Durable superhydrophobic surfaces

Abstract

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.

We claim: 
     
         1 . A superhydrophobic appliance, comprising a polymeric network, the polymeric 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, and wherein the polymeric network comprises a plurality of reinforcing particles dispersed therein, each of the plurality of reinforcing particles having a particle size less than about 100 μm. 
     
     
         2 . The superhydrophobic appliance according to  claim 1 , wherein the re-entrant features comprise non-perpendicular cylinders extending from a base of the at least one surface. 
     
     
         3 . The superhydrophobic appliance according to  claim 1 , wherein the polymeric network is a polydimethylsiloxane network. 
     
     
         4 . 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. 
     
     
         5 . A method of preparing a superhydrophobic appliance according to  claim 1 , comprising:
 providing a membrane comprising a multiplicity of pores;   providing a polymeric precursor;   contacting the polymeric precursor and a face of the membrane that accesses the pores;   forcing the polymeric precursor into the pores;   curing the polymeric precursor into a polymeric network; and   separating the membrane from the polymeric network to expose a superhydrophobic surface of a superhydrophobic appliance.   
     
     
         6 . The method according to  claim 5 , wherein the polymer precursor comprises a polydimethylsiloxane resin. 
     
     
         7 . The method according to  claim 6 , wherein the polydimethylsiloxane resin is an addition curable resin. 
     
     
         8 . The method according to  claim 7 , wherein the addition curable resin is a hydrosilation curable resin. 
     
     
         9 . The method according to  claim 5 , wherein curing is a thermal curing or a photochemical curing. 
     
     
         10 . The method according to  claim 5 , wherein separating is peeling the membrane from the polymeric network. 
     
     
         11 . The method according to  claim 5 , wherein separating comprises dissolving of the membrane in a solvent and removing the solvent residual on and/or absorbed within the superhydrophobic appliance. 
     
     
         12 . The method according to  claim 5 , further comprising modifying the superhydrophobic surface to have a perfluorinated hydrocarbon coating on the polymeric network, wherein the superhydrophobic surface is a superhydrophobic and oleophobic or superoleophobic surface. 
     
     
         13 . The method according to  claim 12 , wherein the polymeric network is a polydimethylsiloxane network and modifying comprises oxidizing the superhydrophobic surface to an oxidized surface and reacting the oxidized surface with a perfluorinated hydrocarbon silane coupling agent. 
     
     
         14 . The method according to  claim 13 , 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. 
     
     
         15 . The superhydrophobic appliance according to  claim 4 , wherein, in addition to being superhydrophobic, the at least one surface is superoleophobic. 
     
     
         16 . 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 polymeric network. 
     
     
         17 . The superhydrophobic appliance according to  claim 1 , wherein the polymeric network is produced by a process comprising:
 providing a membrane comprising a multiplicity of pores;   providing a polymeric precursor;   contacting the polymeric precursor and a face of the membrane that accesses the pores;   forcing the polymeric precursor into the pores;   curing the polymeric precursor into a polymeric network; and   separating the membrane from the polymeric network to expose the at least one surface with the multiplicity of re-entrant features.   
     
     
         18 . The superhydrophobic appliance according to  claim 1 , wherein the plurality of reinforcing particles comprises a metal oxide.