Research On Preparation Technology Of Textured Surface With Bionic Re-entrant Structure Based On Femtosecond Laser

A.Tutejaet al.first designed the oleophobic re-entrant structure surface to make this kind of texture surface a research hotspot.With the discovery of the springtail’s oleophobic cuticle in nature,researchers realized that this highly textured,hierarchically arranged surfacewithre-entrant structure evolved from wingless arthropods has good oleophobicity and highly resistance to infiltration under hydrostatic pressure.These properties make this kind of surface has many potential applications in daily life and industrial production.Researchers have begun to propose a variety of methods for the preparation of textured surfaces with re-entrant structure based on chemical etching and lithography processes.Compared with mainstream micro-nano processing methods,femtosecond laser processing is an emerging processing method,has many advantages such as low thermal effect,high peak power,high precision,and not limited by materials.Above-mentioned advantages make femtosecond laser processing widely used in the micro-nano processing field.This subject focuses on exploring new processing techniques for re-entrant texturesurfaces by combining the shrinkage mismatch between two different materials and the heat assisted self-growth mechanism of shape memory polymers.By introducing the "composite"idea,the bionic re-entrant texturesurface was successfully prepared;At the same time,a dynamic characterization method was innovatively proposed:external vibration was applied to simulate the real scene of the movement of springtails.Theinfluence of re-entrant structure geometric parameters on the anti-infiltration performance and the effect of the external vibration parameters on the droplet infiltration process were explored thoroughly.The main work of this subject includes the following parts:(1)Starting from the memory effect and polymerization mechanism of shape memory polymers,and through understanding the heat shrinkage of thermo-plastic shape memory polymers,a "composite" conceptwas introduced topreparere-entrant structures by using the shrinkage mismatch mechanism between heat shrinkable polystyrene film and non-heat shrinkable silicone tape.Based on this method,a new fabrication process of re-entrant texture surface was designed.(2)On the basis of deeply understanding chirped pulse amplification technology,a femtosecond laser processing platform wasbuilt.The flexibility of femtosecond laser direct writing technology was used to realize the accuratecontrol of plane parameters(diameter and center-to-center distance)of re-entrant structures.At the same time,by combining with the heat shrinkage effect of the shape memory polymer,different heating time were used to control the structure height.(3)Through the construction of the vibration test platform,the influences of different vibration parameters(amplitudes,vibration modes and frequencies)on the infiltrationprocess of droplets were systematically explored.The influence of different structural parameters(height,diameter,and center distance)on the dynamic anti-infiltrationability of re-entrant texture surface was further explored.On the basis of experiment results,in-depth analysis revealed the dynamic infiltrationmechanism of droplets on the structural surface,and the anti-infiltration performance of the texture surface was optimized.