Bottle-brush polyurethane as water-based lubricant additive for hydrophobic interfaces

Water-based lubricants were limited on chemically inert and hydrophobic interfaces due to the difficulty in forming an effective boundary lubrication layer. In this study, a bottle-brush polyurethane (BBP) lubricant additive was designed to address the issue through the establishment of multiple non-covalent interactions. 1 H NMR, FTIR and molecular dynamics (MD) simulation revealed that the backbone and side chains of BBP provided multiple hydrogen bond interactions. QCM-D verified that BBP was capable of constructing a denser interfacial adsorption layer than linear macromolecules. The as-prepared BBP lubricant exhibited outstanding lubrication performance across various hydrophobic interfaces and was better than oleophilic, hydrophilic and amphiphilic lubricants. Meanwhile, BBP lubricant presented extremely low toxicity to cells and earthworms, indicating potential in medical and industrial fields.