A series of ultraviolet (UV)-curable self-healing polyurethane (PU) oligomers were synthesized by incorporating different contents of 2-ureido-4[1H]-pyrimidone and polycarbonate diols (PCDL) with different molecular weights at the end of PU chains. The structure of the oligomers were determined through Nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy. The PU oligomers were used to produce UV-curable self-healing coatings, the properties of which were investigated and the properties of the coatings with different functionality were studied. The results revealed that the performance of the coating was higher when a higher molecular weight of PCDL was used and With functionality increasing, the crosslinking density of the coating ascends, resulting in higher self-healing temperature and upper pendulum hardness and gloss of the coating. To balance the self-healing ability and mechanical properties of the coating, a series of coating formulations were designed by adding different types and amounts of active diluents. Double bond conversion, thermostability, and self-healing ability were investigated to determine the effect of active diluents on coating performance. The results demonstrated that the resultant coating have excellent adhesion, gloss, and thermostability. Coatings prepared used all types of active diluents had favorable self-healing ability, except for that prepared using 2-acryloyloxymethyl-2-ethyltrimethylene diacrylate. Excellent self-healing and mechanical properties were obtained when 20 w.t.% of triethoxylated trimethylolpropane triacrylate was used.
Volume 113, December 2017, Pages 160–16