双网络木质素水凝胶电解质的双交联协同机制及构效关系研究

Lignin is an ideal hydrogel electrolyte material, as its green renewable, low-cost, abundant electrochemical phenol groups in molecular structure. However, the previous reported lignin-based hydrogel can not be used as an electrolyte because of the low mechanical strength, as the structure of industry lignin is amorphous and three-dimensional which induces the crosslinking density of high lignin content hydrogel is low. The explored research of this project showed the double-network approach can effectively improve the mechanical strength of lignin-based hydrogel. Hence, this project will optimize the chemical crosslinking and physical crosslinking by varying the structure of lignin, the functionality and hydrophilicity of chemical crosslinker, and the concentration of acid solution, to reveal the double-crosslinked coordination mechanism of chemical crosslinking and physical crosslinking. Furthermore, this project will study the relationship between the structures of lignin, double-crosslinked network of hydrogel, and the mechanical strength and electrochemical property of lignin hydrogel electrolyte. This project will provide the theoretical guidance for the utilization of lignin hydrogel electrolyte in flexible supercapacitors.

木质素天然高分子因其绿色可再生、低成本、结构上含有电化学活性苯酚基团等特性，是一种理想的高分子水凝胶电解质组成材料。然而，由于工业木质素的无定型三维结构，导致高木质素含量化学交联水凝胶交联密度低，机械强度差，无法满足柔性超级电容器对电解质机械强度的要求。本项目前期工作表明，制备双网络木质素水凝胶，是增强其机械强度的有效途径。因此，本项目通过改变木质素分子结构种类、环氧交联剂官能团数量和亲疏水性、酸溶液浓度，实现对化学/物理交联的有效调控，揭示双网络木质素水凝胶化学/物理双交联协同机制；通过系统测试表征双网络木质素水凝胶电解质的压缩、拉伸、耐疲劳性、和离子导电率，结合超级电容器的比电容、能量/功率密度、循环/机械稳定性等关键性能评价，研究揭示木质素结构、水凝胶双交联网络结构与木质素水凝胶电解质机械强度、电化学性能之间的构效关系，为木质素水凝胶电解质在柔性超级电容器上的应用提供理论指导。

针对工业木质素因其无定型三维结构导致高木质素含量水凝胶交联密度低、机械强度差，无法满足柔性超级电容器对电解质机械强度的要求的问题。本项目利用木质素在稀硫酸溶液中发生的疏水聚集作用，通过化学/物理双交联的策略制备了双网络木质素水凝胶电解质。通过改变木质素分子结构种类、环氧交联剂官能团数量和亲疏水性、酸溶液浓度等实现了对化学/物理交联的有效调控，揭示了双网络木质素水凝胶化学/物理双交联协同机制；通过系统测试表征双网络木质素水凝胶电解质的压缩、拉伸、耐疲劳性和离子导电率，结合超级电容的比电容、能量/功率密度、循环/机械稳定性等关键性能评价，研究揭示了木质素结构、水凝胶交联网络结构与木质素水凝胶电解质机械强度、电化学性能之间的构效关系。并在此研究基础上，本项目进一步证明了化学/物理双交联策略的普适性，将其应用到纤维素、丝蛋白和PVA水凝胶体系中，以此构建了高强韧的纤维素、丝蛋白和PVA双交联网络水凝胶，研究揭示了其双交联机制。构建了导电水凝胶柔性传感器，实现了对不同外界刺激信号的多模式输出，阐明了其传感机理和构效关系，为导电生物基水凝胶在柔性超级电容器和柔性传感器领域的应用提供了理论指导。