Study Of Adhesion,Sliding,Rolling Properties On Constructed Nanoball Matrix Layer Under Simulated Weather Conditions

The wettability on solid surfaces may be one of the most important part of the solid surface properties.Many flora and fauna surfaces in nature exhibit superhydrophobicity,lotus leaf and water strider being two typical representatives.The phenomenon that a water droplet beading up and rolling off freely with dust on a surface were initially named "lotus effect" by Barthlott and Neinhuis.Contact angle,the angle between the solid and liquid surfaces,is commonly used to characterize the wettability of the solid surface.Surface with contact angle greater than 1500 and sliding angle lesser than 10°was called the superhydrophobic surface.The self-cleaning,icephobic,dust proof abilities the superhydrophobic surfaces possess have drawn significant attention from researchers recently.Fluorocarbon polymers(PTFE,PFA,FEP etc.)have ultra-low surface energy due to the strong electron-attracting ability of CF3 group.Besides,the fluorocarbon polymers have broad application prospects on account of the wear and high temperature resistance,self-lubricant capabilities.The anodized aluminum oxide(AAO)with micro-nano binary structure is easy to fabricate thus being an ideal substrate for fabricating polymer superhydrophobic surfaces.In this thesis,fluorocarbon nanoball matrix surfaces were prepared with AAO substrates and theie wettability and water droplet dynamic behaviors were systematically studied thereafter.In addition to that,by altering the environment temperature and relative humidity,the influence of environment conditions on the wettability and droplet dynamic behavior of the nanoball matrix layer was thoroughly studied.The major achievements and innovations of this thesis are:1.The PTFE and PFA modified nanoball matrix hydrophobic surfaces were prepared using AAO substrates with various porous diameters,through a soaking-curing process.The surface morphology was characterized by SEM and the relation of substrate porosity and surface morphology was then discovered.2.The dynamic behavior of a water droplet sliding down the nanoball matrix layer was captured by high speed camera system.Both rolling and slipping behaviors were discovered by analyzing the trajectory of the internal fluidity of a sliding water droplet.By calculating the ratio of these two dynamic behaviors,we found out that surface morphology not only affect the wettability of the surface,the dynamic behavior of a sliding down water droplet was also altered.3.The wettability as well as the dynamic behavior were studied not only in room temperature and relative humidity,but also under simulated weather conditions(5 ?&25 ?,30%-80%RH).The impact of simulated weather conditions on the wettability of the surface and the dynamic behavior of the sliding water droplet were also studied and the correlation between them was discovered,providing a brand-new proof for the wetting transition from Cassie-Baxter wetting mode to Wenzel wetting mode.4.The adhesion and friction force between the lunar dust and the nanoball matrix layer were measured by atomic force microscopy.The correlation between these forces and the surface morphology was discussed.The dust proof capacity of the nanoball matrix layer would have a broad application prospect in aerospace industry.