ORDER DISTRIBUTION FUNCTION OF A LINEAR POLYMERIZED PHOTOPOLYMER ORIENTING A NEMATIC LIQUID-CRYSTAL

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 polariz ed UV light. An exponential decay of the induced birefringence is conn ected to the complex effects of UV light on polymers. A scalar order p arameter of cross-links is inferred from the distribution function, an d is compared to the measured birefringence. The irradiation time infl uences also the order parameter of thin layers of nematic liquid cryst als which are aligned by the polymers, assuming a finite anchoring. Th e UV exposure time dependence of the nematic liquid crystal scalar ord er parameter is also given.