共轭高分子的多级组装

Multi-level Self-assembly of Conjugated Polymers

共轭高分子材料具有质轻、柔软、成本低、性能易于调控且可溶液加工等特点,在有机电致发光二极管、有机光伏、场效应晶体管与传感器件等领域有广泛的应用前景.共轭高分子体系中的多种弱相互作用使其可以形成复杂的多级组装结构,因此深入研究共轭高分子多级组装对于明确高分子功能材料构效关系具有重要意义.本文立足于系统对比共轭高分子多级组装与蛋白质多级组装的相似性,首次划分了共轭高分子多级组装中存在的四级结构:一级结构为通过共价作用形成的一维聚合物链结构,二级结构为通过分子间相互作用如π-π堆积(π-πstacking)、层状堆叠(lamellar packing)和链缠结等形成的一条或多条聚合物链组装结构,三级结构为不同相行为对应的聚集结构,例如结晶、无定形区域(crystalline and amorphous region)和过渡区域等,四级结构为多组分相互作用及相分离的材料体系.多级结构相互关联,共同决定了共轭高分子材料的光、电、热等物理性质.本文总结了近年来共轭高分子多级组装的相关研究工作,为观察和理解并指导高分子多级组装、建立完整的"构效"关系、优化器件性能提供了新视角.

Conjugated polymer materials have properties of light-weight,flexibility,good solution processability,performance tunability and low manufacturing cost.Therefore they hold great promise in various applications like light-emitting diodes,photovoltaics,field effect transistors and sensors.Due to the weak intermolecular interactions between conjugated polymers,subtle chemical structure modification and fabrication process alteration will cause variation of molecule assembly behaviours at a broad range of length scale and change of device performance.Thus,complex and diverse multi-level self-assembly structures of conjugated polymers can be formed.This provides rational molecular design and future industrial application with theoretical basis and applicable design strategies.This also sheds light on understanding the“structure-function relationships”of conjugated polymer materials.For the first time,based on systematic comparison of similarity between multi-level self-assembly behaviours of conjugated polymers and proteins,this review proposes that the assemblies used in optoelectronic devices usually have quaternary structures as in proteins:the primary structure is the onedimensional polymer chain connected by covalent bonding;the secondary structure is multiple polymer chain aggregates forming through interchain interactions like lamellar packing,π-πstacking and chain entanglement;the tertiary structure is the phase behaviour as crystalline and amorphous region with domain size and grain boundary;the quaternary structure is the phase segregation in multi-component mixture through interaction between different component and phase interfacial properties.Multi-level self-assembly behaviours are in concert with each other to functionalize conjugated polymer materials by light,electric,magnet and heat performances.This review summarizes recent progresses on studies of conjugated polymer multi-level self-assembly process,which provides us with a new prospect of better observing,understanding and guiding the conjugated polymer multi-level selfassembly process.And thereby the substantial relationship between chemical structure,fabrication processing,assembly behaviour and macroscopic physical process is established,and the optoelectronic properties of polymer materials is furthermore optimized.