同轴聚吡咯/聚苯胺纳米纤维的生长控制及其储能机理研究

It has been demonstrated that one-dimensional conducting polymer nanofibers and their nanocomposites have excellent energy storage properties, unfortunately, only limited knowledge can be provided for us to understand their nanoscale microstructures, size effects and underlying mechanism for the enhanced physical properties. To provide exact information about the intrinsic structure and properties of the nanofibers, more attempts will be made to control the formation process of the nanofibers with bespoke morphologies, and find the relationship between the microstructure and energy storage properties. The objectives of this program are focused on the technique to obtain controlled structures, and the energy storage mechanism behind the size effects in a coaxial nanofiber with a polyaniline (PANi) core and a polypyrrole (PPY) shell. An ultralong PANi nanofiber with an uniform diameter will be firstly prepared by a novel moving interfacial polymerization of aniline monomers in a capillary tube, and the reaction will be monitored by UV-visible spectrometry. The produced PANi nanofibers with high degree of conjugation and large charge carrier mobility will be used as a 'seed' to fabricate a coaxial PPY/PANi nanofiber by in situ polymerization of pyrrole monomer on the surface of PANi nanofiber. It is worth pointing out that the coaxial PPY/PANi nanofiber with a well-defined microstructure can be prepared predictably and repeatedly. The charge transfer and storage process within isolated coaxial nanofibers with different dimensions and core-shell structures will be studied, and the interface effect will be established by introducing a gradient distribution function for pi-pi interaction between PANi and PPY. The influence of the nanoscale microstructure and size effects on energy storage properties of coaxial nanofibers will be evaluated. More attentions will be paid to understand the faradaic charge-transfer storage mechanism for the coaxial nanofibers, and set up the relationship between the microstructure and energy storage properties. These intensive research works about such nanostructured materials will benefit to give a more detailed knowledge of confined polymers and provide a new facial approach for preparing the electrode materials for high performance flexible supercapacitors.

导电高分子一维纳米纤维及其复合体系表现出更为优异的储能特性，但对其中所涉及的纳米微观结构与尺寸效应及优异物性的起因还缺乏本质认识。要想真实地反映纳米纤维本征结构与性能，就必须能够控制其生长过程、明确其储能特性与纳米微结构的依赖关系。本项目提出一种新颖的移动界面聚合法，结合紫外可见光谱现时监测技术，拟通过反应空间与流动约束，合成出尺寸均匀的超长聚苯胺纳米纤维；再采用"种子"聚合法来实现聚吡咯与聚苯胺的有机集成，制备出结构明确的、可重复的同轴聚苯胺/聚吡咯纳米纤维。结合单根同轴纳米纤维的电荷传递与存储过程，并引入"共轭作用的梯度分布函数"来描述导电高分子的界面效应，阐明同轴纳米纤维的纳米微观结构与尺寸效应对其储能特性的影响，在揭示其导电机理与储能机理的基础上，提炼出普适的构效关系。研究结果将丰富受限空间高分子结构与性能关系的研究内容，并为设计高效轻质超级电容器的电极材料带来新的思路。

构筑形貌结构可控的准直聚苯胺纳米纤维，明确其储能特性与纳米微结构的依赖关系，进而获得出优异的电化学超级电容器电极材料，是一个多学科交叉的热点研究方向，其中规模可控绿色合成是亟待解决的难点之一。通过四年研究，课题组很好地完成了计划任务，取得了如下成果：（1）通过反应空间与流动约束，在4种流动条件下（自由流动聚合、界面移动流动聚合、混合流动聚合和细粗管搭配流动聚合）成功地在水相中可连续化地制备出尺寸均匀的聚苯胺纳米纤维，并清晰地揭示出聚苯胺纳米纤维的形成机制，提出了约束聚苯胺聚合孕育过程是实现聚苯胺纳米纤维可控生长的有效途径；（2）较为详细地研究了界面聚合中迁移控制、齐聚物引发生长以及基材诱导取向对聚苯胺微结构与储能性能的影响，从分子角度出发，解析出聚苯胺纳米纤维的成核、（氢键）组装和取向生长的内在机制，探明有效控制（氢键）组装过程是获得高性能聚苯胺纳米纤维电极材料的重要保证；（3）采用“种子”聚合法来实现聚吡咯与聚苯胺的有机集成，较为详细地考察了聚苯胺形貌微结构对聚吡咯生长的影响，结合纳米纤维的电荷传递与存储过程的研究，从本质上阐明其中所涉及的纳米微观结构与尺寸效应及优异物性的起因，认识到高取向、高电导的聚苯胺纳米纤维显著影响着同轴聚吡咯/聚苯胺纳米复合纤维的最终性能。（4）在揭示出纳米纤维的纳米微观结构与尺寸效应对其储能特性的影响的基础上，实现了高效轻质超级电容器的导电高分子电极材料的规模化绿色制备。这些结果为设计新的适于中性电解液、高效轻质超级电容器电极材料提供了技术支持，也为进一步构筑更为复杂有序的导电高分子纳米结构提供了强有力的理论指导。（5）在国家自然科学基金的资助下，目前相关研究成果已发表学术论文10篇，其中较高学术水平的期刊4篇（有关主体工作的稿件近期将陆续投稿）；培养博士研究生2名，硕士研究生6名（4人已毕业），其中2人获得国家奖学金；参加了6次国际学术研讨会，共提交会议论文12篇；申请发明专利3项，1项已授权。