Synthesis of novel waterborne polyurethane coatings with excellent solid lubricating performance

To minimize friction and wear of dynamic rubber seals and to ensure their long-term functionality by using of an elastomer lubricating coating is of great interests. In the present work, waterborne polyurethanes (WPU) molecules were modified with polydimethylsiloxane (PDMS), and polycarbodiimide (PCD) were further added. Effect of molecular structures on macroscopic performance of the WPU coatings was comprehensively investigated. Our results demonstrated that grafting of PDMS significantly lowered the surface energy of the WPU coating, and thus decreased remarkably its friction and adhesion wear. What’s more, PCD helps construction of a dual-crosslinking structure, and thus enhances mechanical properties, chemical and wear resistance of the coating. Output of this work proposes a new strategy for developing free-maintenance lubricating technologies for numbers of dynamic rubber seals.