Molecular dynamics simulation of liquid crystalline polymer networks and flexible polymer network in liquid crystal solution

Molecular dynamics have been carried out for a flexible regular tetrafunctional network swollen in a low molecular liquid-crystal (LC) solvent. The LC solvent comprises of anisotropic rod-like semiflexible linear molecules (mesogens) composed of particles bonded into the chain by FENE potential. Rigidity of LC molecules was induced by a bending potential, proportional to the cosine of the angle between adjoining bonds. All interactions between nonbonded particles are described by a repulsive Lennard-Jones potential. The size of the network elementary cell was chosen to be close to the length or the mesogen. Simulated systems differ from each other by the volume fraction of LC solvent. For comparison the simulation of network swollen in monomer solvent was carried out. The static and dynamic characteristics of the systems were studied. Both nematic and smectic phases are observed for LC in the network but their density regions are shifted to higher densities in comparison to the pure LC. The presence of the LC solvent results in the anisotropy of translational diffusion of the network. Anisotropy of diffusion increases with increase of the fraction of LC solvent. Computer code was modified to simulate the transformation of these systems into liquid crystalline polymer networks. For such a system the smectic phase is observed at smaller densities as compare to the nonpolymerized LC+network system. The effect of polymerization on the translational mobility of polymer network was studied.