Synthesis and mesomorphic properties of a novel ladder-like 1,4-phenylene-bridged liquid crystalline polysiloxane containing ester-based mesogenic side groups

A new ladder-like 1,4-phenylene-bridged liquid crystalline polysiloxane bearing ester-based mesogenic side groups, LPLCPS, has been synthesized by hydrosilylation of a SiH-terminated ester-based mesogen compound (1) with a ladder-like 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) containing vinyl-terminated side groups in the presence of dicyclopentadienylplatinum(II) chloride (Cp₂PtCl₂) catalyst. Compound 1 was synthesized by hydrosilylation of 1,1,3,3-tetramethyldisiloxane (HMM) with the vinyl-terminated ester-based mesogenic compounds. Various characterization methods including FTIR, ¹H NMR, ¹³C NMR, ²⁹Si NMR, polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction were used and the results combined to demonstrate that LPLCPS shows thermotropic smectic mesomorphic behaviour with a high clearing point and a wide mesophase range.