Molecular Simulation Laboratory

Interactions of polymers with nanoparticles is important in phenomena, such as polymer adsorption, dispersion of nanoparticles and selective phase incorporation of nanoparticles in polymer nanocomposites. We use free energy calculation methods in conjunction with large-scale molecular dynamics simulations to evaluate interfacial phenomena at polymer/nanoparticle interfaces. Examples include stabilization of carbonn nanotubes with polyelectrolytes, polymer adsorption on graphene, and polymer intercalation between graphene platelets.

Layer-by-layer (LbL) fabrication of thin films is a well established method for preparing thin films of soft materials that offers great flexibility in designing the functionality of the thin film. We prepare thin film nano-composites composed of polyelectrolytes and carbon nanotubes using the LbL technique. Our focus is on dispersion control and distribution of carbon nanotubes in the thin film structure, and tuning of polymer-nanotube interactions which will maximize bulk thin film properties, such as electrical conductivity.

Polymer brush-like structures composed of natively unfolded polypeptides play a central in controlling an unique example of ultra-selective macromolecular transport through the nuclear pore complex (NPC), a nanopore that sits on the nuclear envelope in eukaryotic cells. We use coarse-grained moelcular dynamics and Langevin dynamics simulations to simulate that dynamics of these polypeptides, both in isolation and as a collective, to extract biophysical principles that would influence transport across a minimalist NPC.

Radiation damage in metals is a complex phenomena which can lead to the evolution of a variety of defects in the microstructure. An understanding of radiation damage becomes critical in applications, such as pressure tubes, where there is a zero tolerance for failure. The evolution of defects in radiation damage, presumably, starts at the atomistic level with interaction between an impinging projectile (proton, neutron, or an ion) and the lattice atoms. We simulate irradiation damage in metallic materials to study the evolution of lattice defects, of stresses, and interactions of point defects with grain boundaries. This effort is complemented with direct EBSD measurements in Prof Samajdar's laboratory.