Three stage-volume phase transitions of a side-chain liquid crystalline elastomer immersed in nematic solvents

Abstract

We theoretically study volume phase transitions of a side-chain liquid crystalline elastomer (LCE) immersed in nematic solvents. Six different uniaxial nematic phases (N(1 parallel), N(1 perpendicular), N(2 parallel), N(2 perpendicular), N(3 parallel), and N(3 perpendicular)) are defined by using orientational order parameter S(m) of a side-chain mesogen, S(b) of a backbone chain, and S(0) of a nematic solvent inside the gel. We derive the free energy of a side-chain LCE dissolved in nematic solvents and calculate the swelling behavior of the LCE, the order parameters, and the deformations of the LCE as a function of temperature. We find various phase transitions of the LCE, such as the isotropic (I)-N(1 parallel)-N(3 perpendicular) and the I-N(2 parallel)-N(3 parallel), etc., accompanied by volume phase transitions. These results present new concepts in the structure of a side-chain LCE dispersed in nematic solvent molecules.