Metathesis Cyclopolymerization of Imidazolium-Functionalized 1,6-Heptadiyne toward Polyacetylene Ionomer

Metathesis cyclopolymerization (MCP) of ionic 1,6-heptadiyne is successfully applied to synthesize polyacetylene (PA) ionomer in different solvents especially in imidazolium-based ionic liquid (IL), and MCP of ionic monomer in the mixture of THF/IL proceeded in a controlled manner by the action of Grubbs second and third generation catalysts (Ru–II, Ru–III). The influence of catalysts and solvents on polymerization behavior and chain microstructure was investigated, and the results revealed that the isolated polymer yield could reach to 97% and 82% by Ru–III and Ru–II, respectively, in 1:2 THF/IL after optimization, and PAs incorporating imidazolium pendent contained ≥95% five-membered-ring structure and almost all trans-double bonds along the backbone. PAs formed in different solvents reflected significant variance in optical absorption properties, and a bathochromic shift effect was observed with the mixture of THF/IL.