ISSN   1004-0595

CN  62-1224/O4

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仿生层状聚乙烯醇水凝胶润滑材料的设计、制备和摩擦性能研究

Design, Preparation and Tribological Performance Study of Bionic Layered Polyvinyl Alcohol Hydrogel Lubricating Materials

  • 摘要: 聚乙烯醇(PVA)水凝胶因其具有良好的机械性能和生物相容性被视为理想的软骨替代材料,但其单一结构难以满足实际应用复杂工况的需求. 关节软骨是覆盖在关节骨端表面的结缔组织,独特的层状结构及表面状态使其具有优异的润滑功能. 受关节软骨复合结构及其润滑机制启发,本文中基于界面分子链渗透互穿和多次溶剂交换的方法,制备出具有优异机械性能和润滑性能的仿生层状PVA水凝胶. 首先将PVA溶解于二甲基亚砜(DMSO)中获得不同质量分数的溶液,高质量分数溶液用于制备承载基底. 随后向低质量分数PVA溶液中加入多糖润滑物质(羧甲基壳聚糖,CMCS),原位浇筑到承载基底表面以构建润滑层,通过多次溶剂交换实现层状凝胶整体结构强韧化. 通过调控溶剂交换时间和CMCS添加量实现仿生层状PVA水凝胶的机械性能和润滑性能的优化,明确表面模量与摩擦性能之间的关系. 与具有单一网络结构的PVA水凝胶相比,该仿生层状水凝胶具有更低的摩擦系数,摩擦系数在长时间测试(往复循环36 000次)中保持稳定(摩擦系数<0.05),研究结果为设计PVA基水凝胶润滑材料提供了新的思路.

     

    Abstract: PVA hydrogel is a promising candidate for cartilage replacement materials due to its favorable mechanical properties and biocompatibility. However, its structure poses challenges in meeting the demands of complex conditions encountered in practical applications. The mechanical and lubricating performances of PVA hydrogels fall short compared to human tissues, lacking the intricate architecture and functionality inherent in natural tissues. This deficiency results in suboptimal deformation, shock absorption and lubrication capabilities for cartilage substitutes. Consequently, researchers have shifted the focus towards simulating the natural lubricating tissues within the human body to address functional issues related to cartilage replacement materials and friction and wear concerns. Natural articular cartilage with a composite structure is important for supporting, cushioning, and lubricating human joints. The rapid hydration function of brush-like biomacromolecules, in conjunction with the synovial fluid present in the joint cavity, collaborates to sustain a low friction coefficient and minimize friction loss on the cartilage surface. Together with the superior mechanical properties of the cartilage itself, they establish a joint lubrication system characterized by high load-bearing capacity, low friction coefficient, and extended longevity. Inspired by the composite structure of natural articular cartilage and its lubrication mechanism, this paper constructed the interpenetration of molecular chains by casting a composite lubricating layer with CMCS molecules as lubricants on the bearing layer. At the same time, the structure was strengthened and toughed by solvent exchange, and a biomimetic layered PVA hydrogel with excellent mechanical and lubricating properties was prepared. The lubricating layer consisted of a low-concentration PVA hydrogel with CMCS aimed at reducing the friction coefficient while the load-bearing layer comprised highly concentrated PVA hydrogel with high mechanical performance. In addition, by changing the solvent exchange time and the mass fractions of CMCS molecules in the preparation process, the mechanical properties was optimized and the lubricating mechanism was investigated. During the solvent exchange process, the crosslinking network underwent shrinkage and the intercrystal spacing diminishes over time, leading to a denser cross-linked structure that enhanced surface modulus. An increase in CMCS content resulted in a progressive reduction of intercrystal spacing, indicating tighter crystal packing and further augmenting surface modulus. By optimizing both the solvent exchange time and the mass fraction of CMCS, an ideal contact surface with optimal surface modulus could be achieved, facilitating superior hydration lubrication effects without excessive deformation while minimizing the total friction coefficient. In comparison to PVA hydrogel with a single network structure, the biomimetic layered PVA hydrogel exhibited a lower friction coefficient, which remained stable (friction coefficient<0.05) over an extended duration of testing (36 000 cycles). These research findings offerred novel insights for the design of PVA-based lubrication materials.

     

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