Two organo-soluble polyimide resins containing phenyl-substituted quinoxaline units (PIPQ) were successfully prepared via the two-step chemical imidization procedure from an aromatic diamine, 6(7)-amino-2-(4-aminophenyl)-3-phenylquinoxaline (PQDA) and aromatic dianhydrides with flexible molecular structures. The derived PIPQ-1 resin from PQDA and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and the PIPQ-2 resin from PQDA and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) were all soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). The PIPQ/DMAc solutions with the solid contents of 25–35 wt% were used as the starting mediums and the PIPQ ultrafine non-woven fibrous membranes (UFMs) were successfully prepared by the one-step electrospinning (ES) procedure. For comparison, the standard polyimide reference electrospun UFM (PI-ref) was also fabricated via the two-step ES procedure from the soluble poly(amic acid) (PAA) precursor based on pyromellitic anhydride (PMDA) and 4,4′-oxydianiline (ODA), followed by thermal imidization at elevated temperatures from 80–300 °C. The fabricated PIPQ UFMs exhibited good thermal stability with the 5 % weight loss temperatures (T_5%) of 537 °C for PIPQ-1 (6FDA-PQDA) and 517 °C for PIPQ-2 (BPADA-PQDA) in nitrogen, respectively. In addition, the PIPQ UFMs exhibited glass transition temperatures (T_g) higher than 252 °C. Meanwhile, the PIPQ UFMs exhibited improved optical properties with the reflectance values over 75 % at the wavelength of 457 nm and high whiteness. At last, the PIPQ UFMs showed greatly enhanced hydrolysis stability in highly alkaline aqueous solution (sodium hydroxide in water, 20 wt%) either at room temperature or at elevated temperature. The PIPQ UFMs survived even during the aging in boiling aqueous sodium hydroxide solution (concentration: 20 wt%) for 3 h while the PI-ref UFM totally hydrolyzed during the test.

通过两步化学酰亚胺化过程，从芳香族二胺 6(7)-氨基-2-(4-氨基苯基)-3-苯基喹喔啉中成功制备了两种含有苯基取代喹喔啉单元 (PIPQ) 的有机可溶性聚酰亚胺树脂。 PQDA) 和具有灵活分子结构的芳香族二酐。来自 PQDA 和 4,4'-(六氟异亚丙基)二邻苯二甲酸酐 (6FDA) 的衍生 PIPQ-1 树脂以及来自 PQDA 和 2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐的 PIPQ-2 树脂(BPADA) 均溶于极性非质子溶剂，如N-甲基-2-吡咯烷酮 (NMP) 和N,N-二甲基乙酰胺（DMAc）。以固含量为 25-35 wt% 的 PIPQ/DMAc 溶液为起始介质，通过一步静电纺丝 (ES) 程序成功制备了 PIPQ 超细无纺纤维膜 (UFM)。为了进行比较，标准聚酰亚胺参考电纺 UFM (PI-ref) 也通过两步 ES 程序从基于均苯四酸酐 (PMDA) 和 4,4'-氧化二苯胺的可溶性聚酰胺酸 (PAA) 前体制造(ODA)，然后在 80–300 °C 的高温下进行热酰亚胺化。制造的 PIPQ UFM 在 5% 失重温度 ( T _5%) 在氮气中的 PIPQ-1 (6FDA-PQDA) 和 PIPQ-2 (BPADA-PQDA) 分别为 537 °C 和 517 °C。此外，PIPQ UFMS表现出玻璃化转变温度（Ť_克）高于252℃。同时，PIPQ UFM 表现出改进的光学性能，在 457 nm 波长处的反射率值超过 75%，白度高。最后，在室温或高温下，PIPQ UFM 在强碱性水溶液（氢氧化钠水溶液，20 wt%）中显示出大大增强的水解稳定性。即使在沸腾的氢氧化钠水溶液（浓度：20 wt%）中老化 3 小时，PIPQ UFM 也能存活，而 PI-ref UFM 在测试过程中完全水解。