Embedded nanoparticle films and method for their formation in selective areas on a surface

Abstract

The invention is directed to a method of positioning nanoparticles on a patterned substrate. The method comprises providing a patterned substrate with selectively positioned recesses, and applying a solution or suspension of nanoparticles to the patterned substrate to form a wetted substrate. A wiper member is dragged across the surface of the wetted substrate to remove a portion of the applied nanoparticles from the wetted substrate, and leaving a substantial number of the remaining portion of the applied nanoparticles disposed in the selectively positioned recesses of the substrate. The invention is also directed to a method of making carbon nanotubes from the positioned nanoparticles.

1 . A method of positioning nanoparticles on a patterned substrate, the method comprising: 
 providing a patterned substrate with selectively positioned recesses;    applying a solution or suspension of nanoparticles to the patterned substrate to form a wetted substrate; and    dragging a wiper member across a surface of the wetted substrate to remove a portion of the applied nanoparticles from the wetted substrate such that a substantial number of the remaining portion of the applied nanoparticles are disposed in the selectively positioned recesses.    
     
     
         2 . The method of  claim 1  further comprising heating the wiped substrate with the remaining portion of the applied nanoparticles disposed in the selectively positioned recesses.  
     
     
         3 . The method of  claim 1  wherein the nanoparticles are of substantially uniform mean diameter from about 2 nm to 50 nm.  
     
     
         4 . The method of  claim 3  wherein the nanoparticles have a mean diameter from about 1 nm to about 10 nm.  
     
     
         5 . The method of  claim 1 , wherein the mean diameter of the positioned recesses is between one and two times the mean diameter of the nanoparticles.  
     
     
         6 . The method of  claim 1  further comprising contacting the wiped substrate with a wash solution followed by dragging the wiper member across the wash-contacted surface of the substrate, and heating the washed substrate with the remaining portion of the applied nanoparticles disposed in the selectively positioned recesses.  
     
     
         7 . The method of  claim 1  wherein the wiper member is an elastomeric member with a uniform edge.  
     
     
         8 . The method of  claim 5  wherein the wiper member comprises polydimethylsiloxane.  
     
     
         9 . One-dimensional materials prepared from the selectively positioned nanoparticles of  claim 2 , wherein the nanoparticles are catalytic sites for the growth of the one-dimensional materials.  
     
     
         10 . The one-dimensional materials of  claim 9  wherein the diameter of the one dimensional materials is controlled by the diameter of the positioned nanoparticle.  
     
     
         11 . The one-dimensional materials of  claim 10  being carbon nanotubes formed by chemical vapor deposition.  
     
     
         12 . A method of making carbon nanotubes comprising: 
 providing a patterned substrate with selectively positioned recesses;    applying a solution or suspension of nanoparticles to the patterned substrate to form a wetted substrate;    dragging a wiper member across a surface of the wetted substrate to remove a portion of the applied nanoparticles from the wetted substrate such that a substantial number of the remaining portion of the applied nanoparticles are disposed in the selectively positioned recesses;    heating the wiped substrate with the remaining portion of the applied nanoparticles disposed in the selectively positioned recesses to form catalytic sites on the heated substrate; and    forming the carbon nanotubes from the catalytic sites.    
     
     
         13 . The method of  claim 12  wherein the nanoparticles comprise an iron oxide.  
     
     
         14 . The method of  claim 12  further comprising contacting the wiped substrate with a wash solution followed by dragging the wiper member across the wash-contacted surface of the substrate.  
     
     
         15 . The method of  claim 12  wherein the formed carbon nanotubes have a mean diameter of from 10 nm to 50 nm.  
     
     
         16 . The method of  claim 12  wherein the nanoparticles have a mean diameter of from 1 nm to 50 nm.  
     
     
         17 . An array of nanoparticles positioned in one or more recesses of a substrate, wherein the recesses and the positioned nanoparticle have a comparable diameter such that a single nanoparticle is positioned within the one or more recesses.  
     
     
         18 . The array of nanoparticles of  claim 17  wherein the mean diameter of the one or more recesses is between one and two times the mean diameter of the nanoparticle.  
     
     
         19 . One-dimensional materials prepared from the array of positioned nanoparticles of  claim 17 , wherein the nanoparticles are catalytic sites for the growth of the one-dimensional materials.  
     
     
         20 . The one dimensional materials of  claim 19  being carbon nanotubes formed by chemical vapor deposition.