立构微晶增强增韧可修复材料的分子设计及结构与性能调控

Current developed self-healing polymeric materials containing a large number of weakly reversible bonds and flexible chain segments have poor strength, toughness and durability and cannot satisfy the engineering application. It becomes one of the major challenges to improve the mechanical property of self-healing polymeric materials. Polylactide stereocomplex crystallites (PLA-sc) has the advantages of stereoselectivity and strong chain interaction, and has obvious advantages in strengthening and toughening materials. The applicant proposed to build a physical cross-linking network using the PLA-sc to construct a strong and tough self-healing polymer material combined with reversible multiple hydrogen bonding. The active polymerization method is used to prepare copolymer and for accurate control of chain structure. The influence of the chemical composition and treatment condition on the formation of multiple hydrogen bonds, microphase domain and the structure of PLA-sc network is systematically studied. The self-healing, tensile properties and the dynamic evolution of the network structure in the material are analyzed to establish the multi-dimensional and deep interaction relationship between the structure and performance. On this basis, the chemical composition and chain structure are optimized to obtain a new type of self-healing polymeric material with high strength and toughness, expanding its application field.

目前发展的自修复高分子材料因包含大量弱可逆键和柔性链段而导致强度低、韧性差、耐久性弱，极大地限制了其在工程领域中的应用。高旋光度聚乳酸异构体通过立体选择性交替排列而形成的立构复合微晶，因分子链间的自组装效应而更加稳定，作为物理交联点在材料增强增韧方面更具优势。本项目旨在综合利用立构微晶和可逆超分子作用形成的强弱不同双重网络结构，构建强韧自修复高分子材料。采用活性聚合手段制备含有高旋光度左旋（右旋）聚乳酸链段和可逆多重氢键的共聚物，精确调控聚合物链结构；系统研究分子组成、后处理条件与多重氢键、微相区和立构微晶网络结构之间的内在关联；借助多种原位手段表征材料的自修复和拉伸性能，解析微观网络结构的动态演变规律，阐明性能变化的微观作用机理，建立从分子结构到性能的多维度深层次相互作用关系，完善自修复过程的基础理论体系。在此基础上，对聚合物组成和结构进行优化，以期获得新型强韧自修复高分子材料。

兼具优异力学性能和自修复性能的强韧自修复聚合物材料的设计制备目前依然面临挑战。本项目基于多重超分子作用力和结晶微区共同调控的设计理念，利用可控聚合方法高效合成系列自修复聚合物，精确调控化学组成，系统研究多级次氢键、微相分离及结晶等微观网络结构特点及相互作用关系，成功获得强韧自修复聚合物材料。同时，利用多种原位表征手段深入探究了自修复和力学性能变化规律和微观机制，拓展了强韧自修复材料的力致变色功能。设计制备的基于氢键和金属配位键双重动态作用的自修复聚合物材料，通过调控氢键及配位键含量实现了力学和自修复性能的宽范围可调性，其中，键能较弱的氢键提供自修复所需的动态重构特性，键能较强的金属配位键赋予材料强力学性能。进一步，在多级次氢键超分子作用的基础上，结合聚乳酸立构复合微晶作为加强交联点，成功制备了基于结晶结构和氢键交联的强韧自修复聚合物材料，其中，多级次氢键赋予材料自修复性能，聚乳酸立构晶赋予材料优异的力学性能。在此基础上，设计制备了基于多级次氢键的仿生可修复力致变色聚合物复合膜，通过应变诱导的荧光遮蔽层裂隙开关可调节力致变色性能，修复后可实现结构和功能的恢复，在高级信息加密和应力传感等领域具有广阔的应用前景。在本项目及基金委其他项目的共同支持下，共发表科研论文5篇，申请发明专利1篇，培养2名博士研究生和1名硕士研究生。