模块化成环新方法和环形聚合物结构与性能调控

It has a great challenge to innovate the synthetic method for cyclic polymers. On the basis of ring-opening metathesis polymerization of cycloolefin or metathesis cyclopolymerization of 1,6-heptadiyne, we propose this project to developing a novel blocking-cyclization methodology, which is focused on the fundamental study about the exploration for the mechanism of blocking-cyclization of two single-stranded chain segments by a living-propagated double-stranded chain segment, and revealing the characteristics of the new blocking-cyclization technique for synthesizing cyclic polymers. The precise regulation for the cyclic ring size, number, chemical composition, and structure of cyclic polymers could be realized by changing the feeding ratio, number of times, and various combinations of different mono- and bi-functional monomers, providing a series of cyclic polyolefin, cyclic polyacetylene, or alkene-alkyne hybrid cyclic polymers with mono-, bis-, or tri-cyclic rings. The cyclic polymers in gourd string, wedge, dumbbell, and fusiform topological structures will be prepared readily by varying the feeding ratios of monomers. In addition, it is expected to perform the interconversion of cyclic ring size and number depending on the reversible change of coordination-decoordination between phenanthroline groups and metal ion. The distinguishing feature and advantage of cyclic polymers will be manifested through the characterization of topological structure and morphology, and the measurement for physical properties, band gap, and dielectric energy storage capability. In brief, the features of alternative monomer feeding and blocking-cyclization will reliably ensure the successful synthesis of cyclic polymers with high molecular weight via a one-pot procedure. This research is aimed at erecting an original strategy of polymer cyclization for establishing cyclic polymers with abundant topological structure and excellent properties, and therefore it will exhibit the high academic value and scientific significance for developing metathesis polymerization and functional polymer materials.

环形聚合物合成方法的创新，富有挑战性。本项目提出基于开环易位聚合或易位环化聚合的“模块化”成环新方法，拟探索活性增长的双缆链段对单缆链段的模块化成环机制，揭示环形聚合物合成新方法的特征。通过改变不同单体交替投料比例、次数和组合方式，实现环大小、数目和组成结构的精确调控，获得一系列单环、双环和三环形聚烯烃、环形聚乙炔及烯-炔杂化环形聚合物。改变单体投料比，制备葫芦串形、楔形、哑铃形或纺锤形拓扑结构的环形聚合物；利用邻菲罗啉-金属离子弱键的配位-解配位可逆变化，实现环大小和环数的互变。通过结构和形貌表征及物理性能、能带隙和介电储能性测试，充分彰显环形聚合物的特点和优势。总之，交替加料方式和成环的模块化特性，为一锅法合成高分子量环形聚合物提供了可靠保证。本项研究旨在建立一种原创性的聚合物成环和扩环新方法，获得拓扑结构丰富和性能优异的环形聚合物，促进易位聚合和功能材料的发展，具有重要的科学意义。

环形聚合物合成方法的创新和分子拓扑结构的可视化表征，富有挑战性。本项目主要围绕五大体系，开展环形、笼形聚合物的合成和分子拓扑结构表征，系统性研究环形聚合物的热性能、光物理性能、力学性能、介电储能性等。内容丰富，数据翔实，全面完成了研究计划，达到预期目标，取得一系列成果。主要包括：（1）突破现有闭环法和扩环法的局限，创建了基于梯蕃单元、易位聚合衍生的模块化成环法，揭示了成环反应的特征和方法的普适性。（2）精心设计不同侧基结构、不同官能度的环烯烃和二炔烃单体，利用ROMP反应，一锅法合成了大尺寸单环（聚合度达400）、双环、三环聚合物，熟练掌握了合成技巧。明确认识了模块化成环法的基本规律，成功构建了环形、笼形拓扑结构的转换策略，开辟了合成大尺寸笼形聚合物的新途径，佐证了模块化成环法的实用性和优势。（3）优化单体结构和聚合反应条件，简便、高效地制备双环、三环、四环、环挂多环聚合物及三臂单笼、笼形刷、三臂双笼、四臂单笼、六臂单笼聚合物，实现了聚合物拓扑结构、尺寸、环数、性能的调控。详细考察了超大尺寸的双环（聚合度达1100）、四环聚合物和线形聚合物的分子量、流体力学体积、均方旋转半径等特征参数和光物理性能，比较差异，为环形拓扑结构提供支撑依据。双环聚合物的拉伸强度（46 MPa）是线形聚合物的三倍，力学性能显著增强。（4）利用MCP反应，制备了基于聚乙炔共轭骨架的单环、双环聚合物，通过TEM直接观察环形聚合物的分子拓扑结构，有效解决了分子层面的形貌可视化问题。（5）阐明了环形与线形聚合物的介电储能性差异及其与组成和拓扑结构的相互关系，单环聚合物的介电储能密度（Us=4.11 J·cm-3）高于线形聚合物（Us=2.34 J·cm-3），双环聚合物的储能密度更高（Us=4.50 J·cm-3），含金属环形聚合物的储能密度也较高（Us=3.94 J·cm-3）。完成本项研究，创新和发展了易位聚合方法学，丰富了环形聚合物功能性的研究内涵，充分体现了学术价值和科学意义。