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基于醛-胺冷冻聚合反应的亚胺类共价有机框架整体材料制备

丁璐瑶1, 朱淋1, 乔国立1, 刘忠山1,*, 高瑞霞2,*   

  1. 1.陕西师范大学化学化工学院,陕西 西安 710119;
    2.西安交通大学化学学院,陕西 西安 710049
  • 通讯作者: *E-mail:zhongshan.liu@snnu.edu.cn(刘忠山);E-mail:ruixiagao@xjtu.edu.cn(高瑞霞).
  • 作者简介:丁璐瑶,硕士研究生,E-mail:dingluyao@snnu.edu.cn.
  • 基金资助:
    国家自然科学基金项目(项目号22372097).

Preparation of imine-linked covalent organic framework monoliths through aldehyde-amine cryopolymerization

DING Luyao1, ZHU Lin1, Qiao Guoli1, LIU Zhongshan1,*, GAO Ruixia2,*   

  1. 1. School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China;
    2. School of Chemistry, Xi’an Jiaotong University, Xi’an 710049, China
  • Supported by:
    National Natural Science Foundation of China (No. 22372097).

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摘要： 亚胺类共价有机框架材料作为色谱柱分离固定相和样品预处理材料备受关注,但其形貌和形态调控仍面临挑战,严重限制了该类材料在分离分析领域的实际应用。本研究提出了一种基于醛-胺冷冻聚合反应的亚胺类共价有机框架整体材料制备新方法。首先在室温配制单体浓度为5%的均相预聚溶液,然后在液氮条件下使二甲基亚砜溶剂定向冷冻形成晶体模板;多元醛单体与多元胺单体聚集在晶体模板之间的缝隙中,并转移至-18 oC进行聚合反应,形成无定形聚合物;最后通过晶化处理,该聚合物转化为共价有机框架整体材料。扫描电子显微镜图、粉末X-射线衍射谱图和氮气物理吸附数据表明,晶态框架整体材料具有微米级的定向通孔结构和纳米级的有序孔道。进一步采用不同聚合反应体系验证了“先冷冻成型,再高温晶化”的两步法成型制备共价有机框架整体材料的普适性,为推动该类材料在分离分析领域中的应用提供了有益借鉴。

关键词: 共价有机框架, 整体材料, 冷冻聚合, 通孔

Abstract: Imine-linked covalent organic frameworks (COFs) have been attracted considerable attention as stationary phases for chromatographic separation and as sample pretreatment materials. However, existing synthesis methods have the difficulty in controlling morphologies and shapes of COFs, limiting their practical applications. In this work, we report a new method for preparation of COF monoliths through the aldehyde-amine cryopolymerization reactions. Briefly, a homogenous prepolymerization mixture of 5% monomers and dimethyl sulfoxide was frozen in liquid nitrogen bath using a unidirectional freezing technique. The solvent of dimethyl sulfoxide formed crystals, in which the monomers were confined and then in-situ polymerized at -18 oC. The resulting amorphous polymeric monolith was then dried, immersed in suitable solvents for crystallization treatment, and finally transformed into crystal framework monoliths. The characterization using scanning electron microscopy, powder X-ray diffraction instrument and nitrogen adsorption measurement indicated that crystal framework monoliths possess hierarchical porosity including unidirectional macropores and ordered nanopores. The versatility of our two-step method of the freeze shaping followed by crystallization was illustrated by using different building blocks. It is anticipated that this method can produce COFs with desired shapes and morphologies to meet practical application requirements in the field of separations and adsorptions.

Key words: covalent organic frameworks, monolith, cryopolymerization, through-pore

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