含哒嗪环聚酰亚胺的合成及性能表征

Synthesis and Characterization of Polyimides Containing Pyridazine Moieties

以马来酸酐为原料与水合肼反应得到哒嗪酮，再与三氯氧磷反应制备3，6-二氯哒嗪中间体，哒嗪中间体与间氨基苯酚通过亲核取代反应合成了一种新的二胺单体——3，6-二（3-氨基苯氧基）哒嗪．通过^1H—NMR，FTIR及HPLC—MS确证了哒嗪二胺及中间体的结构．这种哒嗪二胺单体与6种芳香二酐单体——均苯四甲酸二酐（PMDA）、3，3’，4，4’-联苯四甲酸二酐（BPDA）、4，4-六氟异丙基邻苯二甲酸酐（6FDA）、3，3’，4，4’-二苯甲酮四甲酸二酐（BTDA）、3，3’，4，4’-二苯醚四甲酸二酐（ODPA）和双酚A型二醚二酐（BPADA）通过两步法聚合制备了一系列的聚酰亚胺，并对其结构和性能进行了研究．结果表明，聚酰胺酸的比浓对数黏度为0．37～0．50dL／g，该系列聚酰亚胺膜具有良好的热稳定性和机械性能，玻璃化温度（Tg）为188～241℃，氮气氛围下5％和10％热失重分别为421～448℃和447～473℃，拉伸强度（Ts）高达102MPa，断裂伸长率（EB）为2．0％～6．5％．紫外可见光谱测试得到的截止波长（λcut-off）为367—389nm．

A new pyridazine-containing aromatic diamine monomer,3,6-bis （3-aminophenoxy） pyridazine, was successfully synthesized by a nucleophilic substitution reaction of 3, 6-dichloropyridazine with metaaminophenol in the presence of potassium hydroxide in dimethyl sulfoxide （DMSO）. ^1H-NMR, FTIR and HPLC-MS were employed to confirm the diamine and intermediates structure. In order to maintain the thermal and mechanical properties, and improve the glass transition temperatures （Tg） and optical property, the novel aromatic heterocyclic diamine monomer was employed to synthesize a series of polyimides by polycondensation with various commercial aromatic dianhydrides in N,N-dimethylacetamide （DMAc） via the conventional twostep method,i, e. , ring-opening polyeondensation forming the poly（amic acid）s （PAA） and further thermal imidization forming the pyridazine-containing polyimides. The resulting PAA possessed inherent viscosities in the range of 0.37 - 0.50 dL/g. High quality polyimide films could be prepared by casting the PAA solutions on glass plates. Experimental results indicated that the polyimide films had good thermal stability, with high initial decomposition temperature （ Td 〉 409 ℃ ） and Ts of 188 -241 ℃ ,and the temperature at 5% and 10% weight loss of 421 - 448 and 458 - 473 ℃ at a nitrogen atmosphere, respectively. Moreover, the polyimide films showed outstanding mechanical properties with tensile strength of 46 -102 MPa,tensile modulus of 2.7 - 3, 5 GPa and elongation at break of 2.0% -6.5%. Most of the polyimide films had good chemical resistance, and were insoluble in common organic solvents, such as NMP, DMSO, DMF, m-cresol and CHC13. The UV-Visible measurements indicated that the cut-off wavelength of polyimide films was in the range of 367 - 389 nm. The pyridazine-based polyimide films showed a good combination of properties.