Self-antibacterial UV-curable waterborne polyurethane with pendant amine and modified by guanidinoacetic acid

Enhancing the dispersion stability and self-antibacterial properties of cationic waterborne polyurethane materials is of vital importance to its various applications. In this work, a novel UV-curable waterborne polyurethane with pendant amine (PWPU) from 4-NCO prepolymer and modified by guanidinoacetic acid (GAA) was prepared by a simple method. The 4-NCO prepolymer is originated from the progressively grafting of tridentate polycaprolactone. The GAA, which is rarely used in coating industry, plays a positive reinforced role in our self-antibacterial coatings. Taking fully advantage of the merits of pendant amine and GAA, PWPU without bactericides possesses excellent properties in gram-negative (92.05%) and gram-positive (94.77%) antibacterial tests. Compared with the linear amine waterborne polyurethane (LWPU), PWPU has significant superiority in stability, and the increase in antibacterial efficiency is about 50%. Moreover, antibacterial efficiency still maintained 87.94% after 12 times washing. AFM results display that GAA and pendant amine increase the hydrophilic groups of coating surface, which improves the antibacterial performance. The experiments of thermal, mechanical performance and chemical resistance proof the reliability of the coatings. Therefore, this work has large potential in the applications of antibacterial materials.