Phase separation kinetics in mixtures of flexible polymers and low molecular weight liquid crystals

A dynamic Monte Carlo (MC) simulation is performed to investigate the phase behavior of mixtures of flexible polymers and low molecular weight thermot ropic liquid crystals (LCs). The polymer is represented by three-dimensiona l self-avoiding lattice chains, while the LC is described by the Lebwohl-La sher nematogen model. The initially homogeneous rod-coil mixture is, follow ing a deep quench, separated into an isotropic phase rich in coils and a ne matic phase rich in rods. The underlying spinodal decomposition (SD) proces s is then simulated and studied extensively. This is the first simulation o f SD in a rod-coil mixture where the nematic ordering is included. Concentr ation fluctuations with a conserved order parameter are thus coupled with o rientation fluctuations with a nonconserved order parameter. It is found th at the early stage SD in the rod-coil mixture still exhibits the dominant s patial wavelength and that the scalar scattering functions in the late stag e of SD obey the Furukawa scaling law. The kinetic difference between the s o-called isotropic and anisotropic SD regions is, however, much less pronou nced than predicted recently by the mean-field theory.