Two-dimensional sheet stabilized emulsion based inks
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.
1 . A flowable conductive ink configured for use in an electronic device, the flowable conductive ink comprising:
a combination of a first solvent and a second solvent, wherein the first and second solvents define an interface therebetween;
a volume of sheet materials distributed at the interface between the first and second solvents based on mixing of the combination;
the flowable conductive ink exhibiting a resistance suited for use in an electronic device;
wherein the second solvent comprises an alkane selected from the group consisting of hexadecane, a longer chain alkane than hexadecane or a combination thereof; and
wherein the flowable conductive ink exhibits substantially no coalescence for at least three months.
2 . The flowable conductive ink as in claim 1 , wherein the first solvent comprises water.
3 . The flowable conductive ink as in claim 1 , wherein the oil comprises hexadecane.
4 . The flowable conductive ink as in claim 1 , wherein the sheet materials comprise at least one of graphene or graphite.
5 . The flowable conductive ink as in claim 1 , wherein the flowable conductive ink exhibits a viscosity between 15,000 cP and 4,000,000 cP.
6 . The flowable conductive ink as in claim 1 , wherein the flowable conductive ink exhibits a shelf life of at least three months.
7 . The flowable conductive ink as in claim 1 , wherein the sheet materials comprise flakes with an average size of 1 micrometer (μm).
8 . The flowable conductive ink as in claim 1 , characterized by at least one of: electrical conductivity and properties suited for at least one of screen-printing, brushing, spraying and use in an ink-jet.
9 . The conductive ink as in claim 1 , wherein the device comprises at least one of: a wearable textile, an antenna, electromagnetic interference (EMI) shielding, a printed electronic device, an indium tin oxide (ITO) replacement, a bio-sensor, printed memory, an organic light emitting diode (OLED), LED lighting, a heater, a flexible display, an energy storage device, a solar cell, a cloth substrate, and a plastic substrate.
10 . An ink comprising a flowable stabilized emulsion of non-mixing solvents, the ink comprising:
a combination of a first solvent that comprises water and a second solvent that comprises a mixture of at least two alkanes, wherein the first and second solvents define an interface therebetween;
a volume of graphite flakes distributed at the interface between the first and second solvents based on mixing of the combination;
wherein the combination of the first and second solvents and the volume of sheet materials define the flowable stabilized emulsion; and
wherein the second solvent comprises an alkane selected from the group consisting of hexadecane, a longer chain alkane than hexadecane or a combination thereof; and
wherein the ink exhibits substantially no coalescence for at least three months.
11 . The ink as in claim 10 , wherein the at least two alkanes comprise heptane and hexadecane.
12 . The ink as in claim 10 , wherein the flowable stabilized emulsion exhibits a viscosity within a range of 15,000 cP to 4,000,000 cP.
13 . The ink as in claim 10 , wherein the ink exhibits a shelf life of at least three months.