Abstract
New ferroelectric liquid crystalline polysiloxanes 5 containing a side chain mesogenic group were prepared by the reaction between poly(methylsiloxane) 4 with various degrees of polymerization and the mesogenic compound possessing terminal olefin, (S)-(−)-4-(2-methylbutyloxycarbonyl)phenyl 4′-(5-hexenyloxy)biphenyl-4-carboxylate 3, in the presence of a platinum catalyst. The polarized microscopic observation indicated that both the olefinic precursor 3 and the resulting polysiloxanes 5 displayed enantiotropic smectic A (SA) and smectic C (SC*) mesophases. The polymers showed transitions from isotropic to SA phases and from SA to SC* phases in the range of 250–220°C and 215–188°C, respectively, where the SC* phase was exhibited even at room temperature. The phase transition temperature increased with increasing molecular weight of the polysiloxane backbone. The small angle X-ray diffraction study indicated that the layer spacing increased and the tilt angle of the mesogenic side chain unit decreased with increasing temperature, and they became constant after a particular temperature of SC*−SA transition. The observed layer spacing of 2.9 nm in SA phase agreed with the calculated value of 3.1 nm. The polymers are switchable by an electric field and the minimum response time was 175 ms.
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