SYNTHESIS OF POROUS POLYMERIC MEMBRANES BY POLYMERIZATION OF MICROEMULSIONS

In this study the polymerization of monomer-containing micro-emulsions to yield porous polymeric membranes is demonstrated. A micro-emulsion system composed of methyl methacrylate and acrylic acid as monomers, ethyleneglycol dimethacrylate as crosslinking agent, sodium dodecylsul fate as surfactant and water was studied. An identical surfactant-free system, formed using the same monomers, crosslinking agent and water but without surfactant, was also studied and the micro-emulsions forme d at certain compositions were polymerized. Our earlier work with thes e systems had indicated the porous morphology of the polymer to be dep endent on the microstructure of the precursor micro-emulsion. In the p resent study micro-emulsion compositions which showed inferential evid ence of a bicontinuous structure were polymerized to form membranes by using photo-initiated polymerization with ultra-violet radiation. The membranes formed had a thickness of 10-12 mum. The swelling character istics in water of the polymeric material constituting the membranes w as evaluated as a function of pH. The tensile properties of the membra nes were also evaluated. The permeability of the membranes was examine d using aqueous solutions of acrylic acid. The results indicate the pe rmeability of the membranes to be dependent on the composition of the precursor micro-emulsion due to the relationship between the polymer m orphology and micro-emulsion structure. This study conclusively shows the feasibility of synthesizing porous polymeric membranes by utilizin g the structure of micro-emulsions.