Fabrication of microcapsules containing dual-functional tung oil and properties suitable for self-healing and self-lubricating coatings

Tung oil-loaded microcapsules with the protection of Poly(urea-formaldehyde) (PUF) shells were prepared by in-situ polymerization method. Microcapsules keep the spherical shape with core content of more than 80.0 wt%. The average diameter was approximately 105 μm. Microcapsules exhibit excellent thermal stability. Dual-functional coatings were prepared by incorporating tung oil-loaded microcapsules into epoxy. Self-healing and self-lubricating function of coatings were realized by the releasing of tung oil from microcapsules under the scarp or wear condition. Tung oil has excellent film-forming property when they contact with oxygen. self-healing anti-corrosion and self-lubricating anti-wear properties were evaluated by salt-immersed corrosion tests and wear tests. Results demonstrated the coatings have an excellent corrosion resistance performance, the corrosion resistance get better as the increasing of microcapsules content. Besides, epoxy coatings demonstrated a favorable self-lubricating performance with the add of microcapsules. The friction coefficient and wear rate were the lowest at the microcapsules content of 10 wt%, there were 17.3% and 78.6% decrease respectively compared to the pure epoxy. The self-healing and self-lubricating mechanism were also discussed.