端巯基超支化聚合物原位点击反应均匀功能化构筑可循环利用碳纳米管薄膜

Preparation and recycling of stably high strength and high conductivity carbon nanotube (CNT) films are key challenges in the manufacture of high-performance carbon nanotube materials. In this project, we will synthesize thiol-ended hyperbranched polymers containing hexahydrotriazine (THBP) and controllable structured CNT aerogel films. THBP will be used to uniformly impregnate and functionalize CNT aerogel films using in-situ thiol-ene click reaction so as to improve the strength, conductivity and recyclability of the final CNT nanocomposite film. The microstructure and wettability of CNT aerogel films will be tuned by adding doping elements and changing synthesis conditions. The complete impregnation and in-situ click reaction of THBP on CNT aerogel film will improve the uniform functionalization of the film and increase the contact, interaction and load transfer between CNTs so as to improve the mechanical strength, electrical conductivity and their stability of the final CNT nanocomposite films. The recyclability of CNT composites film will be achieved by controlling the formation and degradation conditions of the hexahydrotriazine structure. We will investigate how to control the microstructure of the CNT aerogel films with high wettability and the effects of structure, molecular size and content of THBP, the microstructure and wettability of the CNT aerogel films on the interaction and load transfer between CNTs. Factors influencing recyclability and mechanical and electrical properties of the CNT nanocomposite films and the recycling mechanism of the CNT nanocomposite films will also be studied. Through this research, we will produce CNT composite films which are recyclable and possess high strength, high conductivity and high stability, understand their design methods and control their properties. These results will provide theoretical guidance for the design and application of recyclable, high performance CNT nanocomposite films.

高强度、高导电且性能稳定的碳纳米管（CNT）薄膜的制备及循环利用是本研究领域的关键科学难题。本项目拟合成含六氢环三嗪的端巯基超支化聚合物（THBP）和微观结构可控的CNT气凝胶薄膜，均匀浸渍并采用硫醇-烯烃原位点击反应功能化构筑高性能可循环利用CNT薄膜。通过掺杂和合成条件调控CNT气凝胶薄膜的微观结构和润湿性，THBP均匀浸渍和原位反应功能化增加CNT管间相互作用、载荷转移能力、强度、导电性及性能稳定性，调控六氢环三嗪的形成与降解条件从而实现CNT薄膜的循环利用。探索高润湿性CNT微观结构的调控规律，研究THBP结构、尺寸、用量、CNT微观结构和润湿性等因素对CNT管间相互作用和载荷转移能力的影响规律，揭示影响CNT薄膜循环利用次数和性能的规律及循环利用机理。获得高强度、高导电且性能稳定的可循环利用CNT薄膜及设计方法和性能调控规律，为构筑高性能CNT薄膜及应用提供规律性认识和理论指导。

单根碳纳米管（CNT）机械强度高、柔性好、导电性能优异，可望在柔性材料和可穿戴智能纺织品等领域应用，但CNT组装形成的CNT薄膜的机械强度降低近百倍、性能偏差大而不够稳定。因此高强度、高导电且性能稳定的CNT薄膜的设计制备及循环利用是其发展及应用的关键科学难题。（1）采用化学沉积法研究并获得了碳纳米管薄膜的连续制备工艺，通过原位氮掺杂和硫醇-烯烃点击反应氮掺杂提高碳纳米管间的相互作用、润湿性，进而显著提高了碳纳米管薄膜的机械强度和导电性，结果表明：原位氮和硫醇-烯烃点击反应氮掺杂可分别提高CNT薄膜的拉伸强度3.67倍和4.66倍，CNT薄膜从疏水性转变为亲水性，CNT薄膜循环使用3次后拉伸强度保持率超过80%。（2）利用超支化聚合物的拓扑结构优异转移载荷和分散应力的功能，设计制备了端巯基超支化聚合物经硫醇-烯烃点击反应构筑高性能CNT薄膜，研究并获得了机械性能影响的因素和规律，结果表明：端巯基超支化聚合物功能化CNT薄膜，提高拉伸强度6.89倍、提高模量8.18倍、提高比强度4.63倍。（3）设计合成含六氢均三嗪的可降解端巯基超支化聚合物经硫醇-烯烃点击反应功能化构筑高性能可循环利用CNT薄膜，研究并获得了机械性能和导电性能影响的因素和规律，结果表明：可降解端巯基超支化聚合物可提高CNT薄膜拉伸强度17.29倍，最后达到548.8MPa，提高导电率2.73倍，CNT薄膜经降解循环5次后拉伸强度的保持率大于90%，降解产物可再循环利用合成可降解端巯基超支化聚合物，回收的CNT薄膜可重新构筑高性能CNT薄膜。（4）揭示了氮掺杂、巯基功能化构筑CNT薄膜的增强机制和循环回收利用机理，并将此机理成功拓展构筑可循环利用的高性能环氧树脂/碳纤维复合材料，体现方法的普适性。本项目获得了多种端巯基超支化聚合物的结构设计与调控方法，获得了高强度、高导电且性能稳定的可循环利用CNT薄膜的构筑方法和性能调控规律，提出并证实了增强和循环利用机理，为构筑高性能CNT薄膜、碳纤维复合材料及应用提供理论指导。