New chain transfer agents for free radical polymerizations
TL;DR: The palmitoyl ester of N-hydroxypyridine-2-thione showed useful chain transfer properties in free radical polymerizations of methyl methacrylate and styrene as discussed by the authors.
Abstract: The palmitoyl ester of N-hydroxypyridine-2-thione displayed useful chain transfer properties in free radical polymerizations of methyl methacrylate and styrene. Retardation, however, accompanied the lowering of molecular weight in methyl acrylate and vinyl acetate polymerizations.
4-Methyl-3-palmitoyloxythiazol-2(3H)-thione had good chain transfer activity with methyl methacrylate, styrene and methyl acrylate. Although benzyl thionobenzoate exhibited virtually ‘ideal’ behaviour (chain transfer constant Cx ∼1) in styrene and methyl acrylate polymerizations, it was ineffective in lowering molecular weight of poly(methyl methacrylate). Severe retardation was observed with vinyl acetate.
Addition-fragmentation pathways are postulated for chain transfer.
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TL;DR: In this paper, a review of the development of addition-fragmentation chain transfer agents and related ring-opening monomers highlighting recent innovation in these areas is presented, including dithioesters, trithiocarbonates, dithioco-baramates and xanthates.
1,309 citations
TL;DR: This work simulates free-radical homopolymerizations under restricted polymerization conditions with real-world examples of several different types of monomer systems.
Abstract: Several models have been proposed in the literature over the last two decades in order to simulate free-radical homopolymerizations. However, most of these models deal with one specific monomer system, usually under restricted polymerization conditions.
97 citations
TL;DR: In this article, a new N-succinimide activated ester of p-vinyl benzoic acid (PVBE) was reported, with Mn ranging between 44 and 61 kDa and PDI of 1.03 and 1.07.
Abstract: Developing new materials with unique properties for nanotechnology applications, in general, and supramolecular polymers, in particular, lie at the heart of much ongoing research. In line with these efforts, we have been exploring polymers containing terpyridine (terpy) in the side chain. Here we report a new monomer that effectively undergoes reversible addition fragmentation chain transfer polymerization (RAFT) to yield high-molecular-weight (Mn) polymers with narrow polydispersity (PDI). The monomer is an N-succinimide activated ester of p-vinyl benzoic acid. Under RAFT conditions, poly(N-succinimide p-vinylbenzoate)s were generated, with Mn ranging between 44 and 61 kDa and PDI of 1.03–1.07. One of these homopolymers was reacted with an amine functionalized terpy, creating a new homopolymer containing terpy ligands on every monomer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5618–5625, 2007
72 citations
TL;DR: In this paper, a review summarizes nearly 400 references (since 1990) intended to highlight directions on the synthesis of telechelic oligomers and macromonomers by radical techniques, taking into account the recent developments in conventional radical polymerizations, such as dead-end polymerizationand also telomerization reactions.
Abstract: This review summarizes nearly 400 references (since 1990) intended to highlight directions on thesynthesis of telechelic oligomers and macromonomers by radical techniques. This review first takes intoaccount the recent developments in further conventional radical polymerizations, such as dead-end polymerizationand also telomerization reactions. Among all the conventional radical polymerizations, addition–fragmentationtransfer (AFT) polymerization realized a real breakthrough for the synthesis of telechelic oligomersand especially for macromonomers by coupling AFT with catalytic chain transfer. Then, surveys concerningtelechelic oligomers and macromonomers prepared by living radical polymerizations are mentioned. Atom transferradical polymerization, nitroxide-mediated polymerization, reversible addition–fragmentation chaintransfer polymerization and also iodine transfer polymerization allow for accurate control of chain-endfunctionality, either a functional group or a double bond. Novel reactions like radical couplingof oligomers previously obtained by living radical polymerizations are enhanced.
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TL;DR: The aliphatic and alicyclic esters of N-hydroxypyridine-2-thione are readily reduced by tributylstannane in a radical chain reaction to furnish nor-alkanes as discussed by the authors.
487 citations
TL;DR: In this article, a linear relation between the chemical shifts of CS and CO is found: δ(CS) = 1.75·δ (CO) - 79.6 for 0-substituted thioesters and δ (CS)-1.31 for dithioesters.
Abstract: Simple alifatic and aromatic esters, such as ethyl, iso-propyl, and benzyl benzoates, benzyl butanoate, ethyl heptanoate, and ethyl 1- and 2-naphthoate, respectively, react with the dimer of p-methoxyphenylthiono-phosphine sulfide 1 in anhydrous xylene at 140°C to give the corresponding 0-substituted thioesters in nearly quantitative yields. Also simple alifatic and aromatic S-substituted thioesters, such as S-phenyl, S-benzyl and S-tert-butyl thiobenzoates, S-phenyl and S-benzyl thioacetates, and S-ethyl thiobutanoate, produced the corresponding dithioesters in nearly quantitative yields upon treatment with 1 in anhydrous toluene at 110°C. 13C NMR data for the carbonyl- and corresponding thiocarbonyl carbons, have been recorded and a linear relation between the chemical shifts of CS and CO is found: δ(CS) = 1.75·δ (CO) - 79.6 for 0-substituted thioesters and δ(CS) = 1.31.δ (CO) - 22.1 for dithioesters. An anomalous reaction has been observed: Thiobenzoic acid, S,S'-methylene ester 2 reacted with 1 to give 4,5-diphenyl-1-1,3-dithiol-2-thion 3.
128 citations
TL;DR: In this paper, the tautomerism of thiohydroxamic acids has been examined by physical methods and it is confirmed that the esters used are derivatives of the thione tautomers.
Abstract: Carbon radicals derived from the esters of several types of thiohydroxamic acids have been trapped in a number of different ways. Particular attention has been paid to carbon–carbon bond formation by addition to suitably activated ethylenic linkages. Carboxylic acids can be conveniently converted into homo- and bishomo-acids by free radical chemistry based on thiohydroxamic esters. In a coda the tautomerism of the thiohydroxamic acids have been examined by physical methods. It is confirmed that the esters used are derivatives of the thione tautomer.
123 citations