Influence of electronic effects from bridging groups on synthetic reaction and thermally activated polymerization of bisphenol‐based benzoxazines
Influence of electronic effects from bridging groups on synthetic reaction and thermally activated polymerization of bisphenol‐based benzoxazines
复制标题
DOI：
10.1002/pola.24566
复制
发表时间：
2011-03
期刊：
影响因子：
--
通讯作者：
Xiaoying Wang;Feng Chen;Yi Gu
中科院分区：
文献类型：
--
作者：
Xiaoying Wang;Feng Chen;Yi Gu
在甲苯中合成了6种不同桥连基团（-C（CH 3）2 -，-CH 2 -，-O-，-CO-，-SO2-和单键）的双酚类双苯并恶嗪化合物。比较详细地讨论了桥连基团的电子效应对成环反应和热开环聚合的影响。通过高效液相色谱、傅里叶变换红外光谱、核磁共振氢谱、差示扫描量热法和元素分析等手段对化合物的结构进行了表征。通过分子模拟计算了双酚和双苯并恶嗪的量子化学参数。结果表明，吸电子基团通过降低双酚的α-Cs电荷密度，增加反应能垒，抑制了合成反应.而吸电子基团的引入则促进了热活化聚合，这是由于吸电子基团增加了恶嗪环上C-O键长，降低了恶嗪环上C-O键的键能，从而降低了反应活化能和固化温度。此外，由于砜基的吸电子能力较强，在聚苯并恶嗪中存在较多的芳胺亚甲基Mannich桥结构。
Six bis-benzoxazines based on bisphenols with different bridging groups, —-C(CH 3 ) 2 —, —CH 2 —, —O—, —CO—, —SO 2 —, and single bond, were synthesized in toluene. The influence of electronic effects from bridging groups on ring-forming reaction and thermal ring-opening polymerization were relatively discussed in detail. Their structures were characterized by high-performance liquid chromatography, Fourier transform infrared, 1 H NMR, differential scanning calorimetry, and elementary analysis. The quantum chemistry parameters of the bisphenols and bis-benzoxazines were calculated by molecular simulation. The results indicated that the electron-withdrawing groups inhibited the synthetic reaction by decreasing the charge density of α-Cs of bisphenols and increasing energy barriers of the synthetic reactions. However, the electron-withdrawing groups promoted the thermally activated polymerization, which resulted from their activation energy and curing temperature decrease by increasing the bond length and lowering the bond energy of C—O on oxazine rings. Besides, because of stronger electron-withdrawing sulfone group, there were more arylamine methylene Mannich bridge structure in the polybenzoxazine.