Gas Hydrates: Nucleation, Growth and Stability
Gas hydrates are formed when water and certain gases (such as methane, ethane, carbon dioxide) are brought in contact at low temperature and high pressure. They are crystalline solids that look like ice at the macroscopic scale. They comprise water molecules hydrogen bonded to form cages that trap gas molecules within them. Formation of hydrates poses an expensive flow assurance problem in the oil and gas industry. Naturally occurring methane hydrate reserves on the other hand, are potential sources of energy for the future. In our research, we focus on understanding the mechanisms through which gas hydrates form. We are specifically focused on the nucleation and growth of hydrates and use molecular dynamics simulations to get insights into the molecular mechanisms for hydrate formation. We are currently investigating the effects of surfaces on gas hydrates (i.e. heterogeneous nucleation of gas hydrates) using advanced sampling techinques. This project is funded by American Chemical Society Petroleum Research Fund.
Ice Nucleation Relevant to Clouds
Heterogeneous ice nucleation is considered to be the primary pathway for formation of ice in clouds. It is however, not known what factors about a surface make any given surface a good ice nucleating agent. In our research, we are using advanced molecular simulation techniques to study surface-assisted ice nucleation. We are performing detailed analysis of the structure and dynamics of water at these interfaces and correlating these factors to the kinetics of ice nucleation. The findings from this research has implications in any field involving water behavior at interfaces - this really spans almost all fields in materials science! - including biological systems, metal-water interfaces relevant to catalysis, nanoparticle assebmly, developing anti-icing surfaces and semiconductor industry.
Dendrimers and Hyperbranched Polymers
Dendritic polymers are repeatedly branched molecules and comprise three main components – core, interior branch cells and terminal branch cells. The dendrimer core determines the shape, size and multiplicity of the molecule; the branch groups determine the volume and the terminal groups control the interactions of the dendrimer with the guest molecules in the solution. Environmental factors such as pH, solvent ionic strength and temperature can be used to control the dimensions and behavior of the dendrimers. The vast flexibility in the synthesis, physicochemistry and assembly of dendrimers has led to the emergence of several promising applications for dendritic polymers ranging from drug delivery to environmental remediation and energy storage. In our simulations we are using all-atom molecular dynamics simulations and coarse grained simulations to study the dendrimer behavior. Currently, we are investigating the association of aromatic hydrocarbons to dendrimers. This study is motivated by the possibility of using dendrimers to remove polyaromatic contaminants from water. The insights are also relevant to applications such as using dendrimers for drug delivery.