Keywords superhydrophobic surface roughness self

  • No School
  • AA 1
  • 29

This preview shows page 3 - 6 out of 29 pages.

examined on the superhydrophobic coatings. Keywords: Superhydrophobic, surface roughness, self-cleaning, lotus leaf, contact angle, sliding angle, plastron layer, sol-gel process, dip coating, water jet impact. 1. Introduction Owing to their high surface tension, water drops adopt a perfect round shape when tossed up in air, maintain their round shape even when landing on a superhydrophobic surface, and quickly roll off the surface [1-4]. On superhydrophobic surfaces, because of the minimized contact area, the contact angle and roll-off angle for water drops are in the ranges of >150– 160° and <5–10°, respectively [5]. Such a high water repellency observed on superhydrophobic surfaces is due to the rough surface microstructure and low surface energy. In the last decade, excellent water repellency and self-cleaning properties of plant leaves have inspired the extensive development of superhydrophobic solid surfaces [6]. The dual-scale hierarchical micro/nanostructure and low surface energy due to the secreted wax
Image of page 3
Page 3 of 28 Accepted Manuscript material found on lotus leaves has encouraged material scientists to build artificial robust water-repellent surfaces [7]. The industrial applications of such surfaces are not limited to self-cleaning; they also include potential liquid separation [8], anti-corrosive [9], anti-fog [10], anti-biofouling [11], low-drag applications [12], and the list is still growing [13]. Fluoroalkylsilanes (FAS) are well known as low-surface-energy materials. The tail-end group of the FAS molecule is the hydrophobic fluoroalkyl group, and the monolayers of FAS self-assemble on the solid surface, with their molecular axis perpendicular to the surface [14]. Typically, FAS layers are applied in order to lower the surface energy of high- surface-energy rough solid surfaces to render the surface superhydrophobic [15-19]. Xiu and colleagues [18] prepared rough and porous sol-gel silica coatings by effectively removing the eutectic liquid (templating agent) from the porous network that was used in the sol-gel processing steps, and they modified the coating surface with FAS to achieve superhydrophobicity. Li et al. [19] adopted colloidal crystal monolayers and a sol-gel approach to synthesize a hierarchical porous silica surface with a large surface area. The strongly superhydrophilic surface became superhydrophobic after surface chemical modification with FAS. FAS are often used as one of the co-precursors in sol-gel processing in order to achieve superhydrophobic coatings [20-23]. Brassard and colleagues [21] synthesized monodispersed silica nanoparticles by the Stöber method and functionalized the silica surface using FAS in an ethanol solution. By adjusting the number of spin-coating layers of the fluorinated silica nanoparticles, the superhydrophobic state was achieved on aluminum,
Image of page 4
Page 4 of 28 Accepted Manuscript silicon, and glass substrates. Zhou et al. [22] prepared a robust FAS-based polymeric superhydrophobic coating on fabrics by simple dip coating. The nanocomposite coating solution was obtained by dispersing sol-gel-synthesized, FAS-functionalized silica nanoparticles in a PDMS/THF solution containing FAS. The superhydrophobic fabric was
Image of page 5
Image of page 6

You've reached the end of your free preview.

Want to read all 29 pages?

  • Fall '19
  • The Land, Surface tension, Contact angle, superhydrophobic coatings

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask ( soon) You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors