title: Volume phase transitions of cholesteric liquid crystalline gels.
abstract: We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.
authors.affiliation: Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Matsuyama
mesh_terms: D016880:Anisotropy; D004548:Elasticity; D020724:Elastomers / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D008962:Models, Theoretical; D044367:Phase Transition; D012997:Solvents / Q000737:chemistry; D013696:Temperature
chemical_list: D020724:Elastomers; D005782:Gels; D012997:Solvents