Doctor of Philosophy, University of Akron, 2011, Polymer Science

A variety of methods were used to make polymers with different architecture and functionalities. The linking chemistry of vinyldimethylchlorosilane (VDMCS) with poly(styryl)lithium (Mn = 1,700-3,000 g/mol) was studied. The average degree of branching varied from 7.5 to 9.4 with an increase in concentration of VDMCS (1.2 to 5.2 eq). The intrinsic viscosities and melt viscosities (at 160 °C) of the star polymers were found to be less than half of that of the corresponding linear polystyrenes. α-Pyrrolidine-functionalized polystyrene (Mn = 2,700 g/mol, Mw/Mn = 1.03, 92.5%) was successfully synthesized from α-chloromethyldimethylsilane-functionalized polystyrene(Mn = 2,600 g/mol, Mw/Mn = 1.02) based on NMR spectroscopy, MALDI-TOF and ESI mass spectrometry. The stability of silyl hydride groups under atom transfer radical polymerization conditions was proven by copolymerizing methyl methacrylate and (4-vinylphenyl)dimethylsilane (VPDS). Tapered block copolymers of isoprene, VPDS, and styrene with narrow molecular weight distributions (1.04 and 1.05) were synthesized via anionic polymerization. Evidence regarding the topology of cyclic polybutadienes was obtained by Atomic Force Microscopy of grafted polymers obtained by grafting an excess of silyl hydride functionalized polystyrene (Mn = 8,300 g/mol, Mw/Mn =1.01) onto cyclic polybutadiene(Mn=88,000 g/mol, Mw/Mn = 2.0). The reactivity of polyisobutylene carbocations was compared with respect to competitive electrophilic addition to a vinyl group versus silyl hydride transfer by investigating the reaction with VPDS. Based on GPC results, and 1H and 13C NMR spectroscopy, no evidence for any vinyl group addition was observed. A successful attempt was made to prepare electrospun fibers from fluorofunctionalized styrene-butadiene elastomers. The water contact angle of these surfaces was found to be 162.8o ± 3.8o for the fibrous mat of the fluorinated polymers as compared to 151.2o ± 2.4o for the analogous fibrous (open full item for complete abstract)

Committee: Roderic Quirk Dr. (Advisor); Mark Foster Dr. (Committee Chair); Judit Puskas Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member); Kevin Cavicchi Dr. (Committee Member) Subjects: Polymers

Doctor of Philosophy, University of Akron, 2010, Polymer Science

The synthesis of well-defined functionalized polymers is an important area of research due to their wide array of applications. The work presented herein can be divided into three categories: a) functional initiator synthesis; b) chain-end and in-chain functionalization and c) functional monomer synthesis and polymerization. All three methods involve both anionic polymerization and hydrosilation. In this work, all anionic polymerizations were performed at room temperature in hydrocarbon solvent with an alkyllithium initiator. A functional 4-pentenyllithium initiator was prepared in 70% yield and was used for the synthesis of α and α,ω-functionalized polystyrene. 4-Pentenyllithium was used to initiate styrene polymerization in benzene in the presence of 5 equivalents of tetrahydrofuran. Narrow polydispersity indices and good agreement between calculated and observed molecular weights were observed for the methanol-terminated product. α-Triethoxysilyl-functionalized polystyrene was quantitatively prepared by hydrosilation with triethoxysilane and α-4-pentenylpolystyrene. α-4-Pentenyl-ω-silyl hydride-functionalized polystyrene and α-4-pentenyl-ω-thiol hydride functionalized polystyrene were quantitatively prepared by terminating α-4-pentenylpoly(styryl)lithium with chlorodimethylsilane and ethylene sulfide, respectively. The α-4-pentenyl-ω-silyl hydride-functionalized polystyrene showed good agreement between calculated and observed molecular weights and a narrow polydispersity. α-4-Pentenyl-ω-thiol-functionalized polystyrene showed a dimer peak due to oxidative coupling when quenched with methanol. Triethoxysilyl-functionalized, high-1,4-polybutadiene was prepared by reacting the pendant double bonds of the 1,2-units with triethoxysilane via hydrosilation. High-yielding reactions between the polymeric organolithium chain-ends and silyl chlorides were used to obtain the desired polymeric silyl hydrides for further functionalization. In-chain and chain-end cyano-funct (open full item for complete abstract)

Committee: Roderic Quirk Dr. (Advisor); Mark Foster Dr. (Committee Chair); Li Jia Dr. (Committee Member); Judit Puskas Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member) Subjects: Chemistry; Experiments; Molecules; Polymers

Master of Science, University of Akron, 2008, Polymer Science

The purpose of this research was to anionically prepare well-defined polystyrenes that had functional groups either at the chain end or in the middle of the chain. Functional groups were introduced by using a general functionalization method (GFM). For chain-end functionalizations, after poly(styryl)lithium was synthesized, it was terminated with chlorodimethylsilane. This produced chain-end, silyl hydride-functionalized polystyrene. Then, through a hydrosilation reaction between the silyl hydride group and the double bond of a substituted alkene, chain-end functional polystyrene was produced. For in-chain functionalizations, after poly(styryl)lithium was prepared, it was linked with dichloromethylsilane, which placed a silyl hydride functionality in the middle of the chain. This was then reacted with an alkene in a hydrosilation reaction to produce the in-chain functionalized polystyrene. Hydrosilations were performed using Karstedt…#8482;s catalyst in benzene at room temperature. Allyl acetate and methyl-3-butenoate were the alkenes used for both chain-end and in-chain functionalizations, as well as allyl alcohol for in-chain functionalizations. The functionalized polystyrenes were characterized by FTIR, 1H NMR and 13C NMR spectroscopy, and MALDI TOF MS.

Committee: Roderic Quirk PhD (Advisor) Subjects: Polymers

Doctor of Philosophy, University of Akron, 2008, Polymer Science

The synthesis of homopolymers and block copolymers containing metal coordinating ligands is an important area of research due to the potential applications of these polymers in the fields of optics, electronics, and photonics. Specifically, the terpyridine group is very useful, since it can act as a tridentate chelating ligand due to its strategically positioned, three nitrogen atoms. This allows it to form strong complexes with a variety of transition metal ions.The hydroxyl functionality is another important group due to numerous applications of well-defined hydroxyl-functionalized polymers. They can react with other functional groups on other polymers for chain extension, branching, or crosslinking. They can also be used as macroinitiators for the polymerization of other monomers such as lactide and lactone. Alkyllithium-initiated, living anionic polymerization offers excellent control over molecular weight and molecular weight distribution. The absence of termination and chain transfer steps makes these systems ideally suited for the preparation of chain-end functionalized polymers by the reaction of the living chain ends with appropriate monomers or terminating agents. A recently reported general anionic functionalization method was used to create well-defined terpyridine and hydroxyl end-functionalized polymers. In the first step, living polymeric organolithium compounds were reacted with silyl chlorides to form the corresponding silyl hydride-functionalized polymers. Then, these polymers were reacted with substituted alkenes in the presence of a hydrosilation catalyst to form the corresponding functionalized polymers. A new method was also developed, based on similar chemistry, to prepare an in-chain functionalized diblock copolymer where a variety of functional groups can be placed directly at the interface of the two blocks. This method was used to prepare both in-chain hydroxyl- and terpyridine-functionalized polystyrene-b-polyisoprene copolymers. Lewis (open full item for complete abstract)

Committee: Roderic Quirk Ph.D. (Advisor) Subjects: Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2006, Polymer Science

The objective of this work was to anionically synthesize well-defined polymers having functional groups either at the chain-end or along the polymer chain. General functionalization methods (GFM) were used for synthesizing both kinds of polymers. Chain-end functionalized polymers were synthesized by terminating the anionically synthesized, living polymer chains using chlorodimethylsilane. Hydrosilation reactions were then done between the silyl-hydride groups at the chain-ends and the double bonds of commercially available substituted alkenes. This produced a range of well-defined polymers having the desired functional groups at the chain-ends. In-chain functionalized polymers were synthesized by anionically polymerizing a silyl-hydride functionalized styrene monomer: (4-vinylphenyl)dimethysilane. Polymerizations were done at room temperature in hydrocarbon solvents to produce well-defined polymers. Functional groups were then introduced into the polymer chains by use of hydrosilation reactions done post-polymerization. The functionalized polymers produced were characterized using SEC, 1H and 13C NMR, FTIR, MALDI TOF mass spectrometry and DSC. The monomer reactivity ratios in the copolymerization of styrene with (4- vinylphenyl)dimethylsilane were also measured. A series of copolymerizaions was done with different molar ratios of styrene(S) and (4-vinylphenyl)dimethylsilane (Si). Three different methods were used to determine the values of the monomer reactivity ratios : Fineman-Ross, Kelen-Tudos and Error-In-Variable (EVM) methods. The average values of the two monomer reactivity ratios obtained were: rSi = 0.16 and rS = 1.74. From these values it was observed that in the copolymerization of styrene with(4-vinylphenyl)dimethylsilane, the second monomer was preferentially incorporated into the copolymer chain. Also, rSirS = 0.27, which shows that the copolymer has a tendency to have an alternating structure. Amino acid-functionalized polymers (biohybrids) were synth (open full item for complete abstract)

Committee: Roderic Quirk (Advisor) Subjects:

Doctor of Philosophy, University of Akron, 2006, Polymer Science

One of the unique features of living, alkyllithium-initiated, anionic polymerization is the ability to produce a stable carbanionic chain end after complete monomer consumption, which can be followed by reaction with electrophiles to form various end-functionalized polymers. Although a variety of functional polymers have been synthesized in the last few decades, each specific functionalization has had to be designed and optimized individually. Consequently, the development of general functionalization methodologies has drawn recent interest. However, even these general functionalization methods require the use of protecting groups, and the complexity in synthetic routes and the thermal/moisture instability of many protected functional agents have restricted their practical application. This thesis describes a new, general functionalization methodology, combining well-defined, living anionic polymerization with efficient and highly selective, platinum-catalyzed hydrosilation reactions with functionalized alkenes. Well-defined, Si-H functionalized polymers (P-SiH) have been synthesized by sec-butyllithium-initiated, living anionic polymerization in benzene followed by termination with dimethylchlorosilane. Even though the Si-H bond is polar and labile, it is stable with respect to reactions with organolithium compounds in hydrocarbon solvents. These Si-H bonds are also stable to oxygen and moisture in the atmosphere so that Si-H functionalized polymers can be isolated and handled in air. These silyl hydride-functionalized polymers were isolated simply by precipitation into methanol, in which they are also stable. Silyl hydride-functionalized polystyrenes and polyisoprenes have been prepared and characterized by SEC, 1H, 13C and 29Si NMR spectroscopy, FT-IR spectroscopy and MALDI-TOF mass spectrometry. For quantitative analysis, the ratio of the integration area of 1H NMR resonances for the six methyl protons of the dimethylsilane unit at a –0.1 ppm to the other six me (open full item for complete abstract)

Committee: Roderic Quirk (Advisor) Subjects: Chemistry, Polymer