带隙可调吩嗪型共轭微孔聚合物的机械化学制备及其光催化原子转移自由基聚合性能研究

Photoinduced atom transfer radical polymerization (ATRP), especially metal-free photoinduced ATRP, exhibits advantages of mild polymerization, wide range of monomers, simple operation, less side reactions and no metal residue. However, the light sources reported so far are all ultraviolet light or visible light, and the penetration ability to most of the reaction medium is low. In addition, the reactants are easily affected by competitive absorption and the effective utilization of the solar spectrum is greatly limited. In order to overcome these challenges, this project intends to prepare novel narrow-band gap phenazine-type conjugated microporous polymers (CMPs) as novel heterogeneous ATRP photocatalysts, and achieve high-efficiency near-infrared (NIR) initiation under the premise of easy catalyst recovery and no metal residue. The applicant designs a solid-phase polymerization strategy for the preparation of phenazine-type CMPs by Schiff base condensation reaction under high-energy ball milling conditions, thereby realizing to tune the band gap of the polymer. Furthermore, the phenazine-type CMPs with different π-conjugation frameworks will be investigated as photocatalysts for NIR-induced ATRP, and the structure-property relationship between different π-conjugated systems and photo-induced ATRP catalytic properties will be explored. Therefore, new efficient and easily recoverable ATRP photocatalysts will be obtained after completing the research of this project.

光催化原子转移自由基聚合（ATRP），特别是无金属光催化ATRP, 具有聚合条件较为温和，适用单体广泛，操作简单，副反应少，无金属残留的优势。然而，目前报道的光源均为紫外光或可见光，因而对大部分反应介质的穿透能力较低，反应物易对光进行竞争性吸收，且大大限制了对太阳能光谱的有效利用。本项目拟通过制备新型窄带隙吩嗪型共轭微孔聚合物（CMP）作为非均相ATRP光催化剂，在具备催化剂易回收、无金属残余的前提下，同时实现高效近红外（NIR）引发ATRP反应。申请人设计了一种在高能球磨条件下利用席夫碱缩合反应制备吩嗪型CMP的固相聚合策略，从而实现调控聚合物的能级带隙，进一步研究具有不同π共轭效应的吩嗪型CMP作为催化剂对NIR引发ATRP催化性能，从而探索建立不同π共轭体系与光引发ATRP催化性能的构-效关系，最终获得新型高效、易回收ATRP光催化剂。

本项目针对传统均相ATRP光催化剂回收困难且太阳能光谱利用率低的缺陷，提出利用共轭型多孔聚合物用于高效ATRP。本项目成功利用机械化学合成技术，实现了吩嗪-三嗪型多孔聚合物、卟啉-三嗪型多孔聚合物的机械化学制备，实现了在固相条件下的绿色、快速制备多孔高分子。通过优化催化剂用量、球磨时间、球磨频率、磨球个数、磨球直径等参数，成功实现对多孔高分子的产率和比表面积的调控，总结机械化学高效合成的关键参数。通过制备一系列具有类似结构的卟啉-三嗪型多孔高分子，初步探索了不同中心金属对ATRP活性的影响规律。成功实现了在可见光作用下的ATRP反应，得到具有分子量可控，多分散性指数低的一系列高分子产品。循环测试结果表明机械化学法制备得到的多孔高分子与均相催化剂相比回收简单、对产品无污染、且回收后可重复利用，从而能够显著降低材料的使用成本。与此同时，利用机械化学合成技术可以成功实现高效、绿色合成多孔聚合物，这为特定多孔聚合物的拓展提供了新思路。最后，本项目提出的机械化学合成技术还可以进一步拓展到金属掺杂多孔碳材料的合成，同时为制备原子级分散金属负载多孔碳材料提供新方法。