Phenolic aerogel composites, as an excellent thermal insulation material, have been used in aerospace to resist extreme working conditions of severe heating and intense mechanical stress. However, the high cost and lengthy preparation process seriously restricts their more extensive application. Herein, a novel strategy for rapid preparation of aerogel composites by ambient pressure drying is enabled by copolymerization with 4-hydroxybenzenesulfonic acid. That is, the reactive 4-hydroxybenzenesulfonic acid can serve as the acid catalyst to accelerate both the protonation step and the gelation step during the preparation process of phenolic aerogel. After copolymerization with 4-hydroxybenzenesulfonic acid, these sulfonic acid groups significantly accelerate the protonation of benzoxazine intermediates, leading to more carbocation formation. The activation energy of curing reaction is significant decreased from 300 kJ∙mol to 90 kJ∙mol. Thus, 4-hydroxybenzenesulfonic acid containing phenol formaldehyde resin (PFS) aerogel precursors exhibit much faster gelation reaction (within 4 h) than phenol formaldehyde resin (PF) aerogel precursor (12 h), which further facilitates the preparation of phenolic aerogel composites with needled quartz fiber felt by ambient pressure drying. Importantly, the PFS aerogel composites exhibit excellent thermal insulation performance under low heat flux and good fire safety under high heat flux. Rapid gelation of PFS triggered by 4-hydroxybenzenesulfonic acid provides a new approach to develop phenolic aerogel composites with low energy consumption, low cost and short preparation cycle.

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4-羟基苯磺酸常压干燥快速制备酚醛气凝胶复合材料

酚醛气凝胶复合材料作为一种优异的隔热材料，已被应用于航空航天领域，以抵抗剧烈加热和强烈机械应力的极端工作条件。然而，高昂的成本和漫长的制备过程严重限制了其更广泛的应用。在此，通过与 4-羟基苯磺酸共聚，实现了一种通过常压干燥快速制备气凝胶复合材料的新策略。也就是说，反应性4-羟基苯磺酸可以作为酸催化剂，加速酚醛气凝胶制备过程中的质子化步骤和凝胶化步骤。与4-羟基苯磺酸共聚后，这些磺酸基团显着加速苯并恶嗪中间体的质子化，导致更多碳正离子的形成。固化反应的活化能从300 kJ∙mol显着降低至90 kJ∙mol。因此，含有4-羟基苯磺酸的酚醛树脂（PFS）气凝胶前体表现出比酚醛树脂（PF）气凝胶前体（12小时）更快的凝胶反应（4小时内），这进一步促进了针刺酚醛气凝胶复合材料的制备。石英纤维毡经常压干燥而成。重要的是，PFS气凝胶复合材料在低热通量下表现出优异的隔热性能，在高热通量下表现出良好的防火安全性。 4-羟基苯磺酸引发的PFS快速凝胶化为开发低能耗、低成本、制备周期短的酚醛气凝胶复合材料提供了新途径。