Soft-nanocomposite lubricants of supramolecular gel with carbon nanotubes

Abstract

Carbon nanotubes (CNTs) have been the focus of much research due to their excellent lubricity and anti-wear properties. However, when they are used as lubricating oil additives, they tend to agglomerate and precipitate, because of which achieving good dispersion stability is a significant problem. This manuscript reports a new strategy to successfully resolve the problem of poor dispersion stability of CNTs in the lubricating material 12-hydroxystearic acid (12-HSA) supramolecular gel. On the one hand, the carbon nanotubes are trapped in the network of the supramolecular gel which greatly reduces its reaggregation in the 500SN base oil. On the other hand, the carbon nanotubes significantly improved the thermal, mechanical and tribological properties of the supramolecular gel. For example, the decomposition temperature is increased by 30 °C as the 500SN base oil molecules are trapped in the 3-D network of supramolecules. The viscoelasticity of the supramolecular gel is improved when the carbon nanotubes are used as additives. The results also show that a small quantity of modified carbon nanotubes as additives can significantly reduce friction and wear. And the CNTs and acidified carbon nanotubes (CNTHs) can provide the same friction coefficient as both of them are trapped in the 3-D network of the quasi-solid state 12-HSA soft-nanocomposite. In addition, we performed experiments and molecular dynamics simulations to explore the microstructure and self-assembly mechanism of the soft-nanocomposite lubricant. The soft-nanocomposite lubricant not only prolonged the useful life of machinery, but also reduced the waste of resources, which is significant in sustainable development.