High Resolution X-Ray Measurements of the Nematic-Smectic C Phase Transition in the Polymeric Liquid Crystal C-6 Polysiloxane

Abstract We report on high-resolution X-ray measurements of the nematic to smectic C phase transition in the polymeric liquid crystal, C-6 polysiloxane. Preliminary results show that smectic fluctuations measured in the nematic phase are roughly consistent with a Chen and Lubensky type of theory, as was developed for monomeric liquid crystals. The phase transition in C-6 polysiloxane shows pre-transitional smectic fluctuations at least 30°C above the phase transition temperature, TNC, where TNC = 37.84 ± 0.05°C. At TNC, there is a weak first order phase transition to the smectic C phase.