Piezoelectricity of cholesteric elastomers. 1. Influence of the helicoidal pitch on the piezoelectric coefficient

Abstract

Mechanical, optical, and electromechanical investigations were performed on a series of induced cholesteric elastomers. These elastomers are swollen with a chiral low molar mass liquid crystal and exhibit a mechanical coupling coefficient U that is of the same order of magnitude as that for nonswollen nematic elastomers. Above a certain threshold deformation, a macroscopically uniform orientation of the mesogenic side groups is achieved, with the helicoidal axis oriented parallel to the compression axis. Above this threshold deformation, the helicoidal pitch affinely deforms with elastomer compression. This deformation of the helicoidal superstructure is a basic requirement for piezoelectricity in cholesteric elastomers