Order distribution function of a linear polymerized photopolymer orienting a nematic liquid crystal

Abstract

The distribution function of photogenerated cross-links in thin films of poly(vinyl cinnamate) or poly(vinyl 4-methoxycinnamate) is analyzed in terms of the irradiation time of these films with linearly polarized UV light. An exponential decay of the induced birefringence is connected to the complex effects of UV light on polymers. A scalar order parameter of cross-links is inferred from the distribution function, and is compared to the measured birefringence. The irradiation time influences also the order parameter of thin layers of nematic liquid crystals which are aligned by the polymers, assuming a finite anchoring. The UV exposure time dependence of the nematic liquid crystal scalar order parameter is also given.