Partially Biobased Self‐Repairing Poly(Aspartic Ester Polyurea) Coatings

ABSTRACT Poly(aspartic ester polyurea) (PAEU) coating systems, which feature an uncatalyzed and solventless reaction, have attracted attention as a more environmentally friendly, nonreactive coating alternative in both academia and industry. In these coatings, achieving optimal performance requires an impeccable combination of aliphatic polyisocyanates and polyaspartic esters used as cross‐linking agents. In previous applications, petroleum‐based polyisocyanates were used as the second component. In this study, a biobased prepolymer was synthesized as the second component, thus creating a sustainable PAEU coating class without compromising traditional properties. It is known that traditional coatings can become damaged or cracked when exposed to external forces during processing or use. The coatings achieved the self‐healing feature by using varying amounts of disulfide to improve this situation. The samples were deliberately damaged and then allowed to heal for 1 h at room temperature, 40°C, and 80°C. The results demonstrated improved mechanical properties in all samples. Tensile strength increased by 79%–95%, and elongation recovery rates ranged from 73% to 97% after 1 h of room‐temperature repair. These mechanical test results were consistent with the SEM images for all samples.