Light sensitive antiferroelectric achiral copolymers

Five copolymers were prepared by polymerization of azo-benzene methacrylate monomers in solution using AIBN as initiator. The mesophases were observed by a polarizing light microscope which showed tilted smectic C phases for almost all samples. One of them shows just one orthogonal smectic A2 phase. The X-ray diffraction patterns reveal the existence of bilayer smectic C2 mesophases. The spontaneous polarization and pyroelectric response are reported showing an antiferroelectric behaviour for three of the copolymers. The polar phase has to do with a preferable arrangement of side chains in a syndiotactic fashion, which promotes the formation of anticlinicity in the polymer net. We probe that it is possible to induce orientation of the chromophores subjected to irradiation with UV/Vis light and that it is proportional to the amount of monomers without the OH group within the copolymers. This is so far a unique manifestation of polar ordering due to the syndiotactic lateral distribution of mesogens bearing an OH group in a tilted smectic C2 phase.