Preparation and properties of polytolan membranes bearing p-hydroxyl groups

The polymerization of a novel monomer p-(t-butyldimethylsiloxy)tolan (1) with TaCl₅-n-Bu₄Sn provided a high molecular weight polymer (poly(1)), whose M_w reached 4.0×10⁶. The poly(1) membrane was prepared by the casting method, and converted into poly(p-hydroxy)tolan] (poly(2)) with a mixture of trifluoroacetic acid/water. Whereas poly(1) dissolved in low polarity solvents such as toluene and chloroform, poly(2) was practically insoluble in any solvents, although it partly dissolved in methanol and ethanol. The onset weight loss temperatures of poly(1) and poly(2) in air were 320 and 360 °C, respectively, indicating fair thermal stability among substituted polyacetylenes. The oxygen permeability coefficients (P_O2) of poly(1) was 150 barrers, which is relatively small among polytolan derivatives, while that of poly(2) was 8.0 barrers and smaller owing to the presence of polar hydroxyl groups.