多重氢键键合超分子聚合物的受限结晶、多晶态形成与相转变

Supramolecular polymers are a novel class of polymeric materials and their physical properties are determined by both the chain structure and condensed matter structure. Clarifying the principle and mechanism for the formation and manipulation of condensed matter structures in supramolecular polymers are of fundamental importance for the optimization of physical performance and the development of new functions in manufacture and processing. Because of the confinement effects of supramolecular units and the effects of intersegmental interactions, the crystallization behavior of supramolecular polymers is generally different from conventional polymers; it is characteristics of the confined and dynamic process. In this project, we would like to select the supramolecular aliphatic polyesters bonded by multiple hydrogen bonds as a model system and investigate the confined crystallization kinetics, polymorphic phase crystalline formation and transition of supramolecular polymers. Effects of non-covalently bonding manner and interactions between polymer segments on the crystallization kinetics, polymorphic crystalline phase formation and transition of supramolecular polymers will be investigated and the mechanism behind these results will be discussed. The change and transition of chain conformation and microstructure in the nucleation process of supramolecular polymers and their correlations with the interactions between supramolecular motifs will be illustrated. The in-situ and real-time experimental methods to analyze the polymorphic crystallization and phase transition of supramolecular polymers will be established or perfected. This study will establish new methods to control the condensed matter structure and physical performance of supramolecular polymers through the crystallization of chain segments. The mechanistic investigations conducted in this study will help to further understand the principle and theory for the formation and transition of hierarchical condensed matter structure in the polymer system having relatively strong intersegmental interactions and complex chain structures.

作为一类新型高分子材料，超分子聚合物的性能同时决定于其链结构和凝聚态结构，阐明其凝聚态结构形成和调控的规律与机理可指导材料制备、加工中的性能优化和新功能开发。由于超分子基团受限效应和链间相互作用的影响，与传统高分子相比，超分子聚合物的结晶和凝聚行为不同，具有受限和动态的特点。本课题将以多重氢键键合的超分子脂肪族聚酯为模型，研究超分子聚合物在受限条件下的结晶动力学、多晶态形成与相转变，研讨链间非共价键合形式和相互作用对超分子聚合物结晶动力学、多晶态形成与相转变的影响规律与机理，揭示超分子聚合物成核过程中链构象和微观结构的演变规律及其与超分子基团间相互作用的关联，完善原位、实时分析超分子聚合物结晶和多晶间相转变过程的实验方法。本研究将建立基于链段结晶的超分子聚合物凝聚态结构与性能调控的新方法，将有助于进一步理解具有较强相互作用、复杂链结构聚合物体系多层次凝聚态结构形成与演变的规律与理论。

超分子聚合物是基于非共价键（作用）将单体或聚合物链段相连而成的一类新型聚合物。超分子聚合物的性能同时决定于其链结构和凝聚态结构，由于超分子基团的聚集和结晶所产生的受限效应以及链间非共价相互作用的影响，与传统高分子相比，超分子聚合物具有独特的结晶和凝聚行为。本项目以2-脲基-4[1H]嘧啶酮（UPy）四重氢键单元端官能化的超分子聚乳酸（PLA）、聚己二酸丁二醇酯（PBA）为模型体系，通过与传统高分子结晶行为进行对比，揭示了聚合物链段间动态、可逆非共价相互作用对超分子聚合物结晶动力学、微相分离、多晶态结构及其相转变的影响规律及机理。通过研究多重氢键型超分子聚合物的成核过程，阐明了其结晶诱导期内链构象、预有序结构和多重氢键单元聚集结构（如二聚体）的演变过程及其相互影响，对具有较强相互作用和复杂链结构聚合物体系的结晶成核机理有了更深的认识。. 此外，项目以UPy四重氢键、胸腺嘧啶（Thy）二重氢建单元端官能化的超分子聚己内酯（PCL）为模型体系，通过研究其结晶驱动的微相分离过程，发现了超分子单元的多层次有序结构的形成与演变的规律。另外，通过研究UPy官能化的超分子聚乳酸的溶液结晶与溶液中液-液相分离的相互作用，解释了具有较强相互作用、不同结晶结构的聚合物在溶液结晶中的液液相分离、增长动力学和链折叠行为，初步建立了不同形貌的超分子聚合物微球可控制备的方法。. 项目结合同步辐射SAXS/WAXD、原位FTIR等手段，完善和构建了原位、实时分析超分子聚合物结晶和多晶间相转变的方法，以及原位、实时分析超分子聚合物结晶驱动的微相分离和多层次有序结构形成与演变的方法。基于链段结晶和多种结晶组分结晶结构的调控，初步建立了调控多重氢键键合超分子聚合物性能（如力学性能、热性能、形状记忆性等）的方法，可为超分子聚合物材料制备和加工中的性能调控提供指导。