Superhydrophobic nanotextured polymer and metal surfaces

Abstract

A method of manufacturing a multiscale (hierarchical) superhydrophobic surface is provided. The method includes texturing a polymer surface at three size scales, in a fractal-like or pseudo-fractal-like manner, the lowest scale being nanoscale and the highest microscale. The hydrophobic polymer surface may be converted to hydrophobic metal surface by subsequent deposition of a metal layer onto the polymer surface.

What is claimed is: 
     
         1 . A method of manufacturing a hydrophobic surface having an apparent contact angle of at least 150° C., the method comprising:
 i) providing a base substrate and a polymeric material; 
 ii) forming a layer of said polymeric material on said substrate, said layer having a bottom surface attached to said substrate base, and an upper surface, wherein the polymeric material in said layer is structured at two different size scales, the first scale ranging from 0.1 to 2 μm, and the second scale between 0.5-50 μm; 
 iii) further structuring said polymeric material at a third size scale by forming indentations on said upper surface, wherein an average distance between adjacent indentations is from 20 to 200 μm, 
 
       thereby obtaining said hydrophobic surface. 
     
     
         2 . The method of  claim 1 , wherein said second size scale ranges from 2 to 20 μm. 
     
     
         3 . The method of  claim 1 , further comprising depositing a metal layer onto said upper surface of said layer of said polymeric material. 
     
     
         4 . The method of  claim 3 , wherein a thickness of said metal layer is in a range of from 0.01 to 0.1 μm. 
     
     
         5 . The method of  claim 1 , wherein structuring at said first size scale is effected by particles having an average size of from 0.1 to 2 μm, said particles being present in said layer of said polymeric material, and structuring at said second size scale is effected by aggregates of said particles, said aggregates having an average size of from 2 to 20 μm. 
     
     
         6 . The method of  claim 5 , wherein said forming indentations is effected by pressing said indentations into said upper surface of said layer. 
     
     
         7 . The method of  claim 1 , wherein said indentations are arranged in an array of approximately parallel channels. 
     
     
         8 . The method of  claim 1 , wherein said indentations are arranged in a plane network of depressions. 
     
     
         9 . The method of  claim 1 , wherein a width and depth of said indentations are each independently in a range of from 5 to 100 μm. 
     
     
         10 . The method of  claim 1 , comprising:
 i) providing beads of a first polymer having an average size of from about 0.1 to 2 μm;   ii) providing a second polymer;   iii) preparing a solution of said second polymer in a solvent which dissolves said second polymer but not said first polymer, admixing said beads into said solution, and layering the resulting suspension on a base substrate;   iv) evaporating said solvent of said suspension, thereby obtaining said layer of polymeric material comprising bead aggregates of from 2 to 20 μm; and   vi) impressing a web of indentations on said upper surface of said layer, wherein the width and the depth of said indentations are each independently from 5 to 100 μm.   
     
     
         11 . A method according to  claim 10 , wherein said first polymer is polyvinylidene fluoride (PVDF), said second polymer is a polycarbonate based polymer, and said solvent is a chlorinated solvent. 
     
     
         12 . An article comprising a polymer layer exhibiting a hydrophobic surface having an apparent contact angle of at least 150° C., the hydrophobic surface being structured at three different size scales, comprising a structuring at a first size scale ranging from 0.1 to 2 μm, structuring at a second size scale ranging from 2-20 μm, and structuring at a third size scale ranging from 20-200 μm. 
     
     
         13 . The article of  claim 12 , wherein said surface is a metal surface or a polymer surface. 
     
     
         14 . The article of  claim 12 , wherein said structuring at said first size scale comprises a presence of particles in said layer of said polymeric material, said particles having an average size in a range of from 0.1 to 2 μm, and wherein said structuring at said second size scale comprises a presence of aggregates of said particles, said aggregates having an average size of from 2 to 20 μm. 
     
     
         15 . The article of  claim 12 , wherein said structuring at said third size scale comprises indentations in said upper surface of said layer, wherein an average distance between adjacent indentations is in a range of from 20 to 200 μm. 
     
     
         16 . The article of  claim 15 , wherein said indentations are arranged in an array of approximately parallel channels. 
     
     
         17 . The article of  claim 15 , wherein said indentations are arranged in a plane network of depressions. 
     
     
         18 . The article of  claim 15 , wherein a width and depth of said indentations are each independently in a range of from 5 to 100 μm. 
     
     
         19 . The article of  claim 12 , wherein structuring at at least one of said three size scales comprises a presence of a structure element selected from the group consisting of particles, fibers, and particle aggregates, wherein the material of said structure element is selected from the group consisting of natural polymers, synthetic polymers and inorganic materials. 
     
     
         20 . The article of  claim 19 , wherein said size scale corresponds to dimensions of said particles, fibers, or aggregates, or from average distances between adjacent particles, fibers, or aggregates.