Supramolecular Gel Lubricants Based on Amino Acid Derivative Gelators

This work presents an amino acid-derived urea as the low molecular weight gelators (LMWGs) to solidify a variety of base-lubricating oils as well as different organic solvents. LMWGs self-assemble to form fibrous structures by intermolecular hydrogen bonding and van der Waals forces, and the gelation mechanism was proposed according to the NMR analysis. The obtained gels can liquefy upon heating and gelate again after cooling down, showing reversible temperature-induced phase transition. They showed good thixotropic characteristics so that they became mobile under shearing. Therefore, it a great advantage of these supramolecular gels to be used as potential high-performance semisolid lubricants, which can guarantee both good lubrication and the ability to restrain base oil creeping, oil permeation, or leakage, especially for the gears and rolling bearings. The tribological testing results suggest that these gel lubricants could effectively reduce friction and wear of sliding pairs compared with the corresponding blank base oils and greases.