Synthesis of amphiphilic poly(ethylene oxide)-b-poly(methyl methacrylate) diblock copolymers via atom transfer radical polymerization utilizing halide exchange technique

Abstract

Amphiphilic diblock copolymers with different molecular weights and low polydispersities were synthesized by atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) using PEO-Br as an initiator, which was obtained by the esterification of polyethylene oxide) (PEO) with 2-bromoisobutyryl bromide. The polymerization proceeded in solution using halide exchange technique to control ATRP. Fourier transform infrared spectroscopy (FT-IR) and 1H NMR studies confirm the composition of PEO-Br macroinitiator and related diblock copolymers. The results obtained by GPC analysis show that the number average molecular weight was increased versus monomer conversion and the polydispersities were quite low (<1.10), which is the character of a controlled/"living" polymerization. Moreover, the crystallization behavior of PEO-b-PMMA block copolymers was studied by means of differential scanning calorimetry (DSC). It was found that the crystallization behavior of the block copolymers exhibited considerable differences in comparison to the neat PEO. The crystallization rate and the degree of crystallinity decreased by an increase of PMMA content.