Microporous polymeric materials by polymerization of microemulsions containing different alkyl chain lengths of cationic surfactants

Microemulsion systems formulated with methyl methacrylate, 2-hydroxyethyl methacrylate, cross-linking agent, ethylene glycol dimethacrylate (EGDMA) and water using cationic surfactants of n-alkyl trimethyl ammonium bromide with alkyl chain lengths varying from C12 to C16 have been investigated. Photoinitiated polymerization was carried out only for bicontinuous microemulsion samples to form microporous polymeric materials. The opacity of the resulting polymeric materials decreased with the use of shorter alkyl chain lengths of the cationic surfactants. In addition, the morphology of the microporous polymeric solids as observed by Field Emission Scanning Electron Microscope shows a drastic change from worm-like, oval-shaped to globular structures on decreasing the alkyl chain length of the surfactant at a particular concentration. These polymeric materials possessed open-cell structures. Their pore sizes were smaller and their pore volume distributions were narrower for polymer samples using shorter alkyl chain-length surfactants. This study shows the feasibility of controlling the microstructures and pore dimensions of the polymeric materials prepared by polymerization of bicontinuous microemulsions containing different alkyl chain lengths of cationic surfactants. Copyright (C) 1996 Elsevier Science Ltd.