仿生聚合物分子刷的设计制备及界面润滑调控研究

Inspired by the superior lubrication of bottle-brush aggrecan in synovial fluid, chitosan is employed as main backbone of synthetic bottle-brush polymers to mimic natural joint lubricants. Because chitosan has a similar structure with hyaluronic acid, the backbone of bottle-brush aggrecan. Zwitterionic polymer with phosphoryl choline groups, polyelectrolyte and polypeptide are grafted onto chitosan via in situ polymerization to form bottle-brush structure. This preparation method is very simple and almost doesn’t use poisonous solvents and catalysts. Thus, the synthetic bottle-brush polymers maintain the origin biocompatibility of chitosan while significantly improve the interfacial lubrication. The triological properties, biocompatibility and biodegradability of chitosan based bottle-brush lubricants are investigated in detail. The influences of grafted density and molecular weight of side-chains on interfacial lubrication are also inspected. In addition, the temperature responsive hybrid bottle-brush including hydrophilic side-chains and hydrophility-hydrophobicity switchable side-chains is also prepared. The interfacial lubrication properties of hybrid bottle-brush can be tuned with the variation of interfacial adsorption of polymer regulated by external stimulus. Finally, the comparative studies are conducted for the series of bottle-brush polymers to select the best lubricants, which will show potential applications in artificial joints and biomedical devices. This proposal will also be beneficial to the bio-inspired design of advanced lubricants in the future.

受关节滑液中“瓶刷”型蛋白聚糖优异润滑作用的启发，本课题选取与蛋白聚糖主链透明质酸结构非常类似的壳聚糖(Chitosan)作为合成聚合物分子刷的中心骨架，通过原位聚合对其进行接枝改性，分别制备了两性磷酰胆碱聚合物、聚电解质和多肽为侧链的壳聚糖基分子刷。该制备方法简单，制备过程较少使用有毒溶剂和催化剂，希望在保持壳聚糖良好生物相容性的同时，能够显著改善其界面润滑性能。系统研究系列聚合物分子刷的吸附组装行为以及界面润滑性能、生物相容性和生物降解性，并考察了侧链接枝密度和分子量对润滑性能的影响。此外，又制备了响应性杂化聚合物分子刷，通过外界刺激调控聚合物分子刷在界面的吸附与润滑，研究大分子刷在界面吸附与润滑之间的关系规律。最后通过系列聚合物分子刷综合性能的比较研究，筛选出综合性能优良的仿生润滑剂，希望能用于解决人工关节及生物医药设备的润滑问题，并为今后仿生聚合物润滑剂的设计提供理论指导。

高效仿生聚合物润滑剂对退化关节软骨的修复及解决生物植入体及医疗器械的摩擦磨损问题具有重要意义。受关节滑液中“瓶刷”型蛋白聚糖优异润滑作用的启发，本项目以壳聚糖为中心骨架，通过原位聚合接枝侧链，成功制备了壳聚糖接枝磷酰胆碱两性离子聚合物、聚电解质以及聚氨基酸等一系列壳聚糖基仿生润滑剂。以生物医用材料（Ti6Al4V合金）为模型界面，系统评价了这一系列“刷”型接枝共聚物的界面润滑性能，并采用原子力显微镜（AFM）和石英晶体微天平（QCM）等手段研究了“刷”型接枝共聚物在模型界面的吸附、组装及其与润滑性能之间的相互关系，阐明了壳聚糖基仿生润滑剂超低摩擦的主要机制。对综合润滑性能最佳的壳聚糖接枝磷酰胆碱两性离子共聚物（Chitosan-g-PMPC）进行了生物相容性和生物流体中的抗污染性能评价，结果表明，Chitosan-g-PMPC具有很好的生物相容性和抗污染能力，其摩擦系数低至0.008，比商用透明质酸润滑剂的摩擦系数低一个数量级。Chitosan-g-PMPC仿生润滑剂有望应用于解决生物植入体（人工关节、人工晶状体）的摩擦磨损问题和退化关节软骨的润滑修复。在此基础上，还发展了基于多巴胺自聚合辅助一步法制备超润滑和抗污染聚合物纳米涂层的方法，该涂层的摩擦系数可以低至0.003。该方法操作简单，普适性好，适用于多种惰性生物材料表面（Ti6AI4V、PDMS、PS、PMMA等）和生物医用器械表面（医用导管、隐形眼镜等）制备超润滑、抗污聚合物涂层。