Ionic polyacetylenes (iPAs) with the trans configuration and a five-membered ring structure were synthesized by the metathesis cyclopolymerization of dendronized triazolium-functionalized 1,6-heptadiyne. The iPAs bearing flexible pendants had a low glass transition temperature of - 37 degrees C, a high decomposition temperature of 349 degrees C, and a relatively high intrinsic ionic conductivity of 7.3 x 10(-5) S.cm(-1) at room temperature, which further increased to 1.4 x 10(-4) S.cm(-1) by doping with lithium bis(trifluoromethanesulfonyl)imide. Moreover, the iodine-doped iPAs exhibited dual conductivity, i.e., ionic and electronic conductivities of 7.1 x 10(-5) and 5.0 x 10(-5) S.cm(-1), respectively. Therefore, the conjugated iPAs with a good film-forming property provide a potential for making dual-conductive flexible electronics.