石墨烯的化学修饰及光限幅性能研究

Graphene is a single layer of sp2 carbon atoms, in a closely packed honeycomb two-dimensional lattice. It has some unique physical and chemical properties, such as the electrical conductivity, high mechanical strength, large theoretical specific surface areas, room-temperature quantum hall effect and so on. These properties enable it to be used in different fields. However, graphene could not be solved or dispersed in water and organic solvents, because of the π-π stacking interactions between graphene sheets, which limited its applications. Therefore, in order to improve the solubility of graphene, chemical modification attracted much attention. Nitrogen-centered anions, with high reactivity, are an important type of intermediates in chemistry, but merely be used during the functionalization of graphene so far. And also the factors affecting the solubility of graphene haven’t been fully discussed during the covalent functionalization. Our previous work demonstrated that, the solubility of graphene, not only connected with rich π-electron frameworks of the molecule, but also with its stereospecific blockade, which hasn’t received much attention. Thus, basing on the previous results, this project will investigate the method of covalent functionalization based on nitrogen-centered anions systematically, and also the relationship between stereospecific blockade and the solubility of graphene. Hoping to get soluble graphene derivatives, and probe its applications in optical limiting.

石墨烯是由sp2杂化碳原子组成的单原子层二维晶体，具有高的电导率和机械强度、大的理论比表面积、室温量子霍尔效应等特点，这些优异的性能使得它在诸多领域都有潜在的应用空间。然而，石墨烯层与层之间的π-π作用使得它在水及有机溶剂中难溶难分散，制约了其应用。因而，通过化学修饰的方法改善石墨烯的溶解性是目前研究的热点之一。N负离子是一类重要的具有较高反应活性的中间体，但是基于N负离子的化学修饰方法还未被报道。且在石墨烯的化学修饰方面，影响其溶解性的因素未被深入研究。申请人在前期的实验过程中发现，共价键修饰时，石墨烯的溶解性除了与功能化分子的共轭体系有关外，还与其空间构型相关。因而在此基础之上，本项目将发展一种基于N负离子的共价键修饰方法，并对该方法进行系统性研究，考察间隔基团与石墨烯溶解性之间的关系，得到可溶解的石墨烯衍生物并探讨其光限幅效应。

石墨烯是由sp2杂化碳原子组成的单原子层二维晶体，优异的性能使它在各领域都有潜在的应用价值，然而在有机溶剂或水中难溶难分散的特点限制了其应用。近年来，通过化学修饰的方法改善石墨烯的溶解性是研究的热点之一。本项目合成了含四苯乙烯基、咔唑基和苯基的共轭高分子，并用于石墨烯的共价键和非共价键修饰，深入探讨了间隔基团大小对石墨烯溶解性的影响，并对所得材料的光限幅性能及对爆炸物的荧光响应进行测定，取得了以下进展：.1、采用Suzuki方法，合成了含四苯乙烯基、咔唑基和苯基的三个共轭高分子，并完成了高分子的结构鉴定。.2、通过N负离子与石墨烯之间的亲核反应，将合成的高分子用于石墨烯的共价键修饰。虽然三个高分子的反应位点相同，但反应活性、石墨烯复合物的溶解性及光限幅效应差异较大，这与高分子聚合单元的共轭程度、空间结构有关。所得石墨烯复合物中高分子的摩尔百分比分别为0.156%、0.097%和0.161%；当间隔基团为TPE时，所得石墨烯复合物的溶解性最好，在有机溶剂中能够长期稳定分散。.3、通过GO原位还原的方法，将高分子用于石墨烯的非共价键修饰，在π-π作用和高分子包裹效应的作用下，得到了可溶于有机溶剂的石墨烯复合物。三个高分子中， P1对石墨烯溶解性的改善效果最佳，所得复合物rGO-P1在THF中可稳定数月(1.5 mg/mL)。此外，rGO-P1还可溶于DMF、DMSO等有机溶剂，良好的溶解性使石墨烯的加工利用更为便捷。 .4、首次制备了具有AIE效应的石墨烯复合物，聚集态时(THF/H2O=10/90，v/v)，rGO-P1的荧光强度是高分子P1的6.3倍，比溶液态增强了25.7倍。优异的光学性质及AIE效应使其可作为液态或固态化学传感器，用于爆炸物的高灵敏度检测。在聚集态时，对苦味酸的最低检测浓度为1.3 ppb，最大淬灭常数为4.16×106 M-1，高于目前已报道的相关结果，实现了对爆炸物的痕量检测。