Surface-modified fluorescent carbon nanotubes for product verification

A method for producing a material, comprising:

• providing a medium;
• dispersing carbon nanotubes in the medium;
• attaching first fluorescent moieties to functional groups on a first quantity of the carbon nanotubes, the first fluorescent moieties being in a concentration in the material sufficient to make the material fluoresce in the presence of radiation, wherein the first fluorescent moieties fluoresce at a first emission wavelength in the visible spectrum, wherein attaching includes creating a covalent bond between the first fluorescent moieties and the functional groups on the first quantity of the carbon nanotubes;
• and
• attaching second fluorescent moieties to functional groups on the first quantity of the carbon nanotubes, the second fluorescent moieties being in a concentration in the material sufficient to make the material fluoresce in the presence of radiation, wherein a first fluorescent moiety and a second fluorescent moiety are attached to functional groups on the same carbon nanotube from the first quantity of the carbon nanotubes, wherein the second fluorescent moieties fluoresce at a second emission wavelength in the visible spectrum, and the first and second emission wavelengths are different wavelengths.

A method for verifying authenticity of a product having a material, comprising:

• exposing the material to incident radiation, the material including a medium and carbon nanotubes dispersed in the medium, wherein first fluorescent moieties are attached to functional groups on a first quantity of the carbon nanotubes in a concentration sufficient to make the material fluoresce at a first emission wavelength in the presence of radiation, wherein the carbon nanotubes with the first fluorescent moieties attached have a certain homogeneous size and shape;
• detecting emissive radiation having a first emission wavelength within the visible spectrum to verify the authenticity of the product;
• inspecting the material using electron microscopy to determine the certain homogeneous size and shape of the carbon nanotubes, and
• comparing the homogeneous size and shape of the carbon nanotube to a controlled for size and shape of the carbon nanotube to verify the authenticity of the product.