Diarylacetylene monomers having trimethylsilyl groups and other substituents (substitutedbiphenyl, 1a and 1b; trimethylsilylmethylphenyl, 1c–e) were synthesized and polymerized with TaCl5-n-Bu4Sn catalyst to produce the corresponding poly(diarylacetylene)s (2a–d). Polymers 2a–c had high molecular weights and were soluble in common organic solvents. Free-standing membranes of 2a–c as well as previously