Novel green waterborne polyurethane-polytetrafluoroethylene BSLCs: Chemically optimized crosslinking extent for enhancing the mechanical and tribological properties

Waterborne bonded solid lubricating coatings (BSLCs) are normally prepared by physical blending, the basic components of which, however, exhibit poor wetting and dispersing properties and interfacial bonding strength. This article focuses on the structural design and chemical modification of waterborne polyurethane to optimize the adhesion of BSLCs thereof. By virtue of further compounding with polytetrafluoroethylene emulsions, a series of novel environmentally-friendly waterborne BSLCs have been successfully prepared, and then by adjusting the interface bonding between the resin and the lubricant in the coatings, the lubrication and wear resistance of the prepared BSLCs are systematically optimized. Experimental results demonstrate that the prepared waterborne BSLCs can effectively reduce the consumption of fossil resources and show superior physicochemical properties, lubrication and wear resistance, which are comparable to those of the organic solvent-based coatings. Furthermore, through systematic analysis of the damage morphology, structural variations and chemical compositions of the wear marks, the tribological mechanisms of the prepared BSLCs are illustrated. The current study help to promote the development of environment-friendly solid lubricating materials, and provides alternatives for the use of organic solvent-based BSLCs for reducing pollutions.