An investigation on nematic-isotropic phase transition, viscosity and diffusion coefficient of liquid crystalline elastomers at different temperatures using molecular dynamics simulation

Abstract

The most considerable feature of liquid crystalline elastomers (LCEs) is nematic-isotropic phase transition which has severe effects on their properties such as crystallinity, viscosity, and diffusion coefficient. The aim of this work is to investigate the phase transition temperature of LCEs based on 4-bis-[4-(3-acryloyloxypropypropyloxy) benzoyloxy]-2-methylbenzene as monomer using a coarse-grained molecular dynamics simulation. In this regard, by assessing the crystallinity as a function of temperature, the most suitable ratio of crosslinker to other components including monomer and flexible spacer is 50 %; thereby, obtaining the highest nematic phase percentage around 60 %. At this condition, the nematic-isotropic phase transition temperature is predicted 360 K. Besides the crystallinity studies, the viscosity and diffusion coefficient against temperature show that the nematic-isotropic phase transition temperature has significant influence on the variations of structural and dynamic properties of LCEs.