Study On Preparation And Performance Of Shape Memory Anisotropic Slippery Surface

Recently,slippery surfaces inspired by nepenthe plant have played an important role in anti-icing,anti-corrosion and water droplet collection due to their excellent liquid repulsive ability,low contact angle hysteresis and good stability.In particular,anisotropic slippery surfaces show a broad application prospect in the field of droplet directional transportation.However,the current anisotropic slippery surface is usually constructed by the substrate materials with fixed asymmetric physical structure,which can only maintain a constant degree of anisotropy and anisotropy direction.That limits its application in some complex intelligent equipments.Therefore,based on the shape memory polymer(SMP),combined with other response modes,a series of shape memory anisotropic slippery surfaces with different characteristics are prepared,and their applications in the field of smart droplet motion control have also been demonstrated.The main research contents are as follows:Inspired by multiple bionic strategies,the shape memory slippery surface was prepared by infusing lubricant into the surface of shape memory microarray,and its surface structure and shape memory performance were tested and analyzed.After hot pressed by the microgroove template,the surface exhibits anisotropic sliding performance.When the column spacing is 10 μm,the column height is 30 μm,and the microgroove width is 380 μm,the anisotropic sliding performance is the best.After heating again,the surface structure of the sample returns to the original random distribution state,showing the isotropic sliding performance.Due to the excellent shape memory effect(SME)of the surface,the microstructure on the surface can switch reversibly between the randomly distributed state and the regularly arranged microgroove state,thus realizing the reversible transition between isotropic and anisotropic sliding.The mechanism analysis shows that the reversible transformation of the surface microstructure is caused by the conformation transformation of molecular chain,the isotropic sliding property is caused by the lack of obvious energy barrier difference in any sliding direction,and the anisotropic sliding property is caused by the difference of energy barrier in two directions stemmed from the microgroove structure.Based on its excellent SME,the shape memory slippery surface has been successfully applied to a programmable droplet movement platform.By combining the responsive lubricant and the controllable surface microstructure,a lubricant controllable shape memory slippery surface was prepared by infusing temperature-responsive solid/liquid state convertible lubricant into the surface of SMP microarray.The surface morphology and shape memory performance of the slippery surface were studied.With the reversible adjustment of the temperature between 25 ℃and 45 ℃,the lubricant on the surface can be reversibly transformed between solid and liquid to realize the start and stop control of droplet movement.The excellent SME of the polymer endows the prepared slippery surface with the reversible introduction and elimination of linear structural patterns many times.The construction of the linear pattern leads to anisotropic sliding,which can realize the directional movement of the droplets.Based on the synergistic effect of responsive lubricant and shape memory microstructure,the slippery surface has been successfully applied to a smart droplet motion control platform that can simultaneously realize start-stop control of the droplet motion and programmable droplet directional motion.The magnet-induced deformation SMP microstructure surface was prepared by combining magnetic response particles and SMP.Then,the silicone oil was injected into the magnet-induced deformation SMP microstructure surface to obtain the magnetinduced deformation shape memory slippery surface,and its surface morphology and shape memory performance were investigated in detail.The slippery surface exhibits anisotropic sliding behavior after the micro-protrusion arch structure is constructed by the shape memory property.When the height of the constructed micro-protrusion arch structure is 1250 μm,the sample shows the best anisotropic sliding performance,resulting in the anisotropic sliding angle difference of about 51°.Based on its excellent SME,the micro-protrusion arch can be reversibly constructed and eliminated,realizing intelligent control of anisotropic sliding performance by the slippery surface.By combining the magnetic field effect with shape memory effect,the prepared slippery surface not only realizes the non-contact deformation control of the surface microstructure,but also avoids the continuous dependence of the surface structure deformation on the external field.