Dynamics of reorientation of a constrained nematic elastomer
Cavendish Laboratory, University of Cambridge,
Madingley Road, Cambridge CB3 0HE, UK
Published online: 15 June 1999
A model is proposed for the reorientation dynamics of a confined nematic liquid crystal elastomer, where the effect of crosslinks is to couple the director to deformations of the elastic matrix. The model combines the (equilibrium) `neo-classical' theory of liquid crystal rubber elasticity with the simplest time evolution equations for a system described by two coupled, non-conserved order parameters. Relaxation from an orientation imposed by an electric field is studied as a function of elastic softness, starting angle, surface pretilt, and the relative mobilities of director and strain. Most importantly, the absence of a `semi-soft' elastic threshold changes the long-time behaviour of the effective refractive index of the medium from exponential to inverse power law decay. Predictions are compatible with recent experimental results by Chang, Chien and Meyer [Phys. Rev. E 56, 595 (1997)].
PACS: 61.30.Cz – Theory and models of liquid crystal structure / 61.41.+e – Polymers, elastomers, and plastics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999