Superoleophobic surfaces and methods of making same
Disclosed herein is a substrate having a surface modified to impart multi-scale roughness, thereby providing superhydrophobic and/or superoleophobic properties. The surface comprises a pattern of microscale pillars topped by a plurality of nanoparticles having a re-entrant convex shape. The area fraction of the surface is also selected to provide the desired superoleophobic properties. Also disclosed herein is a process for creating the modified surface comprising photolithography, optionally followed by vapor deposition. The substrates may be formed into useful articles or applied to pre-formed articles.
1. An article comprising a substrate, the substrate having a surface comprising a pattern of microscale pillars topped with a plurality of nanoparticles, wherein:
the plurality of nanoparticles together create a re-entrant convex morphology atop each pillar, and
the surface has a contact angle for water of greater than 150°.
2. The article of claim 1 , wherein the pattern comprises an array.
3. The article of claim 2 , wherein the surface also has a contact angle for hexadecane of greater than 150°.
4. The article of claim 3 , wherein the nanoparticles comprise a negative photoresist.
5. The article of claim 4 , wherein the surface has a multi-scale morphology.
6. The article of claim 1 , wherein area fraction, f, of the surface is from 0.01 to 0.10.
7. The article of claim 6 , wherein the surface comprises a fluorinated hydrocarbon.
8. The article of claim 7 , wherein the surface comprises a fluorosilane material.
9. The article of claim 8 , wherein the microscale pillars comprise a negative photoresist.
10. The article of claim 9 , wherein both the pillars and the nanoparticles comprise the negative photoresist.
11. The article of claim 10 , where the substrate comprises silicon, glass, metal or a polymer.
12. The article of claim 11 , wherein the substrate is applied to the article.
13. The article of claim 11 , wherein the polymer comprises an elastomer.
14. The article of claim 13 , wherein the elastomer comprises butyl rubber.