TRIMETHYLSILYL-GROUP CONTAINING POLYPHENYLACETYLENES FOR OXYGEN AND ETHANOL PERMSELECTIVE MEMBRANES

Phenylacetylenes having one or two trimethylsilyl groups at their benz ene ring were synthesized, and polymerized by [Rh (cyclooctadiene) (PP h3)2]PF6, [Rh(norbornadiene) Cl]2, or WCl6 to afford high molecular-we ight polymers in high yields. These poly(phenylacetylene)s were solubl e in many kinds of solvents and were fabricated to tough membranes by the solvent casting method. The oxygen permselectivities of these memb ranes were very good. The oxygen permeability coefficients (P(O2)) and oxygen separation factors (alpha = P(O2)/P(Na)) of poly[2,4(op)-bis(t rimethylsilyl)phenylacetylene] [poly(o-1-p-1)] and y[(4(p)-trimethylsi lyl)phenylacetylene][poly(p-1)] membranes were 4.73 X 10(-8) cc (STP) cm/cm2 s cmHg and 2.65, and 1.52 X 10(-8) cc (STP) cm/cm2 s cmHg and 3 .39, respectively. In the case of poly(o-1-p-1), P(O2) was comparable to that of polymethylsiloxane (PDMS) and alpha was higher than that of PDMS. However, the P(O2) value reduced to 48% of its initial value in about 1 year. In the case of poly (p-1), the P(O2) value did not chan ge in about 1 year. Ethanol permeated preferentially through these mem branes (alpha(EtOH) > 1) in pervaporation of aqueous ethanol solution, whereas poly(phenylacetylene) [poly(PhA)] showed water permselectivit y (alpha(EtOH) < 1). These favorable effects of trimethylsilyl groups on the oxygen and ethanol permselectivities were discussed on the basi s of comparison with those of poly (PhA), other poly (substituted phen yl-acetylene) s, and trimethylsilyl-group containing polystyrenes. (C) 1994 John Wiley & Sons, Inc.