Conversion of retardation dispersion in self-organized smectic reactive mesogen compound and its dependence on the UV polymerization temperature and the molecular orientation

We investigated the dependence of the dispersion of retardation on the UV-polymerization temperature and the molecular orientation in a self-organized smectic host-guest reactive mesogen (RM) compound. The positive dispersion of retardation was converted to the negative dispersion of retardation with decreasing the UV-polymerization temperature. From the Fourier-transform infrared (FT-IR) dichroism measurement, it was found that more fractions of the guest molecules were aligned parallel to the smectic layer plane with decreasing the UV-polymerization temperature. The guest molecules located in the inter-layer space absorb a longer wavelength of UV light compared to the host and induce the negative dispersion of retardation.