Advanced bio-inspired adhesive materials

先进的制造技术已经证明了利用货车德瓦耳斯分子间相互作用对聚合物材料进行微制造的可行性，所述聚合物材料可以模仿壁虎趾垫的可逆和可重复使用的粘合剂性质。这是通过创建由称为原纤维的微米和纳米柱组成的表面微观结构来实现的。随着在这些原纤维的尖端处产生的紧密接触，产生了货车范德华力。这种形式的分层接触细分允许在宏观尺度上产生相关的全局粘附力。一般来说，这种现象不涉及永久的化学键合，因此，只要用于粘合的材料的界面的机械和几何特征不劣化，它就可以无限地重复。从这种生物启发的合成粘合剂衍生的新兴技术的扩散，从工业机器人到极端环境中的运动（例如微重力），正在为固体力学的框架带来新的挑战，需要改进这种材料的设计。只有对所涉现象有更深入的了解，才能指导这种改进。例如，纤维状粘合剂材料的分离机制在每个长度尺度上仍然没有完全理解。文献报道了大量的调查，一个单一的原纤维的脱离，而他们中的许多人的相互作用仍然是通常被忽视。这产生了粗略的近似值，特别是考虑到界面缺陷的尺寸通常可以在比单个原纤维更大的长度尺度上发现。我的目的是调查在多个长度尺度的分离机制，这样的接口，并从这个，推导出改进的设计原则，适用于多层次的结构层次。此外，应该注意到，迄今为止，关于该主题所做的理论和实验工作集中在不可变形表面上的粘附上，因此忽略了粘附材料的顺应性。新兴的可穿戴技术的扩散，在某些情况下，将设备植入人体，正在引起对开发“生物相容性”粘合剂材料的需求。这种材料应该能够以可逆和可重复使用的方式粘附在生物组织上。这一新的挑战激发了拟议研究计划的主要目标。

Advanced manufacturing technologies have proven the feasibility of micro-fabrication of polymeric materials that can mimic the reversible and reusable adhesive properties of gecko toe pads, utilizing van der Waals intermolecular interaction. This is achieved by creation of a superficial microstructure comprised of micro- and nano-metric pillars called fibrils. With intimate contact generated at the tip of these fibrils, van der Waals forces develop. Hierarchical contact subdivision of this form allows for the generation of a relevant global adhesive force at the macroscopic scale. In general no permanent chemical bonding is involved in this phenomenon, and as such it can be repeated indefinitely as long as the mechanical and geometrical features of the interface of the material intended for adhesion do not deteriorate. The proliferation of the emerging technologies derived from such bio-inspired synthetic adhesives, which range from industrial robotics to locomotion in extreme environments (e.g. microgravity), is bringing new challenges to the framework of solid mechanics in the need for improved design of such materials. Such improvements can only be guided by a deeper knowledge of the phenomena involved. For example, the mechanism of detachment of fibrillar adhesive materials is still not completely understood at every length scale. The literature reports a large number of investigations of the detachment of one single fibril, while the mutual interaction of a multitude of them is still commonly neglected. This yields crude approximations, particularly given that the size of interfacial defects can be commonly found at a larger length scales than that of individual fibrils. My aim is to investigate the mechanism of detachment of such interfaces at multiple length scales and, from this, deduce improved design principles to be applied across multiple levels of structural hierarchy. Furthermore, it should be observed that thus far theoretical and experimental work done on this subject has been focused on the adhesion on non-deformable surfaces thus neglecting the compliance of the adhered material. The proliferation of emerging wearable technologies, which in some cases see the implantation of devices on the human body, is giving rise to a need for the development of “bio-compatible” adhesive materials. Such materials should be capable of sticking on biological tissue in a reversible and reusable manner. This new challenge has inspired the main goal of the proposed research program.