Transferring nanofiber forests between substrates
Techniques are described for transferring nanofiber forests using transfer films that either lack a conventional adhesive at the substrate-nanofiber forest interface or that include a diffusion barrier that prevents diffusion of adhesive molecules (or other polymer molecules mobile at ambient temperatures) into the nanofiber forest. These techniques can be applied to single layer nanofiber forests or stacks of multiple nanofiber forest. By selecting the bond strength between the nanofiber forest and the transfer films, the nanofibers can be aligned in a common direction that includes, but is not limited to, perpendicular to a substrate or transfer film.
1. A nanofiber assembly comprising:
an adhesive layer comprising adhesive molecules having a first surface and a second surface opposite to the first surface;
a diffusion barrier on the first surface of the adhesive layer; and
a nanofiber forest comprising a plurality of nanofibers
wherein arcuate ends of the nanofibers of the nanofiber forest penetrate into the diffusion barrier, and
the diffusion barrier comprises a layer of a carbon-containing material which is carbonized.
2. The nanofiber assembly of claim 1 , wherein the carbon-containing material is selected from an adhesive, a polymer, an intervening adhesive film, a solvent, and any combination thereof.
3. The nanofiber assembly of claim 1 , further comprising a release liner on the second surface of the adhesive layer.
4. The nanofiber assembly of claim 1 , further comprising a transfer film on a surface of the nanofiber forest opposite the diffusion barrier.
5. The nanofiber assembly of claim 1 , wherein the carbon-containing material prevents diffusion of adhesive molecules from the adhesive layer into the nanofiber forest.
6. The nanofiber assembly of claim 1 , wherein the arcuate ends of the nanofibers do not penetrate into the adhesive layer.