SYNTHESIS AND GAS-TRANSPORT PROPERTIES OF HIGH-MOLECULAR-WEIGHT BLOCK COPOLYMERS OF STYRENE AND VINYLTRIMETHYLSILANE

Poly(styrene-b-vinyltrimethylsilane) of high molecular weight and varying composition suitable for membrane applications has been synthesized at 50-60-degrees-C. The copolymer could be made as a tapered block copolymer by polymerizing both monomers at the same time (r1 and r2 = 0.08 and 13) or as a pure block copolymer with some homopolymer contaminant by sequential addition of monomers. However, in both methods the copolymer phases out of solution before the reaction is complete. The copolymers can exhibit phase separation in the solid and dissolved states. Poly(styrene-b-vinyltrimethylsilane) membranes have some unique gas transport properties. The poly (vinyltrimethylsilane) segments are phase separated and dispersed in a continuous polystyrene matrix so the resultant membranes can have over twice the permeability of polystyrene but also retain the high selectivity of polystyrene. These results should be applicable to other biphasic systems where the low permeability phase is also the continuous phase.