基于Langmuir-Blodgett技术构筑聚氨酯/银纳米复合薄膜及其导电性研究

Polyurethane-based conductive composites are widely used in the electronics industry, construction industry, aviation field, etc. In view of the problems encountered in the polyurethane composites where the combination interface between the fillers and the matrix is not firm and the fillers are fallen off easily, this project proposes a novel research idea that the conductive polyurethane will be constructed in the form of the complexes formed by metal ions and polyurethane. First, a kind of new polyurethanes containing imidazole functional groups will be designed and synthesized. Polyurethane/Ag(I) films will be formed by Langmuir-Blodgett technique that makes Ag(I) coordinate with imidazole groups uniformly at the air/water interface. Secondly, through in-situ reduction, the metal ions will be changed into nanoparticles embedded in polymer matrix and thus a kind of polyurethane/Ag nanocomposite films, in which the nanoparticles are uniformly dispersed and firmly combined with the interface of matrix, are formed. Thirdly, the relationship between the film structure and film conductivity will be established by controlling the ratio of imidazole group in the molecule, the thickness (layers) of the film, and in-situ reductive conditions as well as the extent of the silver nanoparticles migration to the surface, then the controllable film thickness, controllable conductive capacity and highly ordered polyurethane films will be obtained. On the basis, analyzing and elucidating the conductive mechanism of such polyurethane/Ag composite films will lay a solid foundation for their wide application in organic electronic devices, sensors, etc.

聚氨酯基导电复合材料广泛应用于电子工业、建筑工业和航空等领域。鉴于在聚氨酯中加入导电填料会导致填料粒子与基体界面结合不牢固、易脱落等问题，本项目提出了通过将金属离子与聚氨酯形成络合物的方式制备导电性聚氨酯的研究思路。设计合成一类含咪唑功能团的新型聚氨酯，利用Langmuir-Blodgett技术使Ag(I)与咪唑基团在界面均匀络合，形成Ag(I)络合的聚氨酯薄膜；通过原位还原使金属以纳米粒子的形式镶嵌在聚合物基体中由此形成纳米粒子分散均匀、与基体界面结合牢固的复合薄膜；通过控制咪唑基团在分子中的比例和薄膜的厚度（层数），以及原位还原成银纳米粒子的条件、银纳米粒子向薄膜表面迁移的程度，建立薄膜结构与薄膜导电性之间的构效关系，获得薄膜厚度可控、导电能力可控且高度有序的聚氨酯薄膜；在此基础上，分析和阐明该类复合薄膜的导电机制，为其在有机电子器件、传感器方面获得广泛应用奠定坚实的基础。

聚氨酯作为一种合成高分子材料，具有耐磨、抗撕裂、抗曲挠性好的特点，有优良的加工性能，广泛应用于运输、机械、建筑、国防等领域。聚氨酯基导电复合材料的应用已涉及到电子工业如印刷电路板、压敏原件、电子仪器等，建筑工业如住宅、输油管等，以及航空如集成电路、电磁波屏蔽材料、抗静电材料等各个领域。然而如何提高聚氨酯与金属粒子之间的相容性，是制备聚氨酯基导电高分子材料的一个关键问题。本项目设计合成了不同结构的聚氨酯，利用吡啶N原子与银离子之间的相互作用，通过进一步还原，制备了聚氨酯/Ag复合材料；利用阳离子聚氨酯与锂离子之间的相互作用，制备了新型的固体电解质。项目取得的具体研究进展包括：（1）通过将N位上的氢取代，制备了不同烷基链取代的聚氨酯，并研究了N取代度与反应条件的关系；（2）合成了含吡啶官能团的功能性聚氨酯，通过与Ag离子络合并还原，制得了Ag纳米粒子；（3）制备了烷基链季铵化的树枝状阳离子聚氨酯，利用烷基链的自增塑作用，制备了高导电性的固体电解质，离子导电性是由电荷在络合点与聚集体之间迁移造成的，长的烷基链具有明显的增塑作用，使体系表现出液态行为但又保持了其稳定性；（4）将偶氮基团引入聚氨酯的主链和侧链，制备了光响应性的形状记忆性聚氨酯。培养硕士研究生3名，发表SCI论文6篇，申请国家发明专利3项。