【作者】 张弛；

【导师】 刘平伟；

【作者基本信息】 浙江大学 ， 化学工程与技术， 2021， 硕士

【摘要】 共价有机框架材料(Covalent Organic Frameworks,COF)是一类由共价键连接、具有规整孔道结构的结晶聚合物,结晶性和形貌是影响其应用的关键因素。COF材料一般通过溶剂法合成得到,但是,目前缺乏有效的COF形貌调控手段,具有复杂纳米结构COF材料的可控制备极具挑战。为此,本论文利用亚胺类COF共价键动态可逆特性,通过引入单官能团竞争剂强化反应体系可逆性,同时结合不同的单体加料策略,研究实现对COF产物结晶性的调控、COF中空纳米结构的定制及其负载贵金属催化剂的应用。主要内容包括:(1)研究单官能团竞争剂对COF结晶性与形貌的影响:通过在席夫碱类COF反应体系中加入单官能团竞争剂苯胺、苯甲醛,引入可逆的终止反应,发现该方法可强化反应过程的可逆性,制得结晶度更高、形貌更规整的产物。(2)研究多单体组合体系中加料策略对COF结晶性与形貌的影响:通过提高单体进料中均苯三甲醛与对苯二甲醛单体的配比,同时保持1,3,5-三(4-氨基苯基)苯单体比例不变,发现产物结晶性不断提高,COF颗粒形貌则由实心转化为中空。研究中空形貌演化过程发现,在包含竞争剂的反应体系中,无定型COF组分会逐步溶解,而高结晶性组分则保持稳定导致产物颗粒空心化。(3)中空COF纳米结构的催化负载应用:通过利用中空结构的COF材料作为载体,负载钯纳米催化剂,探究其催化Suzuki反应的效果,发现中空COF载体可提高钯催化剂稳定性,转化率高达99%以上,同时有效降低泄漏量,实现其多次重复利用。更多还原

【Abstract】 Covalent Organic Frameworks(COFs)is a class of crystalline polymer connected by covalent bonds possessing regular pore structure.Crystallinity and morphology are the key factors affecting its application.COFs are generally synthesized by the solvothermal method,but there is currently a lack of effective methods controlling COFs morphology,and it is difficult to control the preparation of COF materials with complex nanostructures.Herein,we make use of the dynamic reversibility of the covalent bond to strengthen the reversibility of the reaction system by introducing a monofunctional group competitor,and combines different monomer feeding strategies to study the realization of the improvement of the crystallinity of the COFs product and the COFs hollow structure;The customization of nanostructures and the application of supporting precious metal catalysts.The main contents include:(1)Study the effect of monofunctional competitor on polymer crystallinity and morphology:add aniline and benzaldehyde monofunctional competitor to the reaction system,introduce reversible termination reaction,and find that it can strengthen the reversibility of the reaction process to obtain a product with higher crystallinity and stable.(2)Study the effect of the feeding strategy in the multi-monomer combination system on the crystallinity and morphology of the COFs:increase the ratio of the 1,3,5-Benzenetricarboxaldehyde and terephthalaldehyde monomers in the system,and find that the crystallinity of the COF product continues to improve.The morphology of the COFs is transformed from a solid sphere to a hollow structure.The study of the evolution process of the hollow morphology found that the low crystallinity COF component gradually dissolves,while the high crystalline component remain.(3)Application of catalytic loading of hollow COF nanostructures:the prepared hollow COF material is used to support palladium catalysts,and the effect of catalyzing Suzuki reaction is explored.It is found that hollow COF supporter can improve the stability of the palladium catalyst,the conversion rate is as high as 99%,and at the same time,it effectively reduces the leakage and realizes its multiple reuse.更多还原