Effect of polymer networks on the smectic-C* phase of a ferroelectric liquid crystal: high-resolution x-ray studies

High-resolution x-ray diffraction was used to investigate how polymer networks affect the tilt angle in the smectic-C* (SmC*) phase of the ferroelectric liquid crystal 4-[(S,S)-2,3-epoxyhexyloxy]-phenyl-4-(decyloxy)-benzoate (W46 or EPHDBPE). Blends comprising W46, a monomer, and a photoinitiator were prepared and photopolymerized at temperatures that correspond to isotropic and the SmC* phases of W46. When compared to the pure material, the tilt in the SmC* phase was found to decrease in both polymerized samples. The effect, however, is greater for the sample that was polymerized while it was in the SmC* phase. Also, the SmA*-SmC* transition in pure W46 is a weak first-order transition that becomes continuous if traces of polymer are added to W46.