Preparation of Hairy Particles and Antifouling Films Using Brush-Type Amphiphilic Block Copolymer Surfactants in Emulsion Polymerization

Abstract

Two series of well-defined brush-type amphiphilic block copolymers of polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PS-b-P(PEGMA300) and PS-b-P(PEGMA1100)) were synthesized via atom transfer radical polymerization (ATRP) and used as surfactants in emulsion polymerization. The self-assembly behavior of these block copolymers in aqueous solution was studied by dynamic light scattering and cryogenic transmission electron microscopy. The critical micelle concentration of the synthesized polymers was found to depend on the length of the PEG side chains, but neither on the molar mass of the P(PEGMA) blocks nor the temperature. All of the block copolymers form micelles in the nanometer range. Emulsion polymerizations of styrene were carried out using the obtained brush-type amphiphilic block copolymers, and the influence of the block copolymer structure, surfactant concentration, and temperature was studied. The PS-b-P(PEGMA1100) copolymers seem to be the most efficient surfactants at low polymerization temperature, providing good colloidal stability. Monodisperse hairy particles with core−shell structures (observed by cryo-TEM) were obtained using the block copolymers with the long PEG side chain and the highest molar mass. Polystyrene films prepared from the latexes, containing the brush-type copolymers, display a lower contact angle than that obtained in films with conventional low molecular weight surfactants. In addition, the incorporation of PEGMA brushes on the polystyrene particles, and hence on the films, decreases the adsorption of proteins and, in this particular case, of bovine serum albumin.