The Influence Of Molecular Excluded-Volum Effects To Order Parameter Of Extended Liquid Crystal Elaxtomers

Liquid crystal elastomers(LCE) is an especial elastomers. Non-cross-linked liquid crystal polymers after appropriate cross-link then it show elasticity in the isotropic state or liquid crystal state ,this material is know as liquid crystal elastomers. With the development of science and improvement of technology, LCE was fast developed at 1990s as a new type elasticity material. Its salient feature is strong coupling between the orientation order of liquid crystal and the characteristics of classic polymers.The existent of mesogenic monomers is the basic of the orientation order of LCE. According to the arrange form and difference of order, LCE is classified smectic phase liquid crystal, nematic phase LCE, cholesteric phase LCE, and it can be classified main-chain LCE ,side-chain LCE , combined LCE by the different locations of mesogenic monomers incorporated into backbone. Nematic phase main-chain LCE is a simplest kind LCE and there are still many investigation on it.In recent years, the experiment research of LCE was made considerable progress. These characteristics such as thermal rebound effect, photo-induced bending effect, photo-mechanical effect make liquid crystal elastomers have broad application prospects in various fields. Theoretical study of LCE is usually from the anisotropic Gaussian distribution of the end-to-end distance vector. We get the basic form of entropy-elasticity free energy form this distribution. Then we can investigate kinds of properties of LCE on basic of the free energy. For classic polymer. We can get zero-order isotropic Gaussian distribution function. Similar, we can gain an anisotropic one through modeling LCE.For nematic LCE, its director will be reoriented when the principal axes of imposed deformation strain does not coincident with the initial director of LCE and this process of re-orientation is discontinuous .This paper, we study the order parameter of LCE as a function of the magnitude of deformation and the rotation of the deformation principal axes insert exclude-volume effects of hard rod theory.