苯并菲盘状侧链液晶聚合物的大分子工程

盘状液晶聚合物兼具盘状液晶的光电性能和聚合物的柔韧性以及优异的成膜加工性能,有望发展成为新一代先进有机聚合物柔性光电功能材料.本文介绍苯并菲盘状侧链液晶聚合物的研究进展,主要结合我们研究组的工作,重点评述采用受控/活性自由基聚合方法可控合成这类侧链液晶聚合物以及对分子量效应和间隔基长度影响等基本问题的阐明.我们采用可逆加成-断裂链转移(RAFT)聚合第一次成功实现了分子量窄分布的苯并菲聚丙烯酸酯侧链盘状液晶聚合物的可控制备.首先提出盘单元局部簇集的分立短柱堆积(DCS)模型,合理解释了聚合度20左右出现的显著分子量效应,尤其揭示并提出了盘状侧链液晶聚合物的正耦合效应(PCE)理论,即短间隔基的较强耦合作用更有利于其有序柱状相的形成,与棒状侧链液晶聚合物经典的柔性长间隔基去耦合理论形成鲜明对照,补充了缺失的理论短板.基于这些原则,我们设计合成的丁氧基苯并菲聚丙烯酸酯侧链盘状液晶聚合物,经飞行时间谱(TOF)测试,表现出比文献报道值高1~2个数量级的载流子迁移率.进一步在手性客体分子掺杂诱导组装形成单手性螺旋结构聚合物复合物,以及拓扑受限环状聚合物和嵌段共聚物的受控制备等方面开展了比较系统的大分子工程实践.盘状侧链液晶聚合物的可控制备及其显著不同于棒状液晶聚合物体系的一些基本特征的阐明,为这类重要有机聚合物半导体材料的理性设计与可控合成提供理论指导,也为加速推进其光电器件化应用奠定基础.

Macromolecular Engineering on Triphenylene Based Discotic Side-chain Liquid Crystalline Polymers

Discotic side-chain liquid crystalline polymers (SCLCPs) are expected to develop into a new generation of flexible organic polymer as advanced optoelectronic functional materials,by combining the order and optoelectronic properties of discotic liquid crystals and the flexibility and excellent film-forming advantages of polymers.This article introduces the research progress of discotic SCLCPs.Based mainly on the research progress of our group,we focus on summarizing and commenting the controlled preparation of triphenylene (TP) based discotic SCLCPs through controlled/living radical polymerization,as well as expounding molecular weight (MW) effect and spacer length influence of discotic SCLCPs.We have successfully realized the controllable preparation of well-defined TP polyacrylate discotic SCLCPs via reversible addition-fragmentation chain-transfer (RAFT) polymerization for the first time.Then,discrete columnar stack (DCS) based intracolumnar stacking mode has been proposed accounting for the remarkable MW effect at degree of polymerization (DP) around 20.Particularly,positive coupling effect (PCE) is disclosed for discotic SCLCPs,that is,the strong coupling effect of the shorter spacers is more favorable for the formation of ordered columnar mesophases,in striking contrast with the renowned classical longer flexible spacer decoupling principle derived from calamitic SCLCPs,complementing the missing theoretical short board.The polyacrylate SCLCPs with butoxy TP side-groups have been designed and synthesized based on these principles,showing a very high charge carrier mobility of one to two orders of magnitude higher than those reported as measured by the time-of-flight (TOF) technique.Our preliminary macromolecular engineering practices are further extended into the field of inducing assembly to form homochiral helical superstructures of electron donor-acceptor polymer complexes by doping with chiral guest acceptors,as well as controlled preparation and properties studies of cyclic polymers and block copolymers.The controllable preparation of discotic SCLCPs and the elucidation of some fundamental issues,such as MW effect and the spacer length influence,will provide guidance for the rational design and controlled synthesis of such kind of important organic polymer semiconducting materials,and lay a foundation for boosting their optoelectronic device applications.