Low interlaminar shear stress, high mechanical strength,
and tunable
structure make Ti3C2T
x
MXene a burgeoning star as solid lubricants and lubricant
additives. Although surface modification strategy can improve its
compatibility with base oils, it will eventually settle due to gravity.
Additionally, base oils are prone to leakage, creep, and volatilization,
which limit their application. To address these issues, supramolecular
gels with surface-modified Ti3C2T
x
were conceived. Apart from the lubrication effect,
the high thermal conductivity of Ti3C2T
x
MXene accelerated the phase transition rate
of supramolecular gels. The thermal-reversible and creep-resistant
properties distinguish them from other conventional lubricants. The
tribological tests showed that the 500 solvent neutral (SN) supramolecular
gel with 0.10 wt % Ti3C2T
x
-octadecylphosphonic acid (Ti3C2Tx-ODPA) reduced the coefficient of friction (COF) by 46.32%
and wear volume by 81.18% compared with pure 500SN oil. Moreover,
they also performed well in load-carrying capacity, temperature tolerance,
and speed adaptability. This work puts forward a new approach to prepare
MXene-based lubricants tailored for some severe lubrication conditions.
These exceptional features enable their application in rolling bearings,
some gears, and other low maintenance mechanisms.
MXene possesses great potential in enriching the functionalities of hydrogels due to its unique metallic conductivity, high aspect ratio, near-infrared light (NIR light) responsiveness, and wide tunability, however, the poor compatibility of MXene with hydrogels limits further applications. In this work, we report a uniformly dispersed MXene-functionalized poly-N-isopropylacrylamide (PNIPAM)/poly-2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) double network hydrogel (M—DN hydrogel) that can achieve switchable friction regulation by using the NIR light. The dispersity of MXene in hydrogels was significantly improved by incorporating the chitosan (CS) polymer. This M—DN hydrogel showed much low coefficient of friction (COF) at 25 °C due to the presence of hydration layer on hydrogel surface. After illuminating with the NIR light, M—DN hydrogel with good photothermal effect rapidly raised the temperature to above the lower critical solution temperature (LCST), which led to an obvious increase of surface COF owing to the destruction of the hydration layer. In addition, M—DN friction control hydrogel showed good recyclability and controllability by tuning “on-off” of the NIR light. This work highlights the construction of functional MXene hydrogels for intelligent lubrication, which provides insight for interface sensing, controlled transmission, and flexible robotic arms.
Hydrogels are becoming increasingly popular in biomedical and soft machine manufacturing, but their practical application is limited by poor mechanical properties. In recent years, Hofmeister effect-enhanced gelatin hydrogels have become...
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