用于变体机翼的大形变电阻稳定的碳纳米管导电弹性体和传感器的研究

Morphing aircraft needs to keep good electronic properties and smart control during shape change of the wings, which requires superelastic conductors and sensors embedded into the skin as wells as other structural materials. Super elastic conductors providing improved properties and new functionalities are needed for applications ranging from electronic interconnects to sensors, and flexible devices. Conducting elastomers have been fabricated by such methods as (1) incorporating conducting particles in rubbers, (2) making coiled spring or serpentine structures, (3) attaching sheets of conducting film, to the surface of a rubber sheets to form one order buckling structure. The elastic conductors made by above methods show either dramatical resistance change, or very limited strain range, or need very complicated fabrication procedures. We have realized a novel fabrication method of stretchable conducting fibers that are very large elastic stretchability and stable conductance by coating highly-oriented carbon multiwall nanotube sheets on a stretched rubber fiber core. In this work, (1) we will characterize the interface between the rubber and the nanotube sheath, to improve the interfacial adhesion by modifying nanotubes and elastomers. (2) We will also realize controllable fabrication of the hierarchically buckled structures. (3) We will improve the performance of the sheath-core conducting fibers, including electrical conductance, mechanical properties, and durability. (4) We will systematically study the correlation between the fabrication methods, hierarchically buckled structures, and the mechanical and electrical properties, to provide instructions for fabrication of ultra stretchable elastic conductors.

理想的变体机翼可在大形变下保持稳定电子电路并实现智能控制，这需要在机翼蒙皮和其他结构材料中嵌入大形变弹性导体和压力、应变等传感器。本课题将开展大形变电阻稳定的多级褶皱结构碳纳米管导电弹性体和传感器的研究。目前导电弹性体主要有三种结构：共混结构、弹簧或蛇形结构、一级褶皱结构。共混结构电阻极不稳定，弹簧或蛇形结构制作工艺非常复杂；一级褶皱结构需光刻工艺，且形变小。申请人在前期工作中将高取向碳纳米管薄膜均匀覆盖大形变预拉伸的弹性体，形成核壳构造和多级褶皱结构；本课题将研究碳纳米管与弹性体表面修饰方法，揭示影响界面粘结力的影响因素；探究碳纳米管和弹性体性质对褶皱结构的影响，开发多级褶皱结构的可控制造方法；对碳纳米管和弹性体进行改性，提高电学、力学、耐久性等性能；设计构建大形变电子电路和各种大形变传感器，研究成果将取得柔性机械制造领域的重大理论突破，有力推动我国变体飞行器研发与制造的进程。

人工智能与可穿戴健康监测是“十三五”规划中的重要方向，其关键硬件基础是在大变形下可以正常工作的可拉伸电子设备。而大变形、高灵敏度的应变传感器在智能可穿戴领域具有广阔的需求，包括弹性电子皮肤、健康监测、和机器人等。如何实现电阻型应变传感器的应变与电阻在大变形下的线性关系仍然是一个挑战。另外，对健康的实时监测是现代医学发展的重要方向。这要求仪器设备和材料小型化、可穿戴、且能够在变形下保持稳定的性能。实现这些应用的关键问题是如何通过结构和材料的设计，构建出可以在大变形下保持电阻稳定的弹性导电材料，并且电导率高、结构均一、容易加工。.本项目针对以上问题，研发并取得的结果如下：.1.使用“形变诱导”方法，构建了“褶皱碳纳米管层”+“褶皱弹性体层”的“双层褶皱结构”复合材料。产生的应变传感器可以可逆地拉伸到600%，线性度高，响应时间快，分辨率高，稳定性好。.2.通过使用铜掺杂的碳纳米管弹性电极制作了高选择性可拉伸葡萄糖传感器，实现了对葡萄糖的高选择性检测。并申请了系列专利用以保护该材料与技术。.3.使用分层褶皱的碳纳米管/橡胶双鞘芯结构制备的柔性可压缩电阻温度传感器，线性度高，重复性好，电阻负温度系数大(NTC = -54.7/ C)，对压缩变形不敏感(可达-20%应变)。.4.使用可拉伸弯曲碳纳米管片的天然橡胶基板(BCNTS/橡胶)制备了一种机械可调谐的THz偏振器。.5.设计了一种夹层弹性导电结构，制备的温度传感器具有明显的纳米管板材屈曲结构，导电性高达4760s /m，电导几乎与应变无关，在1000次以上的拉伸过程中，其电阻变化为1%，拉伸强度为400%。.取得的成果发表在Adv. Funct. Mater. 2017, 27, 1702134（封面文章），J. Nanosci. Nanotech., 2018, 18(4): 2732~2737，Polymers, 2018, 10(4), 375， J. Nanosci. Nanotech., 2017, 17(2): 926~931，Opt. Express, 2018, 26(22): 28738-28750，J. Nanosci. Nanotech., 2017, 17(3): 1934~1941，并申请了5项专利。