room


evaporator.


temperature.


solids


were


resuspended


a minimum


of chloroform


filtered


through


a silica


plug


remove


black


precipitated











when


developed


with


chloroform.


desired


protected


product,


XIII


was


obtained


chromatography


through


silica


eluted


with


chloroform,


Rf=0


as a off-white


solid


mg).


Proton


NMR


CDC13


product


XIII


shows


peaks


methyl


silyl);


methylsilyl);


methyl


silyl);


alkyl)


, methylene


aryl


ether);


, methylene


aryl


ether);


phenolic


OH);


, aromatic);


aromatic);


aromatic).


Carbon-13


XIII


CDCl3


shows


peaks


(silyl


-0.9


(silyl


(silyl


alkyll);


alkyll);


alkyll);


alkyll);


alkyll);


(CDCI3);


, 113


(CDCl3


(CDCl


, 92


.4 and


, 114


remove


silyl


protecting


groups,


XIII


was


diss


olved


in 20


ml of THF


round


bottom


flask.


Next,


8 ml


tetra(n-butyl)ammonium


fluoride


equivalents)


were


added


reaction


mixture


and


flask


was


stoppered.


reaction


was


allowed


proceed


room


temperature


50 minutes


with


occasional


swirling.


The


solvent


was


removed


using


a rotary


evaporator.


Next,


deionized


water


were


added,


resulting


nrtat'-i nri F-^; nn


'I rt L.a s-n, ~ I if~ 1*17~3 Sc.


- -


n


~nl-l II


"' '


* I I


,|,* r





































Figure 2-4. Proton NMR of IV in tetrahydrofuran-d4.


mixture


hexanes


:THF


showed


spots


The


desired


product,


XIV


was


obtained


eluting


impure


solid


through


a silica


column


with


hexanes


:THF.


The


desired


product


comes


off


column


Rf=O


Evaporation


solvent


on a rotary


evaporator


gives


pure


white


solid.


proton


(Figure


2-4)


tetrahydrofuran-d4


alkyl); 3.


product


, acetylenic


shows


proton);


peaks


methylene











triple


bond.


product,


IV slowly


decomposes


over


a few


days


so material


used for


experiments


must


freshly


purified.


Synthesis


2-(10-(4


'-ol-biphenyl-4-oxy)


dodecanoxymethyl)-


antbrvii


-trimethvlsilvlacetvlene


. VII


ove


rall


synthetic


scheme


synthesis


this


mesogen-sub


stituted


anthrylacetylene


shown


Figure


2-5.


U











Synthesis


of 9-bromo.


10-(12-(4


-ol-biphenyl-4-


oxy)dodecanoxymethyl)anthracene


The


dibromomethylanthracene


4-(1


bromododecanoxy)-biphenyl


used


this


reaction


were


provided


Mr. Wei


Shen


Dr. Thomas


Servay.


This


reaction

amount o


requires


f water


that

the


special

reaction


care


flask.


taken

All


minimize


glassware


was


dried


reaction


least


overnight


conditions,


in an oven.


series


To determine


of screening


reactions


best

were


performed.


These


screening


reactions


were


carried


out


in 5


test


tubes


covered


with


rubber


septa.


The


solid


reactants


sso


were


Lived


weighed


ml of


directly


solvent


into


before


test


tube


tubes


was


and


flushed


with


sealed


with


septa.


reactions


which


used


NaH


solid)


base,


was


transferred


reaction


test


tube


with


solvent


before


sealing


tube


with


a septum


first


series,


conditions


were


varied


find


best


base


solvent


use


reaction.


reactions


were


followed


thin


layer


chromotography


(TLC)


developed


with


toluene


:acetone


TLC


were


graded


basis


disappearance


spot


dibromomethylanthracene


(DBMA)


presence


of side


products.


The


reaction











Table
base


2-1.


Screening


solvent


(LDA


reaction


Lithium


results


determination


sopropyl


amide;


t-butyl


Lithium).


solvent


DBMA
imol
(mg)


)mol(
mg)


mole
ratio
(XVI/
DBMA)


Base


equiv


Time


completion,


time


side


products


mmn


1 DMF 3.1 2.4 0.8 NaH 30 @ 25C
(1.1) (0.9) 2.1 25 @ 80C
2 DMF 3.1 2.7 0.9 LDA <5 @ 25C
(1.1) (1.0) 2.0 30 @ 45C
3 THF 5.4 6.2 1.1 LDA >25 @ 80C
(1.9) (2.3) 2.0 30 @ 45C
4 THF 5.4 5.7 1.0 tbL >25 @ 80C
(1.9) (2.1) 2.0 30 @ 45C
5 CH3CN 2.6 2.2 0.9 LDA >25 @ 80C
(0.9) (0.8) 2.0 30 @ 45C



Table 2-2. Screening reactions to determine the optimum
reaction temperature. __________
DBMA XVI mole LDA, Time to completion, min
jmol jimol( ratio equiv
(mg) mg) (XVI/
DBMA)
6 8.2 9.2 1.1 2.0 >30 @-30C
(2.9) (3.4)

7 5.7 5.2 0.9 2.3 >30 @ -30C
(2.0) (1.9)

8 6.9 8.1 1.2 1.8 <30 @ -30C
(2.4) (3.0)

9 2.5 2.2 0.9 2.0 45 @ 0C
(0.9) (0.8)


m~~~~~~~~ b.-_ 11. 11,C


r I


I


I


mt,










find


best


temperature


reaction


optimum


number


equivalents


LDA


(Table


2-2).


Based


results


from


Table


, the


optimum


temperature


chosen


was


30C


mainly


because


side


products


began


show


reaction


after


minutes.


The


reaction


was


up by


dissolving


of XVI


ml of


dimethylformamide


from


a freshly


opened


bottle


2-neck


flask


fitted


with


a dropping


funnel,


septum,


magnetic


stirrer.


A positive


pressure


dry


was


maintained


throughout


reaction.


The


reaction


flask


was


cooled


containing


C by


lowering


isopropanol


into


dry


a shallow


ice.


Next,


Dewar


.6 ml


flask


LDA


was


added


with


a syringe


through


septum.


The


reaction


mixture


turned


light


yellow-lime


green


in color


after


minutes


stirring.


Next,


0.95


DBMA


was


dissolved


in 50


using


mild


heating


facilitate


dissolution.


DBMA


solution


dropping


was


funnel


added


over


minute


reaction

period.


flask

The


through

reaction


mixture


temperature


was


maintained


below


C throughout


reaction.


reaction


After


color.


After


was


15 minutes


Though


DBMA


followed


was


with


reaction


showed


mixture


added,


acetone


was


that


progress


:toluene).


red-orange


DBMA


was











into


water


allowed


to stand


minutes


in a freezer


followed


filtration


through


buchner


funnel.


yellow


solid


was


placed


in a de


ssicator


overnight.


Later


runs


this


reaction


showed


slightly


improved


yields


increasing


amount


DMF


and


running


reaction


No solvent


system


was


found


that


could


separate


product


from


other


material,


so a two


step


procedure


was


used.


first


step


purification,


plug


column


'was


used


with


chloroform


eluting


solvent.


This


plug


column


was


a 350


fritted


glass


filter


which


was


extended


in height


inches


Rudy


Stroh


schein


glass


shop.


product


mixture


is eluted


through


silica


column,


initially,


a broad


band

nearly


of yellow m

y colorless


material

on the


eluted.


column


desired


unless


mater


illuminated


ial is

a black


lamp.


The


use


black


lamp


was


minimized


when


caused


a change


in coloration


material


column.


desired


product


moves


just


in front


a narrow


slow


moving


allow


band


narrow


yellow


band


approaches


within


chloroform


inches


was


bottom


column,


added


no more


column


column


was


allowed


run


until


no more


solvent


came


bottom


even


with


light


pressing


filter


paper











bands


were


scooped


out.


The


band


silica


containing


desired


through

solution


a 350

was


product


was


ml fitted


filtered


scooped


ass


gravity


and


ilter.

through


washed


The


with


THF


resulting


a fine


filter


THF

paper


remove


fine


silica


particles


that


escaped


through


fritted


ass.


The


THF


was


removed


with


a rotary


evaporator


to yield


a light


yellow


solid.


This


solid


was


washed


with


acetonitrile.


The


yellow


solid,


insoluble


proton


acetonitrile


NMR


desired


tetrahydrofuran-d4


product,


product


XVII.


shows


The


peaks


(m,alkyl);


2H, methylene


ether);


methylene


ether


arylether);


linkage


methylene


anthracene


protons


rings);


between


aromatic);


aromati


aromatic);


, anthryl


protons); 8.5 (d,

Mass spectroscopy


anthryl


showed


protons

presence


, 1H,


of material


OH).


with


molecular


weight


of 640


g/mol


calculated


g/mol)


. The


peak


mass


spectrum


was


a double


et corresponding


g/mol


(inten


sity=


76428)


g/ml


(intensity=93000)


which


indicates


that


material


contains


a bromine


atom


(two


isotopes


bromine


are


separate


ed by


amu).


Synthesis


anthrvl)


2-(10-(4-(4


-trimethvlsilvlac


etvlene. VII











glassware


was


dried


least


overnight


in an oven.


triethylamine


solvent


was


held


over


CaH2,


4 days


freshly


stilled


just


prior


use


Next,


XVII


was


placed


in a 200


3-neck


round


bottom


flask


with


of dry triethylamine

condenser, magnetic


which


stir


was


bar,


fitted


with


a rubber


a dry i

septum.


,ce

Next,


equivalents


palladium


dichloride,


XVII)


di(triphenylphosphine)


equivalents),


mg triphenylphosphine


equival


ents)


were


transferred


with


a minimum


triethylamine


reaction


flask.


Finally,


24 j.l


trimethylsilylacetylene


was


added


mixture


with


was


a syringe


allowed


through


stir


room


septum.


reaction


temperature


a few


minutes


while


dry


conden


ser


was


filled.


XVII


does

The


completely


reaction


mixture


dissolve


was


until


heated


with


solvent


a heating


heated.


mantle


controlled


variac


a gentle


reflux.


The


reaction


mixture


is a clear


light


yellow.


progress


reaction


chloroform


followed

as the de


TLC


veloping


on silica

solvent.


plates


After


using

hours


heating


, the


reaction


mixture


was


clear


reddish-orange


with


white


suspended


solids.


Another


palladium


catalyst


was


added


three


hour


mark.


reaction










































Figure


2-6. Proton NMR for VII in CDCl3.


was


taken


in THF


gravity


filtered


through


medium


porosity


filter


paper


remove


precipitated


amine


salts.


The


THF


was


removed


with


rotary


evaporator


a red-orange


solid.


solid


was


stored


freezer


wrapped


in foil


until


purification.


The


desired


product,


VII,


was


obtained


silica


chromatography


using










ether);


methylene


arylether);


OH);


anthryl


methylene


ether);


6.8 d


(aromatic);


aromatic);


aromatic);


anthryl);


anthryl)


FTIR


shows


a sharp


medium


intensity


sorption


at 2139


due


carbon-carbon


triple


bond.


Lanamuir-Blodaett-Kuhn


Experiments


solution


of each


compound,


ca.


mg/ml


in spectro-


grade


chloroform


(Kodak),


was


prepared.


behavior


monolayers


was


investigated


using


a KSV


5000


Langmuir-


Blodgett


System


(KSV


Instruments)


under


a HEPA


filter


hood


(Baker


Company).


Surface


pressure


was


measured


using


modified


Wilh


elmy


balance.


teflon


LBK


trough


was


cm long


14.8


(hydrophili


cm wide.


barriers


Teflon


were


used


(hydrophobic)


compress


or Nylon


monolayers


symmetrically


typical


barrier


speed


of 20


mm/min.


Water


using


subphase


a Milli-Q water


was


system


purified


MO resistivity


(Millipore)


temperature


subphase


glycol/water


was


from


control


a constant


ed by


circulating


temperature


bath


ethylene


slab)


through


channels


trough


base.


UV spectra


deposited


films


were


obtained


using


a Perkin-Elmer


UV/VIS/NIR


Lambda


spectrophotometer.


UV spectra










Langmuir-Blodgett-Kuhn


films


were


deposited


specially


prepared


quartz


plates.


quartz


plates


were


cleaned


using


following


procedure:


plates


were


immersed


in a detergent


solution


and


sonicated


minutes


then


placed


a solution


consi


sting


mixture


containing


NH4OH,


H202


, and


Milli-Q


water


respectively.


plates


solution


were


then


heated


minutes


followed


sonication


minutes,


sequentially,


in each


following


solvents


CHC13,


CHCl3


CH30H,


CH30H.


Hydrophobic


quartz


plates


were


prepared


placing


a clean


quartz


plate


in a mi


xture


pure


decalin,


ml chloroform,


carbon


tetrachloride,


sonicating


octadecyltrichlorosilane


2 hours.


For


dipping,


applied


surface


pressure


could


maintained


computer


controlled


film


balance


poss


ible


value.


automated


dipping


speed


could


varied


both


directions.


dipping


motion


could


delayed


of its


travel


allow


time


previously


deposited


layers


dry


air.


The


trans


ratio


surface


pressure


were


monitored


recorded


during


dipping


process.


Irradiation


LBK


films


with


y-ray


was


performed











slide.


Depending


on the


dose


rate


source,


sample


dose


was


had


left


been


passed


several

through


days

the


until


least


sample.


slide


Mrad


was


kept


a bottle


with


a bakelite


purged


with


nitrogen


before


sealing


bottle


with


teflon


tape.


Irradiation


performed


LBK


placing


films


slide


with


UV light


in a glass


was


wrapped


with


aluminum


foil


purged


with


argon


gas.


A 75 W


mercury


lamp


was


supported


within


with


a clamp


lamp


was


held


approximately


cm from


surface


quartz


slide.


slide


was


irradiated


minutes.


permeation


chromatography


(GPC)


data


were


obtained


using


a Waters


Associates


GPC


with


an LC-75


Perkin


Elmer


Spectophotometric


Detector.


GPC


was


fitted


with


Phenomenex


mm x


mm GPC


columns


in series


prepacked


with


Phenogel


ch has


a 500


pore


size.


Polystyrene


was


used


as a calibration


standard.


Tetrahydrofuran


was


used


eluting


solvent


at a flow


rate


ml/min.


The


samples


were


prepared


washing


LB layers


from


substrate


with


a minimum


amount


of THF.


Results


and


Discussion












The


pure


compound,


formed


unstable


monolayers


air/water


interface.


However,


monolayer


stability


was


improved


blending


compound


interest


with


another


liquid


crystalline


amphiphile


, II,


which


was


known


produce


stable


monolayers.


Monolayers


blends


were


success


fully


deposited


on hydrophobic


and


hydrophilic


quartz


substrates.


Comparisons


were


made


stability


monolayers


over


stability.


reached

stopped.


a give

The


time wi

First,

surface


surface


th

the


stearic


acid


monolayer


pressure


pressure


used


was

the


changes


as a standard


compressed

barrier wa


were


then


until


monitored


as a function


time


slopes


were


compared


with


those


stearic


acid.


An alternate


procedure


determining


monolayer


stability


was


also


used.


this


second


method,


mean


molecular


area


compound


blend


was


monitored


as a function


time


while


keeping


appli


ed surface


pressure


constant.


Plots


of surface


pressure


versus


mean


molecular


area


were


done


compounds


under


study.


compound


ambient


temperature,


surface


pressure


onset


occurred


mean


molecular


areas


(Mma)


1 0 A2 and


apparent


rsnl 1 vnea


nrnr. n..rn .s-~ n a I ~---


-- -- -


5


n


n~..


nrnn


r


m











small


to correspond


formation


of a true


two-


dimensional


recorded


monolayer.


Figure


temperature


shows


6C.


isotherm


apparent


that


lower


temperatures


greater


onse


(higher


than


values


are


obtained


and


collapse


pressure


increased


substantially


These


onset


Mma


values


are


more


reasonable


in view


chemical


structure


monomers


Figure


Isotherm


I at


film


was


compresse


, the


plot


effective


48 0.t5
40 "
a 0.1 m

a 35 -- oo
I / ^ 1


= .1-
w I /
*w~~~ff V r^
' 1o -- 2.\//' -*-


0 4\1
0 .. .. .^ T v . ..r-> ri ri i T i i i 1 | I i t' l ir i | i r ii T I . ,I .. . . . .. . -0 .1 6
0 10 20 30 40 50 80 70 80 90
mMa (A'molecule)











more


negative


molecules


become


closely


packed.


The


effective


dipole


becomes


negative


rather


than


positive


because


acetylene


group


a considerable


dipole


moment


opposing


dipole


methoxy


group


also


carbonyl

negative


ester


value


linkage

molecule


must


contribute


orients


perpendicular


water


surface.


For


good


deposition


liquid


crystal


on a


substrate,


formation


a stable


monolayer


essential.


A monolayer


is considered


stable


when


displays


a steady


Mma


at constant


Stability


studies


surface


versus


pressure


time


over


showed


several


that


minutes.


films


compound


are


stable


over


long


periods


time


>30%


loss


minutes)


temperatures


although


they


show


better


hysteresis


as compared


to higher


temperatures.


general,


lower


temperature


runs


were


characterized


more


reasonable


values


condensed


phase


region


more


stable


monolayers,


but


stable


enough


multilayer


depositions.


In order


improve


monolayer


stability


compound


effect


mixing


other


compounds


which


could


stabilizers


was


explored.


Several


experiments


were


performed


on mixtures











desired,


amount


"monolayer


stabilizer"


minimized.


Isotherms


blends


of compound


with


compound


are


shown


in Figure


2-8.


Concentrations


stabilizin

stabilize


compound


monolayers


were


containing


This


adequate


behavior


might


a greater


degree


intermolecular


- orbital


overlap


between


In general,


much


aromatic


higher


Mma


rings

values


mes


were


ogenic


obtained


groups.

the


condensed


phases


of compound


blends


with


compound


monolayer


stability


of compound


I with


compound


II at


constant


Mma


was


greater


than


that


found


pure


The


slope


curve


values


compounds


blend


I and


lies


, with


intermediate


latter


between


being


more


stable


monolayer


because


terminal


hydroxyl


group


3. In general,


varying


mole


ratio


mixtures


careful


choice


interactant"


one


can


improve


monolayer


stability.


interactant


increases


stability


monolayer


because


packs


well


laterally


with


other


molecule


and


strong


hydrophilic


group


keeps


it '


pinned


' to


water


surface.


Multilayers


were


deposited


on 25


mm x 75


hydrophilic


quartz


plates.


dipping


I+II


blend,


subphase


temperature


was


control


ed at


ca.


150C


with













































Figure
II-.


2-8. Isotherm for the mixture of 95 mole % I and 5


minutes


to allow


time


previously


deposited


layer


to dry


pressure


were


air.


monitored


The


and


transfer


recorded


ratio


during


surface


dipping











placing


holder,


quartz


running


plate


scan,


in a specially


then


constructed


returning


sample


plate


dipping


attachment.


Cast


films


of each


blend


were


made


comparison.


Multilayers


stable


blends


were


successfully


deposited


were


on quartz


deposited


substrates.


mN/m


because


Blends


with


film


compounds


not


I+II


adequately


stable


at higher


surface


pressures.


During


depositions,


transfer


ratio


was


recorded.


transfer


ratio


(TR)


gives


an indication


quality


dipping


process


ideally


should


unity.


I+II


monolayer


was


transferred


substrate


very


well


near


unity)


while


substrate


was


moving


a fraction


deposited


monolayer


was


removed


approaching


when


substrate


was


moving


down


into


subphase.


found


that


Z-type


films


were


formed


blend


using


both


hydrophilic


hydrophobic


quartz


substrates.


Z-type


films


are


defined


those


resulting


from


good


transfer


on the


upstroke


poor


or little


transfer


downstroke.


total


layers


were


deposited


I+II


blend.


The


blend


I+II


tends


towards


Z-type


deposition


after


first


three


layers


on a hydrophobic


substrate.


sorption


(Figure


observed


between


and











































Figure 2-9. UV spectrum for the I+II mixture in an LBK film


on a


hydrophobic


quartz


plate


substituted


mesogenic


group.


73 The


- n


transition


acetylenic


bands)


observed


group


benzene


nm and


allowed


ring


spectra


transition


nm region


due


to the


were


limitations


instrument.


No significant


difference


was


observed


between










Two


blends.


monolayer


methods


first


on the


were


explored


method


trough


which


under


polymerize


involved


monomer


irradiating


or nitrogen


atmosphere


with


UV light


proved


unsuccessful.


second


method,


Langmuir-Blodgett


monomer


films


were


exposed


60Co


y-ray


source.


The


I+II


blend


was


exposed


irradiation


dosage


Mrad.


data


showed


that


deposited


I+II


blend


reacted


form


in 21% conversion


an oligomer


that


was


approximate


10 repeat


units


long,


along


with


very


much


smaller


portions


high


molecular


weight


polymer.


was


calibrated


with


polystyrene


standards.


found


percent


bulk


conversion


polymerization.


is similar


Without


results


further


characterization,


identity


oligomer


could


made.


This


work


demonstrated


Langmuir


film


multilayer


deposition


properties


The


monolayer


properties


compound

suitable


were

co-s


significant

urfactant.


improved


Furthermore,


blending


attempts


with


polymerize


compound


irradiation


gave


similar


results


that


observed


bulk.


Compound


I by


itself


does


form


Langmuir


films


which


will


support


a significant


amount


surface


pressure


room


temperatures.


However


, if











pressure.


other


hand,


compound


was


known


to form


stable


Langmuir


films.


In addition,


this


compound


bears


some


structural


characteristics


common


with


other


compound.


Now,


been


shown


that


blending


these


compounds


Following


leads


production


model


forward


stable


Ishii


Langmuir


may


films.


said


that


interactant"


behavior


mixed


compound


affec


monolayer


equilibrium


dynamic


spreading


behavior.


stable


transferred


blended


quartz


monolayers


substrates


were


successfully


Z-type


Y-type


depositions.


Blend


I+II


showed


Z-type


dipping


behavior.


LBK


Film-forming


undecvnoate)


PrnnsrI-i ~ 4-hurl rnvu
----an -r -- -- -- -- aaj t-a~ s V -3. -r t -


III


previous


section


shown


that


compound


may


processed


with


Langmuir-Blodgett-Kuhn


technique9


only


blending


with


other


compounds


such


as II


or by


cooling


subphase


temperatures


below


100C.


Based


on this


experience,


compound


was


designed


synthesi


zed.


Compound


was


found


to be


an improvement


compared


I because


does


require


either


blending


temperatures


technique


i niir


while

p 2--l


being

Chfltel7


processed


. fIr


with


the

(107o


LBK

\ c.c


, or.4- harmr


Prflnc~rtic~s


d-h vrJ rnuv


h; nh nn tt 1 ,A


1111_


.










monolayer


This


value


indicates


that


molecules


are


interface.


oriented


The


monolayer


perpendicular


of III


to the


air-water


air-water


interface


was


stable


(AmMa


.8 A2/molecule


during


hour)


constant


surface


pressures


mN/m.


film


was


compare


ssed,


plot


effective


dipole

orient


moment

closer


indicates


that


normal


the

with


molecules


are


interface


beginning

beginning


approximately


A2/molecule


effective


dipole


becomes


more


negative


as the


molecules


become


closely


packed.


The


effective


dipole


becomes


negative


rather


than


positive


because


acetylene


group


a considerable


dipole


moment


opposing


dipole


hydroxyl


group


also


carbonyl

negative


value


ester

as the


linkage

molecule


must


contribute


orients


perpendicular


water


surface.


Attempts


polymerize


compound


were


made


irradiating


material


both


as LBK


multilayers


and


as a


monolayer


on water


with


Y ray


dosages


Mrad.


Characterization


formation


with


a small


UV spectre


fraction


scopy

dimer


and

and


GPC


indicated


trimer.


Also


the

the


bulk


crystals


in an evacuated


capillary


were


irradiated


with


y ray


characterized


no polymer


product


was


found.













































Figure 2-10. Isotherm for III at 27 C.


automated


dipping


speed


was


maintained


0.5 mm/min


both


directions


dipping


motion


was


delayed


travel


10 minutes


to allow


time


previously


depo


sited


layers


in the


air.


The


transfer


ratio


surface


pressure


were


monitored


recorded


during


dipping


process.


Depos


ition


of III


on hydrophobic


quartz


fir.4- ~.. C..--t a - a- -C 0 r


'7T 4---k.


LI..


,1


L,,,, C,,


,,L


r A m


r ~ rr


rr ~..~L~r. I* A











indicated


that


acetylene


functional


groups


are


oriented


correctly


desired


reaction


take


place.


LBK


Films


of Mesocien-subsf I i-viitscl Ph~nu1 ancd-ul nno Mnnnmnv-a
-- -- r -a- ~..** *Att*~t.J*SttOL. Li


Film-formino


ethynylbenzoate, VI


4-hexadecyloxyphenyl-4-


Compound


was


provided


. Advincula.


compounds


VI and


are


different


from


other


monomers


that


of the

to the


acetylene


amphiphile.


mesogen,


constrained


along


group


Also


o the

the


functions


acetylene


orientation


director


the liquid


hydrophilic


attached

etylene

crystal


part


directly

will be

The


isotherm


shown


extrapolation


zero


in Figure


surface


2-11.


pressure


From


gives


isotherm,


area


molecule


monolayer


The


monolayer


stability


was


found


.2 A2/molecule


at 20


mN/m


surface


pressure


in 50 minutes


A2/molecule


mN/m


surface


pressure


minutes.


These


monolayer


stability


values


are


as good


as III


or IV because


acetylene


group


does


have


a strong


affinity


towards


water


surface.


sotherm


stability


However,


indicate


through


appreciable


that


efficient


surface


monolayer


packin


pressures


gains


seen


considerable


monomers at


the


of


Ph pn vl ;I ~Pt V1 Pn Cs


I~nnnmrrr~


ProDertiec.








































Figure 2-11. Isotherms for V and VI at 25 C.


down


mm/min.


Polymerization


irradiation


was


attempted


with


this


compound


because


homolog


reported


next


sec


tion


was


more


processable.


LBK


Film-formina


Prone rtie~s


4-octyloxyphenyl-4-


ethynylbenzoate. V


Compound


was


also


provided


. Advincula.










isotherm,


extrapolation


zero


surface


pressure


gives


area


molecule


monolayer


27 A2


ethynylbenzoate


compounds


exhibited


large


hysteresis


repeated


compression


decompre


ssion


cycles


such


that


seen


V in Figure


this


hysteresis


experiment,


monolayer


was


compress


ed beyond


collapse


point


and


results


regions


indicate


remain


that


aggregated


during


because


decompression


subsequent


collapsed


compression


cycle


begins


rise


in surface


pressure


point


where


previous


cycle


reached.


The


monolayer


stability


was


found


A//molecule


at 20


mN/m


surface


pressure


minutes.


This


stability


higher


than


that


seen


with


VI because


shorter


hydrophobic


tail,


thus


weakerhydrophobicity,


better


balanced


with


weak


hydrophili


city


acetylene


group.


As with


monolayers


gain


considerable


stability


through


efficient


packing


resulting


intermolecular


n orbital


interactions.


Dipping


onto


hydrophobic


quartz


gave


transfer


ratios


upstroke


downstroke


with


a dipping


speed


of 0


mm/min.


Using


a dipping


speed


.5 mm/min


troke


.3 mm/min


downstroke


gave


transfer


ratios


respectively,


first


layer
















50
45
40O
S35 --


20
j25 -
220

10 \
Co
5
0-

0 I I \ I I I

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
mMa (A*/molecule)


S


Figure
and de


compr


ess


Hysteresi
ion cycle


exhibited


V during


a compression


dipping


speed


used


was


very


slow


compared


more


common


dipping


speeds


over


mm/min.


The


slow


dipping


speed


was


necessary


scouts


Polymerization


nature


LB films


these


was


monolayers.


attempted


with


irradiation


and


also


UV irradiation


monolayer


- a-


water


surface.


GPC


charanlptri 7.a- rnn


Sn~, P


CFhl-


rfnl F










acetylene


functional


groups


to allow


desired


reaction


take


place.


LBK


Film-forminac


Properties


4-(4


-ol-biphenyl-4-


decanoxy )-phenylacetylene, IV


As described


above,


compound


was


intended


combine


good


film


forming


performance


with


potentially


greater


reactivity


of a phenylacetylene.


The


relatively


short


spacer


length


makes


this


compound


insoluble


usual


spreading


solvents.


Thus


spreading


solution


was


made


a mixture


part


THF


9 parts


chloroform.


This


solvent


mixture


supported


a 0.01


mg/ml


solution


concentration


isotherm


230C)


compound


shown


in Figure


2-13.


From


isotherm,


extrapolation


zero


surface


pressure


gives


area


per


molecule


monolayer


This


value


indicates


that


molecules


are


oriented


perpendicular


air-


water

was s


interface.


table


(AmMa=-0


monolayer


.8 A2/molecule


air-water


during


hour)


interface

at constant


surface


pressures


mN/m.


This


stability


comparable


that


found


with


may


attributed


strong


hydrophilicity


phenolic


OH and


excellent


packing


molecules.



































Figure


2-13


Isotherm


IV at


while


monolayer


was


irradiat


ed with


a UV


mercury


lamp


held


within


cm of


the water


surface


Observation


under


Brewster


angle


microscope


revealed


that


usual


stiff


irregular


shaped


domains


were


fluidi


zed under


influence


UV lamp


To check


this


was


due


heating


effect,


a quartz


heating


lamp


was


held


near


monolayer,


domains


were


fluidi


heat.


Next


argon/water


multilayers


inte


were


rface


irradiated


minutes


m~Fr- nl;


rnl 1 an-aA


nrAr Fh


S.Pr4 4--1-


n -n . --


70

60

I 0 5


2O
E.





20 -

10

0-
0 10 20 30 40 50 60 70 80 90

Molecular Area (A'Imolecule)


Inrr In


n


rr


nT











irradiated

a lower mo


material


lecular


showed


weight


materi


presence

al which


monomer


elutes


after


retention


time


20 minut


es.


relative


peak


height


lower


molecular


weight


material


monomer


peak


increases


with


length


irradiation


time.


results


clearly


showed


that


monomer


was


degraded


argon/water


under


irradiation


dipping,


subphas e


temperature


was


controlled


ca.


230C


with


an applied


surface


pressure


mN/rn.


automated


dipping


speed


was


maintained


mm/min


on the


downstroke


mm/min


upstroke.


dipping


motion


was


to allow


delayed


time


of its


previous


travel


deposited


minutes


layers


to dry


air.


The


transfer


ratio


surface


pressure


were


monitored


recorded


during


dipping


process.


Deposition


on hydrophobic


plates


was


Y-type


with


a average


transfer


ratio


downstroke


and


upstroke.


UV spectra


compound


shows


a series


peaks


210,


aromatic


240,


transi


245,


250,


stions


nm corresponding


phenylacetylene


biphenol


groups.


Following


irradiation


with


a mercury


pencil


lamp


30 minutes


under


argon,


UV spectra


exhibits


a broad
































Figure 2-14. Isotherm for VII at 25 C.


retention


time


18 minut


irradiated


LB layers


showed


a broad


shoulder


extending


from


monomer


peak


down


a retention


time


15 minutes.


According


calibration


with


polystyrene


standards,


a retention


time


15 minutes


4700


corresponds


g/mol.


material


molecular


with


weight


a mol

cons


ecular

istent


weight


with


degree


polymerization


10 repeat


units.


irradiated


LBK


layers


also


have


a large


peak


eluting


minutes


indicating


formation


of degradation


products


similar











Preliminary


Lanarmuir


biDhenvl-4-oxv)


Film


Properties


2-(10-(4


-ol-


dodecanoxymethyl)-anthryl)-


trimethylsilylacetylene. VII


The


first


isotherm


VII


as obtained


Shen


Thomas


isotherm


Servay


suggests


shown


a phase


Figure


transition


The


from


shape


a liquid-


expanded


a liquid-condensed


phase


with


a collapse


pressure


of 52 mN/m.


Extrapolation


isotherm


zero


pressure


gives


an area


per


molecule


approximately


This


is a reasonable


value


anthracene


compounds


with


this


subs


titution


pattern.


Conclusion


this


chapter


, the


synthesis


a mesogen-


subs


tituted


alkylacetylene,


, phenylacetylene,


anthrylacetylene


III


been reported.


Compounds


and


IV form


stable


monolayers


air-water


interface.


Langmuir


film


work


with


compound


VII


complete


time


constraints


work


will


continued


Shen


who


also


been


involved


synthesis


work.


compounds


(except


VII)


have


been


processed


with


LBK


technique.


The


biphenol-undecynoate,


, was


found


to have


superior


n am nfl.. n A


r-9


LBK
*ll,- n-


deposition


behavior


compared


-L 1.a.., I. ~11. ~


CClnr


1










Polymerization


compounds


was


(except


attempted


VII).


irradiation


phenylacetylene,


had


highest


degree


polymerization


compounds


studied


here.


The


UV spectra


and


GPC


retention


times


films


manner


molecular


was


changed


consistent


weight


irradiation


with


formation


equivalent


with


a UV lamp


of oligomers


repeat


units


with


as well


some


degradation


products.


Thus


incorporation


phenyl


ring


does


increase


reactivity


because


could


only


initiated


mainly


with


degradation


y-irradiation.


products.


The other


modest


compounds


success


gave


obtained


with


be related


strong


crystal


forming


tendency


as evidenced


solubility


in most


organic


solvents.


The


quality


films


were


high.


film


quality


can


increased


perhaps


introduction


an interactant


or by


varying


subphase,


then


higher


degrees


of polymerization


may


obtained


Thus,


future


work


should


include


attempts


improve


quality


LBK


film


Before


undertaking


chain


synth


length


esis


alkyl


IV it


spacer


suggested


increased


that


so that


solubility


increased


thus


ease


of handling











initiator


films


of IV could


studied.


surface


pressure


during


LBK


film


deposition


can


influence


tilt


monomers


group


orientation.


monolayers


Therefore,


and t

effe


hus


ct of


functional


applied


surface


pressure


on reactivity


could


studied.


photochemistry


phenyla


cetylene


an important


factor


improved


reactivity


of IV but


equally


important


packing


reactive


groups.


Compounds


V and


are


also


phenylacetylenes


apparently


packing


geometry


correct


polymerization


occur


with


those


compounds.


Generally,


better


understanding


polymerization


mechanism


important


optimize


structure


reactivity.

compounds s


Based


shouldd


obvious


more


next


step


results

closely


would


this


chapter,


related


new


structure


synthesize


analogues


with


different


types


and


lengths


spacers,


example,


ethylene


oxide


chains.


New


monomer


design


should


first


look


sely


work


of Stupp


and


Litt


both


of which


have


achieved


some


success


in crosslinking


liquid


crystalline


monomers


A smectogen


incorporated


into


monomer


design


rather


than


nematogens


reported


here


may


help


maintain


necessary


monomer


orientation.


Future


work


might


also


include


use


a catalyst


such










also


tried


though


experimental


details


such


irradiation

considered


time,

as well


duration,


problem.


location

ms with


should


elimination


gas/water


interface.















CHAPTER


PROPERTIES


OF SOLUBLE
ETHYNYLENE


DERIVATIVES
IN LANGMUIR


OF POLYPHENYLENE-


FILMS


Introduction


A recent


entitled


report76


"Polymer


from


Science


National


Engineering


Research

: The Sh


Council


ifting


Research


Frontiers"


suggests


high


priority


investigations


of polymer


surfaces


and


interfaces


permit


making


materials


smaller


that


structures,


have


thin


same


films,


scale


nanophase


morphological


features


polymers.


The


known


nonlinear optical

be dependent on mol


(NLO) response I

ecular ordering


materials


parameters


The


Langmuir-Blodgett-Kuhn


technique


one


method


which


molecules


be pre-oriented


creation


a well-ordered


thin


film.


78 Thus,


basic


studies


Langmuir


film-


forming


properties


NLO


polymers


can


provide


important


clues


toward


an optimal


molecular


design.


Micro

microscopy


scopy

(BAM)


techniques,


such


epifluorescen


as Brewster a

ce microscopy


ngle

, facilitate


morphological


study


Langmuir


films


79, 80, 81, 82,83,84,85



















OCH3


0011 H22C


OC H OH
11 22


OC11H22


00113


OC11H22OH

-'- PEHU

n




>H

/--- =PPYPYRI
Br n




0H

n PPEHU

-n


Figure 3-1
ethynylene


Soluble


derivatives


polyphenylene


polyphenylene-ethynylene


(Figure


3-1)


surface


concentration


dependence


surface


pressure


surface


potential


along


with


microscopy


are


used


suggest


nanoscale


model


conformation


ese


polymers


UnnFn


fha ...xn4a 4a F n r ,n r a~


mknrch


~hl~tlYlhr r(


~rn


~










Theoretical


Cnn s iLderat axis


Monolavers


of Riaid-Rod


Polymers


well


known


that


a solution


containing


rodlike


molecules


domains.


spontaneously


Theoretical


forms

models


isotropic


such


as Flory


anisotropic


s discrete


lattice


model88


(DLM)


explain


phenomena


such


isotropic


anisotropic


transition


basi


hard-


core


repul


sive


forces


only.


DLM


ignores


attractive


forces


between


molecules


as perturbations


athermal


model.


Flory


lattice


s DLM


repres


cells


with


ents


each


rods


sequence


as sequences


oriented


of occupied


parallel


preferred


domain


axis.


The


free


energy


expressed


terms


orientational


positional


entropy


. The


positional


entropy


derived


from


probability


finding


an occupiable


vacancy


within


system


a rod


with


given


disorientation


from


preferred


domain


axis.


existence


rodlike


many


true


molecules


arguments


long-range


been


order


subject


being


made


a 2D


debate,


against


system


with


Thermal


fluc


tuations


tend


to break


long


range


order.


Increasing


axial


ratios


(length/width)


favor










need


revealed


only


short


range


order


in which


orientational


correlations


over


a di


stance


smaller


than


length


a needle


at all


high


number


dens


ities


Void


area


becomes


negligible


density


rods


increased


because


individual


rods


slip


rotate


to fill


available


space


Cellular


Networks


Many


example


3-dimensional


(3D)


cellular


network


structures


foams,


such


magnetic


bubbles


metal


grain


The


boundaries,


property


soap


2D slice


these


3D structures


are


subject


a mature


body


literature.


92, 93, 94,


95,96


These


diverse


examples


disordered


cellular


systems


suggests


that


their


formation


depends


part,


on universe


guiding


principles


independent


short


range


ces


such


as molecular


inte


actions.


Metal


grain


arrays


and


soap


froths


are


topologically


similar


teams


because


edges


they


, and


contain


vertices


same


The


geome


driving


trical


force


elements


coars


of cell


ending


both


teams


is capillarity


The


main


kinetic


difference


between


systems


stence


time


scales


evolution


in the


soap


froth


, while


only


one


been


found


in metal


grain


growth.


In metal


grain


arrays,


, in











controlled


local


curvature.


Thus,


grain


boundaries


move


locally


straight


move.


Alternately


known


literature


as 2D foams,


cellular


structure


or bubble


patterns;


cellular


networks


Langmuir


films


have


been


investigated


several


research


groups,


though


most


these


studies


have


been


qualitative


nature.


The


research


group


Knobler


did


preliminary


studies


topology


kinetics


fluorescent


probe


labelled


stearic


(octadecanoic)


acid '


foams


'. With


regard


topology,


they


found


that


average


number


cell


sides


was


six with


a non-Gaussian


distribution


skewed


toward


larger


sizes.


They


found


growth


grain


rate


growth


cell


metals


diameter


rather


more


than


typical


behavior


usually


seen


with


2D sli


ces


soap


foams


Libchaber


coworkers


studied


topology


kinetics


fluorescence


labelled


pentadecanoic


acid '


bubble


patterns


'They


noticed


different


regimes


depending


percentage


phase


' in


monolayer.


high


coverage


-75%)


they


observed


polygonal


bubbles


separated


thin


liquid


lines


like


a 2D


soap


froth.


These


polygonal


bubbles


follow


time


evolution


mean


area.


They


also


found


that


most


polygonal


cells











rate


with


evolution


mean


area.


The


probability


distribution


bubble


areas


broadened


continuously


Rondelez


coworkers


studied


2D foams


' of


surfactant


fluorescent


dye,


4-(hexadecylamino)-


7-nitrobenz-


2-oxa-1,3-diazole.


They


focused


on discussion


analogous


behavior


between


monolayer


foams


and


foams.


For


example,


line


tension


between


liquid


phase


regions


plays


a role


similar


that


surface


tension


in conventional


foams.


The


line


tension


determines


thinning


of strips


liquid


monolayer


phase


which


separate


cells.


They


believe


a lower


surface


pressure


corner


regions


causes


equivalent


Plateau


border


suction.


Also


they


speculate


that


a gradient


line


tension


can


lead


a slowing


thinning


proc


ess


when


gradient


opposes


monolayer


flow.


gradient


line


tension


could


come


about


a 1D


equivalent


surface


activity


exis


Stine


coworkers


studied


'foam


morphology'


stearylamine


expanded


coexistence


liquid-condensed


region


phases


between


in Langmuir


liquid-


monolayers.


fluorescent


probe,


4-(hexadecylamino)-7-nitrobenz-2-oxa-


,3-diazole,


was


added


in a concentration


of 0


molepercent.


This


work


notable


because


foam











air/water


interface.


Also


they


observed '


foams


was


possible


to follow


foam


with


time


because


coarsened


quickly


reached


characteristic


zes


larger


than


maximum


laser


field-of-view


beam


their


which


Brewster


was


angle


limited


size


microscope.


One


interest


ting


observation


their


work


was


that


reflectivity


regions


monolayers


dense


polymer


was


less


than


reflectivity


pure


water


surface.


the

line


Thus


Brewster

tension


polymer


angle


dense


microscope


PDMS


regions


images.

on the


appeared


They

order


dark


estimated


10-13


N by


observing


time


required


distorted


isolated


domains


to relax


equilibrium


circular


shape.


Seul


coworkers


studied '


bubble


domains'


Langmuir


dimyri


films


of a mixture


stoylphasphatidylcholine


dihydrocholesterol.


coarsening


dynamics


were


monitored


hours


using


computer


controlled


time-lapse


video


recording.


The


cell


areas


other


data


were


automatically


generated


from


images


average


with


cell


image


area


processing


followed


software.


t0.56


growth


They


rate.


found


They


that


also


found


cell


radii


had


a Gaussian


distribution


about


mean


radius.


Plots


average


cell


area


versus











and


sided


cells).


Aboav-Weire


(described


below)


was


found


followed


as well


with


fitted


parameters


closely


matching


those


a random


Voronoi


lattice


Goldstein


Jackson103


have


reformulated


theory


pattern


formation


in magnetic


fluids


describe


shape


instabilities


isolated


domains


in Langmuir


domains.


They


analyzed


tension


data


from


Seul


relaxation


calculate


times


value


distorted


line


bubble


domains


dimyri


stoylphosphatidylcholine


cholesterol.


They


found


a value


line


tension


10-13


During


past


years


McConnell


coworkers


have


developed


theoretical


basis


variety


domain


shapes


observed


in coexisting


phases


Langmuir


films.


104, 105, 106, 107,108,109, 110,111


present


theory


on 2D


'bubble'


phases


may


described


follows.


theory


simplified


assuming


separated


phases


are


isotropic


there


phases.


is a sharp


free


well-defined


energy


boundary


of mixture


between


given


F =F
'(p


where


bulk


(uniform)


free


energy


contribution,


energy


cost


of creating


wall


in 2D,


mole


fraction.











dipole-dipole


interaction


electrostatic


contribution


interaction.


free


The


energy


dipole-dipole


given


--12=


I|-N'I"3


dA dA'


where


integration


taken


over


poss


ible


dipole


pairs


areas


A and


' and


where


stance


between


points


one


within


phase


domain.


was


For


zero


simplicity,


so 1


dipole


dipole


moment


moment


second


phase.


combined


shape-dependent


part


free


energy


then


reduced


an increase


in domain


size


reduced


continued


subdivision


of domains.


Thus


overall


free


energy


favors


formation


domains


preferred


size.


Topologically,


cellular


networks


are


defined


coordination


number


of 3 at


each


vertex


a conservation


(Euler


n + V =1


s equation).


a 2D planar


Euler's

surface


equation


defined


where


as NF


number


faces


mi


number


of edces


. and


nfimb nr


if 3/


F,


I


r---r


I O


III










structure


results.


In a Langmuir


film,


short


range


forces


are


primarily


those


to line


tension


phase


boundaries


each


dipol


repulsion


In addition,


there


between


are


molecules


entanglements


within


polymer


main


chains


side


chains


as well


as the


steric


repulsion


between


rigid


rods.


As a non-equilibrium


structure,


cellular


network


degrades


over


time.


The


driving


force


dynamics


cellular


tension


within


network

the to


minimization


pological


constraints.


line


Beyond


topological


constraints


ceases


a network.


model


Weire


Rivier,


statistical


entropy


a network


a function


deviation


from


an ideal


hexagonal


network.


shown


Figure


there


are


least


three


proc


esses


which


affect


statistical


entropy


a cellular


network


a cell


neighbor


switching


process.


vertex.


networks.


During


This


The


a T2


process


third


process,


been


process,


a cell


observed


cell


appears


soap


coalescence,


into


cell


is preceded


an edge-thinning


process


during


which


an individual


edge


relea


ses


material


vertices.


Usually,


thinned


edge


breaks


close


one


vertex.


Several


empirically


based


models


describe















































Figure 3-2. Possible topological changes occurring during
coarsening of a cellular network. Cell coalescence is a


third


such


change


sided


cells


varies


linearly


with


been


shown


equation


state


cellular


structures


in stati


stical


equilibrium,


where


statistical


equilibrium


is defined


most


probable


distribution.


91 Aboav


s law


relates


irfi 1 1


nr


nrimhnr


nf:


v; th


nirmhar


3~tdr3n~


r


r ni











addition


of a term,


second


moment


cell


side


distribution.


their


model,


evolution


cellular


network


driven


entropy,


expected


increase


with


time.


Empirical


dynamic


laws


include


Von


Neumann


s Law


which


states


that


rate


growth


a soap


foam


cell


is proportional


number


sides


minus


predicts


that


many


sided


cells


should


grow


area,


sided


cells


should


shrink


six-sided


cells


should


have


constant


area.


Previous


workers


have


performed


numerical


simulations


Cell


of cellular


growth


network


consists


dynamics.


114,115


different


simultaneous


proce


sses.


The


first


process


evolution


of cell


geometry,


that


shape


size,


which


occurs


continuously.


second


process


includes


associated


topological


rearrangements


which


occur


instantly.


Most


simplified


theoretical


models


are


uniform


boundary


boundary


models


energies


which


and


neglect


local


mobiliti


differences


example,


cell


von


Neuman


holds


systems


with


uniform


boundaries


and


mobile


vertices.


Cellular


networks


were


observed


Langmuir


films


polymers


reported


this


chapter.


topology


dynamics


one


polymer


s cellular


networks


have


SO )12











ExDerimental


Methods


polymers


studied


were


provided


Mr. Marc


Moroni


Dr. Jacques


Le Moigne


Groupe


Materiaux


Organiques


, Institute


Physique


Chimie


Materiaux


Strasbourg


in Strasbourg


, France


They


removed


smallest


oligomers


preparative


GPC.


The molecular


weight


resulting


polymers


spectrometry


. GPC


s too


large


could


used


measured


accurately


mass


because


evidence


aggregate


formation


was


seen


The


molecular


weight


resulting


polymers


estimated


order


g/mol


based


GPC


results


The


solid


polymers


are


deep


in color


with


paste


-like


texture


polymers


are


near


perfectly


alternating


copolymers


synthetic


scheme


Soectroscoov


A Perkin-Elmer


Lambda


UV/Vi


s/NIR


spectrophotometer


was


used


obtain


UV spectra


chloroform


solution


thin


film


cast


on a quartz


slide.


A SPEX


Model


1680


Double


Spectrometer


was


used


measure


fluoresence


chloroform


solution


a thin


film


cast


on a quartz


slide.


Trouah


SetuD











(defined


difference


in surface


tension


between


clean


interface


and


film-covered


interface)


was


monitored


with


a paper


Wilhelmy


plate


suspended


from


constant-height


balance


a point


equidistant


from


moving


barriers


approximately


cm from


edge


cm wide


trough.


Surface


ential


was


measured


vibrating

cm diamete


electrode

r. The t


device.


hermostatt


vibrating


ed PTFE


electrode


trough


cm x 32


was


used


with


hydrophilic


polyamide


barriers


symmetric


compression


monolayer.


subphase


was


water


obtained


from


a Milli-Q


water


purification


system


(Millipore).


The


film


balance


system


was


mounted


vibration


isolation


table


under


a downflow


hood.


The


hood


was


turned


during


experiments.


Formation


of a Cellular


Network


2D foam-like


morphology


was


generated


compressing

nm2/repeat


After


film


unit/min)


compression,


a barrier


an area


speed


of 0


direction


20 mm/min


nm2/repeat


barrier


.084


unit.


motion


was


immediately


revers


that


film


was


decompre


ssed


speed


mm/min


nm2/repeat


unit/min)


until


sired


point


along


isotherm


is reached.


For











Brewster


Anale


Microscope


When


an air-water


interface


illuminated


plane


polarized

normal),


light


incident


presence


of a film


Brewster

changes


angle


refractive


o from


index


interface


thus


increase


reflectivity.


This


property


is exploited


Brewster


angle


microcope


(BAM)


technique.


The


BAM1


system


(Nanofilm


Technologies)


was


mounted


on a motorized


film


could


stage


be imag


so that


BAM


different


was


regions


image


a point


equidi


stant


from


both


moving


barriers


and


approximately


BAM


cm from


images


edge


area


cm wide


film


trough.


monitoring


changes


reflectivity


of a He-Ne


laser


beam


that


incident


Brewster


angle


clean


water/air


interface.


Each


pixel


corresponds


The


BAM


polarizer


(analyzer)


between


objective


lens


CCD


camera


film


so it


setting


is possible


this


check


analyzer


birefringence


usual


polari


zation


reflected


beam.


EDifluorescence


Trouah


cm PTFE


trough


with


a quartz


window


in the


4 l.lm2











film.


microscope


was


fitted


with


B-2A


filter


block


which


provides


excitation


wavelengths


between


allows


observation


of emission


wavelengths


greater


than


nm.


Photographs


were


taken


on Kodak


TMAX


P3200


black


white


film


using


a Nikon


camera.


Exposure


time


was


range


sec


onds


In addition,


dynamics


cellular


network


were


recorded


videotape


using


a Optronics


-470


Remote-Head


Microscope


Camera


(Optronics


Imaae


Engineering)


Processing


Microscope


image


were


recorded


videotape


(JCr/)


subsequently


transferred


a Sun


Sparcstation


using


VideoPi


analysis


image


capture


software


board


-Wave)


image


was


used


analysis


correct


Image


images


geometric


line


distortion


sight


caused


BAM


viewing


s objective


angle


lens


between


plane


interface.


Data


extracted


from


captured


images


with


image


analy


software


were


relative


total


reflectivity


areas


corres


ponding


either


phases.


summing


The


grey


total


scal


reflectivity


values


was


over


calculated


in images


captured


from


videotape


The


total


relative


reflectivities