Preparation Of Gecko-inspired Dry Adhesive Microarrays Based On Polyurethane And Research On The Adhesion Control

The amazing adhesion of gecko pads to almost any kinds of surfaces has inspired a active research direction over the last decade,especially after its adhesive mechanism of Vander waals forces was revealed by Autumn et al in2000.Presently, the development of preparation for gecko-inspired dry adhesive microarrays is in a simple and economical direction, and the structure is also more and more sophisticated.Apart from studying the influence of gecko-inspired dry adhesion arrays’morphology on the adhesive properties, but also gradually begin to consider the influential factors of material properties and the base materials. A more comprehensive study on the factors affecting adhesion force were conducted.The works of bionic researchers focus on the prepared gecko-inspired dry adhesion arrays with the practical applications.However, most of the prepared gecko-inspired dry adhesion arrays are just simply to mimic the feature geometry of gecko setae,these materials with adhesive microarrays obtained in adhesion when are often required to provide pre-stress to help them carry out adhesion. They can not reflect controllability in the adhesion process as gecko setae.Therefore, during the preparation of gecko-inspired microarrays, the introduction of actuator materials to explore the control problems of adhesion process,which has become one of the trends in the study of gecko-inspired microarrays.Began with the preparation Of polyurethane-basd gecko-inspired dry adhesive microarrays, the main contents are included:(1)Polyurethane elastomers was prepared to used as base material.Gecko-inspired dry adhesion microarrays with different aspect ratios and different tip morphologies was fabricated based on polyurethane. SEM analysis and DMA tests found that the polyurethane-based microarrays neatly structured morphologies and excellent mechanical properties. Taking into account the casting properties and adhesion properties, Polyurethane elastomers with the elastic modulus of9.2Mpa were used as gecko-inspired dry adhesion microarrays’base materials, then the molar ratio of PTMG and MDI is1.8:1. Meanwhile, the superhydrophobic properties of Gecko-inspired dry adhesion microarrays with different tips morphology were explored.It was found that the tips shape have a great impact on the superhydrophobic properties of adhesion microarrays, the convex tips shape has a relatively finest hydrophobic properties. (2) Vertically grown carbon nanotube arrays were prepared by chemical vapor deposition(CVD) to study the effects of different temperatures on the growth of carbon nanotubes.By means of spin-coating method to control the thickness of the liquid polymer material. Vary the spin speed, polymer viscosity consistency and other parameters of the structure,the polyurethane/carbon nanotube composites were effective adjustments.Finally, we get the carbon nanotubes microarrays with a flexible Polyurethane substrate. This work is expected to help solving the problem which the bending deformation of carbon nanotube arrays can not be restored.It can enhance the reproducibility of gecko-inspired adhesion arrays basedon carbon nanotubes.(3) To explore the combination of magnetic control and dry adhesion, the polyurethane was used as substrate materials in the preparation of gecko-inspired setae arrays, Fe3O4magnetic nanoparticles was introduced to obtain the magnetic composite polyurethane(PU) arrays. Magnetic composite PU mircoarrays based gecko-inspired dry adhesion were prepared in order to actuate their adhesive behavior by magnetic field. Further magnetic analysis and experiments proved magnetic induced deformation capacity and magneto-strain response capabilities. Preload were replaced by the magnetic actuation to achieve the active control of adhesion process.It provides a new way to combine the base material and the actuation of the material.