Nematic to smectic transition and dynamics for semiflexible polymers in very strong slit-like confinement*

We performed GPU-accelerated Langevin dynamics simulations to investigate the density induced nematic to smectic phase transition for semiflexible polymers in slits comparable and smaller than the chain persistence length. The smectic transition occurs with chains with different bending rigiditites, with the persistence length P to slit height H ratios 1.25, 2.5, 3.75, 5 and 25. For all cases, smectic C is found with the polymer director tilted with respect to lateral alignment. The transition density systematically shifts higher for more flexible polymers.
For the isotropic to nematic transition, the overall polymer diffusivity decreased steadily as density increases. In the nematic phase, diffusion along the nematic director increased as the density increased while lateral diffusion decreased. The anomalous diffusion is similar to previously reported behavior for nematic-forming ellipsoids. Polymer diffusivity decreases sharply by two order of magnitude upon the smectic phase transition. The systemic nematic director also reorients, with the global mobility found to decrease systematically with increasing density. The global re-orientation arrests in the smectic phase.