scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Controlled Radical Polymerization by Degenerative Transfer - Effect of the Structure of the Transfer Agent

01 Nov 1995-Macromolecules (American Chemical Society)-Vol. 28, Iss: 24, pp 8051-8056
TL;DR: In this article, various transfer agents of the type R-I were explored, and 1-phenylethyl iodide, iodoacetonitrile, and iodoform were found to be effective in controlling molecular weights and for providing polymers with relatively low polydispersities.
Abstract: Control of the radical polymerization of styrene and acrylates has been achieved by using alkyl iodides in a degenerative transfer process. Various transfer agents of the type R-I were explored. Of those examined, 1-phenylethyl iodide, iodoacetonitrile, and iodoform were found to be effective in controlling molecular weights and for providing polymers with relatively low polydispersities, M w /M n ≤ 1.5. Relatively good control has been also achieved with perfluoroalkyl iodides, whereas most alkyl and aryl iodides have been ineffective transfer agents. Also explored were the effects of initiator structure and reaction temperature on the polymerization systems.
Citations
More filters
Journal ArticleDOI
TL;DR: The authors proposed a reversible additive-fragmentation chain transfer (RAFT) method for living free-radical polymerization, which can be used with a wide range of monomers and reaction conditions and in each case it provides controlled molecular weight polymers with very narrow polydispersities.
Abstract: mechanism involves Reversible Addition-Fragmentation chain Transfer, and we have designated the process the RAFT polymerization. What distinguishes RAFT polymerization from all other methods of controlled/living free-radical polymerization is that it can be used with a wide range of monomers and reaction conditions and in each case it provides controlled molecular weight polymers with very narrow polydispersities (usually <1.2; sometimes <1.1). Living polymerization processes offer many benefits. These include the ability to control molecular weight and polydispersity and to prepare block copolymers and other polymers of complex architecturesmaterials which are not readily synthesized using other methodologies. Therefore, one can understand the current drive to develop a truly effective process which would combine the virtues of living polymerization with versatility and convenience of free-radical polymerization.2-4 However, existing processes described under the banner “living free-radical polymerization” suffer from a number of disadvantages. In particular, they may be applicable to only a limited range of monomers, require reagents that are expensive or difficult to remove, require special polymerization conditions (e.g. high reaction temperatures), and/or show sensitivity to acid or protic monomers. These factors have provided the impetus to search for new and better methods. There are three principal mechanisms that have been put forward to achieve living free-radical polymerization.2,5 The first is polymerization with reversible termination by coupling. Currently, the best example in this class is alkoxyamine-initiated or nitroxidemediated polymerization as first described by Rizzardo et al.6,7 and recently exploited by a number of groups in syntheses of narrow polydispersity polystyrene and related materials.4,8 The second mechanism is radical polymerization with reversible termination by ligand transfer to a metal complex (usually abbreviated as ATRP).9,10 This method has been successfully applied to the polymerization of various acrylic and styrenic monomers. The third mechanism for achieving living character is free-radical polymerization with reversible chain transfer (also termed degenerative chain transfer2). A simplified mechanism for this process is shown in

4,561 citations

Journal ArticleDOI
TL;DR: In this article, a review of recent mechanistic developments in the field of controlled/living radical polymerization (CRP) is presented, with particular emphasis on structure-reactivity correlations and "rules" for catalyst selection in ATRP, for chain transfer agent selection in reversible addition-fragmentation chain transfer (RAFT) polymerization, and for the selection of an appropriate mediating agent in stable free radical polymerisation (SFRP), including organic and transition metal persistent radicals.

2,869 citations


Cites background from "Controlled Radical Polymerization b..."

  • ...A simple example of DT occurs in the presence of conventional RP initiators and alkyl iodides (Scheme 15) [258,259]....

    [...]

Journal ArticleDOI
TL;DR: Atom transfer radical polymerization (ATRP) is one of the most successful methods to polymerize styrenes, (meth)acrylates and a variety of other monomers in a controlled fashion, yielding polymers with molecular weights predetermined by the ratio of the concentrations of consumed monomer to introduced initiator and with low polydispersities as discussed by the authors.

1,189 citations

Journal ArticleDOI
TL;DR: In this article, a review of fundamental kinetic features of living radical polymerization (LRP) is presented, where the authors show that the product from LRP can have a low polydispersity, provided that the number of terminated chains is small compared to the number potentially active.

844 citations

Journal ArticleDOI
10 May 1996-Science
TL;DR: A radical polymerization process that yields well-defined polymers normally obtained only through anionic polymerizations is reported, and has all of the characteristics of a living polymerization.
Abstract: A radical polymerization process that yields well-defined polymers normally obtained only through anionic polymerizations is reported. Atom transfer radical polymerizations of styrene were conducted with several solubilizing ligands for the copper(I) halides: 4,4′-di-tert-butyl, 4,4′-di-n-heptyl, and 4,4′-di-(5-nonyl)-2,2′-dipyridyl. The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities (ratio of the weight-average to number-average molecular weights of 1.04 to 1.05). Similar results were obtained for the polymerization of acrylates.

837 citations