Two-Dimensional Sheet Stabilized Emulsion Based Inks

Abstract

The present disclosure provides advantageous sheet stabilized emulsion based inks, and improved methods for fabricating and using such inks. More particularly, the present disclosure provides improved methods for fabricating conductive inks derived from water-in-oil emulsions stabilized by sheets exfoliated from layered materials (e.g., substantially pristine and non-oxidized graphite or hexagonal boron nitride), and related methods of use. A layered material (e.g., substantially pristine and non-oxidized graphite or hexagonal boron nitride) can be exfoliated into individual sheets, and these sheets can be utilized to stabilize water-in-oil emulsions. In certain embodiments, by utilizing long chain alkanes (e.g., hexadecane), one can advantageously fabricate emulsions with high viscosity and stability. In this form, the emulsions can be used as inks, thereby advantageously providing an inexpensive route to printing electrically conducting and/or insulating lines and shapes.

What is claimed is: 
     
         1 . A method for fabricating an ink comprising:
 a) providing a phase separated system of two non-mixing solvents, the phase separated system including: (i) a first solvent and a second solvent, and (ii) an interface between the first and second solvents;   b) introducing a layered material to the interface of the phase separated system;   c) forming an emulsion of the first and second solvents, at least a portion of the layered material stabilizing the emulsion; and   d) applying the emulsion to a substrate to form an electrically conductive pattern on the substrate.   
     
     
         2 . The method of  claim 1 , wherein the first solvent is a long chain alkane and the second solvent is water. 
     
     
         3 . The method of  claim 1 , wherein the first solvent includes at least one alkane and the second solvent is water. 
     
     
         4 . The method of  claim 1 , wherein the layered material is substantially pristine graphite or hexagonal boron nitride; and
 wherein after step c) the emulsion is stabilized by layers or sheets of the substantially pristine graphite or hexagonal boron nitride.   
     
     
         5 . The method of  claim 1 , wherein the emulsion is formed via a formation step selected from the group consisting of hand mixing, hand shaking, mechanical mixing, mechanical shaking, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the emulsion is a water-in-oil emulsion. 
     
     
         7 . The method of  claim 1 , wherein the emulsion is applied to the substrate via brushing or screen printing. 
     
     
         8 . The method of  claim 1 , wherein the substrate is flexible. 
     
     
         9 . The method of  claim 1 , wherein the first solvent is hexadecane and the second solvent is water. 
     
     
         10 . The method of  claim 1 , wherein the first solvent includes heptane and hexadecane, and the second solvent is water. 
     
     
         11 . The method of  claim 1 , wherein the emulsion has a steady state viscosity of about 4,000,000 cP shear thinning to about 15,000 cP. 
     
     
         12 . The method of  claim 1 , wherein the layered material introduced includes flakes, the flakes having a flake size of about 1 μm. 
     
     
         13 . The method of  claim 1 , wherein the layered material introduced includes graphite flakes, the graphite flakes having a flake size of about 1 μm. 
     
     
         14 . The method of  claim 1 , wherein the first solvent includes alkanes larger than octadecane. 
     
     
         15 . The method of  claim 1 , wherein the layered material is substantially pristine and non-oxidized graphite or hexagonal boron nitride; and
 wherein after step c) the emulsion is stabilized by layers or sheets of the substantially pristine and non-oxidized graphite or hexagonal boron nitride.   
     
     
         16 . The method of  claim 1 , wherein the emulsion is applied to the substrate via spraying or ink-jetting. 
     
     
         17 . A method for fabricating an ink comprising:
 a) providing a phase separated system of two non-mixing solvents, the phase separated system including: (i) a first solvent and a second solvent, and (ii) an interface between the first and second solvents;   b) introducing a layered material to the interface of the phase separated system;   c) forming an emulsion of the first and second solvents, at least a portion of the layered material stabilizing the emulsion; and   d) applying the emulsion to a substrate to form an electrically conductive pattern on the substrate;   wherein the first solvent is a long chain alkane and the second solvent is water;   wherein the layered material is substantially pristine and non-oxidized graphite or hexagonal boron nitride;   wherein after step c) the emulsion is stabilized by layers or sheets of the substantially pristine and non-oxidized graphite or hexagonal boron nitride;   wherein the emulsion is formed via hand mixing;   wherein the emulsion is a water-in-oil emulsion;   wherein the emulsion is applied to the substrate via brushing or screen printing;   wherein the substrate is flexible;   wherein the emulsion has a steady state viscosity of about 4,000,000 cP shear thinning to about 15,000 cP; and   wherein the layered material introduced includes flakes, the flakes having a flake size of about 1 μm.