Ferrocene-Containing Thermotropic Side-Chain Liquid-Crystalline Polysiloxanes

The synthesis, purification, characterization, and liquid-crystalline properties of side-chain polysiloxanes bearing mesomorphic 1,1‘- or 1,3-disubstituted ferrocene units are reported. The polymers were prepared by grafting the appropriate vinyl-containing ferrocene monomer onto commercially available poly(hydrosiloxane)s following a standard procedure. The monomers gave smectic A or smectic A and smectic C phases depending on the length of the flexible chains connected to the ferrocene unit. X-ray diffraction indicated that the polysiloxanes exhibited disordered smectic phases. Variation of the d-layer spacing determined for the polymers containing either 100% or 15−18% of the 1,1‘-disubstituted ferrocene monomer (with the longest terminal alkyl chain) revealed the presence of smectic A and smectic C phases. Thermogravimetry showed a good thermal stability for the polymers.