Synthesis and solid-state polymerization of monomers with a conjugated diyne-triene-diyne structure

Tetradeca-5,7,9-triene-1,3,11,13-tetrayne derivatives with a conjugated diyne-triene-diyne structure were synthesized and their solid-state polymerization was investigated for the first time. The monomers could be polymerized by UV irradiation at 254 nm or 365 nm and increase of the absorption in the visible region was observed during polymerization. Since the absorption tail of the photoproducts shifted to longer wavelength than that of the corresponding monomers, the main photoreaction scheme at the initial stage of polymerization was estimated to be 1,4-addition in the diyne portions. However, no excitonic absorption band observed for polydiacetylene with the regular structure appeared. The crystallinity confirmed by powder X-ray diffraction was lost during photopolymerization and disorder of the polymer was found.