Sustainable repair: A novel healable polyurethane wood coating

 
A water-borne polyurethane with assisted self-healing technology was developed for protective coating applications. The novel self-healing coating can recover physical damage upon exposure to heat, moisture or certain solvents via reversible hydrogen bonding aided by a polyamide soft segment that was developed to provide optimal performance-recovery balance. The technology is suitable to be implemented in exterior and interior wood coatings with protective features comparable to high performance WB systems. Test methods were developed to study the film recovery process to accurately assess the delicate balance between the self-healing and the protective features of the resins. It was found that the best recovery can be achieved using diluted isopropanol solutions, but the recovery is significant at elevated temperatures and in high humidity environment as well, and the recovery-performance balance can be modified by simple formulation changes. The resin was designed for environmentally friendly coating applications with ~20% renewable carbon content at low VOC formulation levels.