Theory of volume phase transitions of side-chain liquid crystalline gels

摘要

We present a mean field theory to describe volume phase transitions of side-chain liquid crystalline gels. Three different uniaxial nematic phases (N-1, N-2, and N-3) are defined by using orientational order parameter S-m of side-chain liquid crystals (mesogens) and S-b of backbone chains. We derive the free energy for the three nematic phases of side-chain liquid crystalline gels dissolved in isotropic solvents and calculate the swelling curve of the gel, the order parameters of a backbone chain and of side-chain liquid crystals, and the deformation of the gel as a function of temperature and an electric field. We find isotropic-nematic (N-1, N-2, and N-3) and N1N2 phase transitions of the gels, depending on the interaction between a backbone chain and a side-chain liquid crystal. (c) 2007 American Institute of Physics.