Durable superhydrophobic surfaces
A superhydrophobic appliance is an elastomeric material with a surface having a multiplicity of re-entrant features. The elastomeric material can be a polydimethylsiloxane network. The superhydrophobic appliance can be formed by infusing a portion of a polydimethylsiloxane polymeric precursor partially into the pores of a porous membrane, curing to the polymeric network, and separating the membrane from the appliance to expose the superhydrophobic surface. The superhydrophobic surface can be subsequently modified to form a fluorinated surface that is oleophobic or superoleophobic in addition to being superhydrophobic.
1. A superhydrophobic appliance, comprising
a polydimethylsiloxane network, the polydimethylsiloxane network having elastomeric properties and comprising at least one surface with a multiplicity of re-entrant features,
wherein the multiplicity of re-entrant features render the at least one surface superhydrophobic,
wherein the re-entrant features have at least one dimension of 100 μm or less,
wherein the re-entrant features comprise non-perpendicular cylinders extending from a base of the at least one surface, and
wherein the polydimethylsiloxane network comprises a plurality of reinforcing metal oxide particles dispersed therein, each of the plurality of reinforcing metal oxide particles having a particle size less than about 100 μm.
2. The superhydrophobic appliance according to claim 1 , further comprising a monolayer on the at least one surface, wherein the monolayer comprises a fluorocarbon, and wherein, in addition to being superhydrophobic, the at least one surface is oleophobic.
3. The superhydrophobic appliance according to claim 2 , wherein, in addition to being superhydrophobic, the at least one surface is superoleophobic.
4. The superhydrophobic appliance according to claim 1 , wherein each of the multiplicity of re-entrant features has a homogeneous composition through any cross-section thereof, and wherein the homogeneous composition is the same as that of the polydimethylsiloxane network.
5. The superhydrophobic appliance according to claim 1 , wherein the polydimethylsiloxane network is produced by a process comprising:
providing a membrane comprising a multiplicity of pores;
providing a polydimethylsiloxane precursor, the polydimethylsiloxane precursor comprising the plurality of reinforcing metal oxide particles;
contacting the polydimethylsiloxane precursor and a face of the membrane that accesses the pores;
forcing the polydimethylsiloxane precursor into the pores;
curing the polydimethylsiloxane precursor into the polydimethylsiloxane network; and
separating the membrane from the polydimethylsiloxane network to expose the at least one surface with the multiplicity of re-entrant features.
6. A method of preparing a superhydrophobic appliance according to claim 1 , comprising:
providing a membrane comprising a multiplicity of pores;
providing a polydimethylsiloxane precursor, the polydimethylsiloxane precursor comprising the plurality of reinforcing metal oxide particles;
contacting the polydimethylsiloxane precursor and a face of the membrane that accesses the pores;
forcing the polydimethylsiloxane precursor into the pores;
curing the polydimethylsiloxane precursor into the polydimethylsiloxane network; and
separating the membrane from the polydimethylsiloxane network to expose a superhydrophobic surface of the superhydrophobic appliance.
7. The method according to claim 6 , wherein the polydimethylsiloxane precursor is a hydrosilation curable resin.
8. The method according to claim 6 , wherein curing is a thermal curing or a photochemical curing.
9. The method according to claim 6 , wherein separating is peeling the membrane from the polydimethylsiloxane network.
10. The method according to claim 6 , wherein separating comprises dissolving of the membrane in a solvent and removing the solvent residual on and/or absorbed within the superhydrophobic appliance.
11. The method according to claim 6 , further comprising modifying the superhydrophobic surface to have a perfluorinated hydrocarbon coating on the polydimethylsiloxane network, wherein the superhydrophobic surface is a superhydrophobic and oleophobic or superoleophobic surface.
12. The method according to claim 11 , wherein modifying comprises oxidizing the superhydrophobic surface to an oxidized surface and reacting the oxidized surface with a perfluorinated hydrocarbon silane coupling agent.
13. The method according to claim 12 , wherein oxidizing comprises treating with a mixture of H 2 O, HCl, and H 2 O 2 and wherein the perfluorinated hydrocarbon silane coupling agent is heptadecafluoro-1,1,2,2-tetrahydrodecyltrichlorosilane.