Thermal study of the Isotropic to Smectic C phase transition in main-chain liquid-crystalline elastomers

Abstract

High-resolution calorimetry has been used in order to investigate the nature of the Isotropic to Smectic C phase transition of main-chain liquid-crystalline elastomers. Two polydomain elastomers with a conical distribution of the layer normal with respect to the director and different compositions and crosslinking concentrations were synthesised. The heat capacity temperature profiles were measured over a broad temperature range, using ac and relaxation runs. The results reveal a first-order behaviour and a substantial amount of latent heat for the Isotropic to Smectic C transition of liquid-crystalline elastomers, with a wide phase-coexistence range.

Keywords:

• main-chain elastomers
• smectic C
• AC calorimetry
• heat capacity

Acknowledgements

This research was financially supported by the EU (Project No. HPRN-CT-2002-00169) and by the Slovenian Office of Science (Project Nos. J1-9368, P1-0125).