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Anionic Synthesis And Functionalization Of Dinaphthylalkyllithium End Functionalized Polystyrene
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Book Synopsis Anionic Synthesis and Functionalization of Dinaphthylalkyllithium End Functionalized Polystyrene by : Gilda M. Lizarraga
Download or read book Anionic Synthesis and Functionalization of Dinaphthylalkyllithium End Functionalized Polystyrene written by Gilda M. Lizarraga and published by . This book was released on 1991 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Anionic Synthesis of Functionalized Polymers by : Jonathan E. Janoski
Download or read book Anionic Synthesis of Functionalized Polymers written by Jonathan E. Janoski and published by . This book was released on 2010 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 [alpha] and [alpha,omega]-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. [alpha]-Triethoxysilyl-functionalized polystyrene was quantitatively prepared by hydrosilation with triethoxysilane and [alpha]-4-pentenylpolystyrene. [alpha]-4-Pentenyl-[omega]-silyl hydridefunctionalized polystyrene and [alpha]-4-pentenyl-[omega]-thiol hydride functionalized polystyrene were quantitatively prepared by terminating [alpha]-4-pentenylpoly(styryl)lithium with chlorodimethylsilane and ethylene sulfide, respectively. The [alpha]-4-pentenyl-[omega]-silyl hydride-functionalized polystyrene showed good agreement between calculated and observed molecular weights and a narrow polydispersity. [alpha]-4-Pentenyl-[omega]-thiolfunctionalized 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-functionalized polystyrenes were prepared. Chain-end, silyl hydride-functionalized polystyrene was prepared quantitatively. Hydrosilation of chain-end, silyl hydride-functionalized polystyrene with allyl cyanide resulted in [omega]-cyano-functionalized polystyrene, which was prepared in 87% yield. In-chain, silyl hydride-functionalized polystyrene was prepared by terminating excess poly(styryl)lithium with dichloromethylsilane. The remaining poly(styryl)lithium was terminated with ethylene oxide to aid in chromatographic separation to yield the pure in-chain, silyl hydride-functionalized polystyrene in 96% yield. Hydrosilation of in-chain, silyl hydride-functionalized polystyrene with allyl cyanide resulted in cyano in-chain functionalized polystyrene in 58% yield after 2 weeks of reaction time at elevated temperature. [omega]-Silyl dihydride-functionalized polystyrene was prepared in 92% yield by inverse addition of poly(styryl)lithium to dichloromethylsilane then reduction with lithium aluminum hydride. Functionalization with allyl cyanide yielded [omega]-dicyanofunctionalized polystyrene quantitatively. Synthesis of functionalized polymers from silyl hydride-substituted monomers was also investigated. para-Dimethylsilylstyrene was prepared from 4-chlorostyrene in 84% yield. Homopolymerization, copolymerization, and end-capping of poly(styryl)lithium in cyclohexane with this monomer was investigated, and it was found that a linking reaction is occuring. meta-Dimethylsilylstyrene was prepared from 3-bromostyrene in 75% yield. Anionic homopolymerization, and copolymerization of this monomer were investigated, and it was found that a more vigorous linking reaction was taking place compared to the para-substituted analog.
Book Synopsis Anionic Synthesis of Chain-end and In-chain Functional Polymers by : Elizabeth Wichman
Download or read book Anionic Synthesis of Chain-end and In-chain Functional Polymers written by Elizabeth Wichman and published by . This book was released on 2008 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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'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."--Abstract.
Book Synopsis Synthesis of End-chain and In-chain Functionalized Polymers by Anionic Polymerization by : Michael Olechnowicz
Download or read book Synthesis of End-chain and In-chain Functionalized Polymers by Anionic Polymerization written by Michael Olechnowicz and published by . This book was released on 2008 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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 bases effect dramatic changes in microstructure, initiation rates, propagation rates and monomer reactivity ratios for alkyllithium-initiated polymerizations of vinyl monomers in hydrocarbon solution. The stability of polymeric organolithium compounds and the mechanism of decomposition in the presence of various stoichiometric equivalents of tetrahydrofuran in benzene solutions were studied due the importance of THF as an additive."--Abstract.
Book Synopsis Synthesis of Well-Defined Multi-End Functionalized Polymers Via Living Anionic Polymerization by : Norazilawati Muhamad Sarih
Download or read book Synthesis of Well-Defined Multi-End Functionalized Polymers Via Living Anionic Polymerization written by Norazilawati Muhamad Sarih and published by . This book was released on 2010 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous applications require specific properties at polymer surfaces that differ from the bulk, while retaining the advantageous properties of the bulk polymer. In this thesis, we describe work aimed at producing a series of multi-end functionalized polystyrene and polyisoprene additives with a wide range of molecular weights, carrying 1 to 3 fluoroalkyl groups that have been prepared by end capping the living chain ends of polymers prepared via anionic polymerization reactions. The resulting polymers have a well-defined structure with interesting surface modifying properties. We have also carried out hydrogenation of end functionalized polyisoprene to form poly(ethylene-alt-propylene) with the same functional group. The resulting polymers have been used as additives in an attempt to render the surface of polymer films hydrophobic/lipophobic and we have characterized these polymer films using static contact angle measurements with water as the main contact fluid. We have systematically studied the effect of additive molecular weight, concentration and annealing conditions on the surface properties. It has been discovered that these additives undergo rapid adsorption to a surface or interface and significantly enhance surface properties. In addition, to support the contact angles results, elastic recoil detection analysis (ERDA) and Rutherford backscattering analysis (RBS) have been carried out to acquire further quantitative evidence of surface segregation.
Book Synopsis Anionic Synthesis of Well-defined Functionalized and Star-branched Polymers by : Manuela Ocampo
Download or read book Anionic Synthesis of Well-defined Functionalized and Star-branched Polymers written by Manuela Ocampo and published by . This book was released on 2007 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Novel methods for the synthesis of chain-end and in-chain functionalized polymers, as well as star polymers, were developed using anionic polymerization techniques. A new mechanism for the reaction of polymeric organolithium compounds with thiiranes has been found. The reaction of poly(styryl)lithium and poly(butadienyl)lithium with propylene sulfide and ethylene sulfide was investigated in hydrocarbon solution for the preparation of thiol-functional polymers. It was found by MALDI-TOF mass spectral analysis of the reaction products that the reaction proceeded by attack of the anion on the methylene carbon atom of the thiirane ring followed by ring opening to form the thiol-functionalized polymer. The reaction of poly(styryl)lithium with trimethylene sulfide did not produce the corresponding thiol-functionalized polymer; the resulting methyl-terminated polymer was formed by attack of the anion on the sulfur atom followed by ring opening to form a primary carbanion. A new method for synthesis of alkoxysilyl-functionalized polymers was developed. Using a general functionalization methodology based on the hydrosilation of vinyltrimethoxysilane with [omega]-silyl hydride-functionalized polystyrene, alkoxysilyl-functionalized polystyrene was obtained in high yield (83 %). The main side product was vinylsilane-functionalized polymer. A small amount of dimer (approximately 2 %) was formed from the hydrosilation reaction of silyl hydride-functionalized polymer and vinylsilane-functionalized polymer. Star polymers with an average number of 6.8 arms were obtained by reacting poly(styryl)lithium with 6.6 equivalents of vinyldimethylchlorosilane in benzene at 30 °C. It was found that, in benzene at 30 °C, vinyldimethylchlorosilane is an efficient linking agent for the preparation of well-defined star-branched polymers. In contrast, the reaction of poly(styryl)lithium with 5 equivalents of vinyldimethylchlorosilane in THF at -78 °C produced vinylsilane-functionalized polymer in high yield (> 93 %). Poly(styryl)lithium was reacted with 2.5 equivalents of vinyldimethylethoxysilane; reaction occurred exclusively by the addition of the living anion to the vinyl group. In-chain, dihydroxyl-functionalized polystyrene was prepared by reaction of poly(styryl)lithium and 1,3-butadiene diepoxide. The hydroxyl functionalities were activated with potassium naphthalenide. Addition of ethylene oxide monomer yielded the corresponding heteroarm polystyrene/poly(ethylene oxide) stars. Two commercially available triepoxides, N,N-diglycidyl-4-glycidyloxyaniline and Tactix 742, were used to prepare the corresponding 3-armed stars in high yield.
Book Synopsis Anionic Synthesis of In-chain and Chain-end Functionalized Polymers by : Sumana Roy Chowdhury
Download or read book Anionic Synthesis of In-chain and Chain-end Functionalized Polymers written by Sumana Roy Chowdhury and published by . This book was released on 2006 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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)dimethylsilane. 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 copolymerizations 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: r(Si) =0.16 and r(S) = 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 polymer chain. Also, r(Si)r(S) = 0.27, which shows that the copolymer has a tendency to have an alternating structure. Amino acid-functionalized polymers (biohybrids) were synthesized by using a simple and efficient, three-step method. The first step was to make a copolymer of styrene with (4-vinylphenyl)dimethylsilane, followed by introduction of amine functional groups into the polymer chain, suing a hydrosilation reactions between the silyl-hydride units in the copolymer chain and the double bond of allyl amine. The third step was a condensation reaction between these amine functional groups on the copolymer chain and the carboxyl group on N-carbobenzyloxy-phenylalanine (a protected amino acid). Although this method has been used to incorporate a particular amino acid onto the polymer chain, it maybe possible to extend this procedure to introduce virtually any amino acid or peptide group into the polymer chain. Finally a thermoplastic elastomer (TPE) was synthesized using the monomer (4-vinylphenyl)dimethylsilane. The first block of this TPE was a copolymer block of styrene with (4-vinylphenyl)dimethylsilane, followed by a polyisoprene block and finally another copolymer block of styrene and (4-vinylphenyl)dimethylsilane. This polymer was characterized using SEC, 1H and 13C NMR, FTIR, DSC, DMTA, TEM and tensile testing. It was seen to exhibit properties similar to those of a regular styrene-diene-styrene TPE. However, the silyl-hydride units introduced into this polymer chain can be easily converted to different functional groups using hydrosilation reactions. Introduction of such functional groups would be helpful in tailoring the properties of the TPE."--Abstract.
Book Synopsis End-group Functionalization of Anionically Synthesized Polymers Via Hydrosilation Reactions by : Hoon Kim
Download or read book End-group Functionalization of Anionically Synthesized Polymers Via Hydrosilation Reactions written by Hoon Kim and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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 ..."--Iii
Book Synopsis Anionic Synthesis of Chain-end Functionalized Polymers by : Kwansoo Han
Download or read book Anionic Synthesis of Chain-end Functionalized Polymers written by Kwansoo Han and published by . This book was released on 1995 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
