The solid‐state polymerization, physical properties, and crystal structures of diacetylene mixed crystals

Suitable substituted diacetylenes, 2,4‐hexadiynylene di‐p‐toluenesulfonate (1a) and 2,4‐hexadiynylene di‐p‐fluorobenzenesulfonate (1b), were cocrystallized to form substitutional solid solutions. By solid state polymerization of mixed crystals of 1a and 1b single crystals of the corresponding copolymers were obtained. The polymerization rate can be varied over a wide range by admixture of the comonomer 1b in the lattice of 1a. The crystal structures of monomer 1b and of the corresponding polymer, 2b, were determined. It was found that the packing of the reactive triple bond systems is identical in both monomers. Comonomer 1b acts as a defect site with a high probability of chain termination.