1 research outputs found
Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman
High load-bearing capacity is one of the crucial indicators
for
liquid superlubricants to move toward practicality. However, some
of the current emerging systems not only have low contact pressures
but also are highly susceptible to further degradation due to water
adsorption and even superlubricity failure. Herein, a novel choline
chloride-based ionic liquid analogues (ILAs) of a superlubricant with
triethanolamine (TEOA) as the H-bond donor is reported for the first
time; it obtains an ultralow coefficient of friction (0.005) and high
load-bearing capacity (360 MPa, more than 2 times that of similar
systems) due to adsorption of a small amount of water (<5 wt %)
from the air. In situ Raman combined with 1H NMR and FTIR
techniques reveals that adsorbed water competes with the hydroxyl
group of TEOA for coordination with Cl–, leading
to the conversion of some strong H-bonds to weak H-bonds in ILAs;
the localized strong H-bonds and weak H-bonds endow the ILAs with
high load-bearing capacity and the formation of ultralow shear-resistance
sliding interfaces, respectively, under the shear motion. This study
proposes a strategy to modulate the interactions between liquid species
using adsorbed water from air as a competing ligand, which provides
new insights into the design of ILA-based macroscopic liquid superlubricants
with a high load-bearing capacity