Toughened polybenzoxazine coating matrix with improved comprehensive performance through hydrogen bond tuning with new polyurethanes

Polybenzoxazine has been explored in coating applications because of its excellent properties, including good processability, excellent thermal stability, and large water contact angles, but its toughness must be improved without compromising its other properties. Herein, a new serious of polyurethanes with varying numbers of ether groups were synthesized to enhance the toughness of polybenzoxazine via tuning the hydrogen bonds. The curing mechanism, chemical structures, and phase morphology of the blends are discussed. The results show that hydrogen bonding is the main reason for improved properties of the cured products. By varying the hydrogen bond content of the modified system, a champion toughness of 20.4 kJ/m(2) without sacrificing processability, thermal stability, and coating performances can be realized, which the char yield is varied between 26.0 % and 28.9 % at 800 degrees C and corresponding coating hardness and adhesion can reach to 6H and 5B, respectively. Furthermore, the modified system-based coatings exhibit a reversible hydrophobic-hydrophilic state by different stimulus with a champion oil-water separation efficiency of 3379 L.m(-2).h(-1), illustrating their potential intelligent applications.