含偶氮侧基聚酰胺酸的合成及三阶非线性光学性质

SYNTHESIS AND THREE-ORDER NONLINEAR OPTICAL PROPERTIES POLYAMIC ACID ATTACHED WITH DIFFERENT AZO SIDE-CHAIN

选取苯代三聚氰胺(BGA)和均苯四酸二酐(PMDA)为单体进行微波辐射溶液聚合反应,所得的聚酰胺酸(PAA)与对位取代基不同的苯胺重氮盐偶合接枝,从而合成了一系列新的具有三阶非线性光学活性的侧链型聚合物。通过红外、紫外、元素分析、拉曼、核磁等测试方法对接枝聚合物的结构进行了表征。通过简并四波混频飞秒激光系统对各个接枝聚合物的三阶非线性极化率系数进行了测定,考察了偶氮侧链的引入对聚合物主链三阶非线性的影响,并考察了侧链上不同取代基的电子效应对主链三阶非线性的影响。结果表明,侧链上偶氮基对提高聚合物主链三阶非线性具有一定的贡献,取代基的电子效应也对聚合物的三阶非线性具有不同的影响。

P-π conjugated polyamic acid(PAA) was synthesized by the poly-condensation of benzoguanamine(BGA) and pyromellitic dianhydride(PMDA) under microwave irradiation. Then PAA was grafted with different side-chain containing azobenzol groups through azo coupling reaction. The new NLO side-chain PAAs synthesized were characterized by FT-IR, UV-Vis, elemental analysis, FT-IR and ()~1H-NMR. The third-order optical nonlinearities and time responses were measured by a phase conjugate forward, 3-dimensional degenerate, four-wave mixing(DFWM) technique. Comparing polymers third-order NLO coefficient, it shows that the χ~^((3)) value increasecs with the introduction of the azobenzol side-chain. The electron withdrawing and push ability of the different substituting group affect the χ~^((3)) value in different degree.