Silane based surfaces with extreme wettabilities

Abstract

In various aspects, the present disclosure provides porous materials having extreme wettability to polar or non-polar fluids, such as water and oil. The porous material has a coated surface comprising a low surface energy fluoroalkyl silane that is treated to exhibit at least one type of extreme wettability. In certain aspects, the disclosure provides a porous material comprising a coated surface that is both superhydrophobic and oleophilic, or superhydrophobic and superoleophobic, or superhydrophilic and oleophobic, by way of example. Methods of forming a porous surface having a predetermined wettability are also provided. Other embodiments include fluidic devices that incorporate porous materials having extreme wettabilities, such as microfluidic devices and separators.

What is claimed is: 
     
         1 . A porous material having a coated surface that is both superhydrophobic, having a first apparent advancing dynamic contact angle of greater than or equal to about 150° for water and superoleophobic, having a second apparent advancing dynamic contact angle of greater than or equal to about 150° for a preselected oil, wherein the coated surface consists essentially of a low surface energy fluoroalkyl silane having a surface tension of less than or equal to about 25 mN/m reacted with hydroxyl groups on the porous material. 
     
     
         2 . The porous material of  claim 1 , wherein the coated surface further comprises a polymeric layer comprising the hydroxyl groups disposed on the porous material beneath the low surface energy fluoroalkyl silane. 
     
     
         3 . The porous material of  claim 1 , wherein the low surface energy fluoroalkyl silane has a surface tension of less than or equal to about 10 mN/m. 
     
     
         4 . The porous material of  claim 1 , wherein the coated surface has a ratio of fluorine to oxygen of greater than or equal to about 2. 
     
     
         5 . The porous material of  claim 1 , wherein greater than or equal to about 60% of the hydroxyl groups on the porous material are reacted with the low surface energy fluoroalkyl silane. 
     
     
         6 . The porous material of  claim 1 , wherein the low surface energy fluoroalkyl silane is selected from a group consisting of: heptadecafluoro-1,1,2,2-tetrahydrodecyl triethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane, heptadecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane, tridecafluoro-1,1,2,2-tetrahydrooctyl triethoxysilane, and combinations thereof. 
     
     
         7 . A microfluidic device comprising:
 a porous material comprising a surface comprising:   (i) a first surface region that comprises a coating that is superhydrophobic, having a first apparent advancing dynamic contact angle of greater than or equal to about 150° for water and superoleophobic, having a second apparent advancing dynamic contact angle of greater than or equal to about 150° for a preselected oil; and   (ii) a second surface region that is hydrophilic, having a first apparent advancing dynamic contact angle of less than or equal to about 90° for water and oleophilic, having a second apparent advancing dynamic contact angle of less than or equal to about 90° for a preselected oil, wherein the second surface region is capable of receiving, transferring, and/or storing a fluid, and   
       wherein the (i) first surface region and (ii) the second surface region together define at least one microscale fluidic pathway for the fluid on the surface of the porous material. 
     
     
         8 . The microfluidic device of  claim 7 , wherein at least one microscale fluidic pathway has at least one dimension that is less than or equal to about 1,000 μm. 
     
     
         9 . The microfluidic device of  claim 7 , wherein the coating of the first surface region comprises a low surface energy fluoroalkyl silane having a surface tension of less than or equal to about 25 mN/m. 
     
     
         10 . The microfluidic device of  claim 9 , wherein the low surface energy fluoroalkyl silane is selected from a group consisting of: heptadecafluoro-1,1,2,2-tetrahydrodecyl triethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane, heptadecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane, tridecafluoro-1,1,2,2-tetrahydrooctyl triethoxysilane, and combinations thereof. 
     
     
         11 . The microfluidic device of  claim 7 , wherein the coating of the first surface region comprises a low surface energy fluoroalkyl silane having a surface tension of less than or equal to about 10 mN/m. 
     
     
         12 . The microfluidic device of  claim 7 , wherein the coating of the first surface region consists essentially of a low surface energy fluoroalkyl silane having a surface tension of less than or equal to about 25 mN/m. 
     
     
         13 . The microfluidic device of  claim 7 , wherein the coating of the first surface region has a ratio of fluorine to oxygen of greater than or equal to about 2. 
     
     
         14 . The microfluidic device of  claim 7 , wherein the surface of the porous material comprises hydroxyl groups. 
     
     
         15 . The microfluidic device of  claim 14 , wherein greater than or equal to about 60% of the hydroxyl groups on the porous material are reacted with a low surface energy fluoroalkyl silane. 
     
     
         16 . The microfluidic device of  claim 7 , wherein the porous material comprises paper or cellulose. 
     
     
         17 . The microfluidic device of  claim 7 , wherein the fluid is selected from a group consisting of: a polar liquid, a non-polar liquid, and combinations thereof.