The Viscosity-Propelled Rotary Nanomotor through the Solid-Liquid Interface

Abstract

This study presents a novel and straightforward model of a nanomotor capable of rotation propelled by friction at the solid-liquid interface. Within this nanosystem operating in a Rotary Electric Field (REF), a pristine carbon nanotube, electrically neutral, is infused with water, serving as the rotor. Polar molecules within the water rotate alongside the REF, generating interface friction that propels the nanotube rotor. Molecular dynamics simulations demonstrate that the nanomotor rapidly achieves a stable rotational frequency (SRF), typically within 200 ps in this investigation. Furthermore, each rotor tube possesses a maximum SRF value, denoted as ωRMax. When the REF frequency (ωE) exceeds ωRMax, the rotor tube, water cluster, and REF exhibit varying rotational frequencies. It is also observed that the relationship between the rotor's SRF and ωE conforms to an inverse square law when ωE surpasses ωRMax. The underlying mechanism is elucidated. These findings can inform the design of a rotary nanomotor constructed from water-filled carbon nanotubes, offering tunable SRF capabilities.