碳纳米管干胶超高/低温下的粘附性能研究

The operational temperature range of convectional adhesives is always limited due to the temperature sensitivity of working mechanism or structural thermal instability, which cannot meet the needs of rapid developments of high-end manufacturing, such as aerospace and electronics. Therefore, the development of adhesive materials that can be applied to extreme conditions is highly required. The automatic Super-growth CVD technique will be used to tune the structural properties of carbon nanotubes (e.g. height, purity, density) through the precise control of growth conditions (e.g. carbon source, growth temperature, catalyst activity ). We intend to reveal how the structural characteristics affect the thermal stability of carbon nanotubes (CNTs), and then to fabricate the CNT dry adhesives that can handle the high/low temperatures. To realize the adhesion at high and low temperatures, plasma technology will further be used to modify the surface morphology of CNT adhesive to achieve the gecko-mimic hierarchical structure. The influence of adhering surface morphology, intrinsic structure, thickness and density on the adhesion properties is planned to be symmetrically studied. The project attempts to address two key scientific issues: 1. What is the link between the micro-structures of CNT dry adhesives and the adhesion properties; 2. What is the working mechanism of CNTs’ adhesion at high and low temperatures? The implement of this project is supposed to provide the theoretical guide and scientific significance to the development of dry adhesives with high performance at extreme temperatures.

随着航空航天等高新产业的发展，对粘附材料在高/低温环境中的粘附性能要求越来越高。常规粘附材料掣肘于自身的作用机制，或结构对温度变化的敏感性，已不能满足日益增长的需求。亟需开发能应用于高低温特殊环境中的粘附材料。本项目拟采用全自动Super-growth CVD技术，通过碳源、气流、温度、催化剂活性等生长条件的精确调控，实现对碳纳米管高度、纯度、密度等结构因素的控制，研究结构特性对其热稳定性的影响，制备耐高低温的碳纳米管干胶。并结合等离子体技术对干胶表面形貌进行修饰，形成类似壁虎粘附的分级层次结构，实现其在高低温下的粘附，并系统研究高低温下碳管干胶表面形貌、内在结构、厚度和密度对其粘附特性的影响，试图回答以下两个关键性科学问题：1. 碳纳米管干胶微观结构与粘附性能的构效关系；2. 碳纳米管干胶在高低温下的粘附机制。本项目的成功实施对超高低温下强粘附性干胶材料的制备有重要的理论指导和科学意义。

受制于自身的粘附作用机理或对温度变化的敏感性，常规粘附材料已不能满足日益增长的航空航天等高新科技发展的需求，所以亟须开发可在高/低温环境下的高粘附强度的新型粘附材料。本项目针对“碳纳米管干胶超高/低温下的粘附性能研究”进行了系统深入的研究并获得如下成果：1.基于全自动 “Super-growth”化学气相沉积(CVD)方法的精确调控，制得碳纳米管阵列管径分布均匀、大长径比、纯度高达99.99%的碳纳米管干胶材料；且获得碳纳米管高度50-2000μm、密度15-50mg/cm3结构参数调控。2. 探索了碳纳米管干胶材料与粘附性能间的构效关系，明晰了预压力、碳管干胶弹性模量及损耗因子对粘附性能的影响，发现250-350μm，密度为50mg/cm3的碳纳米管阵列能够获得最大的粘附强度。进一步结合等离子体表面处理技术，实现了不同基材各级别粗糙度的强力粘附。3. 获得了153±3N/cm2 超强粘附且可在极端温度（-196~1000°C）下使用的碳纳米管干胶材料,并发现粘附强度随温度升高而增强的反常规律：当温度增加到1033°C时，粘附强度增至常温时的6倍之多。通过扫描电镜、透射电镜等多种微观结构表征，提出了“纳米互锁”（Nano-interlocking）机理, 即表面粗糙度的增加会引导碳纳米管管束插入到由于温度造成的表面不规则轮廓中，从而将碳纳米管段机械锁定在表面空穴中。此机理阐释了碳纳米管干胶在高温下的粘附增强的现象。项目相关成果在Nature Comm., Nano Energy,等高水平期刊上发表，并被材料人等网站相继报道；授权专利5项，培养学生11名，受邀在美国材料学会、中日韩三国纳米高端论坛等国际学会上进行汇报。