Wear in-situ self-healing polymer composites incorporated with bifunctional microcapsules

Self-lubricating materials inevitably suffered mechanical damage such as wear, micro-scratch and cracks, which will shorten the service life of materials. The highlight of this work is to improve the wear resistance of the material by coupling self-lubricating and self-healing. Herein, we investigated the ability of a polymer composite incorporated with bifunctional microcapsules to heal mechanical damage. Thermally robust microcapsules containing organic solvent dibutyl phthalate (DBP) and linseed oil (LO) were synthesized by in situ polymerization of urea and formaldehyde in an oil-in-water emulsion. The microcapsules were filled in an epoxy (EP) resin matrix and cured to form composite materials. Multiple characterization methods such as 3D scratch instrument, UMT-5 machine and Atomic Force Microscope (AFM) were adopted to investigate the healing performance and healing mechanism of materials. The composite materials incorporated with bifunctional microcapsules presented excellent scratch self-healing ability (the self-healing efficiency was higher than 96% by volume) and wear resistance (the friction coefficient has been reduced by 92% and the wear rate has been reduced by three orders of magnitude). It was demonstrated that the combination of lubrication enhancement and wear scar self-healing could greatly prolong the service life of lubricating materials.