46762-G6
Hydrophobic Interaction in Surfactants and Hydrocarbons from the Pore Scale to the Reservoir Scale
This grant has been successfully allocated to support several graduate students as well as an undergraduate intern, and to support a summer research fellow to investigate finite-size effects on hydrophobic interactions in polymers. We use both all-atomistic molecular simulations and coarse-grained models to address the thermodynamic and kinetic behavior of alkanes and other polymers in nano-containers with varying geometries. We produced one publication and one manuscript in the first year under the support of this program. In the paper of "Manipulating Biopolymer Dynamics by Anisotropic Nanoconfinement", reported in Nano Letters in 2007, we identified the geometry of a nanocontainer that best enhances the rates of polymer collapse. We are the first to address the use of anisotropic nanoconfinement as a tool to manipulate chemical reactions in nano systems. This study was featured in Research Highlights, Nature Nanotechnology and its impact to nanotechnology communities was acknowledged.
We also completed one of our research goals to address the dynamics of an alkane in nano-sized water droplets. This manuscript is ready to be submitted to a peer-reviewed journal in a few weeks. In this study, we investigated the arrangement of water molecules and void distributions in the proximity of a hexane molecule immersed in nano-sized water droplets. Several sizes of water droplets (with diameters of 10Å, 20Å, and 40Å) were chosen for this study. Thermodynamic properties of a hexane as a function of the end-to-end distance, the radius of gyration, and its position in a pore were computed with an aid of advanced sampling algorithm. Water orientation and water density distribution within the proximity of a hexane were analyzed. This study provides quantitative insights of hydrogen bonding of a network of water molecules interrupted by a hexane molecule in nano-sized pores. We found that finite-size effects are significant to the determination of dominant hexane conformations that are frustrated to compete for available space as well as to satisfy the entropy of water arrangement in small pores at an atomistic detail.
Supports from the ACS PRF helped initiate new projects in my group and gave a strong leverage to attract internal and external funding resources during this time. I have received two internal grants from the University, $20000 TcSUH seed grant and $28999 UH GEAR grant, in the 2008-2009 fiscal years. In addition, some of the research pilot results produced from this program was included in two of my pending NSF proposals that were submitted in November 2007 and July 2008. We are very grateful to the generous support from your prestigious foundation.
