Thermodynamic model to study the ferroelectric behaviour of lactic acid derivatives with keto linkage group

• Published in: Phase transitions Vol. 95; no. 10; pp. 698 - 706
• Main Authors: Singh, Abhilasha, R, Shashidhar, Rastogi, Ayushi
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03-10-2022; Taylor & Francis Ltd
• Subjects: Carbonyl compounds; Carbonyls; Carboxylates; Couplings; Experimental data; ferroelectric liquid crystals; Ferroelectricity; Free energy; Lactic acid; Landau-de-Gennes Theory; Optical properties; Order parameters; phase transition properties; Phase transitions; Polarization; Tensors; Thermodynamic model; Thermodynamic models; Thermodynamics
• ISSN: 0141-1594; 1029-0338
• DOI: 10.1080/01411594.2022.2106227

The electro-optical and structural properties of chiral lactic acid derivatives with keto linkage group ((S)-4-((1-alkoxy-1-oxopropan-2-yloxy) carbonyl)phenyl4'-alkyloylbiphenyl-4-carboxylates denoted as KL n/m) exhibiting Sm C* phase and Sm A*−Sm C* phase transition have been studied by using a thermodynamic model based on Landau-de-Gennes theory. The free-energy density of the system is expanded in terms of three degrees of freedom - tensor orientational order
, the scalar smectic order
, the polarisation vector P, the wave vector q, and the couplings between these order parameters. The values of the Landau coefficients involved in the free-energy density have been calculated by comparing the experimental data of tilt angle, spontaneous polarisation, and pitch of KL n/m. The theoretical and experimental data have been analysed, and a close agreement has been found between the two.