Diphenylacetylenes having various silyl groups (PhC≡CC6H4-SiR 1 R 2 R 3 , SiR 1 R 2 R 3 ) p- SiMe3, respectively) were polymerized with TaCl5-n-Bu4Sn catalyst to provide high molecular weight polymers. The formed polymers (2a-g) afforded tough free-standing membranes by casting from toluene solution. Desilylation of these Si-containing polymer membranes was carried out with trifluoroacetic acid. Para-substituted polymers (2a-e) underwent desilylation completely, while meta-subustituted polymers (2f and 2g) did not. According to thermogravimetric analysis (TGA), both Si-containing and desilylated polymers exhibited high thermal stability, and all the desilylated polymers showed practically the same onset temperature (∼480°C) of weight loss. The membranes of Si-containing polymers showed lower oxygen permeability as the silyl group became bulkier. The oxygen permeability coefficients (P(O 2) 120-3300 barrers) of desilylated polymer membranes were quite different from each other irrespective of the same polymer structure. When bulkier silyl groups were removed, the oxygen permeability increased to larger extents. In ethanol/water pervaporation, both Si-containing and desilylated polymer membranes showed ethanol permselectivity, indicating that these membranes possess large excess free volumes.

Poly(diphenylacetylene)s having various silyl groups are soluble in common solvents, from whose membranes poly(diphenylacetylene) membranes can be obtained by desilylation. The oxygen permeability coefficients of the desilylated polymers are quite different from one another (120-3300 barrers) irrespective of the same polymer structure. When bulkier silyl groups are removed, the oxygen permeability increases to larger extents. Poly[1-aryl-2-p-(trimethylsilyl)phenylacetylene]s are soluble in common solvents, and afford free-standing membranes. These Si-containing polymer membranes are desilylated to give the membranes of poly[1-aryl-2-phenylacetylene]s. Both of the starting and desilylated polymers show very high thermal stability and high gas permeability. 1-Phenyl-2-p-(t-butyldimethylsiloxy)phenylacetylene polymerizes into a high-molecular-weight polymer. This polymer is soluble in common organic solvents to provide a free-standing membrane. Desilylation of this membrane yields a poly(diphenylacetylene) having free hydroxyl groups, which is the first example of a highly polar group-carrying poly(diphenylacetylene). The P CO 2 /P CH 4 and P CO 2 / P N 2 permselectivity ratios of poly(1-phenyl-2-p-hydroxylphenylacetylene) membrane are as large as 47.8 and 45.8, respectively, while keeping relatively high P CO 2 of 110 barrers. V V C

No abstract

No abstract