Novel brush copolymers via controlled radical polymerization

摘要

A combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) techniques were applied for the synthesis of novel polymer brushes by using the "grafting from" approach or a combination of "grafting through" and "grafting from" methods. The procedure included the following steps: (1) Synthesis of 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM), (2a) RAFT homopolymerization of BIEM to obtain PBIEM as the polymer backbone. (2b) RAFT copolymerization of BIEM and PEO macromonomer (PEOMA, M-w = 450 g (.) mol(-1), DPPEO = 9) to obtain a more hydrophilic polymer backbone. Well-controlled copolymers containing almost 25 mol- of PEOMA were obtained, and (3) ATRP homopolymerization of methyl acrylate (MA) and copolymerization of MA with 1-octene using both PBIEM homopolymer and poly(BIEM-co-PEOMA) as polyinitiators resulted in brushes with densely grafted homopolymer and copolymer side chains, respectively. Well-controlled copolymer side chains containing 15 mol- of 1-octene were obtained. Relatively narrow molar mass distributions (MMD) were obtained for the ATRP experiments. The formation of the side chains was monitored using size exclusion chromatography (SEC) and NMR spectroscopy. The copolymer composition in the side chain was confirmed using H-1 NMR spectroscopy. Contact angle measurements indicated that for the brush polymers, containing 1-octene in the side chain, there was a decrease in the surface energy, as compared with the brush polymers containing only the homopolymer of MA in the side chain.GRAPHICSTapping-mode SFM images for the poly(BIEM)-graft-poly(MA-co-octene) brush polymer, dip coated from dilute THF solution on mica.