Liquids and viscoelastic material repellent and anti-biofouling coatings

Abstract

A coated smooth surface of a substrate repels liquids and viscoelastic materials and can have anti-staining and anti-biofouling properties. The smooth surface can be coated by applying a chemical layer on the surface and a lubricant. Such coated surfaces are useful for use in toilets, urinals, or other devices for the processing of liquids and viscoelastic materials such as solid or semi-solid metabolic waste of human digestive system. Such coated surfaces can also be applied to windows for buildings or vehicles such as automobiles or camera lenses to repel liquids (e.g. rain), ice, frost, insect residues, and birds' feces.

What is claimed is: 
     
         1 . A coating on a smooth surface of a substrate having hydroxyl functional groups thereon and an average roughness Ra of less than about 1 μm, the coating comprising:
 a chemical layer grafted on the substrate surface formed from polymerizing a silane or siloxane from the hydroxyl functional groups on the surface of the substrate; and 
 a lubricant layer disposed over the chemical layer, the lubricant layer formed from a lubricant. 
 
     
     
         2 . The coating of  claim 1 , wherein the lubricant has a viscosity of from about 18 cSt to about 1,000 cSt at 25° C. 
     
     
         3 . The coating of  claim 1 , wherein the surface has an average roughness Ra of less than about 100 nm. 
     
     
         4 . The coating of  claim 1 , wherein the chemical layer grafted on the substrate surface comprises a polydimethylsiloxane grafted on the surface of the substrate. 
     
     
         5 . The coating of  claim 1 , wherein the smooth surface of the substrate comprises silicon. 
     
     
         6 . The coating of  claim 1 , wherein the smooth surface of the substrate comprises a metal, ceramic or glass. 
     
     
         7 . The coating of  claim 1 , wherein the smooth surface comprises the substrate of a medical device. 
     
     
         8 . The coating of  claim 1 , wherein the smooth surface is a smooth surface of a toilet, urinal or sink. 
     
     
         9 . The coating of  claim 1 , wherein the lubricant layer comprises a plant oil. 
     
     
         10 . The coating of  claim 1 , wherein the lubricant layer comprises a silicone oil. 
     
     
         11 . A coating on a smooth surface of a substrate, the coating comprising a chemical layer on the smooth surface and a lubricant layer adhered to the chemical layer;
 wherein the smooth surface has an average roughness (Ra) of less than 4 μm;   wherein the chemical layer is formed by polymerizing a silane or siloxane or both from hydroxyl functional groups on the smooth surface of the substrate to form a chemical layer of graft polymers having ends anchored to the smooth surface; and   wherein the lubricant layer is formed from a lubricant having a viscosity of from 1 cSt to about 1,000 cSt at 25° C.   
     
     
         12 . The coating of  claim 11 , wherein the surface has an average roughness Ra of less than 1 μm. 
     
     
         13 . The coating of  claim 11 , wherein the chemical layer has a thickness from 1 nm to m and the lubricant layer has a thickness of from 1 nm to 1 mm. 
     
     
         14 . A process for preparing a repellant smooth surface, the process comprising:
 applying a coating composition onto a smooth surface of a substrate having hydroxyl functional groups thereon, wherein the smooth surface has an average roughness Ra of less than 4 μm and wherein the coating composition includes: (i) a silane or siloxane or both, (ii) a solvent and (iii) an acid catalyst;   anchoring the silane or siloxane or both from the hydroxyl functional groups on the smooth surface of the substrate; and   applying a lubricant on the chemical layer to adhere and maintain a lubricant layer on the smooth surface and form the repellant smooth surface.   
     
     
         15 . The process of  claim 14 , wherein the chemical layer has a thickness from 1 nm to 10 μm and the lubricant layer has a thickness of from 1 nm to 1 mm. 
     
     
         16 . The process of  claim 14 , wherein the lubricant comprises a plant oil. 
     
     
         17 . The process of  claim 14 , wherein the lubricant comprises a silicone oil. 
     
     
         18 . The process of  claim 14 , wherein the lubricant has a viscosity of from about 1 cSt to about 1,000 cSt at 25° C. 
     
     
         19 . The process of  claim 14 , further comprising re-applying the lubricant or applying second, different lubricant to form the lubricant layer adhered to the chemical layer.