Synthesis and surface properties of polydimethylsiloxane-based block copolymers: poly[dimethylsiloxane-block- (ethyl methacrylate)] and poly[dimethylsiloxane-block-(hydroxyethyl methacrylate)]

Abstract

A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)-terminated PDMS and 4,4'-azobis-4- cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2-(trimethylsilyloxy) ethyl methacrylate (TMSHEMA) monomers. The poly(DMS-block-EMA) and poly(DMS-block-TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and (1)H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS-block-HEMA) and poly(DMS-block-EMA) copolymer film surfaces were analysed using scanning electron microscopy and X-ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS-block-EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS-block-HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase-separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. (C) 2010 Society of Chemical Industry