Development of biobased polyol from epoxidized soybean oil for polyurethane anti-smudge coatings

In this work, a vegetable oil-based polyol (ERD) with high hydroxyl value was obtained from ring-opening reaction between the renewable epoxidized soybean oil and ricinoleic acid, and further esterified with 2,2-bis(hydroxymethyl)propionic acid. To achieve anti-smudge coating, the ERD polyol was utilized as the polyol component, hexamethylene diisocyanate trimer was employed as the curing agent, and mono-hydroxy-terminated polydimethylsiloxane (PDMS-OH) was introduced as the low surface energy component. In consequence, the biobased polyurethane anti-smudge coatings are highly smooth and transparent. With the incorporation of 1 wt% of PDMS-OH, the obtained coating exhibited superb anti-ink and self-cleaning performance. Droplets of water, soy sauce, carbon ink, hexadecane, rice bran oil, and pump oil could slide off the coating surface without leaving any wetting footprints. More importantly, the coating was mechanically robust. Even after the coating was subjected to 2000 writing and erasing cycles with an oil-based marker pen, it still displayed good ink shrinkage ability and the ink traces could be easily erased. Besides, this anti-smudge coating retained its good hydrophobicity after being soaked in aqueous solutions with different pH values for 24 h. Therefore, the application of this biobased anti-smudge coating would offer a lower carbon footprint than its petroleum-based counterparts.