Fluorescent Carbon Nanotube Compositions Deposited on Surfaces

Abstract

The present invention is directed toward fluorescent inks and markers comprising carbon nanotubes. The present invention is also directed toward methods of making such inks and markers and to methods of using such inks and markers, especially for security applications (e.g., anti-counterfeiting). Such inks and markers rely on the unique fluorescent properties of semiconducting carbon nanotubes.

1 . A fluorescent composition comprising:
 a substrate; and   carbon nanotubes deposited on the substrate;
 wherein the carbon nanotubes are fluorescent and have diameters of less than about 3 nm; 
 wherein the carbon nanotubes have a visible excitation and an emission following the visible excitation; and 
 wherein the carbon nanotubes comprise a fluorescent ink that is formulated to adhere to the substrate. 
   
     
     
         2 . The fluorescent composition of  claim 1 , wherein the fluorescent ink further comprises a surfactant. 
     
     
         3 . The fluorescent composition of  claim 1 , wherein the fluorescent ink further comprises a polymer. 
     
     
         4 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are dispersed. 
     
     
         5 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are selected from the group consisting of single-wall carbon nanotubes, multi-wall carbon nanotubes, double-wall carbon nanotubes, and combinations thereof. 
     
     
         6 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes comprise single-wall carbon nanotubes. 
     
     
         7 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes comprise an essentially homogenous population of carbon nanotubes;
 wherein the essentially homogenous population comprises a property selected from the group consisting of type, dimension, and species.   
     
     
         8 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes comprise separated carbon nanotubes;
 wherein the separated carbon nanotubes have fluorescence properties tuned within a range of excitation and emission wavelengths.   
     
     
         9 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are homogenized by electronic type. 
     
     
         10 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are chemically derivatized. 
     
     
         11 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are deposited on the substrate in patterned form. 
     
     
         12 . The fluorescent composition of  claim 1 , wherein the substrate comprises a material selected from the group consisting of paper, natural fibers, synthetic fibers, metals, polymeric materials, ceramics, glasses, and combinations thereof. 
     
     
         13 . The fluorescent composition of  claim 1 , wherein the substrate is pretreated to facilitate adhesion of the fluorescent ink. 
     
     
         14 . The fluorescent composition of  claim 1 , wherein the substrate is a security document. 
     
     
         15 . The fluorescent composition of  claim 1 , wherein the substrate is a currency. 
     
     
         16 . The fluorescent composition of  claim 1 , wherein the carbon nanotubes are invisible when deposited on the substrate. 
     
     
         17 . The fluorescent composition of  claim 1 , wherein the emission comprises a near-infrared emission.