Dynamic oil gels constructed by 1,2-dithiolane-containing telechelic polymers: An efficient and versatile platform for fabricating polymer-inorganic composites toward tribological applications

Lubricant additives even performing slightly better in machinery systems would lead in total to the marked reduction of harmful emissions and the significant improvement of fuel economy. Although nanoparticles have demonstrated great potentiality as better lubricant additives, their practical applications have been seriously impeded by their poor colloidal dispersion in base oils. In this work, structurally dynamic gels have been constructed for the first time in base oils by the reversible ring opening reaction of 1,2-dithiolane-containing telechelic polymers. Representative nanoparticles such as MS2 (M = Mo, W), Ag, and Cu can be homogeneously dispersed into the oil gels through strong coordinating interactions with the 1,2-dithiolane groups. Vial inversion experiments displayed that the resulting polymer-inorganic composite gels have long-term colloidal stability at least for one year. As revealed by SRV-IV oscillating reciprocating tribological tests, the coefficient of friction and wear volume of the composite gels drop significantly up to 56% and 99%, respectively. Moreover, the MoS2 based composite gels exhibit a superior load-bearing capacity of > 1000 N. The mechanism behind such excellent lubricating properties is due to the formation of 60-100 nm thick tribofilms containing Fe-oxide compounds and MoS2 nanoparticles on the worn steel surface. This composite-gel concept not only represents a generalized strategy to fully disperse nanoparticles in base oils but also opens a new avenue to developing high-performance lubricant additives for better friction and wear reduction.