Design And Condensate Microdrop Self-Removal Performance Of Bionic Nanostructured Surfaces Prepared By Microinjection Compression Molding

Rapid removal of condensate drops has significance in the enhancement of condensation heat transfer and anti-icing.The preparation of micro-/nanostructured surfaces with condensate microdrop self-removal(CMDSR)function has been widely studied.High-efficient,low-cost,and mass preparation technology is the key to the promotion and application of CMDSR functional surfaces.In this dissertation,the micro-/nanostructure and wetting behavior of several biological surfaces were characterized.The biological surface nanostructures with good CMDSR function were replicated to polypropylene(PP)surfaces by microinjection compression molding(μ-ICM)to obtain the CMDSR functional replicas.Samples with CMDSR function were rapidly and successively prepared byμ-ICM using anodic aluminum oxide(AAO)as template.The micro-/nanostructure and wetting behavior of red rose petal,lotus leaf,Hong Kong orchid tree leaf,and cicada wing were characterized.The results showed that the hydrophobicity of the four biological surfaces decreased under the condensation condition.The contact angle of droplets applied on red rose petal decreased obviously after condensation,which was caused by more condensate droplets entering into the grooves.CMDSR phenomenon could be frequently observed on the cicada wing surfaces.CMDSR on the cicada wing was studied in detail.Most of the farthest jumping distances of droplets from the vertically cicada wing were within 1 mm.The self-propelled behavior could occur for the coalescence of droplets with the radius ranging from 3.5μm to at least 220μm.The jumping speeds could reach as high as 0.287 m/s.By combining electroless plating and electroplating,the nanopillars on the CMDSR functional cicada wing surfaces were accurately replicated onto nickel templates with an inverse pattern.By usingμ-ICM with the nickel templates as mold inserts,the PP replicas with bionic cicada wing nanostructures were fabricated.The results of condensation tests showed that the bionic PP replica without low surface energy modification inherits not only the nanostructures on the original wing surface but also its CMDSR function.Two kinds of V shape AAO templates were used as mold inserts.By usingμ-ICM,two kinds of PP samples with bio-inspired nanostructured surfaces were fabricated.The results of condensation tests showed that the samples with E~*≈0.46 and d/l≈0.26 exhibited a good CMDSR performance.