A molecular dynamics simulation study of semi-flexible main chain liquid crystalline polymers

A hybrid model, which combines the original Gay-Berne/Lennard-Jones (GB/LJ) model and bead-spring model, has been derived to simulate semi-flexible main chain liquid crystalline polymers (LCPs). The hybrid model presents the molecular chain in the form of GB-Spring-Bead-Spring-…-Bead-Spring-GB sections that simplifies the model and reduces the simulation computation by many times. The hybrid model was evaluated by studying the phase behaviors of semi-flexible main chain LCPs through molecular dynamics (MD) simulation. The results, such as the spontaneous phase transition from isotropic phase to nematic phase as the system temperature decreases and the odd-even effect of the assumed number of flexible spacers (na) on its thermodynamic properties agree well with other experimental results as well as simulations using the GB/LJ model. The orientational and translational mobilities of mesogenic units in the hybrid model have also been measured and compared with those in the GB/LJ model with very little differences found.