Synthesis and electro-optical behaviour of a new chiral smectic side-chain polysiloxane

A new chiral side-chain polymer was prepared by hydrosilylation of a dimethylsilane-methyl-hydrosilane copolymer. The chiral group of the mesogenic side-chain was (+)2-chloro-3-(3-nitro-4-hydroxyphenyl)propionic acid butyl ester while the main part of the aromatic nucleus consisted of 4′-hydroxybiphenyl-4-carboxylic acid. Phase behaviour was studied by DSC and polarizing microscopy, and correlated with dielectric measurements. Alignment properties and ferroelectricity were studied in cells with surface-induced alignment and in shear cells. The polymer exhibits chiral C-and A-phases. The spontaneous polarization is 130 nC/cm2 at 60°C and the polymer shows ferroelectric switching at room temperature.