DESIGN, SYNTHESIS, AND PROPERTIES OF SUBSTITUTED POLYACETYLENES

This article reviews recent topics on the polymerization of substitute d acetylenes, focusing on the synthesis of poly(diphenylacetylenes) an d the living polymerization of phenylacetylenes. Diphenylacetylene (DP A) polymerizes with TaCl5-n-Bu(4)Sn to give a polymer which is thermal ly 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(dimeth ylsiloxane). 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 an d chain transfer. PAs with bulky ortho groups (e.g., CF3 and Me(3)Ge) especially undergo virtually ideal living polymerization.