Preparation and properties of organosilicon and castor-oil-modified rosin-based waterborne polyurethane coatings

Renewable resources are receiving increasing attention in the field of waterborne polyurethane (WPU) coatings, to improve the hydrophobic properties and biobased content of WPU coatings, this study introduced castor oil (C. O.) and hydroxyl-terminated polydimethylsiloxane (PHT) into polyurethane resins containing a rosin moiety. The addition of C.O. improves the densification of the coatings to make it acid and alkali resistant, and significantly enhances the wear and corrosion resistance. Subsequently, the introduction of organosilicon can improve the thermal stability and hydrophobicity of the coatings. The polyurethane structure was analyzed through infrared spectroscopy and X-ray photoelectron spectroscopy. Water resistance was evaluated by measuring the static water contact angle and water absorption, while thermal stability was assessed by thermal weight analysis. Additionally, wear resistance was determined by examining the water contact angle after subjecting the coatings to wear. The results indicate that the incorporation of C.O. and PHT into the WPU structure enhances its water resistance, wear resistance, acid and alkali resistance and thermal stability. Electrochemical testing further demonstrates that polyurethane coatings modified with C.O. and PHT exhibit superior resistance to chemical corrosion. This work provides a research basis for the application of high-performance biobased WPU in the field of anticorrosion coatings.