DESIGN, SYNTHESIS, AND PROPERTIES OF SUBSTITUTED POLYACETYLENES

This article reviews recent topics on the polymerization of substituted acetylenes, focusing on the synthesis of poly(diphenylacetylenes) and the living polymerization of phenylacetylenes. Diphenylacetylene (DPA) polymerizes with TaCl5-n-Bu(4)Sn to give a polymer which is thermally very stable but insoluble in any solvents. DPAs with various groups (e.g., p-Me(3)Si, m-Me(3)Ge, p-t-Bu, and p-PhO) polymerize similarly. These polymers are soluble and their ($) over bar M(w)'s reach 1 x 10(6) to 3 x 10(6). Some of them are more gas-permeable than poly(dimethylsiloxane). Several acetylenes (e.g., ClC = C-n-C6H13 and HC = C-t-Bu) have been found to undergo living polymerization with MoOCl4-n-Bu(4)Sn-EtOH. Whereas phenylacetylene (PA) does not polymerize in a living fashion, ortho-substituents in PA more or less suppress termination and chain transfer. PAs with bulky ortho groups (e.g., CF3 and Me(3)Ge) especially undergo virtually ideal living polymerization.