The weak bonding energy and flexibility of hydrogen bonds can hinder the long-term use of hydrogen-bonded organic framework (HOF) materials under harsh conditions. Here we invented a thermal-crosslinking method to form polymer materials based on a diamino triazine (DAT) HOF (FDU-HOF-1), containing high-density hydrogen bonding of N-H⋯N. With the increase of temperature to 648 K, the formation of -NH- bonds between neighboring HOF tectons by releasing NH3 was observed based on the disappearance of the characteristic peaks of amino groups on FDU-HOF-1 in the Fourier transform infrared (FTIR) and solid-state nuclear magnetic resonance (ss-NMR). The variable temperature PXRD indicated the formation of a new peak at 13.2° in addition to the preservation of the original diffraction peaks of FDU-HOF-1. The water adsorption, acid-base stability (12 M HCl to 20 M NaOH) and solubility experiments concluded that the thermally crosslinked HOFs (TC-HOFs) are highly stable. The membranes fabricated by TC-HOF demonstrate the permeation rate of K+ ions as high as 270 mmol m-2 h-1 as well as high selectivity of K+/Mg2+ (50) and Na+/Mg2+ (40), which was comparable to Nafion membranes. This study provides guidance for the future design of highly stable crystalline polymer materials based on HOFs.

中文翻译：

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用于高选择性离子分离的热交联氢键合有机骨架膜。

氢键的弱键能和柔韧性会阻碍氢键有机骨架（HOF）材料在恶劣条件下的长期使用。在这里，我们发明了一种热交联方法，以形成基于二氨基三嗪 (DAT) HOF (FDU-HOF-1) 的聚合物材料，其中包含 NH⋯N 的高密度氢键。随着温度升高到 648 K，基于傅里叶变换红外 (FTIR) 中 FDU-HOF-1 上氨基特征峰的消失，观察到相邻 HOF 构造子之间通过释放 NH3 形成 -NH- 键和固态核磁共振（ss-NMR）。变温 PXRD 表明除了保留 FDU-HOF-1 的原始衍射峰外，还在 13.2° 处形成了一个新峰。水的吸附，酸碱稳定性（12 M HCl 至 20 M NaOH）和溶解度实验得出结论，热交联的 HOFs (TC-HOFs) 是高度稳定的。TC-HOF 制备的膜表现出高达 270 mmol m-2 h-1 的 K+ 离子渗透率以及 K+/Mg2+ (50) 和 Na+/Mg2+ (40) 的高选择性，与 Nafion 相当膜。该研究为未来基于HOFs设计高稳定性结晶聚合物材料提供了指导。