以共价有机框架(COFs)为关键材料构筑规整纳米孔道水处理膜

Building water treatment membrane based on covalent organic frameworks (COFs), which possesses regular nanopore structure, has great potential applications. However, the fabrication of COFs membrane is extremely challenging owing to the less type of water stable COFs , difficult procedure in making particles into a continuous membrane as well as the unclear molecular transfer mechanism of the channel. To solve the above problem, the project intends to carry out from building units to membrane constructing method and then to separation mechanism. Specific content and methods as follows:ⅰ) Designing building units and reversible reactions to develop for the construction of water stable COFs materials and hydrophilization modified of its channel.ⅱ)Using the structure of the other materials to help the construction of COFs membrane, it can be divided into two ways. One is making two-dimensional nanocomposites and the other is using spherical template to make COFs particles changing into hollow ball nanoparticles.ⅲ) Basing on the crystal nucleation growth mechanism, the syntheses of continuous COFs membrane are carried out by Layer-by-Layer or Secondary Growth method.ⅳ) Building models by molecular dynamics simulation to set the radial distribution function for the channel chemical environment, get motion trajectory about the molecular inside and compare it with the experimental results to understand the separation mechanism.

共价有机框架(COFs)具有规整的纳米孔道，在水处理膜领域有巨大的潜在应用性。针对水稳定型COFs种类少，晶体多为粉末难以成膜，以及孔道的分子传递机理不明等关键问题，本项目拟开展从基元设计到膜构筑方法再到分离机理的系列研究，以获得水处理COFs膜构筑方法体系和分离机理。具体内容和方法为：1)以水稳定性连接键为目标，设计COFs构筑基元分子，合成水稳定型COFs，并对COFs孔道进行亲水化修饰；2)以易于成膜的纳米片层材料为基底，负载所合成的COFs，或将COFs制备成纳米中空球，以上述两种纳米COFs为关键材料制备膜；3)基于COFs晶体成核生长机理，拟分别采用layer-by-layer和二次生长的方法控制构筑COFs基元分子间的连接，制备出连续的COFs膜；4)通过分子动力学模拟建立COFs分子模型，设定径向分布函数以探明孔道化学环境，示踪分子运动轨迹，与实验结果比较以探明其分离机理。

共价有机框架材料(COFs)具有规整的孔道结构，是良好的分离膜候选材料。本项目开展了“COFs 基元分子设计-COFs 膜构筑方法建立-传递机理探索”系列研究，建立起以基元分子为支撑的COFs膜构筑方法体系及其膜的分离传输机制取得如下成果：I. 提出了亚胺型二维COFs膜生长过程符合经典成核生长理论模型的论断，并以此为指导，制备了高孔道取向性层状结构二维COFs薄膜，揭示了其分离传质机理；II. 构建了界面聚合辅以多组分调控策略的COFs成膜方法，制得荷电密度可调的二维阳离子型COFs分离膜，揭示了膜对单/多价离子的分离机理；III. 开发了具有不同孔道微化学环境的三维COFs，调控制备了大尺度、连续均匀且少缺陷的COF复合膜；IV. 构建了系列不同粒径和孔径尺寸的COFs中空球材料，并拓展至小分子药物控释和择型催化反应中的应用。项目全面完成了研究计划，取得了多项创新成果，达到了预期目标。在Nat. Comm.、Angew. Chem. Int. Edit.、Adv. Funct. Mater.、Matter、J. of Membr. Sci.等化学工程领域相关顶级期刊发表论文7篇；培养毕业博士生1名和硕士生4名，出站博士后1名；研究成果获得了2020年教育部高等学校科学研究优秀成果奖自然科学二等奖。