Current research topics

  • Nonequilibrium statistical physics of driven disordered solids
    Amorphous metals, polymers, and oxide glasses find many applications in sustainable, energy saving devices. Improving their performance requires fundamental insight into the molecular level processes that control yield, flow, stability, resistance to wear, and dissipation. We use atomistic simulations of model glasses subject to mechanical and thermal excitation to obtain statistical measures of the local elastic and plastic properties in such disordered packings, and characterize their nonequilibrium response. This information is used to build coarser (mesoscopic or mean-field) descriptions with the goal of building a statistical theory of plastic flow that is systematically linked to processes at the atomic scale.

  • Thermal transport in nanostructures and amorphous polymers
    We study materials with unusually high or low thermal conductivity. Carbon nanotubes are among the best known 1D heat conductors, yet nanotube forests were found to be able to localize heat and function as thermionic devices. By contrast, the thermal conductivity of amorphous polymers is among the lowest of all materials, which limits their applications in electronic packaging, OLEDs or photovoltaics where heat must be removed quickly. We use direct molecular simulations and Boltzmann transport theory to compute thermal properties of materials, and to learn how we can tune it at will by engineering the molecular interactions.

  • Polyelectrolyte hydrogels for sensors and diodes
    Growing interest in motion capture, soft robotics, and wearable medical technologies has stimulated increasing interest in electronic materials that are flexible, conductive and biocompatible. Polyelectrolyte gels are particularly interesting materials that can respond to a pressure gradient with an electrical potential. This so-called piezoionic effect can be used to builld touch-sensors. Layered structures can act as a diode, i.e. they rectify a ionic current. We study these phenomena on the molecular level using molecular dynamics simulations, which we use to test and improve continuum electrostatic descriptions that can be deployed more readily on the engineering scale.

Past projects