The Fabrication And Application Of Superhydrophobic Uhmwpe Surfaces With Different Adhesion

Superhydrophobic surfaces with a water contact angle greater than 150° have attracted tremendous attention over the last decade in both academic and industrial areas.They can be used in many fields,including anticorrosion,antifouling,antiicing,and oil/water separation.Water adhesion is an important performance determining the behavior between water droplet and the solid surface.In general,there are two types of superhydrophobic surfaces in nature: slippery superhydrophobic surface with low adhesion,as observed in lotus leaf and sticky superhydrophobic surface with high adhesion,as observed in rose petal.In this study,ultra-high molecular weight polyethylene(UHMWPE)is chosen as raw material.On the basis of the adhesive force difference,sticky superhydrophobic UHMWPE surface with high adhesion and slippery superhydrophobic UHMWPE surface with low adhesion were prepared.This paper not only focuses on the exploration of the differences and connections between the two kinds of superhydrophobic UHMWPE surfaces but also discusses their practical application in different directions.(1)UHMWPE powder was dissolved in ortho-xylene to form a uniform solution at 140 °C.Then,the UHMWPE/ortho-xylene solution was cast onto culture dish.After drying in an oven at 50 °C,a high adhesion superhydrophobic UHMWPE surface was obtained.The membrane surface displays micro/nano hierarchical structure with a static water contact angle of 151°.Based on different adhesion,the prepared high adhesion superhydrophobic UHMWPE surface can be used as a “mechanical hand” to grasp small water droplet from a slippery superhydrophobic surface and transfers the droplet to a hydrophilic one.More importantly,when heptane is dropped on the prepared high adhesion superhydrophobic UHMWPE surface,it can be immediately absorbed,which demonstrates that the sample has good oleophilic property.Because of the hydrophobic and oleophilic properties,the prepared membrane not only can selective absorption cyclohexane on water but also can selective absorption DCM in water.Moreover,the prepared membrane can absorb organic liquids,and exhibits absorption storage capacity ranging from 6 to 13 times of its own weight,depending on the viscosity and density of the organic liquids.The membrane basically retains its absorbency after 20 adsorption/centrifugation cycles and exhibits excellent reusability.(2)By improving the experimental method mentioned above,cyclohexanone was added into the UHMWPE/ortho-xylene solution.Some of UHMWPE/ortho-xylene/cyclohexanone solution was cast onto substrate and the solvent was evaporated at room temperature in a fume hood,a slippery superhydrophobic UHMWPE surface with low adhesion was obtained.The surface displays micro/nano hierarchical structure with a static water contact angle of 158° when the ratio of ortho-xylene to cyclohexanone is 1:5.Firstly,the difference between two kinds of superhydrophobic UHMWPE surfaces in the process of water droplet evaporation is studied.The evaporation of a water droplet on the high adhesion superhydrophobic UHMWPE surface obeys the constant liquid-solid contact diameter mode and on the low adhesion superhydrophobic UHMWPE surface follows the constant contact angle mode.Secondly,the stability and practical application of low adhesion superhydrophobic UHMWPE surface in complex environments are emphatically studied.Water droplet and continuous water flow impact experiments suggest that as prepared surface has an excellent antiwetting performance during the dynamic water impact.Water contact angle can still remain above 150° even after repeated peeling tests up to 20 times.More importantly,the prepared low adhesion superhydrophobic UHMWPE surface can also repel other liquids in daily life and the proposed method is feasible to modify various materials.Moreover,the prepared low adhesion superhydrophobic UHMWPE surface shows excellent self-cleaning and anti-staining properties.