Research in our group encompasses broadly in the areas of theoretical chemistry involving statistical mechanics of soft condensed mater systems. Specifically we are interested currently in the following: Dynamics of Model Polymer Systems: Rupture models has been studied extensively to understand the microscopic origin of various physical phenomena involving the relative motion of surfaces. We focus on one such tractable, generic, one-dimensional model, involving a flexible polymer connected to a rigid substrate by interconnecting bonds which rupture stochastically under external stress; in an attempt to capture the microscopic mechanism at the single polymer level. The problem was simulated, and by using a mean field approximation and travelling wave formalism, we could derive a closed form expression for rupture fronts that detach the flexible polymer from rigid substrate, thus providing useful insights into the stability of modeled system.   Ref: Soft Matter, 2016, 12, 4406 – 4417. Polymer Melt Dynamics: Many theoretical and experimental studies show that polymer melts and glass forming liquids display heterogeneous dynamics near glass transition temperature, or under supercooled, or undercooled conditions. The possibility of dynamical heterogeneities in these systems specifically polymer melts well above their glass transition temperature is rather less reported. We investigate, characterize dynamical heterogeneities in polymer melts well above their glass transition temperature, and attempt to address the molecular origin of these transient high and low mobility regions in the melt.   The analysis of centers-of-mass simulation trajectories of unentangled
polyethylene melts shows that a tagged polymer undergoes transient periods of
small-amplitude motion followed by periods of large-amplitude displacements. These
long-range unidirectional center-of-mass (c.m.) displacements are found to be
correlated with the stretched conformations. A molecular mechanism
based on density fluctuations about the tagged polymer has been suggested.
Further the density fluctuations about the tagged polymer are connected to
entropy. Ref. Results in print. |