The method of decay Poiseuille flow was applied to study rheological properties of the nematic mixture (ZhK 440) confined to porous polymer (PET) matrix with sub micron diameters of pores. The Newtonian character of the flow was established. It made possible to determine the values of the effective shear viscosities for different temperatures. The analysis of experimental data was made taking into account the influence of weak surface anchoring effects on the orientational structure of liquid crystals.

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Rheological Properties of Liquid Crystals in Porous Polymer Films with Submicron Sizes of Pores

Autocorrelation function g2() and intensity (I) of the depolarized scattered light were obtained at the study of a dynamic light scattering from the composite liquid crystal (LC) material, consisting of porous polyethylenterephthalate (PET) film filled with oсtylcyanobiphenyl (8CB). The simultaneous analysis of these parameters made possible to extract the temperatures TIN and TNA of the isotropic liquid – nematic (N–I) and nematic – smectic A (N-SmA) phase transitions in LC samples confined into cylindrical pores of diameters in the range of 0.02 ... 2 μm. The dependences of TIN and TNA on the pore diameter were obtained and compared with the theoretical predictions. It was shown that simultaneous investigations of dynamic and static light scattering can be considered as a perspective approach for a study of phase transitions in LCs at strong confinement, which is typical for composite LC materials.

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A. O. Zhirkov

Papers

Dynamic and static light scattering at phase transitions in liquid crystal confined into porous polymer film