Microporous polymeric materials by microemulsion polymerization: Effect of the ratio of long and short alkyl chain length cationic surfactants

Bicontinuous microemulsions consisting of methyl methacrylate, 2-hydroxyethyl methacrylate, ethylene glycol dimethacrylate, and water mixtures of long and short alkyl chain length cationic n-alkyltrimethylammonium bromides as surface-active agent, were used as precursors for the formation of porous polymeric materials. It was found that the mixing ratio of long and short chain length surfactants has a pronounced influence on the morphology and microstructure of the polymeric materials so obtained. At a particular ratio of long to short alkyl chain length cationic surfactants, the pores were found to be irregular and sponge-like in structure resembling that of a bicontinuous structure. All electron microscopy investigation, swelling and permeability studies indicate an increase in pore sizes of the polymeric materials on increasing the weight ratio of long chain length relative to that of short chain length surfactant. The modification in the microstructure of the polymeric materials is discussed in terms of the interfacial film rigidity. Copyright (C) 1996 Elsevier Science Ltd.