梳状光学活性螺旋聚氨酯固体电解质的制备及其吸波性能研究

In response to the problems of low conductivity, poor stability and insufficient mechanical strength of the polymer electrolyte, this project intends to graft the ion donor with flexible macromolecular chain on the optically active helical polymer as the mainchain, and investigate the ion migration procedure in crystalline structure, accordingly develop a new solid polyelectrolyte as the absorbing materials. The details are as following, at first, based on the chiral amplification effect of helical polymer and isocyanate-phenol synthesized previously, the "majority rule", "domino effect" and "sergeant and soldier effect" will be utilized to prepare the optically active polyurethanes with high configuration stabilities, the adjustment mechanism of chiral parameters is also clarified. Secondly, ion donors of polycarboxylate lithium will be prepared through the RAFT polymerization technique and spliced on the helical backbones by the click chemistry. The conductivity and permeability related to the macromolecular structure will be investigated, and the transportation model of current carrier is then established. Thirdly, electromagnetic loss mechanism of the polyelectrolyte under different chiral parameters is to be studied by the analysis of electromagnetic parameters, thus the reasonable match and regulation between microwave absorption and infrared radiation will be achieved. By carrying out above experiments, the helical secondary structure can be used as the space of ionic conduction.This has important guiding significance to the design and preparation of high-performance polyelectrolyte,hence expands the application of the material in the field of electromagnetic wave absorbing.

本项目针对聚合物电解质电导率低、稳定性差、机械强度不足等问题，拟将柔性高分子离子供体接枝于光学活性螺旋聚合物主链上，开展晶态结构中离子迁移机制的研究，并据此开发新型吸波材料用全固态螺旋聚电解质。内容包括：（1）根据螺旋聚合物的手性放大效应，基于前期开发的异氰酸酯-酚单体及其合成方法，通过"少数服从多数效应"、"多米诺效应" 和"长官与士兵规则"，制备具有高构象稳定性的光学活性聚氨酯，明确手性参数的调节机制；（2）聚羧酸锂离子供体的RAFT制备及其与螺旋骨架的点击化学拼接，考察材料的电导率、磁导率等性能与大分子结构的关系，建立相应的载流子传输模型；（3）通过电磁参数的分析研究不同手性参数下材料的损耗机理，实现微波吸收与红外辐射之间的合理匹配与调节。通过本项目的开展，以螺旋二级结构作为离子传导的空间，对高性能聚电解质的设计制备具有重要的指导意义，同时也拓展了材料在电磁波吸收领域中的应用。

本项目以酪氨酸为原料分别合成了手性与外消旋双酚单体，并通过与二苯甲烷二异氰酸酯聚合制备了相应的光学活性螺旋聚氨酯和外消旋聚氨酯。结果表明，手性不对称场的诱导作用使得聚合物形成了单手螺旋结构，其大分子链更加规整和有序，使得光学活性聚氨酯的氢键作用明显强于相应的无规外消旋体系。规整有序的二级结构有利于热量的传导和散失，协同聚合物结构中存在的大量氢键作用使其不饱和度大大降低，改变了聚合物的分子振动模式，导致光学活性聚合物的红外发射率明显低于外消旋体系。在此基础上，进一步采用化学接枝法，通过γ-氨丙基三乙氧基硅烷的架桥作用，制备了光学活性聚氨酯@La2O3、外消旋聚氨酯@La2O3和叠层核壳结构光学活性聚氨酯/TiO2/MnO2有机/无机纳米复合材料。复合材料的红外发射率都明显低于无机粉体本身，且基于光学活性聚氨酯复合材料的红外发射率低于相应的外消旋复合物。同时，随着包覆层的增加，材料红外发射率呈现逐渐下降的趋势，界面作用、晶态结构的形成、光学活性聚合物规整有序的二级结构共同发挥了至关重要的作用。同时，基于酪氨酸自聚物分别制备了双离子、单离子固态电解质薄膜，考察了不同锂盐、锂盐含量、单体对映体过量百分数相应固态电解质电导率的影响，随着聚合物螺旋二级结构含量的增加，其离子电导率逐渐升高，相对于外消旋聚合物体系的电导率（1.09×10-7S/cm），基于100%对映体过量（手性单体）聚氨酯的电导率提升1个数量级，达到3.70×10-6S/cm，基于该螺旋聚氨酯的单离子导体的室温电导率为8.06×10-7S/cm，螺旋结构对于材料离子电导率的提升发挥了重要作用。通过本项目的实施，我们明确了大分子规整有序的二级结构、分子间作用力、界面体系对于材料红外辐射性能、离子电导率的影响和作用机制，为后续新型宽频吸波材料、全固态电解质锂离子电池的研发工作奠定了理论基础。