共轭聚电解质/碳纳米管复合热电材料的构筑及其性能研究

Polymeric thermoelectric materials have recently drawn increased attention due to their unique properties, such as low thermal conductivity and high Seebeck coefficient. Conjugated polymers are basically with low conductivity in the undoped state, and the conductivity can be significantly enhanced after chemical doping, however, conjugated polymers are unstable in the doped state, which prevent the practical applications of polymeric thermoelectric materials. In this project, in order to improve the conductivity of conjugated polymer, we attempt to graft the ionic liquid contained alkyl chains to conjugated polymer backbones to achieve a series of self-doped conjugated polyelectrolytes. The correlations between the polymer structures, Seebeck coefficient, and carrier concentration will be elucidated through systematically investigation. The self-doped conjugated polyelectrolytes with good thermoelectric performance will be selected for construction of thermoelectric composites with long carbon nanotubes, which possess good conductivity and mechanical strength. By dispersing them in water or EtOH solution with ultra-sonication, soft conjugated polyelectrolyte /carbon nanotube thermoelectric composites will be prepared by facile vacuum filtration method. Improving the conductivity of the composites by tuning the orientations of the conjugated polymers wrapped around the carbon nanotubes, the self-doped conjugated polymers/carbon nanotubes with high figure of merit (ZT) will be eventually fabricated. This study will provide new ideas and methods to achieve high performance polymeric thermoelectric materials.

聚合物热电材料由于其高Seebeck系数、低热导的特点，成为热电材料的研究热点。共轭聚合物本身导电性非常低，通常需要经过化学掺杂提高其导电性，然而化学掺杂剂的引入使得聚合物存在稳定性差等缺陷，大大限制了聚合物热电材料的应用。本项目拟向共轭聚合物骨架引入含离子液体功能基团的烷基侧链，制备出具有自身掺杂功能的共轭聚合物，从而提高其导电性。通过研究分子结构与载流子浓度、迁移率之间的制约机制，找出聚合物结构对热电性能的影响规律。筛选出性能优良的自掺杂共轭聚合物与具有优异导电性和机械强度的长尺寸碳纳米管在乙醇或水中分散后，采用真空抽滤法得到柔性复合热电材料膜。通过调控聚合物在复合界面中的取向，提高复合材料的整体导电性，最终构建具有高热电优值的柔性共轭聚合物/碳纳米管复合热电材料。本课题本研究将为高性能热电材料的构筑提供新理论和新方法。

随着化石能源的逐渐耗尽，发展绿色能源材料已经成为了全球性重要研究课题。其中如何将传统工业和生活中产生的大量废热进行回收利用，已经引起了很多成为研究者的关注。热电材料具有将热能转换成电能的功能，已经发展成为新型能源材料的重要成员。相比已经发展相对成熟的无机热电材料，有机热电材料的开发与应用还处在萌芽阶段，具有高性能热电性能的材料依然稀缺。. 我们在以下几方面做了研究：1、聚合物主链结构对自掺杂型苯基导电聚合物热电性能的影响；2、侧链长度对自掺杂PEDOT热电性能的影响；3、新型共轭聚合物/碳纳米管复合热电材料的制备及其热电性能分析等方面的工作，这些研究的开展为纯共轭聚合物及聚合物/碳纳米管复合膜材料体系的构筑提供新的思路和方法。