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.

Soft Elasticity in Main Chain Liquid Crystal Elastomers

“…Polydomain smectic MCLCEs have been extensively studied [20,[60][61][62][63][64][65][66][67]. Sánchez-Ferrer et al [64] reported the polydomain to monodomain (P-M) transition caused by uniaxial strain in these materials.…”

Isotropic to smectic-C phase transition in liquid-crystalline elastomers

“…The temperature dependence of the heat capacity in the isotropic phase of the I-SmC transition of liquidcrystalline elastomers was reported by Cordoyiannis et al 24 As can be observed from the Fig. 2 of Cordoyiannis et al, 24 the normal heat capacity is much higher than anomalous contribution.…”

“…It is the goal of this paper to investigate the I-SmC phase transition in LCEs, which has been studied experimentally, [22][23][24] but theoretically not at all. Sanchez-Ferrer et al 22 reported the synthesis of the SmC LCEs.…”

“…The I-SmC phase transition is found to be more strongly first order both for low molecular weight SmC materials [25][26][27][28] and SmC elastomers. [22][23][24] Recently published x-ray data have shown a direct I-SmC transition for SmC a) E-mail: pkmuk1966@gmail.com. Tel.…”

“…: +91-33-224- 11-977. elastomers. 22,23 Cordoyiannis et al 24 measured the temperature dependence of the heat capacity for conically distributed polydomain liquid-crystalline elastomers MCEB7Azo2-2.5 and MCEB7-10.0 both above and below the phases of the I-SmC phase transition. The analysis of the temperature dependence of the heat capacity reveals an appreciable anomalous component.…”