Jenis Thongam | Searcharxiv

arXiv2024

Two-stage assembly of patchy ellipses: From bent-core particlesto liquid crystal analogs

We investigate the two-dimensional behavior of colloidal patchy ellipsoids specifically designed to follow a two-step assembly process from the monomer state to mesoscopic liquid-crystal phases, via the formation of so-called bent-core units at the intermediate stage. Our model comprises a binary mixture of ellipses interacting via the Gay-Berne potential and decorated by surface patches, with the binary components being mirror-image variants of each other - referred to as left-handed and right-handed ellipses according to the position of their patches. The surface patches are designed so as in the first stage of the assembly the monomers form bent-cores units, i.e. V-shaped dimers with a specific bent angle. The Gay-Berne interactions, which act between the ellipses, drive the dimers to subsequently form the characteristic phase observed in bent-core liquid crystals. We numerically investigate -- by means of both Molecular Dynamics and Monte Carlo simulations -- the described two-step process: we first optimize a target bent-core unit and we then fully characterize its state diagram in temperature and density, defining the regions where the different liquid crystalline phases dominate.

cond-mat.soft↗

arXiv2022

Effect of topology on the statics and dynamics of a polymer chain at the fluid-fluid interface: a molecular dynamics simulation study

The effect of chain topology on the statics and dynamics of chain at the interface of two immiscible fluids is studied by means of molecular dynamics simulations. For three topologically different chains, namely, linear, ring, and trefoil-knot of same molecular weight the effect of varying both polymer--fluid and fluid--fluid interaction nature on the width of the fluid interface, chain conformation, shape, and chain dynamics. For sharp-interface binary-fluid system, the interface width is insensitive to both topology and polymer-fluid interaction nature, while a weak non-monotonic variation is seen for weak-interface system. Chain extension normal to the interface plane is significantly affected by the topology with trefoil-knot chain, due to the additional constraint, has the largest value compared to both linear and ring polymers. Instantaneous shapes are also quantified through shape parameters. Furthermore, it is observed that the qualitative behavior of center of mass mean-square displacement (MSD) is independent of topology, i.e., all the chain types show same diffusion exponent $\alpha~(\approx 1)$. However, the self-diffusion constant depends on the topology and it is largest for trefoil-knot chain. An interesting observation pertaining the early time behavior of monomeric-MSD is that, within the sub-diffusive regime, the values of $\alpha$ for different parameters (independent of topology) are grouped into two distinct ranges (0.52--0.59 and 0.62--0.67) which is related to the different chain conformation for polymer-fluid interaction range below and above a threshold value equal to that of the self-interaction of the pure fluid phase.

cond-mat.soft↗