RAFT synthesis of branched acrylic copolymers

Vo, Cong-Duan, Rosselgong, J, Armes, Steven P and Billingham, Norman C (2007) RAFT synthesis of branched acrylic copolymers. Macromolecules, 40. pp. 7119-7125.

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Abstract

We report the synthesis of branched acrylic copolymers based on 2-hydroxypropyl acrylate using reversible addition fragmentation chain transfer (RAFT) polymerization in tert-butanol at 80 °C. Three branching comonomers were investigated in this study:  ethylene glycol diacrylate, bisphenol A ethoxylated diacrylate and a disulfide-based diacrylate. The latter comonomer allows chemical degradation of the branched acrylic copolymers to produce thiol-functionalized primary chains. Gel permeation chromatography analysis of these degraded copolymer chains indicated low polydispersities (Mw/Mn < 1.22), which confirmed that the living character of the RAFT chemistry was retained under branching conditions. RAFT allows significantly more than one branching agent per primary chain to be used in the copolymerization without causing gelation. This result was obtained with all three branching comonomers and differs from the near-ideal copolymerizations previously reported for the ATRP synthesis of branched methacrylic copolymers (Macromolecules 2006, 39, 7483−7492). Detailed HPLC analysis of the RAFT copolymerization of 2-hydroxypropyl acrylate with bisphenol A ethoxylated diacrylate indicates near-statistical incorporation of the latter comonomer. We suggest that intramolecular cyclization is the primary reason for the apparent violation of classical Flory−Stockmayer gelation theory. This hypothesis is supported by the observation that substantially more ethylene glycol diacrylate than bisphenol A ethoxylated diacrylate can be tolerated in such branching copolymerizations without causing gelation.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Norman Billingham
Date Deposited: 06 Feb 2012 19:55
Last Modified: 26 Mar 2012 09:43
URI: http://sro.sussex.ac.uk/id/eprint/22977
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