The Effect Of Plasma Deposited Fluorocarbon Film On Nano-texture And Properties Of Polypropylene Surface

The multifunctional surfaces with low-reflectivity,anti-drop impacting and super-hydrophobicity are widely used in aerospace,optics and other fields.Plasma etching to fabricate nanostructures and combining with deposition of fluorocarbon film on polymer surface is one of the most effective ways to fabricate functionalized surfaces such as low reflectivity and anti-droplet impacting functionalized surface.In this experiment,different nanostructures were fabricated on the surface of polypropylene(PP)by oxygen etching and different fluorocarbon film deposition time.The surface of PP is treated with oxygen for 10 min and fluorocarbon for 1-20 minScanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),UV-Vis spectrophotometer(UV-Vis)and other analytical characterization methods are used to analysis the formation process and mechanism of nanostructures and chemical composition of the PP surface.At the same time,surface droplet evaporation process,surface anti-droplet impacting performance and anti-reflection performance are also characterized.The results show that nano-texture appears on the surface of PP after oxygen etching by SEM.After deposition of fluorocarbon film,nano-texture evolves into nano-pillar structure.With the increasing of deposition time of fluorocarbon film,the deposition rate of plasma polymer on the side of the nanocolumn is reduced due to the ion sputtering in the sheath,so that the nanocolumn is further transformed into a nano-conical structure after 20 minutes of deposition of the fluorocarbon film.XPS shows that the deposition time of fluorocarbon film induced the increase of F content but has no effect on the C1s composition and relative content of fluorocarbon film on PP surface.On the PP surface of the nanocolumn and nanocone structure,the evaporation temperature does not affect the evaporation state of the water droplets,and the water droplet state changes from the low adhesion Cassie state to the high adhesion Wenzel state during evaporation.However,at the same evaporation temperature,the formation of the nano-cone structure reduces the duration time of constant contact angle(CCA)from 80%to 6.6%comparing to the nano-pillar structure.The nano-cone structure can significantly improve drop impacting resistance of the PP surface.Comparing with the nano-column,the critical impact velocity increases to 2.79 m/s.The residual droplet recover from the high-adhesion Wenzel state to the low-adhesion Cassie state under natural oscillation,so that the superhydrophobic surface can still maintain good hydrophobic stabilityThe analysis UV-Vis shows that the formation of fluorocarbon film can reduce the surface reflectivity of PP,which is lowered 2.38%comparing the original PP surface at the incident angle of 60°.At the same time,the increasing of deposition time of the fluorocarbon film can further reduce the reflectivity of the PP surface.Comparing with the PP surface with deposition 1 min fluorocarbon film,the reflectivity of the PP surface deposited for 20 min fluorocarbon film can be reduced at least 0.5%.The formation of the nano-cone structure can greatly reduce the reflectivity of the PP surface at different incident angles,and the maximum reflectance of the original PP surface was reduced from 11.26%to 5.85%.