Micropatterning of conductive graphite particles using microcontact printing
Methods involve a combination of polyelectrolyte multilayer (PEM) coating or silane self assembly on a substrate; microcontact printing; and conductive graphite particles, especially size controlled highly conductive exfoliated graphite nanoplatelets. The conductive graphite particles are coated with a charged polymer such as sulfonated polystyrene. The graphite particles are patterned using microcontact printing and intact pattern transfer on a substrate that has an oppositely-charged surface. The method allows for conductive organic patterning on both flat and curved surfaces and can be used in microelectronic device fabrication.
1. A conductive circuit comprising exfoliated graphite nanoplatelets disposed on a polyelectrolyte multilayer (PEM) thin film, wherein the PEM thin film consists of multiple layers of alternating oppositely charged polyelectrolytes, and wherein the nanoplatelets form a continuous pattern on an outer surface of the thin film.
2. The conductive circuit according to claim 1 , wherein the exfoliated graphite nanoplatelets have a first surface charge and the PEM thin film has a second surface charge opposite the first.
3. A circuit according to claim 2 , wherein the nanoplatelets are coated with a polyanion and the surface charge of the PEM thin film is cationic.
4. A circuit according to claim 2 , wherein the nanoplatelets are coated with a polycation and the surface charge of the PEM thin film is anionic.
5. A circuit according to claim 1 , wherein the surface area of the graphite nanoplatelets is 50 m 2 /g or higher.
6. A circuit according to claim 1 , wherein the surface area of the graphite nanoplatelets is 100 m 2 /g or higher.
7. A circuit according to claim 2 , wherein the aspect ratio of the nanoplatelets is 1000 or higher.
8. A circuit according to claim 3 , wherein the polyanion is sulfonated polystyrene.
9. A circuit according to claim 4 , wherein the cation is polydiallyldimethylammonium chloride.
10. A circuit according to claim 1 , wherein the PEM thin film comprises alternating layers of sulfonated polystyrene and polydiallyldimethylammonium chloride.
11. A conductive circuit comprising a charged conductive material deposited by microcontact printing on an oppositely charged surface, surface of a polyelectrolyte multilayer (PEM) thin film, wherein the PEM thin film consists of multiple alternating layers of oppositely charged polyelectrolytes and wherein the charged conductive material comprises a layer by layer assembled multilayer comprising alternating layers of a) graphite particles coated with a first polyelectrolyte and b) a second polyelectrolyte of opposite charge to the first polyelectrolyte, wherein the layer by layer assembled multilayer is conductive.
12. A circuit according to claim 11 , wherein the surface area of the graphite particles is 100 m 2 /g or higher.
13. A circuit according to claim 11 , wherein the graphite particles comprise exfoliated graphite nanoplatelets.
14. A circuit according to claim 13 , wherein the aspect ratio of the nanoplatelets is 1000 or higher.
15. A circuit according to claim 11 , wherein the polyelectrolyte multilayer thin film comprises 10 or more bilayers of alternating polyanion and polycation.
16. A circuit according to claim 11 , wherein the layer by layer assembled multilayer comprises 4 or more alternating layers of graphite particles a) and second polyelectrolyte b).
17. A circuit according to claim 11 , in the form of an antenna.
18. A circuit according to claim 11 , in the form of an RFID antenna.
19. A circuit according to claim 11 , in the form of an electromagnetic interference shielding material.