Synthesis and characterization of sequential interpenetrating polymer networks of polyurethane acrylate and polybenzoxazine

The purpose of this research is to improve performance of UV curable polyurethane acrylate coating by alloying with thermally curable polybenzoxazine. The hybrid polymer networks of polyurethane acrylate and polybenzoxazine were prepared by sequential cure methods i.e. UV cure method followed by thermal cure method. The effects of sequential cure methods were investigated in term of mechanical, thermal and physical properties of the resulting polymer alloy films. The experimental results revealed that the presence of the polybenzoxazine in the alloy network significantly affected the obtained properties of the PUA/BA-a alloys. The fully cured PUA/BA-a alloy films were transparent and showed only single glass transition temperature, suggesting high compatibility or no phase separation between the PUA and BA-a networks. The storage modulus in a glassy state and the glass transition temperatures (Tg) of PUA/BA-a alloys from the sequential cure method were found to substantially increase with increasing the BA-a mass fraction. Furthermore, Td at 10% weight loss of the PUA/BA-a alloy films was relatively high whereas the char yield at 800๐C was found to increase with an incorporation of the BA-a. Hardness, and water contact angle were enhanced whereas water absorption and water permeability of the alloy films were suppressed by the incorporation of the BA-a into the polymer alloys. As a consequence, thermal, mechanical and physical properties of the UV curable polyurethane acrylate networks can be positively tailored and enhanced by forming hybrid network with the BA-a. From the above results, the PUA/BA-a alloy at a 50/50 mass ratio was found to be the most suitable composition for e.g. high performance coating application.

本研究旨在通过将紫外光固化聚氨酯丙烯酸酯（UV curable polyurethane acrylate，下文简称PUA）与热固化苯并恶嗪（polybenzoxazine）共混合金化，改善该类涂层的综合性能。研究采用分步固化工艺制备PUA与苯并恶嗪的杂化聚合物网络，即先实施紫外光固化，再进行热固化。本研究探究了分步固化工艺对所得聚合物合金薄膜力学、热学及物理性能的影响。实验结果表明，合金网络中苯并恶嗪的引入对PUA/BA-a合金的最终性能具有显著影响。完全固化后的PUA/BA-a合金薄膜呈透明状态，且仅表现出单一玻璃化转变温度，这表明PUA与BA-a网络之间具有高度相容性，未发生相分离。经分步固化法制得的PUA/BA-a合金，其玻璃态储能模量与玻璃化转变温度（Tg）均随BA-a质量分数的提升而显著升高。此外，PUA/BA-a合金薄膜在10%质量损失时的热分解温度（Td）相对较高，且800℃时的残炭率随BA-a的掺入而提升。向聚合物合金中引入BA-a后，薄膜的硬度与水接触角得到提升，而吸水率与水渗透率则得到抑制。综上，通过与BA-a构建杂化网络，可有效调控并优化紫外光固化聚氨酯丙烯酸酯网络的热学、力学与物理性能。基于上述实验结果，质量比为50/50的PUA/BA-a合金为最优组合物，适用于高性能涂层等应用场景。