Nanoscale Dynamics and Transport in Highly Ordered Low-Dimensional Water

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Understanding water behavior under confinement is crucial for various applications.
• Hydrophobic nanochannels present unique environments for molecular interactions.
• Previous studies suggest altered water properties in confined spaces.

Purpose of the Study:

• To investigate the structural and dynamic properties of water in hydrophobic one-dimensional channels.
• To elucidate the role of confinement and intermolecular interactions on water's state.
• To compare water's self-diffusion within nanochannels to bulk water.

Main Methods:

• Neutron scattering techniques were employed to probe water structure and dynamics.
• Experiments were conducted in hydrophobic one-dimensional channels with a van der Waals diameter of 0.78 nm.
• Adsorption processes and molecular interactions were analyzed.

Main Results:

• Highly ordered and cooperative water, exhibiting both solid and liquid properties, was observed.
• Water molecules initially occupied pore wall niches, followed by filling of the central pore area.
• Confinement intensified intermolecular interactions, forming ordered hydrogen-bonded water chains and cooperative vibrations.
• Two relaxation processes were identified, including spontaneous position exchange between water molecules.
• Axial self-diffusion was significantly slower than in bulk water due to these exchanges.

Conclusions:

• Confinement in hydrophobic nanochannels induces unique water structures and dynamics.
• Intermolecular interactions are key to forming ordered water chains and cooperative motions.
• Restricted molecular mobility leads to significantly reduced self-diffusion rates within the channels.