基于多巴胺-金属动态配位键的可水下自修复憎水性聚合物

This proposal aims at developing hydrophobic polymer solids that can be repeatedly healed under water. The polymers consist of hyperbranched polyurethane and epoxy resins that are crosslinked by DOPA–metal ions coordinate bonds. To promote the diffusion and collision of molecular chain in the water, a certain amount of hydrophilic groups were grafted on the molecular chain ends of hyperbranched polymers. Consequently, underwater self-healing and recycling of polymer materials can be yielded due to overcoming of the shielding effect of water between hydrophobic polymers. When the polymer is damaged in seawater, reshuffling of the hyperbranched polymer networks across the crack interface, owing to the dynamic DOPA-Fe3+ crosslinkages activated by water, rebinds the damaged site. This process is not sensitive to the pH value of the water. By taking advantage of the same mechanism, the polymer can also be remolded with the help of seawater and the recycled polymer is still self-healable in seawater. Meanwhile, the performance of the material itself can be conveniently adjusted by changing the content of hydrophilic groups as well as the structure and flexibility of hyperbranched chains. We will focus on molecular design, synthesis approaches and self-healing mechanism, etc. It is believed that water triggered dynamic feature of coordination bond and its influence on the self-healing process will be revealed. The effects of hyperbranched polymer molecular structure, DOPA–metal ions coordinate bonds, the hidden hydrophilic group, etc. on the mechanical properties and underwater self-healing will be illuminated. Based on these researches, this kind of polymer structure and performance will be optimized. On the whole, this project will provide deeper understanding about underwater self-healing of hydrophobic polymers solid.

基于我们最近发现的多巴胺-金属离子配位键在水中具有动态可逆性这一新现象，本项目拟在超支化聚合物分子链端引入该配位键，利用前者大量的支链，构筑富含多巴胺-金属离子配位键的交联网络，发展一种可在较宽pH范围（7~9）水下反复多次自修复的结构用憎水性聚合物。为突破水屏蔽憎水性聚合物断面间重新键接的障碍，还将引入适量隐藏亲水基团，在保证目标聚合物憎水性的同时，使其在水中损伤后，断面上分子链能相互扩散和碰撞，进而通过水激发配位键的交换以及网络重排，实现断面的配位键链接、愈合裂纹，恢复材料的承载能力。本项目将深入开展分子设计、合成方法与修复机理研究，揭示水激发配位键的动态反应规律及其对修复过程的影响，阐明超支化聚合物的分子结构、各种多巴胺-金属离子配位作用、隐藏亲水基团等与材料力学性能和水下自修复性的相关性。在此基础上，优化此类聚合物的结构与性能，为将自修复型聚合物拓展至不同水环境中应用提供科学依据。