Design And Fabrication Of Bionic Periodic Microstructured Surfaces And Study On Their Wettability

Learned from the lotus effect of nature, controlling the wettability on material surfaces by constructing or transforming its microstructures can well meliorate the integrated capabilities of materials. Transition of wetting mode on microstructured surfaces is an important aspect of study on surface wettability and the foundation of study on design, fabrication and application of superhydrophobic surfaces. Some theoretic analyses and experimental discussions were carried out for transition of wetting mode on several bionic microstructured surfaces by a combination of theoretic illations and experimental validations.Three kinds of surfaces with parallel grating, circular holes and square pillars array microstrucrures were designed and equations for theoretic forecast of the apparent contact angle on them were deduced based on the classical wetting theories.The mechanism for transition of wetting mode on microstructured surfaces was debated. From this two geometry-based theoretic criterions for transition of wetting mode on parallel grating and circular holes microstrucrured surfaces were found out through theoretic modeling. Based on previous research results, an energy-based theoretic criterion for transition of wetting mode on square pillars array microstrucrured surfaces was posed by synthetically considering the possible relations among the energy parameters during the transition of wetting mode.A series of samples with parallel grating and circular holes microstrucrures were fabricated on K9 glass by using fs laser micro-fabrication system. And the wetting modes of them were tested and characterized. Pilot experimental validations on the two geometry-based theoretic criterions for transition of wetting mode were made after analyzing experimental results and calculating theoretic values. It shows that a majority of experimental results meet the theoretic forecast which reveals that the two theoretic criterions are basically reasonable but require farther meliorations and discussions.Five series of silicon-based square pillars array samples with different groove depth were prepared through plasma etching technology. And the apparent contact angles on every sample surface were measured. The effects of microstructure geometrical parameters to transition of wetting mode on sample surfaces were summed up from the experimental results. Then Pilot validations on the energy-based theoretic criterions for transition of wetting mode on square pillars array microstracrured surfaces were fulfilled by calculating the energies for transition of wetting mode on the surfaces of three group samples which had been displayed transition of wetting mode.The principle of interaction between fs laser and metal, also the formation mechanism of microstructures on metal surfaces treated by fs laser were briefly discussed. Four square pillars array samples with different pillar space were fabricated on titanium substrates by using fs laser micro-fabrication system. Through experimental tests and analyses on superhydrophobicity and stability of wetting modes, it proved that the surfaces of the titanium-based samples with square pillars array microstructures which had been prepared were provided with steady superhydrophobicity in a certain range.