Janus型双亲性长链超支化聚合物的合成与性质研究

Hyperbranched polymers have attracted lots of research interest due to their high branching density, high end-group functionality and special physical properties. Many efforts have been devoted to the introduction of multiple components, multiple topologies and long linear chains into one hyperbranched polymer to improve the properties. Since Janus-type amphiphilic long-chain hyperbranched polymers enjoy the triple excellent properties from hyperbranched polymers, amphiphilic polymers and long linear chains, their study will achieve some exciting foundings. In this project study, with the principles of molecular design, we firstly figure out the appropriate structures from Janus-type amphiphilic long-chain hyperbranched polymers, the intermediates of Seesaw macromonomers to the starting chemicals, as well as the synthesis procedures to avoid the possible side-reactions and physical limits. Secondly, through the combination of various living/controlled polymerization techniques and click chemistry, we will obtain different Janus-type amphiphilic long-chain hyperbranched polymers with regular branching chain length and perfect asymmetrical topology, where Seesaw-type macromonomers are used as the integrating construction units. The different routes to Janus-type amphiphilic long-chain hyperbranched polymers will be employed, such as hy-hy coupling, coupling with linker, divergent polymerization and interface-aided synthesis. Thirdly, to understand the mechanism concerning with the growth of hyperbranched polymer and the formation of Janus topology, we will investigate the polycondensation kinetics of Seesaw macromonomers, the reactivity variation of focal groups with time and the micro-phase separation during the formation of Janus-type long-chain hyperbranched polymers. Fourthly, in viewpoints of both synthesis chemistry and polymer physics, the key factors such as chemical structure, reaction condition, the chain conformation and micro-phase separation will be mostly concerned to achieve the effective control over the chemical structure and chain topology of the resulted polymers. In all, we will manage to fulfill the integrated and programmed procedure to obtain Janus-type long-chain hyperbranched polymers. Finally, the self-assmebly of Janus-type long-chain hyperbranched polymers will be studied.

超支化聚合物发展至今，许多学者将多组分、多拓扑结构和长支化链组合到超支化聚合物中，以改善超支化聚合物的性质。Janus型双亲性长链超支化聚合物，结合超支化聚合物、长线形链和Janus结构的三重优点，将在许多领域展示出自己的优越性。申请项目从聚合物的结构设计出发，借助活性/可控聚合和高效、专一的化学反应，以Seesaw型大分子单体作为模块单元，通过两两结合法、链接分子结合法、外向结合法和界面辅助聚合法，合成出支化链长度均匀、Janus型双亲性长链超支化聚合物，着重研究超支化聚合物的反应动力学、核心官能团的反应活性和动力学限制微相分离等基本问题，从合成化学和高分子物理两个角度考察Janus型双亲性长链超支化聚合物结构控制的关键因素，以求获得合成Janus型长链超支化聚合物的模块化、程序化的途径，并以Janus型双亲性长链超支化聚合物作为自组装的构建基元，获得新颖的结构。

获资助项目围绕长链超支化/树枝状聚合物的合成和性质，开展系列研究工作，取得了阶段性研究成果。在长链超支化聚合物的形成机理方面，制备出不同种类、不同链长的跷跷板型大分子单体，在不同组成的混合溶剂中进行长链超支化聚合物的生长，确认大分子单体类型、链长和链构象对长链超支化聚合物形成的影响，揭示大分子单体和超支化聚合物自环化难以避免，建立长链超支化聚合物的生长动力学。. 长链超支化/树枝状聚合物的合成方法方面，发展出一种基于选择性沉淀分级的、简易高效的长链树枝状聚合物合成途径，可实现产物的简捷分离、原料的重复利用，生长至五代的长链树枝状聚苯乙烯仍保持很好的分子量均一性，并确定长链树枝状聚苯乙烯的玻璃化转变温度和特性粘数对代数的依赖性。.在Janus长链超支化/树枝状共聚物方面，利用两亲性共聚物自组装构建出合成过程的物理受限环境，在核心分子上交替进行Janus结构不同组分的生长，从而获得Janus型的长链超支化共聚物（-lhb-PSt/lhb-POEGMA）、长链树枝状共聚物（-PSt-G2/PtBA-G2），发现-lhb-PSt/lhb-POEGMA和-PSt-G2/PtBA-G2在选择性溶剂中形成单分子纳米胶束，-lhb-PSt/lhb-POEGMA依据成膜溶剂而呈现不同的薄膜微相分离行为，Janus结构的长链树枝状PSt/PtBA共聚物其本体相分离存在代数依赖性。. 在长链超支化聚合物的应用方面，对长链超支化聚合物进行接枝改性，获得两亲性的超支化共聚物，确认其响应性的负载/释放特性、在选择性溶剂的聚集和凝胶化行为。通过乙烯基自结合聚合方法，利用特定组分与药物分子的特殊相互作用，同步实现长链超支化共聚物的合成和药物的高效负载。将具有抗菌活性的聚丙烯酸氨基乙酯超支化和树枝化，确认长链超支化聚丙烯酸氨基乙酯更高的抗菌活性，获得了具有高抗菌活性、酶响应性的树枝状模拟抗菌肽。