Herein, we developed a new diamine monomer termed TA-BOC that features a tert-butoxycarbonyl (t-Boc) protected group. This t-Boc group could shield one of the reactive amine sites present in the commercial tris(4-aminophenyl)amine (TAPA) monomer. Then, this difunctional TA-BOC analogue is employed as a comonomer alongside TAPA and 6FDA to regulate the cross-linking density of polyimide material by varying the molar ratio of TAPA to TA-BOC. Moreover, due to the bulky steric hindrance of the t-Boc group, we attempted to remove the t-Boc group via thermal treatment to create more microporosity within membranes. Therefore, because of the synergistic effect of reduced cross-linking density and heat treatment, the gas separation performance of the prepared membranes is greatly improved. Furthermore, the presence of trifunctional TAPA monomer in the network structures significantly enhances the membrane’s resistance to plasticization. For instance, 6F-TA:TA-BOC(1:3)-450 has a high CO₂ permeability of 865.3 Barrer and an excellent CO₂/CH₄ selectivity of 41.8, meanwhile its CO₂ plasticization pressures exceeding 35 bar. These values surpass the 2008 Robeson upper bound,, indicating its great potential for efficient gas separation processes. We expect that this study will provide new perspectives for the reasonable design of network polyimide membranes possessing an enhanced gas separation performance and strong plasticization resistance.

中文翻译：

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通过降低交联密度和热处理来增强网状聚酰亚胺膜的气体传输性能


在此，我们开发了一种新的二胺单体，称为 TA-BOC，它具有叔丁氧基羰基 （t-Boc） 保护基团。该 t-Boc 基团可以屏蔽商业三（4-氨基苯基）胺 （TAPA） 单体中存在的反应性胺位点之一。然后，这种双官能团 TA-BOC 类似物与 TAPA 和 6FDA 一起用作共聚单体，通过改变 TAPA 与 TA-BOC 的摩尔比来调节聚酰亚胺材料的交联密度。此外，由于 t-Boc 基团的巨大空间位阻，我们试图通过热处理去除 t-Boc 基团，以在膜内产生更多的微孔。因此，由于降低交联密度和热处理的协同作用，所制备的膜的气体分离性能大大提高。此外，网络结构中三官能 TAPA 单体的存在显着增强了膜的抗塑化性。例如，6F-TA：TA-BOC（1：3）-450 具有 865.3 Barrer 的高 CO₂ 渗透率和 41.8 的优异 CO₂/CH₄ 选择性，同时其 CO₂ 塑化压力超过 35 bar。这些值超过了 2008 年 Robeson 的上限，表明其在高效气体分离工艺方面具有巨大潜力。我们期望本研究为合理设计具有增强气体分离性能和强塑化能力的网络聚酰亚胺膜提供新的视角。