Articles having a surface with low wettability and method of making

Abstract

An article comprises a textured surface disposed on a substrate. The surface has an effective liquid wettability sufficient to generate, with a reference liquid, a contact angle in a range from about 120° to about 180°. The surface comprises a material having a nominal liquid wettability sufficient to generate, with the reference liquid, a nominal contact angle in a range from about 60° to about 90°, the material comprising at least one material selected from the group consisting of a polymer and a ceramic. The properties of the surface may include low-drag or low-friction, self-cleaning capability, and resistance to icing, fouling, and fogging, and the like. Methods of making such a surface are also described.

1 . An article comprising: 
 a surface disposed on a substrate, wherein the surface comprises    a. a material having a nominal liquid wettability sufficient to generate, with a reference liquid, a nominal contact angle in a range from about 60° to about 90°, the material comprising at least one material selected from the group consisting of a polymer and a ceramic; and    b. a texture comprising a plurality of features;    wherein the surface has an effective liquid wettability sufficient to generate, with the reference liquid, a contact angle in a range from about 120° to about 180°.    
     
     
         2 . The article according to  claim 1 , wherein the surface consists essentially of the material.  
     
     
         3 . The article according to  claim 1 , wherein the material is selected from a group consisting essentially of polycarbonates, polyimides, polysilazanes, acrylates, polyurethanes, epoxies, polyether imides, polysulfones, block copolymer/copolymer mixtures, and combinations thereof.  
     
     
         4 . The article according to  claim 1 , wherein the material comprises a ceramic.  
     
     
         5 . The article according to  claim 4 , wherein the ceramic comprises a ceramic selected from the group consisting of an inorganic carbide, an inorganic oxide, an inorganic nitride, and combinations thereof.  
     
     
         6 . The article according to  claim 5 , wherein the ceramic comprises a ceramic selected from the group consisting of tin oxide, titania, silicon carbide, titanium nitride, stibinite, zirconia, hafnia, titanium oxynitride, and combinations thereof.  
     
     
         7 . The article according to  claim 1 , wherein the texture comprises a plurality of features, wherein each of the plurality of features has a dimension in a range from about 10 nm to about 50,000 nm.  
     
     
         8 . The article according to  claim 7 , wherein the dimension is in the range from about 10 nm to about 10,000 nm.  
     
     
         9 . The article according to  claim 8 , wherein the dimension is in the range from about 10 nm to about 1000 nm.  
     
     
         10 . The article according to  claim 7 , wherein the plurality of features are spaced from each other by a spacing dimension, wherein the spacing dimension is substantially equal to the dimension.  
     
     
         11 . The article according to  claim 7 , wherein the plurality of features are substantially close-packed.  
     
     
         12 . The article according to  claim 7 , wherein the plurality of features comprise at least one of bumps, cones, rods, wires, channels, substantially spherical features, foamed structures, substantially cylindrical features, pyramidal features, prismatic structures, and combinations thereof.  
     
     
         13 . The article according to  claim 7 , wherein the plurality of features is arranged in an ordered array on the surface.  
     
     
         14 . The article according to  claim 7 , wherein the plurality of features is sprayed onto the substrate.  
     
     
         15 . The article according to  claim 7 , wherein the plurality of features is stamped onto the surface.  
     
     
         16 . The article according to  claim 7 , wherein the plurality of features are chemically formed on the substrate.  
     
     
         17 . The article according to  claim 1 , wherein the article further comprises a bulk portion disposed beneath the surface, and wherein the plurality of features of the texture of the surface extends into a bulk portion of the article.  
     
     
         18 . The article according to  claim 1 , wherein the article is one of an airfoil, a turbine component, a heat exchanger, a watercraft hull, an appliance, and a fabric.  
     
     
         19 . The article according to  claim 16 , wherein the article is an airfoil and the surface is disposed on at least a leading edge of the airfoil.  
     
     
         20 . The article according to  claim 1 , wherein the reference liquid comprises water.  
     
     
         21 . The article according to  claim 1 , wherein the reference liquid comprises at least one hydrocarbon.  
     
     
         22 . An article comprising: 
 a surface disposed on a substrate, wherein the surface comprises    a. a material having a nominal wettability sufficient to generate, with water, a nominal contact angle in a range from about 60° to about 90°, the material comprising at least one material selected from the group consisting of a polymer and a ceramic; and    b. a texture comprising a plurality of features;    wherein the surface has an effective wettability sufficient to generate, with water, a contact angle in a range from about 120° to about 180°.    
     
     
         23 . A method for making an article, the method comprising: 
 a. providing a substrate and    b. forming a surface on the substrate, wherein the surface comprises a material having a nominal liquid wettability sufficient to generate, with a reference liquid, a nominal contact angle in a range from about 60° to about 90°, the material, comprising at least one material selected from the group consisting of a polymer and a ceramic, and the surface further comprising a texture, wherein the texture comprises a plurality of features;    wherein the surface has an effective liquid wettability sufficient to generate, with the reference liquid, a contact angle in a range from about 120° to about 180°.    
     
     
         24 . The method according to  claim 23 , wherein forming comprises spraying the plurality of features onto the substrate.  
     
     
         25 . The method according to  claim 23 , wherein forming comprises stamping the plurality of features onto the substrate.  
     
     
         26 . The method according to  claim 23 , wherein forming comprises chemically forming the features onto the substrate.  
     
     
         27 . The method according to  claim 26 , wherein chemically forming comprises at least one operation selected from the group consisting of 
 a. forming at least one discrete chemical phase on the surface of the substrate, and    b. chemically etching the substrate using at least one etchant selected from the group consisting of an acid, a base, and a solvent.