Nematic anisotropic liquid-crystal gels -: Self-assembled nanocomposites with high electromechanical response

The uniqueness of liquid crystals (LCs) lies in the large anisotropies of their properties, which can be utilized to generate high electromechanical responses. In a properly oriented LC polymer system, an external field can induce reorientation of the of the mesogenic units possessing a dielectric anisotropy, which, when coupled with the shape anisotropy of the mesogenic units, can in turn produce large mechanical strain. Anisotropic LC gels, which can be obtained by in-situ photopolymerization of the reactive LC molecules in the presence of non-reactive LC molecules in an oriented state, are an example of such liquid-crystal polymer systems. It is shown that a homeotropically aligned LC gel in its nematic phase exhibits high electrically induced strain (>2%) with an elastic modulus of 100 MPa and a high electromechanical conversion efficiency (75%) under am electric of 25 MV/m. These anisotropic LC polymer materials could provide a technologically compatible system for such applications as artificial muscles and as micromechanical devices.