Micropatterning of conductive graphite particles using microcontact printing

Abstract

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 method of depositing conductive materials onto substrates, comprising
 providing a substrate having a charged surface layer;   microcontact printing an oppositely-charged conductive material onto the charged surface layer in a pattern that covers less than 100% of the surface with charged material.   
     
     
         2 . A method according to  claim 1 , wherein the substrate comprises a polyelectrolyte membrane (PEM). 
     
     
         3 . A method according to  claim 1 , wherein microcontact printing comprises intact pattern transfer of a layer by layer (LBL) assembled multilayer comprising alternating layers of a) graphite particles coated with a first polyelectrolyte and b) a second electrolyte of opposite charge to the first polyelectrolyte. 
     
     
         4 . A method according to  claim 1 , wherein the conductive material comprises exfoliated graphite nanoplatelets. 
     
     
         5 . A method according to  claim 3 , wherein graphite is coated with a polyanion and the charged surface layer is cationic. 
     
     
         6 . A method according to  claim 3 , wherein the graphite is coated with a polycation and the charged surface layer is anionic. 
     
     
         7 . A method of fine patterning conductive material onto a surface for electronic applications, the method comprising
 exposing high surface area graphite particles to a solution of a charged polymer to form a charged conductive material;   applying an ink comprising the charged conductive material to the surface of a stamp; and   bringing the surface of the stamp into contact with a polyelectrolyte multilayer thin film, wherein the polyelectrolyte multilayer thin film has an outer surface of charge opposite the charge conductive material;   
       wherein the surface area of the graphite particles is 50 m 2 /g or higher. 
     
     
         8 . A method according to  claim 7 , wherein the surface area is 100 m 2 /g or higher. 
     
     
         9 . A method according to  claim 7 , wherein applying the ink comprises layer by layer assembly of alternating layers of a) an ink comprising the charged conductive material and b) a polyelectrolyte having a charge opposite of the charged conductive material. 
     
     
         10 . A method according to  claim 9 , wherein the aspect ratio of the graphite particles is 1000 or higher. 
     
     
         11 . A method according to  claim 7 , wherein the graphite particles are exfoliated graphite nanoplatelets (x-GnP). 
     
     
         12 . A method according to  claim 11 , wherein the charged conductive material is coated with a polyanion. 
     
     
         13 . A method according to  claim 11 , wherein the charged conductive material is coated with a polycation. 
     
     
         14 . A method of depositing a pattern of conductive material onto a surface, comprising
 coating exfoliated graphite nanoplatelets with a charged polymer;   forming an ink comprising the coated platelets;   applying the ink to a microstamp; and   transferring the coated platelets onto a surface by microcontact printing with the microstamp.   
     
     
         15 . A method according to  claim 14 , wherein the exfoliated graphite nanoplatelets are coated with a polyanion. 
     
     
         16 . A method according to  claim 15 , wherein the polyanion is sulfonated polystyrene. 
     
     
         17 . A method according to  claim 14 , wherein the nanoplatelets are coated with a polycation. 
     
     
         18 . A method according to  claim 17 , wherein the polycation is polydiallyldimethylammonium chloride. 
     
     
         19 . A method according to  claim 14 , wherein the surface comprises the outer charged layer of a polyelectrolyte multilayer film. 
     
     
         20 . A method according to  claim 19 , wherein the polyelectrolyte multilayer film comprises 10 or more bilayers of alternating polyanion and polycation. 
     
     
         21 . A method according to  claim 14 , wherein applying the ink to the microstamp comprises layer by layer assembly of alternating layers of a) an ink comprising the charged conductive material and b) a polyelectrolyte having a charge opposite of the charged conductive material. 
     
     
         22 . A method according to  claim 14 , wherein transferring comprises intact pattern transfer of a LBL layer by layer assembled multilayer comprising alternating layers of a) graphite particles coated with a first polyelectrolyte and b) a second electrolyte of opposite charge to the first polyelectrolyte 
     
     
         23 . An RFID antenna comprising exfoliated graphite nanoplatelets conductive particles in a pattern laid down by the method of  claim 14 . 
     
     
         24 . A conductive circuit comprising exfoliated graphite nanoplatelets deposited on a PEM thin film. 
     
     
         25 . A circuit according to  claim 24 , in the form of an antenna. 
     
     
         26 . A circuit according to  claim 24 , in the form of an RFID antenna. 
     
     
         27 . A circuit according to  claim 24 , in the form of an electromagnetic interference shielding material. 
     
     
         28 . Exfoliated graphite nanoplatelets coated with a charged polymer. 
     
     
         29 . Exfoliated graphite nanoplatelets according to  claim 28 , coated with a polyanion. 
     
     
         30 . Exfoliated graphite nanoplatelets according to  claim 28 , coated with a polycation. 
     
     
         31 . Exfoliated graphite nanoplatelets according to  claim 28 , having an aspect ratio of 1000 or greater. 
     
     
         32 . An ink comprising water and exfoliated graphite nanoplatelets according to  claim 28 .