Generally,re-entrant structures are a key part of fabricating superoleophobic surfaces,and this structure appears in almost all kinds of published research articles regarding superoleophobicity.However,the application...Generally,re-entrant structures are a key part of fabricating superoleophobic surfaces,and this structure appears in almost all kinds of published research articles regarding superoleophobicity.However,the application of related fabrication methods is usually too complex and costly in real practice.In this paper,we present a simple method to generate micro-cauliflower structures,which work as re-entrant structures in microcone arrays,to promote the formation of superoleophobic surfaces.The heating process after alkali-assisted surface oxidation is the main reason for the appearance of a micro-ball structure,and the oxidation time can influence the size of the micro-ball.To the best of our knowledge,the influence of the heating process after alkali-assisted surface oxidation on the birth of the micro-ball structure is seldom researched.A low-surface-energy treatment was also analyzed in influencing the size of the re-entrant structure and its relative wettability.Droplets of 5μl of n-decane show contact angles of 155±1°on the as-prepared superoleophobic surface,and air pockets can be clearly seen underneath,indicating a stable Cassie contacting state and a promising application value in the near future.展开更多
Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and f...Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and find their limitations.The effect of parameters including solid fractions(or roughness factors),arrangement of pillars(with same solid fractions),pillar height,and droplet size on contact angles was investigated.It shows that the Cassie equation is suitable for droplets on uniform pillared surfaces including different solid fractions,arrangement of pillars and pillar height,when there is no meniscus of droplets.The Wenzel equation is also suitable for droplets on uniform pillared surfaces including different roughness factors,arrangement of pillars and pillar heights.Moreover,whether the droplet size has an influence on the contact angle depends on the pinned place of the contact line.In the Wenzel state,the contact line is pinned although increasing the droplet size,resulting in increasing the contact angle,while the contact angle decreases to the initial value again when the droplet size increases enough to allow the contact line moving to the next pillar.The results provide insights toward the wettability of droplets on surfaces in nanoscale.展开更多
基金This work was fnancially supported by National Postdoctoral Program for Innovative Talents(No.BX20190233)National Natural Science Foundation of China(No.52105477).
文摘Generally,re-entrant structures are a key part of fabricating superoleophobic surfaces,and this structure appears in almost all kinds of published research articles regarding superoleophobicity.However,the application of related fabrication methods is usually too complex and costly in real practice.In this paper,we present a simple method to generate micro-cauliflower structures,which work as re-entrant structures in microcone arrays,to promote the formation of superoleophobic surfaces.The heating process after alkali-assisted surface oxidation is the main reason for the appearance of a micro-ball structure,and the oxidation time can influence the size of the micro-ball.To the best of our knowledge,the influence of the heating process after alkali-assisted surface oxidation on the birth of the micro-ball structure is seldom researched.A low-surface-energy treatment was also analyzed in influencing the size of the re-entrant structure and its relative wettability.Droplets of 5μl of n-decane show contact angles of 155±1°on the as-prepared superoleophobic surface,and air pockets can be clearly seen underneath,indicating a stable Cassie contacting state and a promising application value in the near future.
基金This work was supported by the National Natural Science Foundation of China(51905315)Shandong Provincial Natural Science Foundation(ZR2019BEMO12)+3 种基金the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents(2019RCJJ001)the Fundamental Research Funds for theCentral Universities(20CX02317A)the Opening Fund of National Engineering Laboratory of Offshore Gcophysical and Exploration Equipmentthe Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation Team(Environment function material innovation team).
文摘Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and find their limitations.The effect of parameters including solid fractions(or roughness factors),arrangement of pillars(with same solid fractions),pillar height,and droplet size on contact angles was investigated.It shows that the Cassie equation is suitable for droplets on uniform pillared surfaces including different solid fractions,arrangement of pillars and pillar height,when there is no meniscus of droplets.The Wenzel equation is also suitable for droplets on uniform pillared surfaces including different roughness factors,arrangement of pillars and pillar heights.Moreover,whether the droplet size has an influence on the contact angle depends on the pinned place of the contact line.In the Wenzel state,the contact line is pinned although increasing the droplet size,resulting in increasing the contact angle,while the contact angle decreases to the initial value again when the droplet size increases enough to allow the contact line moving to the next pillar.The results provide insights toward the wettability of droplets on surfaces in nanoscale.
