【摘要】 以均苯四甲酸酐(PMDA)、4,4’-二氨基二苯醚(ODA)和四甲基-双(γ-氨丙基)二硅氧烷(APDS)合成了氨端基聚酰胺酸预聚体,然后分别用甲苯二异氰酸酯(TDI)和二苯甲烷二异氰酸酯(MDI)扩链制得聚脲酰胺酸,经亚胺化制备了两种聚脲酰亚胺POAU(T)和POAU(M)。通过TGA和IR研究聚脲酰亚胺的热稳定性,测试聚脲酰亚胺在频率为0.1~105Hz和温度50~300℃的介电常数(ε)和介质损耗(tanδ)。结果表明:聚脲酰亚胺分子链段中存在两个转变温度Tg,脲基链段的Tg为244℃(POAU(T))及243℃(POAU(M)),酰亚胺环链段的Tg温度为329℃(POAU(T))及331℃(POAU(M))。预倾角测定(TBA)结果表明该聚脲酰亚胺是一种良好的液晶分子定向膜材料。更多还原

【Abstract】 Polyimide acid prepolymers were synthesized from pyromellitic dianhydride(PMDA), 4,4′-diamino diphenyl ether(ODA), and tetramethyl-bis-(γ-aminopropyl) disiloxane(APDS), and the polyureas-imide acids were prepared by chain extension reaction with toluene diisocyanate(TDI) and methylene diphenyl diisocyanate(MDI) respectively, then two kinds of polyureas-imide POAU(T) and POAU(M) were prepared by imidization. The thermal stability of the polyureas-imides was studied by IR and TGA, and the dielectric constant and dielectric dissipation factor at 0.1~105Hz and 50~300 ℃ were tested. The results show that the polyureas-imide molecule exist two glass transition temperature(Tg), and the Tgof HN-CO-NH group is 244 ℃(POAU(T)) and 243 ℃(POAU(M)), the Tgof imide ring is 329 ℃(POAU(T)) and 331 ℃(POAU(M)). The pretilt angle test result shows that the polyureas-imide is a good alignment film material for liquid crystal molecules.更多还原