Surfaces, including microfluidic channels, with controlled wetting properties

Abstract

The present invention generally relates to coating materials, including photoactive coating materials. In some aspects of the invention, a sol-gel is provided that can be formed as a coating on a microfluidic channel. One or more portions of the sol-gel can be reacted to alter its hydrophobicity, in some cases. For instance, in one set of embodiments, a portion of the sol-gel may be exposed to light, such as ultraviolet light, which can be used to induce a chemical reaction in the sol-gel that alters its hydrophobicity. In one set of embodiments, the sol-gel can include a photoinitiator, that upon exposure to light, produces radicals. Optionally, the photoinitiator may be conjugated to a silane or other material within the sol-gel. The radicals so produced may be used to cause a polymerization reaction to occur on the surface of the sol-gel, thus altering the hydrophobicity of the surface. In some cases, various portions may be reacted or left unreacted, e.g., by controlling exposure to light (for instance, using a mask). Such treated surfaces within a microfluidic channel may be useful in a wide variety of applications, for instance, in the creation of emulsions such as multiple emulsions.

What is claimed is: 
     
         1 . An article, comprising:
 a sol-gel coating coated on at least a portion of a microfluidic channel, wherein the sol-gel comprises a moiety containing a double bond.   
     
     
         2 . The article of  claim 1 , wherein the microfluidic channel is defined within a microfluidic device comprising polydimethylsiloxane. 
     
     
         3 . The article of  claim 1 , wherein the microfluidic channel is defined within a microfluidic device comprising glass. 
     
     
         4 . The article of  claim 1 , wherein a first portion of the sol-gel coating is relatively hydrophobic, and a second portion of the sol-gel coating is relatively hydrophilic. 
     
     
         5 . The article of  claim 1 , wherein the coating comprises a silane. 
     
     
         6 . The article of  claim 1 , wherein the coating comprises a fluorosilane. 
     
     
         7 . The article of  claim 1 , wherein the coating comprises heptadecafluorooctylsilane. 
     
     
         8 . The article of  claim 1 , wherein the coating comprises heptadecafluorosilane. 
     
     
         9 . The article of  claim 1 , wherein the coating comprises a photoinitiator. 
     
     
         10 . (canceled) 
     
     
         11 . The article of  claim 1 , wherein the coating comprises a moiety comprising a thiol. 
     
     
         12 . The article of  claim 9 , wherein the photoinitiator is chemically coupled to a silane. 
     
     
         13 . The article of  claim 12 , wherein the photoinitiator is coupled to the silane via a urethane bond. 
     
     
         14 . The article of  claim 9 , wherein the photoinitiator is Irgacure 2959. 
     
     
         15 . The article of  claim 1 , wherein the sol-gel coating has a thickness of no more than about 10 micrometers. 
     
     
         16 . The article of  claim 1 , wherein at least a portion of the sol-gel coating contains acrylic acid. 
     
     
         17 . The article of  claim 1 , wherein at least a portion of the sol-gel coating comprises acrylic acid. 
     
     
         18 . The article of  claim 17 , wherein the acrylic acid is chemically bonded to the sol-gel coating. 
     
     
         19 . The article of  claim 1 , wherein the portion of the sol-gel coating comprising acrylic acid is less hydrophobic than a portion of the sol-gel coating free of acrylic acid. 
     
     
         20 - 60 . (canceled)