Experimental observations show that the N-I transition temperature (T_{NI}) for liquid crystals embedded in solid porous materials is lower compared to that of the bulk liquid crystals and T_{NI} is reduced linearly with the inverse pore diameter. To explain this, various theoretical studies have been proposed. We propose to use the mean field approach. We modify the Maier-Saupe mean field theory to include the disordering effects of porosity as a disordering surface potential. A molecule near the surface is assumed to feel the mean field potential (the Maier-Saupe type) and also the surface induced potential. We calculate the values of the nematic order parameter and hence find the T_{NI} for different pore diameters. The weighted average of the order parameter is calculated considering the cylindrical symmetry of the pores. Our calculations on the variation of T_{NI} with pore diameter agree with experimental data. Also, the calculated values of specific heat peak decrease with decrease in pore radius, in agreement with experimental trends.
(4-(4'octylobiphenyl)carboxylan) 4-(2-methylobuthyl) phenol (CE8), the substance showing complex polymorphism, has been investigated using the dielectric spectroscopy method. This substance exhibited polymorphism during heating and cooling: a few smectic phases, a cholesteric phase, and a blue phase as well. Despite the fact that the substance polymorphism depends on the rate of heat flow existing of the blue phase has been confirmed by polarizing microscopic observations as well as dielectric spectroscopy investigations.
(4-(4'-octylo-biphenyl)carbo-xylane) 4-(2-methylo-buthyl) phenol, the substance showing complex polymorphism, has been investigated using the calorimetric, microscopic and X-ray methods. This substance exhibited polymorphism during heating and cooling: a few smectic phases, a cholesteric phase and a blue phase as well. However, the substance polymorphism depends on the rate of heat flow. Existing of the blue phase has been confirmed by polarizing microscopic observations done at several temperature rates.
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