Microporous polymeric materials from polymerization of zwitterionic microemulsions

Abstract

A new microemulsion system consisting of a polymerizable zwitterionic surfactant of (((acryloyloxy)-undecyl)dimethylammonio)acetate (AUDMAA), methyl methacrylate (MMA), water with or without a cross-linking agent of ethylene glycol dimethacrylate (EGDMA) was investigated. Transparent solid polymeric materials can be produced by photoinitiated polymerization of some of these microemulsion compositions. Microemulsions with higher concentrations of EGDMA (>4%) or MMA (>50%) produced only turbid polymeric materials. However, it required a minimum of about 25% AUDMAA for producing a transparent polymeric material. Most of the bicontinuous microemulsions investigated could be gelled within 10 min and transparent solid polymers were finally obtained. Electron micrographs of these transparent polymers reveal the existence of not only the open-cell type microstructures but also the bicontinuous nature. The widths of the bicontinuous structures were about 50-70 nm, their lengths were long and winding and they appear to be randomly distributed. The microporous structures of these transparent polymeric materials seem to be related to the microstructures of the precursor bicontinuous-microemulsions. Perhaps, this is the first report to show the bicontinuous structures of microporous polymeric materials prepared by microemulsion polymerization. © 1995 American Chemical Society.