Design,Fabrication And Precisely Controllable Adhesion/Friction Properties Of Bionic Microarrayed Surfaces

In the process of survival,evolution and competition of organisms,functional microstructures with excellent performance have been developed on their surface/interface.Inspired by nature,lots of bionic surface/interface materials with superior performances have been designed and fabricated through material synthesis and micro/nanostructure manufacturing technologies,which are widely applied in energy,environment,military,medical and other fields.However,the current bionic surface/interface materials prepared through simply artificial replication of biological microstructure and function by physical and chemical methods are not sufficient under complex,changeable and extreme working conditions.Differently,organisms can flexibly regulate their surface/interface functions by virtue of their microtopographies,so they are better adapt to the complex and changeable working environment.Researches have shown that the actively environmental adaption capability of biology is mainly based on the dynamic deformation of their surface morphology.Therefore,in order to improve the adaptability of bionic surface/interface materials to complex working conditions,it is necessary to develop bionic surface/interface materials with adjustable micromorphology through multi-factor coupling bionic design technology including bionic structure shape,intelligent deformation,function regulation and other elements,achieving controllable functions in a demand manner on smart surface/interface.At present,some stimulation-responsive materials,such as elastic materials,magnetic fluid,magnetic composites,etc.,have been emerged in manufacturing controllable micromorphologic surfaces,and have been applied in optical control,wettability control,adhesion control,friction control and other fields.Compared with traditional bionic surface/interface materials,smart surface/interface materials with adjustable ability show stronger functionality and working condition adaptability when facing complex and changeable application environment.However,although the micromorphology controlled surfaces fabricated by the above materials can achieve intelligent adjustment of surface functions,there are still some problems:complex preparation process,most of them are dependent on hard-to-fabricate microstructures;regulation difficulty,they always need continuous external stimulus to maintain the micromorphology and function of the regulated state;low control precision,it is difficult to precisely control the local region morphology and function due to the limitation of materials and control methods.How to realize efficient manufacturing,precise functional regulation and improve the performances of micromorphology controlled surfaces have become an urgent problem to be solved in this field.To solve the above problems,inspired by typical organisms with droplet adhesion or friction functional surfaces,a kind of near-infrared light responsive shape memory polymer(SMPU)composite that can realize shape programming without continuous external stimulation was synthesized.Then,multiple shape memory surfaces with precisely controlled microtopography are prepared through efficient manufacturing processes.Finally,all-in-situ precise control of the surface droplet adhesion and friction characteristics is achieved.Meanwhile,the mechanism of the precisely controllable adhesion and friction is deeply studied,and their application prospects in the fields of microfluidic control,microsolid motion regulation and biochemical detection are discussed.The main research contents are as follows:(1)A kind of SMPU composite was designed and synthesized,then the precisely controlled shape memory microtopography surface was prepared by the laser direct writing technology and templating method.The shape memory properties and the precisely controllable micromorphology of the SMPU composite were deeply studied,revealing the mechanism of precisely controllable friction behavior.And the application prospect of the surface in the fields of precisely controllable microsolid motion and rewriting Braille panel is explored.(2)The precisely controlled surfaces in static and dynamic droplet adhesion were developed based on the shape memory materials.The precisely controllable micromorphology,wettability and droplet adhesion of these surfaces were studied and the mechanisms were revealed.The precisely controlled droplet adhesion surfaces can be developed as a "re-constructable" Lop on a Chip,microdroplet evaporation modulator or microreaction controller.(3)In order to improve the in situ precise control ability of droplet adhesion and surface friction characteristics,a kind of shape memory surface with high-aspect-ratio microstructure array was fabricated through a soft template preparation technology.The precise control ability of regional microtopography on the surface under near-infrared light irradiating and pressing stimuli was deeply studied.The relationship between the high-aspect-ratio microstructure and the in situ precise control ability of adhesion and friction behaviors on the surface was revealed.The application prospect of the surface in microdroplets and microsolids precise motion control was discussed.(4)A kind of ultra-high-aspect-ratio shape memory microarrays was developed in a low cost and high efficiency magnetic assembly fabrication process.The magnet-assisted manufacturing technique of shape memory microstructures with ultra-high-aspect-ratio was optimized.The relationship between the ultra-high-aspect-ratio microstructure and the all-in-situ precise control ability of adhesion and friction behaviors on the surface was demonstrated.The potential application value of this surface in the microchemical reaction control field was explored.