Reactive crystals. IV. Crystalline state photopolymerization of 5,5′-1,4-phenylene-bis(2-cyano-2,4-pentadienoic acid) derivatives

5,5′-1,4-Phenylene-bis(2-cyano-2,4-pentadienoic acid) derivatives were prepared. Many of this series of compounds were found to be polymerizable in the crystalline state by irradiation with light of wavelength λ > 340 nm. The polymers obtained contain a benzene and a cyclobutane ring in the main chain and have a cyanoacrylate as the side chain. They are crystalline and some of them are soluble in organic solvents. Photopolymerization was found to follow a stepwise mechanism. The polymerization process is separable into an oligomerization and a subsequent polymerization by controlling the wavelength of the irradiating light; an oligomer was obtained by an irradiating light; an oligomer was obtained by an irradiating light of wavelength λ > 430 nm.