取代基电子效应对聚苯并噁嗪热稳定性影响研究

Influence of Electronic Effects of Substituted Group on the Thermal Stability of Polybenzoxazine

以苯酚/苯胺型苯并噁嗪和苯酚/4,4'–二苯甲烷二胺型苯并噁嗪为参照对象,通过DSC、TGA和TGA-FTIR联用测试,研究了酚羟基对位连有不同电子效应的取代基时,苯并噁嗪中间体开环聚合及其聚合物热稳定性的变化。结果表明,酚羟基对位氯原子的取代降低了苯并噁嗪中间体开环聚合的温度,而甲基的取代使苯并噁嗪中间体开环聚合的温度升高;由于氯原子的吸电子效应导致聚苯并噁嗪Mannich(曼尼希)桥上的C—N和C—C键被削弱,使得其热稳定性下降;甲基的取代使聚苯并噁嗪的交联密度下降,因而也降低了其热稳定性。

In order to study the influence of electronic effect of substituted group in para-position of phenolic hydroxyl on ring-opening polymerization of benzoxazine and thermal stability of polybenzoxazine, choosing the benzoxazine based on aniline and phenol or based on phenol and 4, 4＇-diaminophenyl methane as a reference, and several benzoxazines and their polymer with electron-withdrawing or electron-donating groups were analysed through DSC, TGA and TGA-FFIR. The results showed that the substituent of chlorin atom with electron-withdrawing decreased the temperature of ring-opening polymerization and the substituent of methyl with electron-donating made the polymerization temperature increasing. The electron-withdrawing effect of chlorin atom weakened C-N and C-C bonds in the Mannich bridges of polybenzoxazines, which reduced their thermal stability. The substituent of methyl lessened the crosslink density of polybenzoxazine, and resulting in the decrease of their thermal stability.