Paper Citing NAMD - Abstract
Dai, Zheng-Wei; Wan, Ling-Shu; Huang, Xiao-Jun; Ling, Jun; Xu, Zhi-Kang
Selective Adsorption of Isopropyl Alcohol Aqueous Solution on Polypropylene Surfaces: A Molecular Dynamics Simulation
JOURNAL OF PHYSICAL CHEMISTRY C, 115:22415-22421, NOV 17 2011
Surface modification for hydrophilization is a versatile approach to significantly improve the separation performance of membranes prepared from hydrophobic polymers such as polypropylene (PP). This improvement is closely related to changes in the chemical characteristics of membrane surface and alterations in the adsorption behaviors of feed components. We simulated the interaction of isopropyl alcohol aqueous solution with nascent and hydrophilized PP surfaces by molecular dynamics to understand the molecular mechanism of these variations. The results were used to evaluate the selective adsorption of isopropyl alcohol on the model surfaces. The isopropyl alcohol molecule shows surfactant-like behaviors due to one hydroxyl group as the polar end and two methyl groups as the apolar end. For nascent PP surface, dispersive force plays a key role in the interaction of isopropyl alcohol molecules with model surface. Isopropanol is therefore selectively adsorbed from the aqueous solution, and water is repelled out of the interfacial layer. For the hydrophilized surfaces, however, the electrostatic interaction between water molecules and surface polar groups exceeds the effect of dispersive force. As a result, water molecules are attracted onto the modified surface and hydration layers are observed.
