基于多重响应性大分子单体的超分子超支化聚合物的构筑与自组装研究

Supramolecular hyperbranched polymers (SHPs) have attracted interest due to their unique chemical and physical properties. Compared with other supramolecular polymers (SPs), SHPs have three-dimensional topological features, little molecular entanglement, low viscosity, high solubility, and plenty of functional terminal groups. Therefore, SHPs possess the combined advantages of SPs and hyperbranched polymers. Till now, lots of investigations has been done to synthesize novel SHPs; however, several drawbacks are still remained, including difficulties on the effective regulation and precise characterization for polymer structure, inadequate multifunctionality of polymer backbone, and lack of investigation method for the self-assembly process in aqueous solution. To address the above issues, we here propose a novel idea to construct the structure-tunable SHP using ABx (x>2) type multi-stimuli-responsive macromonomer (MSRM). The backbone of MSRM has different covalent polymer segments including poly(N-isopropylacrylamide) and poly((N-amidino)ethyl acrylamide), S-S dynamic covalent bonds and β-cyclodextrin/ferrocene-based noncovalent bonds. Thus, the final SHP will possess temperature-, CO2-, redox-, and voltage-quadruple-responsive properties. On the basis of the above tunable polymer structure and quadruple-responsive features, the self-assembly morphology, size and hierarchical self-assembly of SHP in aqueous solution can be effectively regulated. More importantly, the self-assembly process and corresponding mechanism will be well-defined investigated by low-field nuclear magnetic resonance technique using relaxation time as physical parameter. To summary, the proposed project opens a new idea to synthesize the structure-tunable SHPs with multifunctionality, and develops an effective method to investigate the self-assembly process of SPs in aqueous solution.

超分子超支化聚合物（SHP）既具有传统超支化高分子的三维拓扑结构，又拥有超分子聚合物的动态可逆特性，因此是一类具有广泛应用前景的新型高分子。但目前在SHP研究过程中仍存在结构参数较难调控及表征、骨架功能性较为单一、自组装过程和机理缺乏有效研究手段等问题。申请者从寻找构筑SHP的新基元、新方法入手，提出利用ABx型（X>2）多重刺激响应性大分子单体（MSRM）合成结构可控的SHP的新思路。借助MSRM结构中不同分子层次的共价型长链、动态共价键和非共价键，赋予最终SHP骨架温度、二氧化碳、还原、以及电压等四重刺激响应功能。综合利用SHP的可控结构和各种刺激响应性之间的协同效应，实现对其水溶液中自组装体形貌、尺寸，以及分级自组装行为的调控；重点运用低场核磁共振技术从分子水平上对其自组装过程和机理进行研究。本项目为制备结构可控的多功能SHP提供了新思路，也为超分子聚合物自组装过程研究开辟了新途径。

虽然目前超分子超支化聚合物（SHP）作为一种新型的高分子物种已引起研究人员的广泛关注，但其研究过程中仍存在骨架功能性较为单一、自组装过程和机理缺乏深入研究等问题。基于此，本项目将刺激响应性基元引入单体结构，利用单体间的超分子作用构筑了一系列结构可控的刺激响应性SHP，深入研究了超分子自组装体的结构参数、动态组装过程、以及单体组装方向性的调控机制，并将所构筑的SHP自组装体应用于药物控释、抗菌、防伪等领域。本项目取得的代表性成果包括：（1）提出了刺激响应性大分子单体的设计新策略，解决了SHP结构稳定性和功能性的问题，达到了对其结构调控的目的；（2）提出了双重超分子作用协同互补新策略，达到了对SHP预组装和二次组装过程多级调控的目的，实现了对单体自组装方向性的有效控制；（3）基于SHP的触发响应特性和多键协同效应，实现了其自组装体作为智能超分子材料的功能应用。通过本项目的研究，课题组迄今已在Angew. Chem. Int. Ed.（1篇），Macromolecules (1篇)，PNAS (1篇)，ACS Macro Lett.（1篇），Chem. Commun.（4篇）等期刊上正式发表SCI论文31篇，会议论文2篇；获得陕西省高等学校科学技术一等奖1项；授权中国发明专利1项；培养中青年学术带头人1名（优青），培养博士研究生3人（已毕业2人），硕士研究生8人（均已毕业）。以上研究成果被J. Am. Chem. Soc., Angew. Chem. Int. Ed., Chem. Soc. Rev., Macromolecules等国际著名SCI期刊正面引用和积极评价。