Elastic deformations of nematic laterally attached dimers

Abstract

Temperature dependences of the optical anisotropy and elastic constants of nematic laterally connected dimers, in which two rod-like 2,7-disubstituted fluorene moieties are linked through their 9-positions by flexible-OOC(CH2)m COO- residues, were determined by using the Freedericksz method of threshold transitions in a magnetic field. It was shown that the possibility of rotation of the mesogenic groups about their short axes influences the dependence of the order parameter on spacer length. No marked dependence of splay and bend elastic constants on spacer length was observed. The results are compared with literature data for polymer and low molecular mass nematics.