(247c) Spatially Varying Chemical and Physical Properties Modulate Interfacial Hydrophobicity of Self-Assembled Monolayers
- Conference: AIChE Annual Meeting
- Year: 2019
- Proceeding: 2019 AIChE Annual Meeting
- Group: Computational Molecular Science and Engineering Forum
- Time: Tuesday, November 12, 2019 - 8:45am-9:00am
Experiments using an atomic force microscope (AFM) revealed specific chemical and physical properties have unexpected effects on the strength of HIs. In this work, we used molecular dynamics simulations to investigate with atomistic resolution the origin of those effects. We found that the hydrophobicity of SAMs can be altered by changing interfacial properties (e.g., alkyl chain length, functional group chemistry, and ligand composition). Specifically, we observed functional group chemistry modulates the hydrophobicity of the adjacent nonpolar domains in mixed SAMs. Further, we investigated the roles of molecular fluctuations and SAM order to determine the key component influencing nonpolar SAM hydrophobicity. We find that spatially varying SAM order leads to interfaces that appear chemically heterogeneous. We identified that perturbations to the nanoscale structure of nearby water molecules can explain the effects of interfacial properties on hydrophobicity. These perturbations were then quantified to provide a mechanism to explain how spatially varying interfacial properties modulate hydrophobicity. These physical insights can then be applied to new experimental systems to predict interfacial hydrophobicity.