Giant slip length at a supercooled liquid-solid interface

TL;DR

This study uses molecular dynamics to explore how temperature affects slip length at a supercooled liquid-solid interface, revealing superlubricity due to surface crystallization and structural incommensurability.

Contribution

It demonstrates the temperature-dependent behavior of slip length in supercooled liquids and links superlubricity to surface crystallization and structural mismatch.

Findings

Slip length increases dramatically in the supercooled regime.

Interfacial friction can decrease or remain Arrhenian as temperature lowers.

Surface crystallization leads to superlubricity at low temperatures.

Abstract

The effect of temperature on friction and slip at the liquid-solid interface has attracted attention over the last twenty years, both numerically and experimentally. However, the role of temperature on slip close to the glass transition has been less explored. Here, we use molecular dynamics to simulate a bi-disperse atomic fluid, which can remain liquid below its melting point (supercooled state), to study the effect of temperature on friction and slip length between the liquid and a smooth apolar wall, in a broad range of temperatures. At high temperatures, an Arrhenius law fits well the temperature dependence of viscosity, friction and slip length. In contrast, when the fluid is supercooled, the viscosity becomes super-Arrhenian, while interfacial friction can remain Arrhenian or even drastically decrease when lowering the temperature, resulting in a massive increase of the slip length. We rationalize the observed superlubricity by the surface crystallization of the fluid, and the incommensurability between the structures of the fluid interfacial layer and of the wall. This study calls for experimental investigation of the slip length of supercooled liquids on low surface energy solids.