Citation
Marine-Degradable Polyesters through Incorporation of Esteracetals, and a Comparison of a Radical Polymerization Matrix Vs. Romp Matrix for Molecular Imprinting

Material Information

Title:
Marine-Degradable Polyesters through Incorporation of Esteracetals, and a Comparison of a Radical Polymerization Matrix Vs. Romp Matrix for Molecular Imprinting
Creator:
Martin, Ryan Thomas
Publisher:
University of Florida
Publication Date:
Language:
English

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Chemistry
Committee Chair:
MILLER,STEPHEN ALBERT
Committee Co-Chair:
CASTELLANO,RONALD K
Committee Members:
SMITH,BEN W
DOLBIER,WILLIAM R,JR
SLOAN,KENNETH B
Graduation Date:
5/3/2014

Subjects

Subjects / Keywords:
Alcohols ( jstor )
Chlorides ( jstor )
Copolymers ( jstor )
Methane ( jstor )
Molecules ( jstor )
Nitrogen ( jstor )
Plastics ( jstor )
Polymerization ( jstor )
Polymers ( jstor )
Seas ( jstor )
degradable
degradation
esteracetal
green
marine
mip
pla
plastic
polymer
romp
sustainable
Atlantic Ocean ( local )

Notes

General Note:
The oxa-lactone 1,3-dioxolan-4-one was prepared from glycolic acid and formaldehyde, the final step along a viable pathway employing C1 feedstocks from biomass: methanol, formaldehyde, and carbon monoxide. The ring-opening polymerization (ROP) of 1,3-dioxolan-4-one was effected with tin (Sn(octanoate)2/benzyl alcohol), resulting in a regioregular polyesteracetal thermoplastics having melting temperatures ranging from 143-217 degrees C, depending on initiator concentration. Computational studies (G3(MP2)) imply that the ring-strain of this five-membered heterocycle (delta H = -6.7 kcal/lmol) is similar to that of gamma-butyrolactone (delta H = -7.6 kcal/mol), which has unfavorable ROP thermodynamics. Nonetheless, opening of 1,3-dioxolan-4-one engages two specific anomeric interactions with oxygen lone pair donations into the sigma star of an adjacent C-O bond (worth 2.8 kcal/mol) and an adjacent C-C(O) bond (worth 1.5 kcal/mol). These presumably restrict polymer conformations, contribute to crystallization polymerization, and allow for overall favorable polymerization thermodynamics. Copolymers of 1,3-dioxolan-4-one with L-lactide were synthesized, and with a feed ratio of 90:10 lactide:dioxolanone, the copolymers exhibited highly accelerated degradation. With an estimated 5-10 year degradation profile and thermal properties on par with traditional thermoplastics, these copolymers make excellent candidates to replace materials coming from non-renewable sources. Finally, Molecular Imprinted Polymers (MIPs) were made using ROMP methodology. Reported is a comparison of radical polymerization vs. ROMP matrices in molecular imprinting technology. Although the radical polymerization method enjoys the greatest usage and applications, the ROMP method of polymerization not only improved the binding properties of the polymer but also increased the selectivity. The ROMP method creates the polymers much faster and uses mild conditions, moreover, the tolerance of Grubbs' catalyst to a large number of functional groups provides a wide range of molecules that can be used.

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Source Institution:
UFRGP
Rights Management:
Copyright Martin, Ryan Thomas. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
5/31/2016

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1 MARINE DEGRADABLE POLYESTERS THROUGH INCORPORATION OF ESTERACETALS, AND A COMPARISON OF A RADICAL POLYMERIZATI ON MATRIX VS ROMP MATRIX FOR MOLE CULAR IMPRINTING By RYAN T. MARTIN A DISSERTATION PRESENTED TO THE GRADUATE S CHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 201 4

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2 201 4 Ryan T. Martin

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3 To my Mom

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4 ACKNOWLEDGMENTS I would like to thank the University of Florid a and my advisors, Eric Enholm and Steve Miller. I especially thank Steve for putting up with my insistence on doing things my own way. Steve is a brilliant scientist who taught me much along the way. I also am very grateful for the all my fellow group m embers, past and present, most especially Florent Allais and Alexander Pemba. Florent taught me the fundamentals of working in a lab, and our conversations and debates throughout the years have been challenging and enlightening. Alexander has been an inv aluable friend both in and out of the lab. We have had a blast together, gotten into some trouble together, and learned a lot about life together along the way.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 LIST OF SCHEMA ................................ ................................ ................................ ........ 13 LIST OF ABBREVIATIONS ................................ ................................ ........................... 14 ABSTRACT ................................ ................................ ................................ ................... 15 CHAPTER 1 HOMOPOLYMERIZATIONS OF 1,3 DIOXOLAN 4 ONE ................................ ....... 17 Introduction ................................ ................................ ................................ ............. 17 Cyclic Esteracetal Monomers ................................ ................................ ................. 20 Homopolymeriz ations of 1,3 dioxolan 4 one ................................ ........................... 21 2 POLYESTERACETAL COPOLYMERS ................................ ................................ .. 29 Copolymerizations of 1,3 Dioxolan 4 one with Lactide ................................ ........... 29 1 H and 13 C NMR of Copolymers ................................ ................................ ............. 36 3 MARINE DEGRADATION OF POLYESTERACETALS ................................ .......... 42 Introduction ................................ ................................ ................................ ............. 42 Global Ecosystem Impacts of Marine Debris ................................ .......................... 43 Reduce, Reuse, Recycle. . Reinvent ................................ ................................ .... 44 Principles of Green and Applied Chemistry ................................ ............................ 46 Degradation of Polylactic Acid 9 ................................ ................................ ............... 47 Conclus ions 9 ................................ ................................ ................................ ........... 55 4 A COMPARISON OF A RADICAL POLYMERIZATION MATRIX VS. ROMP MATRIX FOR MOLECULAR IMPRINTING ................................ .......................... 56 Background ................................ ................................ ................................ ............. 56 Binding Agents ................................ ................................ ................................ ........ 57 Radical Polymerization ................................ ................................ ........................... 57 ROMP Polymerization ................................ ................................ ............................. 58 Results and Discussion ................................ ................................ ........................... 60 Conclusions ................................ ................................ ................................ ............ 65

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6 5 EXPERIMENTAL ................................ ................................ ................................ .... 67 General ................................ ................................ ................................ ................... 67 1,3 dioxolan 4 one (1) ................................ ................................ ............................. 68 [BHTLiTHF] 2 (3) ................................ ................................ ................................ ..... 69 [BHTNaTHF] 3 (4) ................................ ................................ ................................ ... 69 BHT 2 MgTHF 2 (5) ................................ ................................ ................................ ... 69 BHT 2 CaTHF 3 (6) ................................ ................................ ................................ .... 70 [(EDBPH)Na(THF) 2 ][Na(THF)(EDBPH)] (7) ................................ ............................ 70 General Procedure for Ring Opening Polymerization ................................ ............. 70 Poly(1,3 dioxolan 4 one) (8) ................................ ................................ ................... 71 Poly(1,3 dioxolan 4 one) (9) ................................ ................................ ................... 71 Poly(1,3 dioxolan 4 one) (10) ................................ ................................ ................. 71 Poly(1,3 dioxolan 4 one) (11) ................................ ................................ ................. 72 Poly(1,3 dioxolan 4 one) (12) ................................ ................................ ................. 72 Poly(1,3 dioxolan 4 on e) (13) ................................ ................................ ................. 73 Poly(1,3 dioxolan 4 one) (14) ................................ ................................ ................. 73 Poly( caprolactone co 1,3 dioxolan 4 one) (15) ................................ .................... 74 Poly(L lactide) (16) ................................ ................................ ................................ 74 Poly(lactide co 1,3 dioxolan 4 one) (17) (90:10 feed ratio ) ................................ ..... 75 Poly(lactide co 1,3 dioxolan 4 one) (18) (80:20 feed ratio) ................................ ..... 75 Poly(lactide co 1,3 dioxolan 4 one) (19) (70:30 feed ratio) ................................ ..... 76 Poly(lactide co 1,3 dioxolan 4 one) (20) (60:40 feed ratio) ................................ ..... 76 Poly(lactide co 1,3 dioxolan 4 one) (21) (50:50 feed ratio) ................................ ..... 77 General Procedure for Radical Polymerization ................................ ....................... 77 General Procedure for ROMP Polymerization ................................ ........................ 78 Bicyclo[2.2.1]hept 5 en 2 yl methanol or 5 Norbornene 2 methanoI ...................... 78 Hexanedioic acid dibicyclo[2.2.1]hept 5 en 2 ylmethyl ester ................................ .. 79 APPENDIX A SPECTRAL DATA ................................ ................................ ................................ .. 80 B GEL PERMEATION CHROMATOGRAPHY DATA ................................ ................ 96 C AMERICAN CHEMICAL SOCIET Y COPYRIGHT PERMISSION ......................... 138 LIST OF REFERENCES ................................ ................................ ............................. 140 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 146

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7 LIST OF TABLES Tabl e page 1 1 Polymerization and thermal characterization data for polyesteracetals from 1,3 dioxolan 4 one. ................................ ................................ ............................. 26 2 1 Charac teristics of PLA/PEA copolymers varying monomer feed ratio. ............... 32 2 2 Characteristics of PLA/PEA copolymers varying polymerization temperature. ... 32 2 3 Proton signal incorporation attributed to DOX ................................ .................... 41 3 1 Film Degradation of Poly(D,L)lactic acid a ................................ .......................... 50 3 2 Film Degradation of 90:10 Poly(L lactide) co (1,3 dioxolan 4 one) a ................... 51

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8 LIST OF FIGURES Figure page 1 1 Polylactic acid is typically prepared by fermentati on of glucose and ring opening polymerization (ROP) of lactide using various metal based initiators. .. 18 1 2 The structure of methane hydrate (a.k.a., methane clathrate, methane ice) 8 a sample of methane hydrate from the Gulf of Mexice, a sample undergoing combustion 5 and its global marine distribution 10 ................................ ............... 20 1 3 Tin (II) octoate. ................................ ................................ ................................ ... 22 1 4 butyrolactone and 1,3 dioxolan 4 one have similar ring strain ........................... 27 1 5 Proposed Mechanism of ROP of O xalactone Initiated by Stannous Octoate. .... 28 2 1 Differential Scanning Calorimetry of a series of PLA copolymers with increasing amounts of 1,3 dioxolan 4 one comonomer. ................................ ..... 33 2 2 Direct comparison of PLA (black) and 90:10 PLADOX (green) by (A) differential scanning calorimetry and (B) thermal gravimetric analysis. .............. 34 2 3 Visual comparison of thin films of PLA and PLADOX made under the same standard conditions. ................................ ................................ ........................... 35 2 4 PLADOX creates strong, flexible, and transparent thin films. ............................. 36 2 5 1 H NMR spectrum of (15) in hexafluoroisopropanol (HFIP), below; and HFIP above. ................................ ................................ ................................ ................. 37 2 6 13 C NMR spectrum of (15) dissolved in hexafluoroisopropanol (HFIP), below; and HFIP above. ................................ ................................ ................................ 38 2 7 Overlay of 1 H NMR spectra of copolymer series (16) to (21) ............................. 40 3 1 Degradation data ................................ ................................ ................................ 52 3 2 Electron microscopy ................................ ................................ ........................... 54 4 1 Acetylcholine binding agents. ................................ ................................ ............. 57 4 2 Radica l polymerization matrix with edrophonium chloride as the print molecule. ................................ ................................ ................................ ............ 62 4 3 ROMP matrix with edrophonium chloride as the print molecule ......................... 63

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9 4 4 Radical polymerization matrix with pyridostigmine bromide as the print molecule. ................................ ................................ ................................ ............ 64 4 5 ROMP Matrix with Pyridostigmine Bromide as the Print Molecule ...................... 64 A 1 HNMR of (1) ................................ ................................ ................................ ....... 80 A 2 CNMR of (1) ................................ ................................ ................................ ....... 81 A 3 HNMR of (15) ................................ ................................ ................................ ..... 82 A 4 CNMR of (15) ................................ ................................ ................................ ..... 83 A 7 HNMR of (17) ................................ ................................ ................................ ..... 86 A 8 CNMR of (17) ................................ ................................ ................................ ..... 87 B 1 GPC (16) ................................ ................................ ................................ ............ 96 B 2 GPC (17) ................................ ................................ ................................ ............ 97 B 3 GPC (18) ................................ ................................ ................................ ............ 97 B 4 GPC (19) ................................ ................................ ................................ ............ 98 B 6 GPC (21) ................................ ................................ ................................ ............ 99 B 7 GPC (22) ................................ ................................ ................................ ............ 99 B 8 GPC (23) ................................ ................................ ................................ .......... 100 B 9 GPC (24) ................................ ................................ ................................ .......... 100 B 10 GPC (25) ................................ ................................ ................................ .......... 101 B 11 GPC ( 26) ................................ ................................ ................................ .......... 101 B 12 GPC (27) ................................ ................................ ................................ .......... 102 B 13 GPC (28) ................................ ................................ ................................ .......... 102 B 14 GPC (29) ................................ ................................ ................................ .......... 103 B 15 GPC (30) ................................ ................................ ................................ .......... 103 B 16 GPC (32) ................................ ................................ ................................ .......... 104 B 17 GPC (33) ................................ ................................ ................................ .......... 104 B 18 GPC (34) ................................ ................................ ................................ .......... 105

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10 B 19 GPC (35) ................................ ................................ ................................ .......... 105 B 20 GPC (36) ................................ ................................ ................................ .......... 106 B 21 GPC (37) ................................ ................................ ................................ .......... 106 B 22 GPC (40) ................................ ................................ ................................ .......... 107 B 23 GPC (41) ................................ ................................ ................................ .......... 107 B 24 GPC (42) ................................ ................................ ................................ .......... 108 B 25 GPC (43) ................................ ................................ ................................ .......... 108 B 26 GPC (44) ................................ ................................ ................................ .......... 109 B 27 GPC (45) ................................ ................................ ................................ .......... 109 B 28 GPC (46) ................................ ................................ ................................ .......... 110 B 29 GPC (48) ................................ ................................ ................................ .......... 110 B 30 GPC (49) ................................ ................................ ................................ .......... 111 B 31 GPC (50) ................................ ................................ ................................ .......... 111 B 32 GPC (51) ................................ ................................ ................................ .......... 112 B 33 GPC (52) ................................ ................................ ................................ .......... 112 B 34 GPC (53) ................................ ................................ ................................ .......... 113 B 35 GPC (54) ................................ ................................ ................................ .......... 113 B 36 GPC (55) ................................ ................................ ................................ .......... 114 B 37 GPC (56) ................................ ................................ ................................ .......... 114 B 38 GPC (57) ................................ ................................ ................................ .......... 115 B 39 GPC (58) ................................ ................................ ................................ .......... 115 B 40 GPC (59) ................................ ................................ ................................ .......... 116 B 41 GPC (60) ................................ ................................ ................................ .......... 116 B 42 GPC (62) ................................ ................................ ................................ .......... 117 B 43 GPC (63) ................................ ................................ ................................ .......... 117

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11 B 44 GPC (64) ................................ ................................ ................................ .......... 118 B 45 GPC (65) ................................ ................................ ................................ .......... 118 B 46 GPC (66) ................................ ................................ ................................ .......... 119 B 47 GPC (67) ................................ ................................ ................................ .......... 119 B 48 GPC (68) ................................ ................................ ................................ .......... 120 B 49 GPC (71) ................................ ................................ ................................ .......... 120 B 50 GPC (72) ................................ ................................ ................................ .......... 121 B 51 GPC (73) ................................ ................................ ................................ .......... 121 B 52 GPC (74) ................................ ................................ ................................ .......... 122 B 53 GPC (75) ................................ ................................ ................................ .......... 122 B 54 GPC (76) ................................ ................................ ................................ .......... 123 B 55 GPC (79) ................................ ................................ ................................ .......... 123 B 56 GPC (80) ................................ ................................ ................................ .......... 124 B 57 GPC (81) ................................ ................................ ................................ .......... 124 C 1 DSC trace of (8) ................................ ................................ ................................ 125 C 2 DSC trace of (9) ................................ ................................ ................................ 126 C 3 DSC trace of (10) ................................ ................................ .............................. 1 27 C 4 DSC trace of (11) ................................ ................................ .............................. 128 C 5 DSC trace of (12) ................................ ................................ .............................. 129 C 6 DSC trace of (13) ................................ ................................ .............................. 130 C 7 DSC trace of (14) ................................ ................................ .............................. 131 C 8 DSC trace of (16) ................................ ................................ .............................. 132 C 9 DSC trace of (17) ................................ ................................ .............................. 133 C 10 DSC trace of (18) ................................ ................................ .............................. 134 C 11 DSC trace of (19) ................................ ................................ .............................. 135

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12 C 12 DSC trace of (20) ................................ ................................ .............................. 136 C 13 DSC trace of (21) ................................ ................................ .............................. 137

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13 LIST OF SCHEMA Scheme page 1 1. Es teracetal ring formation. ................................ ................................ .................... 21 1 2. Polyesteracetals from biomass. ................................ ................................ ............ 21 1 3. Metal BHT complexes. ................................ ................................ .......................... 23 1 4. EDBPH 2 complex. ................................ ................................ ................................ 25 2 1. CAP DOX copolymer. ................................ ................................ ........................... 29 2 2. Kinetic rationale. ................................ ................................ ................................ .... 30 3 1. The full lifecycle of polylactic acid (PLA) generally relies upon enzymatic biodegradation. ................................ ................................ ................................ ... 48 3 2. Esteracetal copolymers. ................................ ................................ ........................ 49 4 1. Radical polymerization. ................................ ................................ ......................... 58 4 2. ROMP ................................ ................................ ................................ ................... 60

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14 LIST OF ABBREVIATION S AIBN Azobis(isobutyl nitri le) C1 A one carbon molecule DSC Differential Scanning Calorimetry GC MS Gas Chromatography Mass Spectrometry GPC Gel Permeation Chromatography HDPE High Density Polyethylene MIP Molecular Imprinted Polymer NMR Nuclear Magnetic Resonance P(DL)LA meso Polyl actic Acid PEA Polyesteracetal PLA Polylactic Acid POM Polyoxymethylene ROMP Ring opening Metathesis Polymerization ROP Ring opening Polymerization T G Glass Transition Temperature T M Melting Temperature

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15 Abstract of Dissertation Presented to the Gradu ate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy MARINE DEGRADABLE POLYESTERS THROUGH INCORPORATION OF ESTERACETALS, AND A COMPARISON OF A RADICAL POLYMERIZATION MATR IX VS. ROMP MATRIX FOR MOLECULAR IMPRINTING By Ryan T. Martin May 2014 Chair: Stephen A. Mi ller Major: Chemistry In a future less reliant on fossil fuels, polymeric materials must be realized which, along with being economically advantageous, come fro m sustainable sources, are at least as useful as fossil fuel plastics, and, when their useful lifetimes are up, be amenable to returning to biological and geological life cycles in reasonable timeframes. In other words, plastics of the future must have a green birth, an effective lifetime, and a green death. To this end, we examined the use of a heretofore unutilized functional group in polymer chemistry, the esteracetal. The oxa lactone 1,3 dioxolan 4 one was prepared from glycolic acid and para formalde hyde, which in turn can be made from georenewable small molecules such as methanol, carbon monoxide, and formaldehyde. Ring opening polymerization (ROP) of 1,3 dioxolan 4 one can be accomplished in modest yields using tin octoate/benzyl alcohol co initiato r system affording crystalline, insoluble materials. M elting temperatures of these homopolymers range from 143 217 C, d epending on initiator concentra tion.

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16 Though of interest as homopolymers, perhaps more commercially attractive is the use of esteracetal s as comonomers. When a small amount (app. 4%) of dioxolanone is incorporated in the ROP of lactide, the resulting modified polylactic acid (poly(L lactide co 1,3 dioxolan 4 one)) exhibits a small increase in glass transition temperature (a rarity in copo lymerizations), while simultaneously enhancing the degradation profile of PLA by around 100 fold. Utilizing this approach to modifying polyesters can create highly attractive and cost effective candidates for either enhancing or replacing existing thermop lastic materials coming from non renewable sources. Finally, Molecular Imprinted Polymers (MIPs) were made using ROMP methodology. Reported is a comparison of radical polymerization vs. ROMP matrices in molecular imprinting technology. Although the radic al polymerization method enjoys the greatest usage and applications, the ROMP method of polymerization not only improved the binding properties of the polymer but also increased the selectivity. The ROMP method creates the polymers much faster and uses mil d conditions, moreover, the range of molecules that can be used.

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17 CHAPTER 1 HOMOPOLYMERIZATIONS OF 1,3 DIOXOLAN 4 ONE Introduction Throughout the 20th century, commodity t hermoplastics were almost exclusively derived from non renewable fossil fuels and have been driven by two main factors: cost and utility. In the 21st century, however, there is a strong push for a more responsible and holistic approach to plastics; an ap proach that includes a greater emphasis on the sources from which plastics are derived, as well as the ultimate fate of the materials after their useful lifetime is exhausted. In other words, modern sustainable plastics of the 21st century and beyond must be considered in terms of a green birth, a useful life, and a green death. The U.S. Biomass Research and Development Technical Advisory Committee issued a directive in 2002 stating that the production of chemicals and materials from biobased products sho uld increase from the current 5% to 12% by 2012, to 18% by 2020, and to 25% by 2030 1 There are two primary strategies for converting biomass into tractable organic molecules: (1) fermentation of sugars derived from cellulose; and (2) classical wood distil lation. Unfortunately, methods for the efficient depolymerization of cellulose are far less economical than those for the depolymerization of starch 2 Polylactic ac id (or, polylactide, PLA). has enjoyed the most commercial success as a starch based, gre en polymer (Figure 1 1) PLA has several drawbacks, however. PLA suffers from a low glass transition temperature (ranging from about 45 to 65 C) relative to its petroleum based counterpa rts (70 C for PET and 100 C for polystyrene). For this reason,

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18 PLA can be made from sustainable sources, most commonly corn, and it is believed to possess the ability to de grade on a shorter timescale than traditional thermoplastics. While PLA is more ammenable to degradation pathways than traditional hydrocarbon based thermoplastics, the mechanisms by which it can degrade are limited, and are best done under very controlle d circumstances, such as composting. Left to degrade on its own in landfill leachate or marine conditions, it is questionable whether PLA will degrade appreciably faster than traditional petroleum products. 3 Figure 1 1 Polylactic acid is typically prepared by fermentation of glucose and ring opening polymerization (ROP) of lactide using various metal based initiators. Methanol and methane are becoming increasingly important C1 feedstocks in polymer chemistry. Classical wood distillation was the method for all methanol (wood alcohol) production prior to the 1920s, when natural gas and coal became more attractive feedstocks. Methanol itself does not resemble a typical monomer for polymerization; however, about 40% of all methanol is dehydrogenated to formaldehyde, which is a common C1 monomer in the arsenal of the polymer chemist. In recent efforts to diversify the thermomechanical properties of polyformaldehyde (polyoxymethylene, POM) 1 alkene oxides were successfully c opolymerized with trioxane, the cyclic trimer of formaldehyde. The result was a family of POM copolymers with tunable side chain alkyl branching up to 20 mol%. 4

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19 Methane is the major component of natural gas, though an important additional source of methane may come in the form of methane hydrate. Methane hydrate can be found in enormous quantities thro ughout the world in marine envir onments (Figure 1 2 ). Methane hydrate is estimated to exist at a volume of 4x10 17 cubic feet 5 or 64,700 times the proven re serves of conventional natural gas (6,183 trillion cubic feet 6 ) Methane hydrate may b e the most abundant fossil fuel, as this amount is generally considered to gas, and coal deposits combined 6 While c hallenges exist in harvesting this solid form of ice and methane 7 as technologies evolve in this area, the econom ic benefits of using this methane source in polymer production will become undeniably favorable.

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20 Figure 1 2 Clockwise from top right: Th e structure of methane hydrate (a.k.a., methane clathrate, methane ice) 8 a sample of methane hydrate from the Gulf of Mexice, a sample undergoing combustion 5 and its global marine distribution 10 Cyclic Esteracetal Monomers We subsequently sought a more cost effective comonomer utilizing C1 feedstocks for disrupting main chain conformational regularity and were inspired by a patent from 1972 that claimed the cationic copolymerization of trioxane and carbon monoxide to yield polymers having essentially a polyglycolic acid structure 11 Intent on adapting these feedstocks to ring opening polymerization (ROP) methods, we targeted the 5 membered heterocycle 1,3 dioxolan 4 one 12 (1), which bears both the ester and acetal functional groups:

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21 Scheme 1 1 Esteracetal ring formation. We synthesized this oxa lactone from para formaldehyde and glycolic acid w hich, in turn, can be made via hydrocarboxylation of formaldehyd e with carbon monoxide ( Scheme 1 1). 13 Alternatively, several catalysts have been described that produce 1,3 dioxolan 4 one directly from formaldehyde and carbon monoxide. 14 Scheme 1 2 Polyesteracetals from biomass. Homopolymerizations of 1,3 dioxolan 4 one In selecting initiators for polymerization of 1,3 dioxo lane 4 one it was instructive to look first to effective initiators of the ROP of lactones and lactides, such as metal complexes comprising aluminum 15 zinc 16 tin 17 or lanthanides 1 8 Of these, tin(II) 2 ethyl hexanoate (2) (Figure 1 3) (also known as t in( II) octoate or stannous octoate ) is most commonly and effectively used, along with a hydroxyl co initiator, for ROP of lactide.

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22 Figure 1 3 Tin (II) octoate. In addition to standard tin initiator systems 21 more nov el systems were also investigated 19,20 Metal BHT ( 2,6 di tert butyl 4 methylphenol ) systems have shown high polymerization activity for lactide and caprolactone. BHT systems including lithium, sodium, magnesium, and calc ium (Scheme 1 3) were examined here for their usefulness in polymerizing 1,3 dioxolane 4 one Additionally, BHT has the designation of Generally Recognized As Safe by the U.S. Food and Drug Administration as a food antioxidant and additive 21

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23 Schem e 1 3 Metal BHT complexes.

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24 ethylidene bis (4,6 di tert butyl phenol) (EDBPH 2 ) (Scheme 1 4) was targeted as a polyesteracetal ROP initiator. EDBPH 2 is a multidentate and sterically bulky ligand which has shown great polymerization control with lactides and lactones, and has the added benefits of low cost and approval by the U.S. Food and Drug Administration as a food additive and for food contact in packaging 22 EDBPH 2 complexes with s odium the most abundant metal ninth most abundant element in the human body (0.14%). 23

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25 Scheme 1 4. EDBPH 2 complex. Investigations of above ROP initiators for the polym erization of 1,3 dioxolan 4 one afforded the first regioregu lar polyesteracetal. The ester acetal functional group is absent from the polymer literature except for a few random copolymers presumed in the aforementioned pate nt and its preceding literature 1 1 Poly(1,3 dioxolan 4 one) is

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26 obtained as a white powder Polymers (10) and (11) exhibit characteristic melting temperatures (Table 1 1) satisfyingly between the melting temperatures of the related polyester (T M butyrolactone) = 53C) 2 4 and that of polyoxymethylene (181C). 2 5 Table 1 1 Polymerization and thermal characterization data for polyesteracetals from 1,3 dioxolan 4 one. Entry a initiator [M]:[I] b T M (C) c T G (C) c Yield (%) 1 1 (8) (2) ,BnOH 500 217 -10 1 2 (9) (2) ,BnOH 400 205 23 13 1 3 (10) (2) ,BnOH 200 156 15 20 1 4 (11) (2) ,BnOH 133 1 43 38 26 1 5 (12) (2) ,BnOH 50 1 89 7 37 1 6 (13) (2) ,BnOH 10 1 86 3 70 1 7 (3) ,BnOH 200 --n.r. 1 8 (4) ,BnOH 200 --n.r. 1 9 (14) (5) ,BnOH 200 169 -49 1 10 (6) ,BnOH 200 --n.r. 1 11 (7) ,BnOH 500 --<5 a Polymerization conditions: 24 hrs at 100C in toluene; b mono mer:initiator molar ratio; c determined by DSC While the five butyrolactone will not undergo ROP because of its ring stability, 2 6 the same sized oxa lactone exhibits no such reluctance. A plausible explanation for this mirrors that given for the facile ROP of seemingly stable trioxane. In POM, the acetal functional group enforces conformational regularity and compels chain chain interactions via its strong local dipole. 27 ,2 8 These effects promote crystallization polymerization 2 9 in which favorable thermodynamics are achieved by exothermic polymer precipitation, a phenomenon not observed for pol butyrolactone) because of its relatively weak chain chain interactions and low crystallinity. 4

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27 Figure 1 4 butyrolactone and 1,3 dioxolan 4 one have similar ring 7.6 vs. 6.7 kcal/mol), according to computational results (G 3(MP2)) that combine these heterocycles with methyl acetate. Upon opening, however, only the product from 1,3 dioxolan 4 one can attain anomeric interactions, which increase conformational rigidity. The energy minimized conformer suggests oxygen lone pai r O and C C(O) bonds, valued at 2.8 and 1.5 kcal/mol, respectively, compared to alternative conformers. The intra chain inflexibility, along with a greater density of inter chain dipole dipole interactions, expla ins the much higher T M of poly(1,3 dioxolan 4 one) (189C) vs. poly( butyrolactone) (53C) and rationalizes the crystallization polymerization phenomenon. These results also suggest that the conformationally preferred form of a polyesteracetal includes g auche interactions reminiscent of the all gauche conformation observed for POM 2 Figure 1 4 Computational results of isodesmic reactions (G3(MP2)) suggest ing butyrolactone and 1,3 dioxolan 4 one have similar ring st rain. Only the open form of 1,3 dioxolan 4 one realizes two specific anomeric interactions, worth O) and 1.5 ( C(O)) kcal/mol in model compounds. 9 The oxalactones prepared i n this investigation underwent ring opening polymerization using st annous octoate as initiator. ROP initiated by stannous octoate is proposed to occur by a coordination insertion mechanism shown in Figure 1 5 whereby

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28 the stannous octoate first coordinates with an added alcohol. In this initiator system, the alcohol acts Figure 1 5 Proposed Mechanism of ROP of Oxalactone Initiated by Stannous Octoate

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29 CHAPTER 2 POLYESTERACETAL COPOLYMERS Copolymerizations of 1,3 Dioxolan 4 one with Lactide Assuming a generally low reactivity for homopolymers of 1,3 dioxolan 4 one, we chose to examine copolymers, and began with caprolactone as comonomer. We sought to take advantage of disparities in reactivities of comonomers by kinetically trapping less reactive 1,3 dioxolan 4 one by using a much larger concentration relative to the lactone monomer (Scheme 2 1) (15) Scheme 2 1 CAP DOX copolymer. Similar systems have been described in this fashion, such as lactide/ caprolactone 66 s tyrene/butadiene 67 and caprolactone/ butyrolactone 66 The kinetic rationale behind this is as follows (Scheme 2 2) assuming reactivity of 1,3 dioxolan 4 one is much less than reactivity of caprolactone:

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30 Scheme 2 2 Kinetic rationale. When [DOX] >> [CL], DOX units can be kinetically trapped in the growing polymer chain by addition of a CL unit, faster than the rate of depolymerizing a DOX unit from the chain. The result is an alternating copolymer with a maximum of 50% incorporation of the less reactive monomer.

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31 Surprisingly, however, when 1,3 dioxolan 4 one was copolymerized with caprolactone at a feed ratio of 11:1, the result was a polymer with not with 50:50 incorporation, but rather a makeup very near the feed ratio. [See NMR Discussion below] Homopolymers of 1,3 dioxolan 4 one are highly crystalline and insoluble in common o rganic solvents, and therefore particularly challenging to characterize using traditional solvated polymer characterization techniques such as NMR or GPC. Unlike its unacetalized analogue polyglycolic acid (PGA), homopolymer of 1,3 dioxolan 4 one is insol uble even in a solvent as strong as hexafluor o isopropanol. However, when 1,3 dioxolan 4 one is copol ymerized with a small amount (~8 % feed) of caprolactone, such as described above, the added aliphatic segments of the caprolactone impart just enough solubility to allow the homopolymer to be dissolved in hexafluroisopropanol, making characterization by NMR possible. By this method we were abl e to confirm the polyesteracetal structure. We then examined the effects of introducing the esteracetal functionality into other known polyesters such as PLA. The facile polymerizability of 1,3 dioxolan 4 one is further demonstrated by copoly merizations described in Table 2 1 Incorporating a relativ ely small amount (10%, entry 2 2 ) of esteracetal into the backbone of PLA results in the improvement of several characteristics, including molecular weight, polydispersity, and thermal propert ies relative to PLA homopolymer (Figure 2 1)

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32 Table 2 1 Characteristics of PLA/PEA copolymers varying monomer feed ratio. Entry a Comonomer Feed Ratio b Yield (%) M w c (kD) PDI c T M ( C) d T G ( C) d 2 1 (16 ) 100:0 93 53 2.03 174 44 2 2 (17 ) 90:10 91 100 1.56 157 51 2 3 (18 ) 80:20 85 54 1.47 152 52 2 4 (19 ) 70:30 76 41 1.51 139 49 2 5 (20 ) 60:40 68 32 1.54 120 42 2 6 (21 ) 50:50 51 14 1.40 102 42 a Polymerization Conditions: 24 hrs at 100 C in toluene using 500:1 [monomer]:[initiator] of tin(II)ethyl hexanoate and benzyl alcohol; b L lactide:1,3 dioxolan 4 one; c Determined by GPC using polystyrene standard; d Determined by DSC Table 2 2 Characteristics of PLA/PEA copolymers varying polymerization temperature. Entry a T P b ( C) Yield (%) M w c (kD) PDI c T M ( C) d T G ( C) d 2 7 100 91 100 1. 56 1 57 51 2 8 85 85 40 1.70 15 5 48 2 9 75 8 6 48 1.40 15 7 52 2 10 65 85 37 1. 92 1 57 4 8 2 11 55 6 4 46 1. 20 1 60 46 2 12 2 13 45 35 20 10 15 9 1. 18 1.08 1 43 135 42 37 a Polymerization Conditions: 24 hrs in toluene using 5 00:1 [monomer]:[initiator] of tin(II)ethyl hexanoate and benzyl alcohol feed ratio of 90:10 L lactide:1,3 dioxolan 4 one; b Polymerization temperaure c Determined by GPC using polystyrene standard; d Determined by DSC

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33 Figure 2 1. Differential Scanning Calorimetry of a series of PLA copolymers with increasing amounts of 1,3 dioxolan 4 one comonomer. Figure 2 2 directly compares the thermal properties of PLA homopolymer with 90:10 poly(lactide) co (1,3 dioxolan 4 one) (PLADO X) This small incorporation of esteracetals affects a noticeable change in properties including a 7 C increase in glass transition temperature, a decrease in melt temperature of 17 C (easier to melt process), an increase of 20 C in the thermal stabili ty range, and a decrease in crystallinity (leading to improved optical clarity ) The improved optical clarity and film stab ility can be seen in Figures 2 3 and 2 4

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34 Figure 2 2 Direct comparison of PLA (black) and 90:10 PLADOX (green) by (A) d ifferential scanning calorimetry and (B) thermal gravimetric analysis

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35 Figure 2 3 Visual comparison of thin films of PLA and PLADOX made under the same standard con ditions.

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36 Figure 2 4 PLADOX creates strong, flexible, and transparent thin films. 1 H and 13 C NMR of Copolymers Figure 2 5 shows the 1 H NMR spectrum of (15) dissolved in HFIP, with a proton spectrum of HFIP above for reference. It is presume d that the alpha proton (f) of the DOX segments is obscured/overlapping with the HFIP methyne proton (i). Therefore, this proton spectrum by i tself is inconclusive to suggest esteracetal repeat units. The 13 C NMR spectrum of (15) shown in Figure 2 6 howe ver, is more clear. In it, when compared with the HFIP spectrum the three carbon signals (a), (b), and (c) of the esteracetal repeat unit s are visible, suggesting a polyesteracetal copolymer.

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37 Figure 2 5 1 H NMR spectrum of (15) in hexafluoroisopropanol (HFIP), below; and HFIP above.

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38 Figure 2 6 1 3 C NMR spectrum of (15) dissolved in hexafluoroisopropanol (HFIP), below; and HFIP above

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39 An overlay of 1 H NMR spectra for lactide/dioxolanone copolymers (16) (21) is shown in Figure 2 7 As DOX incorporation is increased in the series, the portion of the spectra attributable to DOX not only increases in area, but also in complexity. A poss ible explanation for this is as follows : First, a s DOX feed increases, there is an increasing possibility of glycolate unit incorporation as a side product. As a result of this, formaldehyde would be extruded, resulting in polyester segments, and greater peak area toward the downfield 5.0 ppm region associated with polyglycolic acid. If the extruded carbonyls where to be reinserted during the reaction, oxymethylene units could be incorporated, diminishing the regioregularity of the esteracetal units, and again increasing the complexity of the 4.5 5.0 ppm region as can be seen in Figure 2 7 Second, a s DOX feed increases, there is an increase in distinct triads in the esteracetal region With small [DOX], DOX chain segments are likely to be only isolate d units flanked by LA, or perhaps double DOX units ( ldl or ldd / ddl ). However, as [DOX] increases, when considering the increasing possibility of glycolate side product units, the 4. 5 to 5.0 ppm region soon can become complicated with possible triad combin ations ( ldl ldd / ddl ddd gdg gdd / ddg gdl / ldg lgl lgg / ggl ggg dgd dgg / ggd dgl / lgd ). Furthermore, oxymethylene segments could form as the result of reversible formaldehyde extrusion, further complicating the peak region more than exponentially. A nother unfortunate result of increasing DOX feed in the copolymers is the decreasing solubility of the products. Coupled with triad problem described above, this makes carbon signals in 13 C NMR from DOX segments indistinguishable from the noise in the ba s eline for feeds above 10%

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40 Figure 2 7 Overlay of 1 H NMR spectra of copolymer series (16) to (21) The complexity of the esteracetal region notwithstanding, the incorporation of DOX units into the chain was a pproximated using 1 H NMR. Relative to an 8 proton integration for the LA regions of the spectra (6 methyl protons at 1.6 ppm and 2 alpha methyne protons at 5.2 ppm), the % DOX incorporation associated with 4 DOX protons is approximated as follows: %DOX inc orporation = [ 2( integration of DOX region ) ]/ [ 2 (integration of DOX region) + (integration of LA region )] x 100% with DOX incor poration summarized in Table 2 3

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41 Table 2 3 Proton signal incorporation attributed to DOX Entry LA:DOX feed ratio DOX region integration %DOX incorporation (16) 100:0 0 0 (17) 90:10 0.18 4. 3 (18) 80:20 0.44 9.9 (19) 70:30 0.92 18.7 (20) 60:40 1.32 2 4.8 (21) 50:50 2.25 36 a Determined by 1 H NMR relative to a lactide integration of 8.0

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42 CHAPTER 3 MARINE DEGRADATI ON OF POLYESTERACETALS Introduction Plastic marine debris is a global environmental problem, the consequences of which go far beyond mere esthetics 30 Plastic debris facilitates the transportation of harmful and persistent organic pollutants and invasive species 31 kills and injures diverse ecosystems and species of marine life 3 2 is harmful to human health 33 causes severe navigational and shipping problems 30 and damages fisheries and tourism 34 The plastic debris crisis is truly worldwide in scope, stre tching beyond national jurisdictions and boundaries 35 Marine debris is defined as any form of processed or manufactured material that becomes disposed of or abandoned in the marine environment, whether intentionally or unintentionally 36 While this encom passed a wide range of materials, plastics by far make up the major component of marine debris globally 34 Despite attempts at debris removal and legislation aimed at restricting dumping at sea, quantities of marine debris are increasing 35 Plastic debris can have long term environmental impacts along shorelines and near shore, as well as in the open ocean. Due to their durability and buoyancy, plastic items are able to persist and travel substantial distances. Law et al., in a recent publication in the journal Science presented over two decades of data demonstrating that some of the most substantial accumulations of plastic debris now reside in oceanic gyres far from land 37 The accumulation of plastic marine debris has been identified as a top global emerging issue, similar in scope and impact to other key issues such as climate change, the acidification of oceans, and loss of biodiversity 38

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43 Global Ecosystem Impacts of Marine Debris More than 260 species have already been identified as being negativel y affected by plastic marine debris through ingestion and entanglement 3 2 It is important to note that the plastic debris crisis is not limited to the macro scale. While many types of plastic debris are large (e.g., bottles, bags, fishing gear, and other consumer products), plastics debris can fragment down to the micro and nano scale. These small particles are of great concern because they can be ingested by a wide range of organisms and can lead to adverse physical effects by disrupting digestion 35 Microplastic and nanoplastic form by physical, chemical, and biological fragmentation of larger articles or by direct release of industrial waste. These small particles do not biodegrade, and are therefore expected to increase and accumulate in marine e nvironments 39 Nano sized particles can disrupt critical parts of the marine food web upon which global climates depend. For example, Bhattacharya et al. have reported that nanopolystyrene beads can cause oxidative stress and inhibit photosynthesis in al gae 40 Of particular concern is the ability of plastic debris particles to adsorb persistent organic pollutants and transport these pollutants great distances. Examples of these pollutants include monomers and oligomers, phthalate plasticizers, bisphenol A, antimicrobial additives, and flame retardants. Within short time periods (days and weeks) these organic pollutants can become orders of magnitude more concentrated on the surface of plastic debris, compa red to surrounding waters 31 These pollutants a re then distributed throughout water columns and ingested by marine organisms. Once these negative effects occur, there is no method of reversal or remediation, therefore

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44 the key to mitigating increases in marine debris is prevention at the sources and un derlying causes. Some of the major sources of marine debris are well known, and can be either land based or sea based. These commonly include sewage run o ff, materials from beach users, and materials disposed of at sea from shipping and fishing activitie s. Marine debris originating on land is transported either by rivers or storm drains, or is blown by weather events such as winds and hurricanes, rain and floods 41 A substantial source of marine debris is also sea based. The dumping of waste at sea, wh ile regulated by many agreements and conventions, is difficult to enforce. To date, most implementations of best practices and responses to the global of end of pipe appr oaches include clean up campaigns on shorelines and at sea, port waste reception facilities, and provision of educational notices and litter bins on beaches. These measures are important, but in no way represent a long term solution. Plastic production a nd consumption have shown exponential increase, with more plastics being produced in the first decade of the 21 st century than in the entire 20 th century 42 Clearly, in order to address this global problem, a paradigm shift is required. Reduce, Reuse, R ecycle. . Reinvent Unsustainable production and consumption patterns are at the heart of causes of the plastic debris problem. Materials and products are designed and marketed globally with little or no regard to environmental source or fate, or to the ability of these products to be recycled at locations close to where they are sold. There exists a disconnect between commercial practices and the philosophies of a life cycle perspective. Commodity thermoplastics typically originate from unsustainable s ources, have a useful

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45 but short lifetime to the consumer, and ultimately are discarded and persist in the environment in negative and damaging capacities. Both raw materials and our ability to deal with waste are limited, and current practices of product ion and consumption lack long term sustainability 35 A potential major testing ground for a green economy concept is in our ability to address and solve the marine plastic debris problem through a full life cycle approach to plastics: green birth; green l ife; green death. The major challenge of our day is to use fewer resources and reduce environmental impact, without compromising economic output and growth. Applied to plastics, the answer to this challenge encompasses not only reducing plastic consumpti on and increasing recycling and reuse, but also promoting economic changes and incentives to encourage the innovation and production of environmentally friendlier alternatives, promoting investments in alternative technologies and raw materials, and suppor ting a commercial environment with responsible regulations and standards. In Recognition that the marine plastic debris problem is not mer ely a waste management issue is key. The initiative to reinvent lies uniquely and squarely on the shoulders of chemists. Consideration of the full life cycle of materials must be by design, at the molecular level, rather than when a material becomes wast e. Some bio based plastics have had important commercial success, such as polylactic acid, polyhydroxyalkanoates, and corn starch based materials. However, until now, there has been no single plastic polymer available that is subject to degradation unde r in situ marine environmental conditions.

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46 Principles of Green and Applied Chemistry The great benefits the synthetic polymer industry has brought to m odern society have come with a great price. The technical advantages polymers hold over conventional m aterials like glass and metal prove to be disadvantages when the polymer reaches the end of its useful life cycle 43 Traditional petroleum based polymers not only contribute to the depletion of non renewable resources, but are also believed to persist i n the environment many centuries after being discarded. In the last twenty years, a growing awareness of this problem has led to a push to develop biorenewable materials. This is one of the major areas making up green chemistry. The Pollution Preventio n Act of 1990 pr ovides methods for realizing a greener chemical industry. In addition to establishing a sustainable polymer production and recycling system, the act puts forth the following goals that are applicable to the polymer industry in particular 4 5 : 1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up. 2. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment. 3. Use r enewable feedstocks: Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined. 4. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagent s, which are used in excess and work only once. 5. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals.

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47 6. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible. 7. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment. In or der to apply new technologies with these green characteristics on a commodity scale, three additional criteria must be considered alongside the previous seven: 1. Simplicity: New material products must be synthesized in as few steps as possible from the raw materials. 2. Ease of Implementation: New methods of production must be able to utilize existing manufacturing infrastructures. 3. Low cost: New material products must be not be cost prohibitive if a paradigm shift from petroleum economies is be realized. Degradation of Polylactic Acid 9 Polylactic acid (PLA) has arguably enjoyed the most commercial success as a sustainable thermoplastic. 46 PLA can be made from sustainable resources, most commonly corn, and it is believed to possess the ability to degrade o n a shorter timescale than traditional thermoplastics. While PLA is more amenable to degradation pathways than traditional hydrocarbon based thermoplastics, the mechanisms by which it can degrade are limited, and are best done under very controlled circum stances, such as industrial composting, which requires enzymatic biodegradation (Scheme 3 1). 47 Left to degrade on its own in anaerobic landfill leachate or marine conditions, it is questionable whether PLA will degrade appreciably faster than traditional fossil fuel based polymers, such as polyethylene. 48

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48 Scheme 3 1. The full lifecycle of polylactic acid (PLA) generally relies upon enzymatic biodegradation. We sought to install an abiotically hydrolyzable functional gr oup into the main chain of PLA and targeted the acetal functional group because of our prior experience with polyacetals 49 and the ubiquity of the acetal group in nature. Indeed, it is the most prevalent monomer connecting group on earth since it links th e glucose units of the most abundant polymer, cellulose. Intent on a ring opening copolymerization with lactide strategy, we pursued the 5 membered heterocycle 1,3 dioxolan 4 one (DOX), 50 which bears both the ester and acetal functional groups. We synthe sized this oxa

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49 lactone from formaldehyde and glycolic acid which, in turn, can be made via hydrocarboxylation of fo rmaldehyde with carbon monoxide 51 both pote ntially renewable C1 feedstocks 52 Alternatively, several catalysts have been described that prod uce 1,3 dioxolan 4 one directly from formaldehyde and carbon monoxide (Scheme 3 2). 53 Standard 54 and proprietary 55 ring opening polymerization (ROP) initiators are effective for the copolymerization of 1,3 dioxolan 4 one with lactide, installing the est eracetal functional group that is essentially absent from the polymer literature (Scheme 3 2 ). 56 The persistence of the acetal functional group which can conceivably be lost via formaldehyde extrusion during polymerization is readily verified and quantifi ed by 1 H NMR. Scheme 3 2 Esteracetal copolymers.

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50 Preliminary degradation studies were performed on thin films (0.25 mm thickness prepared by evaporation of chloroform and thickness measured by caliper ) of pol y(DL la ctide) (PDLLA) and the 90:1 0 polyesteracetal copolymer (PLA co DOX). These polymers were stirred in aqueous acid, buffered to pH = 1.0. The films were monitored over time by mass (after rinsing the films with deionized water and drying) and by molecular w eight (GPC, also after rinsing and drying). Table 3 1 and Table 3 2 summarizes the results of the film degradation experiments. Table 3 1. Film Degradation of Poly(D,L)lactic acid a Entry pH b Duration (days) Mass (mg) Mass % M N (kD) c M W (kD) c M W % PDI (22) 1 0 53.77 100.00 82 126 100.00 1.54 (23) 1 5 53.77 100.00 79 126 99.68 1.60 (24) 1 15 53.69 99.85 78 126 99.45 1.61 (25) 1 25 53.73 99.93 79 125 99.23 1.68 (26) 1 35 53.77 100.00 82 126 99.67 1.59 (27) 1 45 53.80 100.06 81 125 98.99 1.55 (28) 5 0 51.83 100.00 82 126 100.00 1.54 (29) 5 5 51.85 100.04 82 126 99.85 1.54 (30) 5 10 51.81 99.96 82 126 99.67 1.54 (31) 5 15 51.75 99.85 ----(32) 5 20 51.75 99.85 82 126 99.62 1.54 (33) 5 25 51.81 99.96 82 126 99.77 1.53 (34) 5 35 51.79 99.92 82 126 99.82 1.54 (35) 5 45 51.81 99.96 82 125 99.33 1.54 (36) 7 0 57.23 100.00 82 126 100.00 1.54 (37) 7 5 57.17 99.90 82 125 98.89 1.53 (38) 7 10 57.14 99.84 ----(39) 7 15 57.10 99.77 ----(40) 7 20 57.11 99.79 82 126 99.70 1.54 (41 ) 7 25 57.13 99.83 82 126 99.40 1.53 (42) 7 35 57.14 99.84 81 126 99.47 1.55 (43) 7 45 57.14 99.84 81 125 99.23 1.54 (44) sea 0 53.88 100.00 82 126 100.00 1.54 (45) sea 5 53.98 100.19 81 126 99.35 1.54 (46) sea 10 53.87 99.98 81 125 99.28 1.55 (47) s ea 15 53.82 99.89 ----(48) sea 20 53.80 99.85 80 125 99.19 1.56 (49) sea 25 53.87 99.98 83 126 100.00 1.53 (50) sea 35 53.87 99.98 81 126 99.62 1.56 (51) sea 45 53.83 99.91 80 125 98.98 1.57 a Degradation conditions: 0. 25 mm thick films of INGE O PLA continuously agitated in water. b Alkaline seawater obtained from Atlantic Ocean, Melbourne, Florida, coastline. c Molecular weights determined by GPC using polystyrene standards

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51 Table 3 2 F ilm Degradation of 90:10 Poly( L lactide) co (1,3 dioxolan 4 one) a Entry pH b Duration (days) Mass (mg) Mass % M N (kD) c M W (kD) c M W % PDI b (52) 1 0 73.87 100.00 64 100 100.00 1.56 (53) 1 5 73.61 99.65 55 96 96.21 1.74 (54) 1 15 73.30 99.23 47 93 93.20 1.97 (55) 1 25 73.26 99.17 45 90 89.58 1.99 (56) 1 35 72.14 99.01 44 88 87.4 2.00 (57) 1 45 73.08 98.93 42 86 85.55 2.05 (58) 5 0 75.23 100.00 64 100 100.00 1.56 (59) 5 5 75.00 99.69 60 98 97.56 1.63 (60) 5 10 74.64 99.22 58 96 95.71 1.66 (61) 5 15 74.53 99.07 ----(62) 5 20 74.43 98.94 56 94 93.65 1. 68 (63) 5 25 74.36 98.84 54 90 90.28 1.68 (64) 5 35 74.18 98.60 52 89 88.72 1.70 (65) 5 45 74.01 98.38 50 87 87.07 1.75 (66) 7 0 76.65 100.00 64 100 100.00 1.56 (67) 7 5 76.44 99.73 63 99 99.00 1.58 (68) 7 10 76.06 99.23 61 98 97.52 1.59 (69) 7 15 7 5.89 99.01 ----(70) 7 20 75.76 98.84 ----(71) 7 25 75.67 98.72 59 94 93.73 1.58 (72) 7 35 75.50 98.50 56 91 90.43 1.62 (73) 7 45 75.29 98.23 54 89 88.91 1.66 (74) sea 0 77.04 100.00 64 100 100.00 1.56 (75) sea 5 76.68 99.53 61 98 97.7 6 1.61 (76) sea 10 76.37 99.13 58 96 95.51 1.64 (77) sea 15 76.24 98.96 ----(78) sea 20 76.15 98.84 ----(79) sea 25 76.16 98.86 56 93 92.53 1.64 (80) sea 35 75.84 98.44 55 92 91.43 1.66 (81) sea 45 75.72 98.29 53 89 88.41 1.66 a Degra dation conditions: 0. 25 mm thick films continuously agitated in water. b Alkaline seawater obtained from Atlantic Ocean, Melbourne, Florida, coastline. c Molecular weights determined by GPC using polystyrene standards. Analysis revealed that the polyesterac etal copolymer decomposed appreciably with more than 1% mass loss occurring over 45 days ( Figure 3 1(A) ), and 35% molecular weight loss ( M n ) over the same time period (Figure 3 1(B) ). In contrast, films of PDLLA showed no appreciable degradation over the 45 day study.

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52 Figure 3 1. Degradation data. Whereas polylactic acid (PDLLA) is not affected, the polyesteracetal (4% DOX) shows considerable molecular weight loss (a) and mass loss (b) upon exposure to aqueous environments of pH 1, pH 5, pH 7 (distil led water), and seawater, over 45 days. Similar experiments conducted in pH 5 water, pH 7 water (distilled water), and seawater (Atlantic Ocean, pH = 7.5) showed that the polyesteracetal copolymer decomposed under slightly acidic, neutral, and slightly ba sic conditions (Figure 3 1 ). In pH 7 water, the polyesteracetal copolymer degraded with nearly 2% mass loss and

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53 more than 15% molecular weight loss ( M n ) over 45 days. Films of PDLLA showed no appreciable degradation over the 45 day study under these cond itions. Interestingly, the polyesteracetal copolymer showed the most rapid degradation by mass under neutral conditions, yet molecular weights decreased most precipitously under highly acidic conditions. The mechanism for this phenomenon is a topic for a dditional study. The SEM images of Figure 3 2 further illustrate the water degradability conferred by the acetal functional group. Images 3a and 3d depict the relatively smooth surfaces of PDLLA and the polyesteracetal (DO X = 4.4 mol%), respectively, imme diately following sample preparation. Image 3 2(B) and 3 2(C) depict the fate of PDLLA after exposure to aqueous pH = 7 and pH = 1 conditions for 45 days, respectively. Note that very little change in the surface roughness can be discerned under these co nditions. Images 3 2(E) and 3 2(F) depict the appearance of the polyesteracetal after being subjected to aqueous pH = 7 and pH = 1 conditions for 45 days, respectively. While little surface change is found for the pH = 7 conditions, the surface erosion a t pH = 1 for the polyesteracetal is substantial and sharply contrasts with the unperturbed outcome for PDLLA under identical conditions. Indeed, the presence of the acetal functional group facilitates surface degradation, often a critical first step in po lymer decomposition. 57

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54 Figure 3 2. Electron microscopy. Under various aqueous conditions, surface erosion over 45 days is insignificant for PDLLA but is quite conspicuous for the polyesteracetal when pH =1. 9

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55 Conclusions 9 The acetal functional group ha s been incorporated into the main chain of polylactic acid (PLA) via ring opening copolymerization of lactide and the oxa lactone, 1,3 dioxolan 4 one. This comonomer was prepared by condensation of glycolic acid and formaldehyde, the final step along a co nceptual pathway employing C1 feedstocks from biomass: methanol, formaldehyde, and carbon monoxide. The presence of the acetal functional group, even at just 4 mol% abundance, substantially altered the properties and behaviour of the PLA. For example, i t increased the glass transition temperature of PLA for acetal incorporati ons in the range of 4 mol% to 36 mol%. Facile degradation of the polyesteracetal was observed in aqueous media over 45 days, including pH = 1, pH = 5, pH = 7 (distilled water), and seawater (pH = 7.5). Mass loss, molecular weight loss, in addition to surface erosion (by SEM, for pH = 1), were observed for the polyesteracetal (DOX = 4 mol%), whereas PLA showed no measurable change under these conditions. The polyesteracetals describ ed herein are designed to have thermomechanical properties similar to those of PLA homopolymer, yet undergo more facile main chain hydrolysis via simple water degradation under abiotic conditions. Thus, enzymatic hydrolysis is likely still feasible, but n ot necessary for the initial degradation steps that convert high molecular weight polymer to oligomers. With an extrapolated 5 10 year degradation profile in seawater and constituent building blocks derived from biomass, these polyesteracetals constitute excellent sustainable alternatives to traditional thermoplastics originati ng from non renewable resources

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56 CHAPTER 4 A COMPARISON OF A RA DICAL POLYMERIZATION MATRIX VS. ROMP MATR IX FOR MOLECULAR IMPRIN TING Background Molecularly imprinted polymers (MIP s), discovered about 35 years ago, represent a new class of materials that have artificially created receptor sites. 58 During the past decade, the development of assays, sensors, and membranes have been areas in which MIPs provide opportunities of advancem ents. 60 Molecular imprinting technology has recently developed into a viable approach for mimicking natural recognition entities, such as antibodies and biological receptors. 60 Polymer matrices with very high selectivity and stability can be obtained, find ing applications in elevated temperature and pressure or reactions under acidic or basic conditions and in organic solvents. 61 In this technology, recognition sites are created in a polymer matrix using a molecular template (print molecule) in a casting p rocedure. Radical polymerization is almost the exclusive method to prepare the MIP matrix; this polymerization functions well with a wide range of applications. Radical polymerization does have certain drawbacks because it cannot be used with some light/he at sensitive compounds and many unstable biomolecules like enzymes, hormones, and polypeptides. There has been little work on ring opening metathesis polymerization (ROMP) as an MIP matrix. 62 The recent discovery of well defined transition metal catalysts for the metathetical polymerization of olefinic compounds makes available a wide range of unique materials. 63 The most effective catalysts have been those derived from [Reprinted in part with permission from American Chemical Society Copyright Office. See Appendix D, infra. Full text and support ing info available at http://pubs.acs.org/doi/abs/10.1021%2Fma061429z (accessed December 11, 2013)]

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57 ruthenium; these have been developed and promulgated by Grubbs. This paper reports on t he comparison of ROMP vs radical polymerization matrices for the synthesis of MIPs. To our knowledge, this is the first comparison of these two matrices in MIPs. Binding Agents We chose a cetylcholine binding agents for this study because of their biologic al interest, inherent positive charge, and inexpensive commercial availability, as shown in Figure 4 1. Eserine has a mesomeric zwitterion or hyperconjugative form that leads to at least a partial positive charge on nitrogen. The templates are polar and a re able to create hydrogen bonds present in the MIP matrices. Figure 4 1. Acetylcholine binding agents Radical Polymerization For the radical polymerization 64 reactions, the template was allowed to form solution complexes pr ior to radical initiation with functional building blocks derived from methacrylic acid. These complexes were subsequently fixed using the cross linking monomer, ethylene glycol dimethacrylate, into a rigid polymeric network, locking the complexes in posit ion in the resulting material, as shown in Scheme 4 1. We used the usually reported template/monomer/cross linking agent ratio of 1:4:16. 65 Thermal conditions with AIBN initiation were used because our templates were light sensitive.

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58 Mechanically grinding the polymer to a powder and removal of the print molecule by refluxing the polymer in ethanol/acetic acid then exposed the recognition sites. It was ensured that the print molecules were totally removed in each case by weighing the mass recovered after ref lux and checking the NMR for of the recovered print molecule for authentication. Scheme 4 1 Radical polymerization. ROMP The ROMP matrices using Grubbs' catalyst provided a cross linked polymer insoluble in methylene chlorid e in less than 1 min, while it took about 10 h for each

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59 radical polymerization to go to completion. Different templa te/monomer/cross linking agent ratios were tested, and it appeared that the best one, in terms of rate of polymerization and mechanical prop erties of the polymer, was 1:4:16, exactly the ratio used for the radical polymerization studies. Second generation Grubbs' catalyst proved to be the most efficient; it allowed not only a faster polymerization but also a higher degree of cross linking. 63 A fter removal of the solvent, the remaining solid was ground to a fine powder, which was subsequently refluxed in ethanol to remove th e template, as shown in Scheme 4 2 After filtration the powdered MIP was ready for selectivity tests.

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60 Scheme 4 2 ROMP Results and Discussion We used GC MS methods to determine the competitive affinity of the polymer for two of the acetylcholine binding compounds, discussed above. Each polymer was suspended in a solution of the print molecule: e ither pyrostigmine bromide or edrophonium bromide. Eserine was selected as the compound competing for the sit es on the MIP with either pyridostigmine bromide or edrophonium bromide Aliquots were taken over time after after removing the polymer by filtrati on and the remain ing solution

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61 was analyzed by GC MS to determine its composition. From the starting amount of material and the amount present in each aliquot, we could quantitatively measure the percentage of binding for each compound to the polymer m atrix The percentage of what remains in solution for both the template and the test molecule were calculated and plotting those against time allowed us to quantitatively compare the binding of each molecule. Comparing the selectivity properties of the radical polymerization vs ROMP matrices was then possible. The first print molecule exami ned was edrophonium chloride with its MIP formed under radical polymerizat ion conditions. When eserine and edrophonium chloride molecules were in competition for the polym er binding sites in solution, there was little differentiation, as shown in Figure 4 2 The peaks and troughs indicate an exchange process; that is, the concentration of the test molecule and the templates kept changing over several minutes. However, the t roughs provided by the polymer formed under free radical conditions were not selective enough to trap either molecule preferentially. The strongest attraction occurred at the trough at the 15 min mark leading to further dissociation after 20 min. It appear s that over time the radical MIP became less selective. The templates and test molecules were not well differentiated by the radical polymerization matrix.

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62 Figure 4 2. Radical polymerization matrix with edrophonium chloride as the print m olecule Next, we examined the same print mo lecule, edrophonium chloride with its MIP formed under ROMP conditions. When eserine and edrophonium chloride molecules were in competition for the polymer binding sites in solution, the selectivity was greatly enhanced and only the desired template molecules (edrophonium chloride) got trapped in the matrix, as shown in Figure 4 3 At 20 min, over 98% of the eserine remained in solution compared with only 9% of the edrophonium chloride. This result indicates that the MIP made by ROMP methodology gave more selective and better shaped cavities than the ones present in the radical induced MIP.

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63 Figure 4 3 ROMP matrix with edrophonium chloride as the print m olecule The seco nd print molecule we studied was pyridostigmine bromide which followed a behavior similar to edrophonium chloride. Once again, the radical polymerization polymer remained fairly unselective, as shown in Figure 4 4 With eserine and pyridostigmine bromide binding in competition, the polymer seemed unable to differentiate them. The pyridostigmine bromide appears to bind best early in the test at the 2 3 min mark, the bound less strongly as time progressed. However, with the ROMP polymer, the selectivity was greatly enhanced and only the print molecule pyr id ostigmine bromide was absorbed in the matrix ( Figure 4 5 ).

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64 Figure 4 4 Radical polymerization matrix with pyridostigmine bromide as the print m olecule Figure 4 5 ROMP Matrix with Pyridostigmine Bromide as the Print Molecule In both cases, we were pleased to see that the "trapping" process of the template took less than 20 min. Note that over 98% of the eserine remained in solution while only

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65 abou t 3% of the pyridostigmine bromide remained in solution. The ROMP matrix appears to be much more selective in this case, as well. Rather than having the print molecules in the cavities within the MIP matrix, they could simply attached on the surface of th e polymer. Thus, the selectivity provided by the MIP would not come from the cavities but only from the nature of the interactions between the molecules and the surface of the polymer. To make sure that the molecules were not on the surface of the polyme r (adsorption), an analysis was performed with blank polymers (no print molecule) for both the radical polymerization and ROMP MIPs. Each blank polymer was mixed with one solution of pyridostigmine bromide, edrophonium chloride or eserine of known weight (the conditions and quantities used in these control tests were identical to those used in the synthesis of the printed polymers). The mixture was stirred under argon and after 10 min, the suspension was filtered. The filtrate was concentrated and the pe rcentage of mass recovered was calculated. The control experiments showed that only a small quantity (average of 3.5%) of molecules was trapped by the blank polymers, meaning that the surface was not responsible for the high selectivities previously obser ved. Conclusion s We report a comparison of ROMP vs radical polymerization matrices in molecular imprinting technology. The ROMP method of polymerization not only improved the binding properties of the polymer but also the selectivity. It is also worth no ting that the comparison of the two polymers is not a perfect one. Different polymers and different starting compounds (methacrylic acid vs norbornenes) were used for radical polymerization vs ROMP matrices. It is also possible that eserine does not bind well to the ROMP polymers, too. As we compared them here, the ROMP method is

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66 faster and uses milder conditions. It is now possible to synthesize highly selective MIPs in a few minutes, not hours. The tolerance of Grubbs' catalyst to a large number of f unctional groups also provides a wide range of molecules to be used.

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67 CHAPTER 5 EXPERIMENTAL General All air sensitive reactions were carried out in oven dried glassware and procedures were per formed under an atmosphere of nitrogen in a glovebox or using s tandard Schlenk techniques. Solvents, benzyl alcohol, and deuterated solvents were purified before use. L Lactide was purchased from PURASORB and was sublimed prior to use. BHT (2,6 di tert butyl 4 methylphenol), sodium hydride, n butyllithium in hexanes ( Acros), EDBP ethylidenebis(4,6 di tert butylphenol)), di n butylmagnesium in heptane (Aldrich), calcium iodide, and sodium bis(trimethylsily)amide (Alfa Aesar) were used as received. 1 H and 13 C NMR measurem ents were performed on a Varian Mercury 300 or 400 MHz spe ctrometer and referenced to resonances due to residual protons in the deuterated solvents or the 13 C resonances of the deuterated solvents. Gel permeation chromatography (GPC) was performed using an internal differential refractive index detector (DRI), in ternal differential viscosity detector (DP), and a Precision 2 angle light scattering detector (LS). The light scattering signal was collected at a 15 angle, and the three in line detectors were operated in series in the order of LS DRI DP. The chromatogr aphy was performed at 45 C using two tandem injection volume. In the case of universal calibration, retention times were calibrated versus narrow range molecular weight polystyrene standards. All standards were selected to produce Mp or Mw values well

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68 ion LS was calibrated using a narrow range polystyrene standard with Mw = 65 500 g/mol. Differen tial scanning calorimetry (DSC) was performed using a DSC equipped with a controlled cooling accessory at a heating rate of 5 C/min unless otherwise specified. were analyzed using an empty pan as a reference and empty cells for a subtracted baseline. All mass spectroscopy was performed by the Mass Spectroscopy Service at the University o f Florida Department of Chemistry. T he GC/MS analyses were performed on a Shimadzu GC 17 NGCMS QP5000. 1,3 dioxolan 4 one (1) Glycolic acid (2 2 8 0 g, 30 0 mmol) and paraformaldehyde (1 2 9 0 g, 36 0 mmol) were dissolved in b enzene (80 0 mL). p TsOH H 2 0 ( 2.42 g 14.0 mmol) was added and the mixture was refluxed for 12 h using a Dean Stark apparatus. The mixture was cooled, washed with 5% aqueous NaHCO 3 water and brine, and dried with magnesium sulfate. Evaporation of the so lvent and distillation over Ca H gave the product (7.39 g 23 %) as a colorless oil 1 H NMR (CDCl 3 300 MHz) 4.2 (s, 2H), 5.5 (s, 2H); 13 C NMR (CDCl 3 75 MHz) 62.3, 96.0, 171.5.

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69 [BHTLiTHF] 2 (3) P repared following lit erature procedures. 19 [BHTNaTHF] 3 (4 ) Prepared following literature procedures. 19 BHT 2 MgTHF 2 (5) Prepared following literature procedures. 19

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70 BHT 2 CaTHF 3 (6 ) Prepared following literature procedures. 19 [(EDBPH)Na(THF) 2 ][Na(THF)(EDBPH)] (7) Prepared following literature procedures. 20 General Procedure for Ring Opening Polymerization 1,3 dioxolan 4 one (4.148 g, 46 mmo l) was dissolved in anhydrous toluene (46 mL, 1 mol L 1 ) under nitrogen at 100 C. A solution of tin(II)2 ethylhexanoate (571 mg, 1.4 mmol) and benzyl alcohol (151 mg, 1.4 mmol) in anhydrous toluene (3.92 mL) was added into the flask through a septum. A r esulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr.

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71 Poly(1,3 dioxo lan 4 one) (8 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate ( 37.08 mg, 0.0909 mmol) and benzyl alcohol ( 9. 81 mg, 0.0909 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insolubl e product (0.40 g 10% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxo lan 4 one) (9 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate ( 46.35 mg, 0.1136 mmol) and benzyl alcohol ( 12.26 mg, 0.1136 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed with in 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product (0.52 g 13% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxo lan 4 one) (10 )

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72 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate ( 92.7 0 mg, 0.2272 mmol) and benzyl alcohol ( 24.52 mg, 0.2272 mmo l) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product (0.80 g 20% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxolan 4 one) (11 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nit rogen at 100C. A solution of tin(II)2 ethylhexanoate ( 139.05 mg, 0.3408 mmol) and benzyl alcohol ( 36.78 mg, 0.3408 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product (1.04 g 26% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxo lan 4 one) (12 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate ( 370.80 mg, 0.9090 mmol) and benzyl alcohol ( 98.10 mg, 0.9090 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within

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73 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product (1.48 g 37% ) was wash ed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxolan 4 one) (13 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate ( 1.854 g 4.545 mmol) and benzyl alcohol ( 490.50 mg, 4.545 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture w as allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product (2.80 g 70% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. Poly(1,3 dioxolan 4 one) (1 4 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) was dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of (5) ( 121.58 mg, 0.2272 mmol) and benzyl alcohol ( 24.52 mg, 0.2272 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. A resulting transparent precipitate was noticed upon addition and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the insoluble product ( 1.96 g 49% ) was washed with 200 mL of cold methanol, and dried under vacuum a t room temperature for 24 hr.

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74 Poly( caprolactone co 1,3 dioxolan 4 one) (15 ) 1,3 dioxolan 4 one (4 g, 4 5.45 mmol) and caprolactone ( 0.518 g, 4 .54 mmol) w ere dissolved in anhydrous toluene ( 10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexan oate ( 61.36 mg, 0.1515 mmol) and benzyl alcohol ( 11.23mg, 0.1515 mmol) in anhydrous toluene ( 5 mL) was added into the flask through a septum. T he reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product (3.31g 73% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 6 hr. The resulting product was soluble only in hexafluoroisopropano l (HFIP). NMR was taken while dissolved in HFIP. 1 H (CDCl 3 ) ppm 1.36 (m, 2H), 1.62 (m, 4H), 2.38 (t, 2H), 4.04 (t, 2H), 4.21 (s ), 4.83 (s 2 H); 13 C (CDCl 3 ) ppm 61.96 130.82, 168.45 Poly( L lactide ) ( 16 ) L lactide ( 6.551 g, 45.45mmol) was dissolved in anhydrous toluene (10 mL ) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol) in anhydrous toluene (5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 h r and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product ( 6.08 g 93% ) was washed with 200 mL of cold methanol, and dried under

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75 vacuum at room temperature for 24 hr. 1 H (CDCl 3 ) : ppm 1.56 (d, 3 H), 5.13 (q, 1 H). 13 C NMR (CDCl 3 ): 16.87, 69.24, 169.84 Poly( lactide co 1,3 dioxolan 4 one ) ( 17 ) (90:10 feed ratio) 1,3 dioxolan 4 one ( 0. 4 g, 4 545 mmol) and L lactide (5.896 g, 40.91 mmol) was dis solved in anhydrous toluene (10 mL) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol) in anhydrous toluene (5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product ( 5.74 g 91 % ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. 1 H (CDCl 3 ) ppm 1.56 (d, 6H), 4.75 (m, 4H), 5.13 (q, 2H); 13 C (CDCl 3 ) ppm 16.86, 61.00, 69.23, 95.71, 166.73, 169.83 Poly( lactide co 1,3 dioxolan 4 one ) ( 18 ) (80:20 feed ratio) 1,3 dioxolan 4 one ( 0.8 g, 9.09 mmol) and L lactide (5. 24 g, 36.36 mmol) was dissolved in anhydrous toluene (10 mL) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol) in anhydrous toluene (5 mL) was added into the flas k through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product ( 5.13 g 85 % ) was washed with

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76 200 mL of cold methanol, and dried under vacuum at r oom temperature for 24 hr. 1 H (CDCl 3 ) ppm 1.56 (d, 6H), 4.75 (m, 4H), 5.13 (q, 2H) ; 13 C (CDCl 3 ) 169.83. Poly( lactide co 1,3 dioxolan 4 one ) ( 19 ) (70:30 feed ratio) 1,3 dioxolan 4 one ( 1.2 g, 13.64 mmol) and L lactide (4.59 g, 31.82 mmol) was dissolved in anhydrous toluene (10 mL) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol) in anhydrous toluene (5 mL) was a dded into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product ( 4.40 g 76% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. 1 H (CDCl 3 ) ppm 1.56 (d, 6H), 4.75 (m, 4H), 5.13 (q, 2H); 13 C (CDCl 3 ) 16.86, 69.21, 169.77. Poly( lactide co 1,3 dioxolan 4 one ) ( 20 ) (60:40 feed ratio) 1,3 dio xolan 4 one ( 1.6 g, 18.18 mmol) and L lactide (3.93 g, 27.27 mmol) was dissolved in anhydrous toluene (10 mL) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol) in anhydrous tol uene (5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under

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77 nitrogen for 24 hr. After removal of toluene, the product ( 3.76 g 68% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. 1 H (CDCl 3 ) ppm 1.56 (d, 6H), 4.75 (m, 4H), 5.13 (q, 2H); 13 C (CDCl 3 ) 169.83. Poly( lactide co 1,3 dioxolan 4 one ) ( 21 ) (50:50 feed ratio) 1,3 dioxolan 4 one ( 2.0 g, 22.73 mmol) and L lactide (3.28 g, 22.73mmol) was dissolved in anhydrous toluene (10 mL) under nitrogen at 100C. A solution of tin(II)2 ethylhexanoate (37.08 mg, 0.0909 mmol) and benzyl alcohol (9.81 mg, 0.0909 mmol ) in anhydrous toluene (5 mL) was added into the flask through a septum. A resulting white precipitate was noticed within 1 hr and the reaction mixture was allowed to stir under nitrogen for 24 hr. After removal of toluene, the product ( 2.69 g 51% ) was washed with 200 mL of cold methanol, and dried under vacuum at room temperature for 24 hr. 1 H (CDCl 3 ) ppm 1.56 (d, 6H), 4.75 (m, 4H), 5.13 (q, 2H); 13 C (CDCl 3 ) 169.84. General Procedure for Radical Polymerization Pyridostigmine bromid e (0.75 mmol, 195.8 mg) was added to a round bottom flask, methacrylic acid (30.0 mmol, 0.28 mL) was poured and the mixture was allowed to stir for 10 minutes under argon. Ethylene glycol (12.0 mmol, 2.25 mL), AIBN (0.17 mmol, 28 mg) and distilled acetonit rile (3 .0 mL) were added. The mixture wa s refluxed for 8 hours. The white solid obtained was then ground, suspended in ethanol and

PAGE 78

78 refluxed overnight to remove the template (pyridostigmine). The powder was dried under vacuo to give the polymer. General Procedure for ROMP Polymerization Pinacolyl methylphosphonate (0.76 mmole, 138.0 mg), bicyclo[2.2.1 ]hept 5 en 2 carboxylic acid (3.06 mmol 422.0 mg) and hexanedioic acid dibicyclo[2.2.1] hept 5 en 2 ylmethyl ester (12.3 mmol 4.4 g) were dissolved in CH 2 C l 2 (31 mL). After waiting 30 minutes for electrostatic bonding to occur between monomers and templates, generation II Grubbs catalyst (0.09 mmol 81.3 mg) was added and the solution was allowed to stir until a solid formed. In few minutes, the solution bec ame a soft gelatin structure with a pink color. To remove Grubbs c atalyst, the solid was washed with CH 2 Cl 2 (100 mL) and ethyl vinyl ether after grinding. The solution was stirred 15 minutes and fi ltered. To remove excess ethyl vinyl ether and monomers, th e solution was washed with EtOAc and filtered. Then to remove the template, the mixture was refluxed overnight with ethanol, filtered and the solvent was removed under reduce d pressure. Bicyclo[2.2.1]hept 5 en 2 yl methano l or 5 Norbornene 2 methanoI Aldeh yde (1.23 mol, 15 g, 14.9 mL) was dissolved in methanol (150 mL) and the mixture was cooled to OC. Sodium borohydride (0.49 mol, 18.6 g) was added and the solution was stirred overnight. A saturated solution of ammonium chloride was added and the solution was filtered. The white solid was washed with water. The aqueous layer was then extracted with chloroform. The solvent was removed in vacuo and the crude product (14.9 g, 98%) was used without further purification. 1 H (CDCl 3 ) 6.1 8 (m, 1H), 5.96 (m, 1 H ), 3.38 3.25 (m, 2H), 2.95 (m, 1H), 2.82 (m, 1 H), 1.82 (m, 1 H), 1.47 (m, 2H), 1.38 (m, 2H); 13 C (CDC l 3 ) 136.93, 136.40, 136.23, 132.01 66.72, 66.74, 49.22, 44.65, 43.32, 43.03, 41.95, 41.36, 41.26, 41.20, 29.34, 28.62.

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79 Hexaned ioic acid dibicyclo[2.2.1]hept 5 en 2 ylmethyl ester Norbornene alcohol (0.81 mmol, 100 mg) was dissolved in freshly distilled methylene chloride (2 mL), pyridine (2.42 mmol, 191.4 mg, 0.2 mL) was added at room temperature and the solution was allowed to s tir for 30 minutes. The reaction was then cooled to OC and adipoyl chloride (0.885 mmol, 0.13 mL) was added slowly. The solution was stirred overnight. Brine was added to the mixture and the aqueous layer was extracted with methylene chloride. The organi c layers were then dried over magnesium sulfate. The solvent was removed in vacuo and the crude material was purified by flash chromatography with ether/hexane (50/50) to give a clear oil (267 mg, 92%). 1 H (CDCl 3 ) 6.14 (dd, 2H), 5.93 (m, 2H), 3.82 (dd, 2 H), 2.84 (d, 4H), 2.34 (m, 7H), 1.82 (m, 2H), 1.64 (m, 4H), 1.42 (dq, 2H), 1.26 (m, 5H); HRMS for [ C 22 H 31 0 4 +2H] + calc. 360.2144, found 360.2251.

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80 APPENDIX A SPECTRAL DATA Figure A 1. HNMR of (1)

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81 Figure A 2. CNMR of (1)

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82 Figure A 3. HNMR of (15 )

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83 Figure A 4. CNMR of (15 )

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84 Figure A 5. HNMR of ( 16 )

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85 Figure A 6. CNMR of (16)

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86 Figure A 7 HNMR of (17 )

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87 Figure A 8 CNMR of ( 1 7 )

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88 Figure A 8 HNMR of (1 8 )

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89 Figure A 9. CNMR of (18)

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90 Figure A 10 HNMR of (1 9 )

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91 Figure A 11. CNMR of (1 9 )

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92 Figure A 12 HNMR of ( 20 )

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93 Figure A 13. C NMR of (20)

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94 Figure A 1 4 HNMR of (21 )

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95 Figure A 15. CNMR of (21)

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96 APPENDIX B GEL P ERMEATION CHROMATOGRAPHY DATA Figure B 1 GPC (16)

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97 Figure B 2. GPC (17 ) Figure B 3. GPC (18 )

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98 Figure B 4. GPC (19 ) Figure B 5. GPC (20 )

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99 Figure B 6. GPC (21 ) Figure B 7. GPC (22 )

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100 Figure B 8. GPC (23 ) Figure B 9. GPC (2 4 )

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101 Figure B 10. GPC (25 ) Figure B 11. GPC (26 )

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102 Figure B 12. GPC (27 ) Figure B 13. GPC (28 )

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103 Figure B 14. GPC (29 ) Figure B 15. GPC (30 )

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104 Figure B 16 GPC (32 ) Figure B 17 GPC (33 )

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105 Figure B 18 GPC (34 ) Figure B 19 GPC (35 )

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106 Figure B 20 GPC (36 ) Figure B 21 GPC (37 )

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107 Figure B 22 GPC (40 ) Figure B 23 GPC (41 )

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108 Figure B 24 GPC (42 ) Figure B 25 GPC (43 )

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109 Figure B 26 GPC (44 ) Figure B 27 GPC (45 )

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110 Figure B 28 GPC (46 ) Figure B 29 GPC (48 )

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111 Figure B 30 GPC (49 ) Figure B 31 GPC (50 )

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112 Figure B 32 GPC (51 ) Figure B 33 GPC (52 )

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113 Figure B 34 GPC (53 ) Figure B 35 GPC (54 )

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114 Figure B 36 GPC (55 ) Figure B 37 GPC (56 )

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115 Figure B 38 GPC (57 ) Figure B 39 GPC (58 )

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116 Figure B 40 GPC (59 ) Figure B 41 GPC (60 )

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117 Figure B 42 GPC (62 ) Figure B 43 GPC (63 )

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118 Figure B 44 GPC (64 ) Figure B 4 5 GPC (65 )

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119 Figure B 46 GPC (66 ) Figure B 47 GPC (67 )

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120 Figure B 48 GPC (68 ) Figure B 49 GPC (71 )

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121 Figure B 50 GPC (72 ) Figure B 51 GPC (73 )

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122 Figure B 52 GPC (74 ) Figure B 53 GPC (75 )

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123 Figure B 54 GPC (76 ) Figure B 55 GPC (79 )

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124 Figure B 56 GPC (80 ) Figure B 57 GPC (81 )

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125 APPENDIX C D IFFERENTIAL SCANNING CALORIMETRY DATA Figure C 1 DSC trace of (8)

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126 Figure C 2 DSC trace of (9)

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127 Figure C 3 DSC trace of (10)

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128 Figure C 4 DSC trace of (11)

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129 Figure C 5 DSC trace of (12 )

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130 Figure C 6 DSC trace of (13 )

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131 Figure C 7 DSC trace of (14 )

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132 Figure C 8 DSC trace of (16)

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133 Figure C 9 DSC trace of (17)

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134 Figure C 10 DSC trace of (18)

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135 Figure C 11 DSC trace of (19)

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136 Figure C 12 DSC trace of (20)

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137 Figure C 13 DSC trace of (21)

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138 APPENDIX D AMERICAN CHEMICAL SOCIETY COPYRIGHT PERMISSION

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139

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140 LIST OF REFERENCES (1) US Congress. B iomass Research and Development Act of 2000 http://www.csree s.usda.gov/about/offices/legis/pdfs/biomass.pdf (accessed December 11, 2013). (2) Biomass R&D Technical Advisor y Committee, Vision for Bioenergy and Biobased Products in the United States ; Washington D.C., Oct. 2002. (3) Royte, E. Corn Plastic to th e Rescue. Smithsonian [Online] Aug 2006 http://www.smithsonianmag.com/science nature/plastic.html (accessed December 11, 2013). (4) Ilg, A. D.; Price, C. J.; Miller, S. A. Macr omolecules 2007 40 7739 7741. (5) U.S. Department of Energy. Methane Hydrate http://energy.gov/fe/science innovation/oil gas research/methane hydrate (accessed December 11, 2013). (6) ( 6 a) PennWell Petroleum Group Oil & Gas Journal 2006 104(47) 22 25 ( 6 b) Department of Energy/Energy Information Administration. Inte rnational Energy Outlook 2007. DOE/EIA 0484 ( 2007 ). http://library.uoregon.edu/ec/e asia/read/dork 6.pdf (accessed December 11, 2013). (7) ( 7 a) Oak Ridge National Laboratory. Methane Extra ction and Carbon Sequestration. ORNL Review 2002 35(2) 4 5. www.ornl.gov/info/ornlreview/v35_2_02/v35_no2_02review.pdf accessed December 11, 2013). ( 7 b) Oak Ridge National Laboratory. Methane Hydrates: A Carbon Management Challenge. ORNL Review 2000 33(2) 14 15. www.ornl.gov/info/ornlreview/v33_2_00/vol33_no2.pdf (accessed December 11, 2013) (8) Amundsen, L.; Landro, M. Gas Hydrates. GeoExPro [Online], 2012 3(9) http://www.geoexpro.com/article/Gas_Hydrates_Part_I_Burning_Ice/69fe2a11.asp x (accessed December 11, 2013) (9) Text and Figures from a paper in preparation for submission authored by Mart in, R. T. ; Carmargo L. P. ; Miller S. A. (10) Burwicz, E. B.; Ruepke, H.; Wallman, K. Geochimica et Cosmochimica Acta 2011 75 4562 4576. (11) (11 a) Cevidalli, G.; Ragazzini, M.; Modena, M. Copolymers of Carbon, U.S. Patent 3,673,156, June 27, 1972 ( 11 b) Modena, M.; Ragazzini, M.; Gallinella, E. J. Polym. Sci., Part B: Polym. Lett 1963 1(10) 567 570. (11 c) Ragazzini, M.; Modena, M.; Gallinella, E.; Cevidalli, G. J. Polym. Sci., Part A: Gen. Pap 1964 2(10) 5203 5212.

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146 BIOGRAPHICAL SKETCH Originally from the Jersey Shore, Ryan came to Gainesville as a UF undergrad, a National Merit Scholar, a Hugh O'Brian Youth Leader, and a Boys State Alumnus. As a Gator, Ryan excelled both in and out of the classroom and received a B.S. in Biochemistry. Ryan was the Varsity Men's Captain for the UF Rowing Team, as well as a leader in his church, leading a bible study and several mission trip s both in the US and overseas. Ryan was also a frequent volunteer for the University Homeless Council. In addition, Ryan has personally served his community and state by being a volunteer prison minister since 2003. Ryan has counseled inmates and encourage d them to be better husbands and fathers and to become productive members of society. Ryan even found time to spend a summer in New York City, studying acting and has landed work on stage, film, and TV, including among other things a few episodes of All My Children. Ryan's interests and abilities reach farther an avid runner, swimmer, surfer, and overall adventurer. A self taught guitarist, he also occasionally performs on GROW based music radio station. Ryan continued his education at UF as a Ph.D. student in organic chemistry. Ryan became an author of multiple publications in the area of polymer chemistry and innovated a new class of sustainable and degradable plastics. So great was the impact of this invention that R yan was awarded the 2011 Cade Prize for Innovation and Invention. With a great appreciation for invention and intellectual property and always eager for new challenges, Ryan enrolled in and excelled at law classes while completing his Ph.D. Ryan was a stan dout student in law, and it earned him a position on the professional staff of one of the top intellectual property law firms in the country. While

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147 working at the firm, Ryan had the rare experience of being able to work on the prosecution of his own patent on his doctoral work in sustainable and degradable plastics. Ryan started his company Florida Sustainables in 2011 to commercialize green plastics such as those described herein. Within just months of forming the company, Ryan and Florida Sustainables had already received attention and praise from Forbes, Fast Company and MSNBC, along with many other professional, scientific and industrial publications around the globe. Florida Sustainables was even honored with a World Economic Forum Young Scientist/Entre preneur Partnership Award. Florida Trend magazine selected Florida Sustainables as the 2011 Newsmakers of the Year for Science and Innovation. Ryan also has the honor of being named the 2012 Face of Technology for the Florida High Tech Corridor. Ryan is cu rrently leading Florida Sustainables through scale up and manufacturing and is committed to creating more jobs specifically in the Gainesville area and North Central Florida. Not only is Ryan's work having a great impact on this community, but also it will have a hugely positive impact worldwide, in helping to mitigate the plastic trash crisis in our oceans and landfills. Ryan has cast a vision for Florida Sustainables that includes not only creating industry leading, sustainable and degradable plastics, bu t also being fully committed to the community and world through pollution clean up and education. Ryan is passionately committed to education and spurring on innovation in younger people. Ryan spent several years as a graduate student teaching organic chem istry laboratory classes and consistently received the highest evaluations and appreciation from his

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148 students. Ryan can frequently be found encouraging science education in younger students by volunteering for science fairs (including the Alachua County Sc ience Fair), in classrooms, or at the Cade Museum, and has served as a judge and keynote speaker for Florida's Junior Science and Humanities Symposium. Ryan also has been an invited guest speaker at UF to teach on innovation and entrepreneurship, and was a n invited speaker at the 2011 Global Entrepreneurship Week in Miami as a panelist in the