Incorporating trifunctional 1,6-heptadiyne moiety into polyacetylene ionomer for improving its physical and conductive properties

Metathesis cyclopolymerization of a branched 1,2,3-triazolium-substituted 1,6-heptadiyne ionic monomer and a tris(4-N,N-dipropargylaniline)amine trifunctional comonomer was conducted to afford a polyacetylene-based copolymer with a branched structure and flexible solid state when using an appropriate amount of comonomer, which performed better than the viscous semi-solid ionic homopolymer in forming a film. The branched copolymer exhibited a high intrinsic ionic conductivity of 2.6 × 10^-5 S cm^-1 at 30 °C, which could reach 9.0 × 10^-5 S cm^-1 and 1.0 × 10^-3 S cm^-1 after doping with LiTFSI and a mixed dopant of ionic liquid/LiTFSI, respectively. Furthermore, the polyelectrolyte composite of LiTFSI-doped copolymer displayed good electrochemical stability with a high decomposition voltage of 5.2 V and ionic transference number of 0.39 versus Li/Li⁺, indicating that the flexible and stretchable copolymer has potential applications in electronic devices.