High-Performance Bio-Based Polyurethane Antismudge Coatings Using Castor Oil-Based Hyperbranched Polyol as Superior Cross-Linkers

Bio-based antismudge coating, as a substitute for the petroleum-based one, has excellent liquid repellency and self-cleaning ability, which is of great value to keep a coated surface free of contaminants. In this study, we report a facile strategy to fabricate high-performance biobased hyperbranched polyurethane antismudge coatings. More specifically, a castor oil-based hyperbranched polyol was employed as a coating precursor, a hexamethylene diisocyanate trimer was used as the curing agent, and a mono-hydroxyl-terminated poly(dimethysiloxane) (PDMS-OH) was introduced as a low-surface-tension lubricant through covalent bonding. Consequently, a highly transparent smooth coating was obtained after the coating solution was completely cured. The coating loaded with 0.5 wt % PDMS-OH exhibited superb liquid repellency and self-cleaning ability, as attested by liquids such as water, hexadecane, peanut oil, pump oil, salt solution, strong acid, and strong alkali solutions that could slide off the coated surfaces cleanly. In addition, even after 1000 writing and erasing cycles, the coating still retained its ability to contract ink traces and the contracted ink could be easily removed with tissue paper. Apart from antigraffiti and antifingerprint performance, the coating applied on tin plate surfaces showed an adhesion grade of 5B and a pencil hardness of 3H and displayed superior corrosion resistance. Furthermore, this mechanically robust coating could withstand 1000 abrasion cycles without sacrificing its ink contraction ability. Therefore, this biobased antismudge coating should provide an alternative avenue for developing green and sustainable functional coatings.