烯-炔易位聚合构筑有规立构的纳米介电聚合物

It is a new trend for the research of polymer dielectrics by developing the insulating/conducting nanodielectric materials. The combined method of ring-opening metathesis polymerization (ROMP) and metathesis cyclopolymerization (MCP) with living characteristics was adopted to synthesize the insulating/conducting ene-yne block copolymer with tailored components and structure, as well as the tuned stereoregularity and functionality; meanwhile, the core-shell nanostructure consisted of polyacetylene core and polyolefin shell was constructed in situ by “polymerization-induced self-assembly”. By introducing the electron-withdrawing group, ionic group, or conjugated chain structure, the actions of dipole polarization, ionic polarization, or electronic polarization from different functional units should be strengthened, and further integrating the positive contribution from the nano-scaled interfacial polarization of core-shell interface and asymmetric space structure, the obviously increase in dielectric properties may be achieved. It is expected to obtain a novel type of nanodielectric materials based on the ene-yne block copolymer with excellent stereoregularity, high dielectric constant, low dielectric loss, outstanding stability, and good film-forming properties. The study is aimed at erecting the generally adaptability of combined ROMP-MCP method, which would be a valuable strategy for establishing a novel family of ene-yne block copolymer, and finally to provide full and accurate evidence for finely control over the stereoregularity and dielectric properties. It has the high academic value and strongly applied prospect for enriching and developing the researched new field in metathesis polymerizations and nanodielectric materials.

发展绝缘/导电型纳米介电材料，是介电聚合物研究的新动向。本项目拟将具有活性特征的开环易位聚合和易位环化聚合联用，制备结构和组成可裁剪、有规立构和功能性易调控的绝缘/导电型烯-炔嵌段共聚物；并经“聚合诱导自组装”，原位构建以聚乙炔为核、聚烯烃为壳的纳米结构。通过强吸电子基团、离子基团和共轭链的引入，强化各功能单元的偶极极化、离子极化或电子极化的作用；并结合纳米尺度的核-壳界面极化和不对称空间结构的正向贡献，来实现对聚合物介电性能的显著提升，以期获得一类立构规整性强、介电常数高、介电损耗小、稳定性和成膜性好的烯-炔嵌段共聚物纳米新材料。本项研究旨在建立易位聚合联用的可靠方法，为聚合物链的有规立构和介电性能的有效调控提供翔实的依据，这对于丰富和发展高分子化学和新材料体系，具有重要的科学意义。

研究绝缘/导电型纳米介电聚合物，是介电材料发展的新动向。本项目利用易位聚合制备结构和组成可裁剪、有规立构和功能性易调控的绝缘/导电型嵌段共聚物，通过聚合物在选择性溶剂中自组装，构建以导电链段为内核、绝缘链段为外层的纳米结构。通过极性基团、离子基团和共轭链，强化功能单元的偶极、离子、电子、纳米界面多重极化作用，获得了立构规整性好、介电常数高、介电损耗小、储能密度高的全聚合物纳米介电新材料。通过系统性研究，圆满完成了研究计划和预期目标，取得丰硕成果。主要包括：（1）光响应嵌段共聚物。通过ROMP反应，合成含肉桂酸酯和偶氮苯侧基的降冰片烯类嵌段共聚物。endo-构型立构嵌段的介电常数（15.5）比exo-构型嵌段（7.1）高，体现有规立构链的贡献。肉桂酸酯基紫外交联，自由体积降低，介电常数提高到16.6；强极性偶氮苯侧基使介电常数较高（19.1），介电损耗低（0.02），在240 MV m-1场强下储能密度为5.54 J cm-3，光照介电常数可逆变化。光异构化和交联调控和改善了聚合物的介电性能。（ii）烯-炔嵌段共聚物。利用ROMP-MCP串联反应，合成含多种极性侧基的烯-炔嵌段共聚物，可组装成结构规整的不同纳米形貌，绝缘性外层对导电性内核的屏蔽保护作用，有效地抑制导电链段的漏电现象，介电常数升为30，介电损耗低至0.002，在450 MV m-1场强下储能密度达到11.45 J cm-3，能量转换效率高达99%。实现了聚合物纳米结构的可控改性，并首次观察到共轭链发生反常规的先Alder-ene、后Diels-Alder反应，使介电常数从16.2增加到20.3，储能密度从6.46 J cm-3增加到9.95 J cm-3。（iii）基于梯蕃结构的嵌段共聚物。将梯蕃离子导电域、电子导电域、离子-电子杂化导电域（HCD）引入嵌段共聚物中，构建多重极化的全聚合物纳米介电材料，抑制了“分子复合物”的漏电流和介电损耗，介电常数和介电损耗分别为33和0.02，储能密度达到9.96 J cm-3，远高于商品化BOPP介电膜（400 MV m-1为1.6 J cm-3）和大多数介电聚合物。完成本课题，为易位聚合和全聚合物介电储能性研究提供了重要参考。