(346bt) Utilizing Molecular Dynamics Simulations to Predict the Modulation of Interfacial Hydrophobicity By Chemical and Physical Properties
- Conference: AIChE Annual Meeting
- Year: 2020
- Proceeding: 2020 Virtual AIChE Annual Meeting
- Group: Computational Molecular Science and Engineering Forum
- Time: Wednesday, November 18, 2020 - 8:00am-9:00am
In this study, we utilized classical molecular dynamics (MD) simulations with enhanced sampling techniques to explain the experimentally observed modulation of interfacial hydrophobicity by the physical and chemical properties of self-assembled monolayers (SAMs). First, we used this methodology to explain how the molecular-level order of uniformly nonpolar SAM alters hydrophobic interactions by perturbing interfacial water structure. Next, we applied this methodology to SAMs with polar and nonpolar groups mixed on the surface (chemically heterogeneous SAMs) to understand how specific chemical groups modulate hydrophobicity. This study revealed how each group uniquely perturbs the interfacial water structure and hydrogen bonding network, resulting in changes to the hydrophobicity of the SAMs. Finally, using the insights gained from the previous two studies, we modeled small (< 5 nm radius) SAM-protected gold nanoparticles (AuNP) to understand how both physical and chemical heterogeneities cooperatively and/or competitively influence hydrophobicity. The physical heterogeneity arises from the curvature of the AuNP whereas the chemical heterogeneity arises from the different chemical groups decorating the surface of the AuNP. We developed an analysis technique to map hydrophobicity onto the complex geometries of the AuNPs to understand how these features perturb the interfacial water structure and hydrophobicity. The results from our study provide new insights into the relationship between interfacial chemical and physical properties and hydrophobicity that can be used to guide the design of functionalized materials.