Block copolymerization of poly(ethylene glycol) with methyl methacrylate using redox macroinitiators

Abstract

Abstract A series of block copolymers of poly(ethylene glycol) (PEG) with methyl methacrylate (MMA) were prepared using a redox system consisting of ceric ion and PEG of various molecular weights in aqueous medium. The block copolymerization experiments were carried out under such conditions in which there was no homopolymerization of MMA by Ce 4+ alone. The intermediacy of the PEG macroradical in the redox process was substantiated by ESR spectroscopy and a polymerization proceeding through ‘blocking from’ mechanism was postulated. The formation of the block copolymers was confirmed by chemical test and fractional precipitation as well as by FT‐IR and FT‐NMR ( 1 H and 13 C‐( 1 H)) spectroscopy. The triblock nature of the block copolymers was ascertained through the cleavage of the ether linkage of the PEG segment. Simultaneous TG/DTA studies of the block copolymers revealed multiple stage decomposition patterns and their DSC curves exhibited two glass transition temperatures. GPC investigation of the block copolymers revealed unimodal molecular weight distribution with M n values showing a smooth increase with ascending molecular weights of PEG. SEM studies indicated a fine dispersion of PEG in the continuous PMMA matrix.