Interface water-induced hydrophobic carbon chain unfolding in water

Abstract

The folding and unfolding of the carbon chain, which is the basic constitutional unit of polymers, are important to the performance of the material. However, it is difficult to regulate conformational transition of the carbon chain, especially in an aqueous environment. In this paper, we propose a strategy to regulate the conformational transition of the carbon chain in water based on the all-atom molecular dynamics simulations. It is shown that the unfolded carbon chain will spontaneously collapse into the folded state, while the folded carbon chain will unfold with an external electric field. The regulation ability of the electric field is attributed to the electric field-induced redistribution of interface water molecules near the carbon chain. The demonstrated method of regulating conformational transition of the carbon chain in water in this study provides an insight into regulating hydrophobic molecules in water, and has great potential in drug molecule design and new polymer material development.

Molecular Mechanisms of the Generation and Accumulation of Gas at the Interface

“…As mentioned above, catalytic gas generation can work continuously in the presence of an external electric field. Since the gas molecules are nonpolar molecules while water molecules are polar molecules, only the water molecules can be affected by the electric field. − To understand the changes in the structure of the water molecules under the electric field, we first calculated the density distribution of the water molecules along the z -direction, as shown in Figure a. It can be seen that the density distribution of water fluctuates and increases as the water molecules approach the interface.…”

Nanoscale Three-Phase Transport in a Shale Pore Network with Phase Change and Solid–Fluid Interaction

“…The current thermodynamic and transport models designed for micron scale porous media consequently fail to predict multiphase thermodynamic equilibrium and transport behavior in nanoporous shale. Studies have been done to understand the fluid thermodynamic equilibrium in nanoporous shale by a modified equation of state (EOS) − and molecular simulation. − Travalloni et al established the extended Peng–Robinson equation and van der Waals equation to study the multicomponent hydrocarbon phase change in confined nanopore space considering pore size change and molecule–wall interaction. , The interfacial capillary pressure was further incorporated into fugacity balance calculation based on the simplified single circular pore model. − Numerous studies have been performed to understand the hydrocarbon transport property in a single pore with water distribution using molecular simulation. − Zhan et al and Zhang et al studied the single component octane transport in nanopores with the presence of a thin water film by molecular dynamics (MD) simulations and found that the liquid slippage cannot be neglected for estimating hydrocarbon transport capacity. Kim and Devegowda and Liu et al studied multicomponent hydrocarbon–water distribution in different nanopore types based on MD simulation and found that the water phase tends to be adsorbed on to the inorganic pore surface.…”