链式缩聚法合成可控结构超支化聚合物

Because of their unique highly branched structure, hyperbranched polymers exhibit some incomparable properties with their linear analogues, such as better solubility, higher thermal stability,easier processibility, abundant end groups, easier to form amorphous films of high quality and morphological stability. So, hyperbranched polymers have attracted major attention from industries and scientists for their real and potential novel applications in the fields of coating, resin nanocomposite, additives, drug delivery, sensors, nanoreactors, and special optical, photonic, catalytic, magnetic or electronic materials. Controllable structure is important for hyperbranched polymers to obtain enhanced properties. Considerable attention has focused on controlled synthesis of hyperbranched polymers. Compared to the tranditional step-grouth polycondensation of AB2 monomers, chain-grouth polycondensation usually behaves as a living polymerization to obtain polymers with controlled molecular weight and low polydispersity. In this project, the synthesis of well-defined hyperbanched polymers by chain-grouth polycondensation of AB2 monomers will be investigated. Suitable AB2 aromotic monomers with an amino group and two ester groups ,with resonance effect or inductive effect between the amiono group and ester group, will be designed and synthesized. The effects of polymerization conditions on chain-growth polycondensation of the obtained monomers will be investigated in terms of initiator, base to abstract proton of amino group, solvent, and temperature etc. Based on these researches, living polymerization will be achieved to synthesize well-defined hyperbranched polymers. The properties and functionilization of the obtained hyperbranched polymers will be studied to explore the application of the polymers.

超支化聚合物因其独特的结构，具有许多相应线形聚合物不可比拟的优越性能，在多方面具有重要的现实与潜在应用。超支化聚合物分子结构的可控性是其获取优异性能的重要基础，研究合成可控结构超支化聚合物具有重要意义。相比于传统的AB2单体的逐步缩聚反应，链式缩聚反应易于实现活性聚合，可实现对聚合产物分子结构的精确控制，优势明显。本申请项目将以氨基芳香酯单体为研究对象，通过分子设计，合成适宜的AB2型单体，其分子结构中含有一个氨基和两个与氨基具有对位共轭效应或间位诱导效应的酯基，系统考察各种反应条件对其链式缩聚反应的影响，通过调控反应条件实现所得单体的活性聚合，在此基础上研究合成可控结构的超支化聚合物，并研究其性能与功能化，为获得高性能的可控结构超支化聚合物新材料提供基础。

超支化聚合物因其高度支化结构，比相应的线形聚合物具有许多更优势的性能，研究合成可控结构超支化聚合物具有重要意义。链式缩合聚合反应是新近发展起来的由链式聚合机理获得可控分子量与分子量分布缩聚产物的活性聚合手段，研究由链式缩聚反应合成可控结构超支化聚合物不仅具有重要的理论意义，而且对于合成新型的高性能超支化聚合物具有重要应用价值。本项目主要研究了三类分别适于Kumada, Suzuki和Sonagashira反应的AB2单体的合成及其催化剂转移链式缩聚反应，系统考察了各种反应条件对三类单体超支化聚合反应的影响，结果表明其中由AB2单体S2合成超支化聚(对亚苯亚乙炔-alter-间亚苯亚乙炔)（hb-PMPE）的的Sonagashira超支化聚合反应具有较好的可控性，聚合产物分子量分布窄（PDI~1.3），支化度高（DB可达0.62~0.64），分子量随单体/核分子摩尔比增大而增大，具有一定可控性。并对所得超支化聚合物hb-PMPE进行末端改性合成了以hb-PMPE为核、线形聚乙二醇为壳的醛基功能化杂化聚合物，所得杂化聚合物可在水中进行自组装得到粒径< 50 nm的醛基功能化、最大发射波长~500nm的荧光胶束，在功能化纳米荧光标记领域具有潜在应用。