2023 Volume 15 Issue 2 Pages 36-41
To understand the molecular transport from micro-sized aqueous droplets to nano-sized reverse micelle of Span 80, we perform molecular dynamics simulations of reverse micelles with different contents of water. Span 80 is a nonionic surfactant, and its reverse micelle is expected to be applied for the selective enrichment of solutes in microdroplets. We focus on hydrogen bonds (HBs) inside reverse micelles and calculate the lifetime of HBs between water molecules, between surfactants, and between water and the surfactant. It is found that the reverse micelle with less water has longer HB lifetime for all molecular pairs. The longer HB lifetime between water molecules prolongs the HB lifetime between surfactants, thereby making the reverse micelle itself more rigid in the system with less water. Since the HB lifetime of water-water in the reverse micelles is much longer than that of bulk water, the water environment in the nano-sized reverse micelle is much different in the bulk system.
