以单宁酸为水相转移、固定化因子构建纳米共轭碳材料功能性涂层的研究

Aromatic conjugated nano-carbon (ACN) layers are widely accepted as promising material in the development of novel materials for energy storage, bio-sensing and flexible devices due to their excellent electrochemical properties and good thermal conductivity. However, the fabrication process of ACN layer still meets problem with low performance and structural instability. This is due to several reasons including destruction of conjugated structure induced by hydrophilic modification, lack of interaction between layer and substrate which results in phase separation, etc. Here we intend to establish a feasible and universal concept for the fabrication of aromatic conjugated nano-carbon (ACN) layers through the assistance of tannic acid (TA) in aqueous condition. The existence of non-covalent interaction between TA and ACN enables TA as agent in the immobilization and fixation of ACN onto targeted substrates thus forming carbon-based surface coating. Since chemical modification of carbon materials is not required in this system, the advantages of ACN are preserved. Through the strong bridging effect of TA between ACN and substrate, the integrity as well as stability of the synthesized material can be assured. This project will be carried out mainly from following three aspects: (1) The formation mechanism of dispersible TA/ACN complex will be studied using different types of TA and ACN; (2) To reveal the role of TA, the immobilization and fixation mechanism of various types of TA/ACN complexes on different substrates will be studied; (3) Correlations between the properties and effecting factors to the immobilization and fixation of TA/ACN layers will be established to make it a novel and feasible concept for the fabrication of carbon-based layers with high performance. This will enable a bright future of both material design and highly value-added utilization of tannic acid.

纳米共轭碳材料涂层因其优秀的电化学性质与良好的导热性能，在储能、生物传感以及柔性器件等新材料领域引起广泛关注。然而，在涂层制备过程中仍存在亲水性改性对共轭结构的破坏、相互作用缺失导致涂层与基质分离等问题，严重影响材料性能与整体性。为此，本研究拟引入单宁酸作为转移、固定化因子，通过非共价键作用与纳米共轭碳材料形成水分散配体，负载纳米共轭碳材料转移、固定到目标基质，进而在保留碳材料原有性状基础上组装形成碳材料涂层。本研究将：(1)构建可转移、固定化的多类型单宁酸/纳米共轭碳材料水性分散配体并探究其形成机理；(2)探求不同配体在基质表面转移、固定化行为机理，揭示单宁酸作为纳米共轭碳材料转移、固定化因子的作用机制；(3)明确固定化后碳材料涂层的性能与转移、固定化行为中各个因素间的关系等以上三个方面开展研究，以期建立构建高性能碳材料涂层的新方法，实现单宁酸的高值化应用。

本研究为解决纳米碳材料涂层的绿色加工问题，引入单宁酸基多酚作为水相转移、固定化因子，来负载碳材料，进而将其转移、固定到目标基质，在保留碳材料原有性状基础上，在水相中完成碳材料涂层的构建。本项目研究了：①多类型单宁酸/纳米共轭碳材料配体的构建以及其形成机理研究。构建了四种复合配体1.单宁酸/纳米碳材料（石墨烯、碳纳米管、聚苯胺）；2. 低聚单宁酸/纳米碳材料；3.鞣花酸/纳米碳材料；4. 单宁酸/有机氨阳离子/纳米碳材料四种配体，成功实现了多类型纳米碳材料在水相中稳定分散，并利用分子模拟研究了稳定分散机理，确定了单宁酸和单宁酸多聚体主要依靠π-π堆积作用实现对纳米碳材料的贴附，同时调节pH控制单宁酸分子形态释放部分未贴附多酚自由支链，作为配体的活性电荷，通过静电排斥作用实现配体在水中的分散。对于单宁酸/有机氨阳离子/纳米碳材料体系，研究发现氨阳离子的加入构建了更厚的“三明治”边界层能够更有效地隔开纳米碳材料实现分散；②研究了不同配体在基质表面转移、固定化行为的机理研究以及揭示转移、固定化行为与最终固定化得到的碳材料涂层性能之间的关系。通过对表面氨基化改性的硅材料（石英，单晶硅，PDMS），以及壳聚糖水凝胶表面成功负载纳米碳材料涂层，证明了转移行为需要配合酚羟基发生相互作用，同时考察了涂层的厚度与pH以及水相配体浓度之间的构效关系，发现只有中性pH（6~8）才能最大限度的发挥多酚对碳材料的π-π相互作用以及第三方的固定化作用。探索了基于多酚/纳米碳材料配体构建的电传感器以及锂离子电池等应用表现，发现低聚单宁酸/纳米碳材料配体由于其大的分子接触面积，在相同涂布量下其导电率以及比电容的均要高于单分子单宁酸/纳米碳材料配体构建的涂层材料。另外利用单宁酸实现了将碳量子涂层的构建，实现了水凝胶涂电导率的光响应变化。综上，本研究扩展了以单宁酸为代表天然多酚的应用范围，为多酚的高值化应用奠定良好基础，具有一定的学术价值和应用前景。