Thermal bending coupled with volume change in liquid crystal gels

Abstract

We investigate the thermal bending behavior of liquid crystal gels with hybrid alignment (H-LCGs) accompanied by volume change in isotropic and nematic solvents. The curvature (r⁻¹) of H-LCGs in each solvent markedly depends on the temperature (T) in the nematic state including the reversal of the bending direction, as in the case of the corresponding elastomers in the dry state (H-LCE). The thermal bending of three systems—H-LCGs in isotropic and nematic solvents and H-LCE—differs significantly in several aspects including the T range where r⁻¹ depends on T and the total variation of r⁻¹. The differences in these features among the three systems result from the differences in the magnitude as well as the T-dependence of the nematic order (S), which is correlated with the T-induced volume change. We demonstrate that the T-dependence of the reduced curvature in each system is satisfactorily described by a combination of linear bending theory and the anisotropic Gaussian network model using the corresponding S–T data.