基于纳米层修饰界面结构提高仿生材料强度、敏感性的研究

Inspired by the multi-scale interphase in biomaterials, we will design and prepare new multifunctional biomimetic composites through introducing ultra-thin nanofilms into the interphase between fibre and matrix. It is well known that the interphase between reinforcement and matrix plays a critical role in the performance of both natural (or biological) materials and man-made composites. The interphase serves as a transferring region of stress, heat, electricity, and so on. According to the investigations of interphase in biomaterials, it is found that the multi-scale interphase brings about many unique performances for materials. Bones serve as an example of those hierarchically structured bio materials and have been studied with the fibre reinforced composite model. The reinforced interphase by mineral-protein offers a balance between stiffness and flexibility, which results in a high strength as well as light-weight materials. From a design standpoint, the interphase can potientially be tailored, through appropriate manipulation of the processing and material variables, derived from fundamental understanding and modelling, to achieve the desired properties and performance of the composites. Consequently, we will deposite various nano-films,including carbon nanotube(CNT), ZnO and so on, onto fibres' surface to form a multi-scale interphase in biomimetic composites. The electropherotic deposition (EPD) and atomic layer deposition (ALD) will be ultilized in our project. Then the coated fibres will be embeded into epoxy resin and polydimethylsiloxane resin,respectively. The relationship between micro-scale interphase and macroscopic performances of materials will be revealed. Owing to the flexible and small size, the coated single fibre by nanomaterials could be used as miniaturized, high-sensitive devices. At the same time, it is expected that the composites with oriented network structure of coated fibres alignment could be exploited as a stretchable, transparant, high-sensitive biomimetic materials, like artificial skin or muscle. In previuos work, the proposer has successfully deposited multi-walled carbon nanotubes (MWNTs) onto insulative glass fibre's surface and the conductive pathway has been formed. The interficial adhension strength has be siginificantly enhanced. The single MWNTs-glass fibre was utilized as an in-situ strain sensor to monitor the microcrack in composites and this sensor can predict the fracture of materials in advance. Based on the above results, the propsoed method of modifying interphase by ultra-thin nanofilms will allow us to fabricate novel biomimetic composites which could be used for the highly sensitive artificial skin or muscle.

无论在天然生物材料还是人造复合材料中，界面结构都被认为是决定材料宏观性能的关键因素之一，它控制复合材料的所有性质和服役行为，并且影响着复合材料整体对载荷的响应。因此，本项目拟模仿天然材料"完美"的纳-微多尺度界面结构，采用电泳、原子层沉积方法在玻璃纤维以及弹性纤维表面均匀沉积碳纳米管、氧化锌等纳米涂层，继而与不同聚合物基体（环氧树脂，弹性硅橡胶）复合制备多功能仿生材料。通过纳米涂层扩大界面化学键合和物理吸附，增强界面机械啮合等效应，提高界面粘接强度。测试界面微区以及材料的整体性能，揭示材料微结构与宏观性能之间的关系，确立更有效的复合材料界面强化技术和方法。提出利用纤维定向排布实现拟生物体神经网络结构的新方法，并研究界面区域的纳米网络对材料的环境敏感性的影响，以制备对微应力/应变、温度、湿度变化具有高度敏感性，灵活弯曲，可应用于人造皮肤、肌肉等的仿生材料。

无论在天然生物材料还是人造复合材料中，界面都被认为是影响材料整体性能的关键因素之一，它是一个从增强材料到基体的三维过渡区域，对发挥复合材料的功能起着传递，吸收和诱导作用。通过对天然生物材料所拥有的“完美”界面结构的研究发现，纳米矿物质在生物界面中起到了刚性与柔性的平衡作用。基于这种异质、多尺度复合结构的界面构想，本方案采用电泳，原子层沉积等技术将超薄纳米涂层（碳纳米管，氧化锌等）沉积在纤维表面，通过分布于界面区域的纳米网络将多种功能引入复合材料中，并利用纤维载体的可弯折性，易排布性，制备具有高敏感性，多功能性，可伸缩仿生材料。. 在研究过程中，我们发现并证实了纳米修饰层厚度对材料的宏观性能有很大的影响。首先，对于材料的机械强度来说，通过纳米层的修饰，界面接触面积增大，机械锁合能力增强，杨氏模量提高都有利于提高界面强度，从而提高复合材料整体的机械强度。但是，利用原子层沉积技术，对纳米层厚度精确控制，通过实验结果的分析，我们首次提出要实现最高界面粘接强度纳米修饰层有一个临界厚度存在，这个厚度为今后设计高强度复合材料提供了重要的参考。.同时，纳米修饰层引入了许多新的功能于纤维及复合材料中，例如，紫外光敏感性，湿度敏感性，气体敏感性等。在现阶段的研究中，我们发现纳米层厚度对敏感性也有很大的影响，通过实验结果分析，理论计算，我们提出了表面吸附层在氧吸附、脱附过程中的作用，并利用简化模型，计算出表面吸附层临界厚度，以及变化量。这些关键参数对于未来利用单根纤维进行紫外光探测技术高敏感性发展提供了重要的依据。.利用碳纳米管修饰的中空纤维制备了轻质各向异性的复合材料。基于渗阈理论，对这种复合材料的低导电渗阈值，介电弛豫现象进行了深入的研究。这部分研究内容能使我们跟好理解仿生多尺度复合材料结构与电性能之间的关系，为设计新型吸波材料，储能材料提供了基础。.对于纳米层修饰的纤维多功能性的研究，除了紫外光敏感的探测，我们还研究了利用单根碳纳米管修饰的玻璃纤维原位、实时监控聚合物基体的交联固化，玻璃化转化，结晶，熔融过程；利用氧化石墨烯修饰的纤维制备高敏感水汽敏感设备等研究。