Porous PS- and PMMA-based polymeric monoliths prepared by PEO-PS block copolymers stabilized High internal phase emulsion templates

Abstract

In this contribution, two well-defined amphiphilic block copolymers, i.e., polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) and poly(ethylene oxide)-b-polystyrene (PEO-b-PS) were synthesized through activators regenerated by electron transfer atom transfer radical polymerization. The as-prepared block copolymers with similar molar mass successfully served as stabilizer for preparing both styrene (St) and methyl methacrylate (MMA) containing HIPEs. The properties of HIPE and the effects of processing conditions (e.g., type and concentration of stabilizer, shearing rate, and aqueous phase volume) on the morphology of the resulting polyHIPEs were investigated by the rheology and scanning electron microscopy analysis. The results show that the block copolymer stabilized HIPEs and the corresponding polyHIPEs possess higher strength compared with the samples stabilized by span80. In addition, PS-based polyHIPEs from the block copolymer stabilized emulsion have an almost closed-cell structure, while PMMA-based polyHIPEs have an open-cell structure. Moreover, it is proven that the concentration of stabilizer plays a critical role in preparing PMMA-based polyHIPEs with high-porosity. It is believed that other functional polymeric porous monoliths can be readily prepared through HIPE templating by using the commonly known PEO-PS block copolymers without the sophisticated surfactant design.