Cure behavior and compatibilization of epoxide hyperbranched polyurethane on silica/benzoxazine blend

The compatibility of polymer blends is pivotal for their performance enhancement due to the large surface tension and weak interaction among individual components. In this work, epoxide hyperbranched polyurethanes (EHPU) was used to realize the compatibility between silica (SiO2), generated in situ from tetraethoxysilane, and benzoxazine (BZ). The compatibilization effect and mechanism of EHPU on SiO2/BZ were investigated via the differences of cure characteristics and kinetics between BZ, SiO2/BZ, and EHPU-SiO2/BZ blend. EHPU-SiO2/BZ blend exhibited lower initial curing temperature and wider curing window than those of SiO2/BZ and neat BZ. In addition, the co-curing reaction was existed between EHPU and BZ, which contributed to the reactive compatibilization. More importantly, the growth of SiO2 particles was hindered by the nonreactive compatibilization due to the hydrogen interaction between EHPU and the silanols. Thus, the compatibilization of EHPU on SiO2/BZ blend is a result of the synergetic effect of the hydrogen interaction and the co-curing. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46879.