DISPERSIONS

Abstract

A method of forming a liquid dispersion of 2D material/graphitic nanoplatelets is disclosed. The method comprises the steps of (1) creating a dispersing medium; (2) mixing the 2D material/graphitic nanoplatelets into the dispersing medium; and (3) subjecting the 2D material/graphitic nanoplatelets to sufficient shear forces and or crushing forces to reduce the particle size of the 2D material/graphitic nanoplatelets. The liquid dispersion comprises the 2D material/graphitic nanoplatelets, at least one grinding media, and at least one non-aqueous solvent.

Claims

1. A method of forming a liquid dispersion of 2D material/graphitic nanoplatelets comprising the steps of: (1) creating a dispersing medium by mixing at least one grinding media and at least one non-aqueous solvent until the grinding media and non-aqueous solvent mixture is substantially homogenous, wherein the at least one grinding media comprises an aldehyde resin; (2) mixing the 2D material/graphitic nanoplatelets into the dispersing medium; and (3) subjecting the 2D material/graphitic nanoplatelets to sufficient shear forces and or crushing forces to reduce the particle size of the 2D material/graphitic nanoplatelets; characterised in that the liquid dispersion comprises the 2D material/graphitic nanoplatelets, the at least one grinding media, and the at least one non-aqueous solvent in which the 2D material/graphitic nanoplatelets are comprised of one or more of graphene nanoplatelets, graphitic nanoplatelets, and 2D material nanoplatelets and in which the graphene nanoplatelets are comprised of one or more of graphene nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer reduced graphene oxide nanoplates, trilayer graphene nanoplates, trilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer reduced graphene oxide nanoplates, and graphene nanoplates of 6 to 10 layers of carbon atoms, and the graphitic platelets are comprised of graphite nanoplates with at least 10 layers of carbon atoms, the graphitic platelets are comprised of one or more of graphite nanoplates with 10 to 20 layers of carbon atoms, graphite nanoplates with 10 to 14 layers of carbon atoms, graphite nanoplates with 10 to 35 layers of carbon atoms, graphite nanoplates with 10 to 40 layers of carbon atoms, graphite nanoplates with 25 to 30 layers of carbon atoms, graphite nanoplates with 25 to 35 layers of carbon atoms, graphite nanoplates with 20 to 35 layers of carbon atoms, or graphite nanoplates with 20 to 40 layers of carbon atoms, and the 2D material nanoplatelets are comprised of one or more of hexagonal boron nitride (hBN), molybdenum disulphide (MoS.sub.2), tungsten diselenide (WSe.sub.2), silicene (Si), germanene (Ge), Graphyne (C), borophene (B), phosphorene (P), or a 2D in-plane or vertical heterostructure of two or more of the aforesaid materials.

2. (canceled)

3. (canceled)

4. A method according to claim 1 in which the at least one non-aqueous solvent is comprised of one or more of an organic solvent, butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2 butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, parachlorobenzotrifluoride, tert-butyl acetate, propylene carbonate and (1R)-7,8-Dioxabicyclo[3.2.1]octan-2-one, or a mixture of two or more of these solvents.

5. (canceled)

6. (canceled)

7. A method according to claim 1 in which the step (3) of subjecting the 2D material/graphitic nanoplatelets and dispersing medium mixture to shear forces and or crushing forces is performed using one or more of a dissolver, a bead mill, or a three-roll mill.

8. A liquid dispersion comprising 2D material/graphitic nanoplatelets, at least one grinding media, and at least one non-aqueous solvent, wherein the at least one grinding media comprises an aldehyde resin, in which the 2D material/graphitic nanoplatelets are comprised of one or more of graphene nanoplatelets, graphitic nanoplatelets, and 2D material nanoplatelets, and in which the graphene nanoplatelets are comprised of one or more of graphene nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer reduced graphene oxide nanoplates, trilayer graphene nanoplates, trilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer reduced graphene oxide nanoplates, and graphene nanoplates of 6 to 10 layers of carbon atoms, and the graphitic platelets are comprised of graphite nanoplates with at least 10 layers of carbon atoms, the graphitic platelets are comprised of one or more of graphite nanoplates with 10 to 20 layers of carbon atoms, graphite nanoplates with 10 to 14 layers of carbon atoms, graphite nanoplates with 10 to 35 layers of carbon atoms, graphite nanoplates with 10 to 40 layers of carbon atoms, graphite nanoplates with 25 to 30 layers of carbon atoms, graphite nanoplates with 25 to 35 layers of carbon atoms, graphite nanoplates with 20 to 35 layers of carbon atoms, or graphite nanoplates with 20 to 40 layers of carbon atoms, and the 2D material nanoplatelets are comprised of one or more of hexagonal boron nitride (hBN), molybdenum disulphide (MoS.sub.2), tungsten diselenide (WSe.sub.2), silicene (Si), germanene (Ge), Graphyne (C), borophene (B), phosphorene (P), or a 2D in-plane or vertical heterostructure of two or more of the aforesaid materials.

9. (canceled)

10. (canceled)

11. A liquid dispersion according to claim 8 in which the at least one non-aqueous solvent is comprised of one or more of an organic solvent, butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2 butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, parachlorobenzotrifluoride, tert-butyl acetate, propylene carbonate and (1R)-7,8-Dioxabicyclo[3.2.1]octan-2-one, or a mixture of two or more of these solvents.

12. A liquid dispersion according to claim 8 manufactured using a method according to claim 1.

13. A liquid coating composition comprising a liquid dispersion according to claim 8.

Description

BRIEF DESCRIPTION

[0052] For a better understanding of various examples that are useful for understanding the detailed description, reference will now be made by way of example only to the accompanying drawings in which:

[0053] FIG. 1 provides a graph showing the relationship between viscosity and shear rate for samples BA1 to BA3 of table 1;

[0054] FIG. 2 provides a graph showing the relationship between viscosity and shear rate for samples MEK1 to MEK3 of table 6; and

[0055] FIG. 3 provides a graph showing the relationship between viscosity and shear rate for samples X1 to X3 of table 11.

DETAILED DESCRIPTION

Examples

[0056] Dispersions of graphene/graphitic materials were manufactured using the methods of the present invention and comparative samples made using other techniques.

[0057] All dispersions were manufactured on a horizontal beadmill. Dispersions were milled for 15 minutes on recirculation mode at maximum speed.

Characterisation of Dispersions

[0058] Particle size was measured on a Mastersizer 3000 to determine the effectiveness of the grinding resin and dispersant in deagglomeration and particle size reduction.

[0059] Viscosity was measured to aid understanding of the rheological properties of the dispersion. This was done using a Kinexus Rheometer.

[0060] Storage stability was determined through the use of a Turbiscan Stability Analyser. Turbiscan stability index (TSI) is a relative measure of stability, which allows comparison of multiple samples. As a relative measure, it allows for a quantifiable assessment of closely related formulations.

Example 1: Dispersion of Graphitic Material A-GNP10 in Butyl Acetate

[0061] Samples of dispersions referenced as BA1 to BA3 were made up including graphitic material A-GNP10 and butyl acetate as shown in Table 1.

TABLE-US-00001 TABLE 1 Graphene/ Sample Graphitic Reference material Grinding resin Wetting agent Solvent BA1 10 wt % AGNP-10 — — Butyl acetate BA2 10 wt % AGNP-10 — DISPERBYK-2150 Butyl acetate BA3 10 wt % AGNP-10 Laropal A81 — Butyl acetate

[0062] Graphitic material A-GNP10 is commercially available from Applied Graphene Materials UK Limited, UK and comprises graphite nanoplatelets of between 25 and 35 layers of atoms thick. The graphite nanoplatelets are supplied as a powder and are generally aggregated into clumps of nanoplatelets.

[0063] Each of samples BA1 to BA3 was made up using the following steps:

1 To the butyl acetate any grinding resin and or wetting agent present in the sample was added. This was stirred until any solids were dissolved and the mixture was substantially homogenous;
2 The 10 wt % of AGNP-10 was calculated on the basis of the weight of the butyl acetate and added to the mixture and stirred until the powder was evenly dispersed in the mixture;
3 The mixture was bead milled for 15 minutes recirculation in a bead mill using beads.

TABLE-US-00002 TABLE 2 Particle Size Distribution of Butyl Acetate Dispersions Sample Particle Size Distribution (μm) Reference GNP Type D × 10 D × 50 D × 90 BA1 A-GNP10 0.0145 0.03 4.29 BA2 A-GNP10 0.026 0.803 4.81 BA3 A-GNP10 0.18 1.16 7.99

TABLE-US-00003 TABLE 3 Viscosity of butyl acetate dispersions measured on manufacture at a shear rate ({dot over (γ)}) of 10 s.sup.−1 at 23° C. Sample Initial Viscosity Reference GNP Type (Pa .Math. s) BA1 A-GNP10 0.13 BA2 A-GNP10 0.0017 BA3 A-GNP10 0.011

[0064] FIG. 1 provides a graph showing the relationship between viscosity and shear rate for samples BA1 to BA3 of table 1.

TABLE-US-00004 TABLE 4 Storage stability of butyl acetate dispersions Sample Reference Stability Comment (4 weeks at 40 C.) BA1 Development of clear liquid phase and sediment BA2 No clear phase but some sediment BA3 No clear phase but some sediment

TABLE-US-00005 TABLE 5 Sample: BA1 BA2 BA3 TSI Index 0.25 0.55 0.15 Clear layer development 9 days 9 days none (days) Clear layer thickness (at 2 mm 1 mm 0 35 d)

[0065] The use of a wetting agent provides marginal improvement to a graphene dispersion in Butyl Acetate. Use of a grinding resin significantly reduces sedimentation and synereisis while not impacting final performance characteristics.

Example 2: Dispersion of Graphitic Material A-GNP10 in Methyl Ethyl Ketone

[0066] Samples of dispersions referenced as MEK1 to MEK3 were made up including graphitic material A-GNP10 and methyl ethyl ketone as shown in Table 6.

TABLE-US-00006 TABLE 6 Graphene/ Sample Graphitic Reference material Grinding resin Wetting agent Solvent ΛΛEK1 10 wt % AGNP-10 — — Methyl ethyl ketone MEK2 10 wt % AGNP-10 — DISPERBYK-2150 Methyl ethyl ketone MEK3 10 wt % AGNP-10 Laropal A81 — Methyl ethyl ketone

[0067] Each of samples MEK1 to MEK3 was made up using the same steps as used in connection with samples BA1 to BA3 as set out above.

TABLE-US-00007 TABLE 7 Particle Size Distribution of MEK Dispersions Sample Particle Size Distribution (μm) Reference GNP Type D × 10 D × 50 D × 90 MEK1 A-GNP10 0.388 3.03 13.2 MEK2 A-GNP10 0.28 2.66 12.9 MEK3 A-GNP10 0.62 7.75 17.7

TABLE-US-00008 TABLE 8 Viscosity of MEK Dispersions measured on manufacture at a shear rate ({dot over (γ)}) of 10 s.sup.−1 at 23° C. Sample Initial Viscosity Reference GNP Type (Pa .Math. s) MEK1 A-GNP10 0.000826 MEK2 A-GNP10 0.00104 MEK3 A-GNP10 0.9375

[0068] FIG. 2 provides a graph showing the relationship between viscosity and shear rate for samples MEK1 to MEK3 of table 6.

TABLE-US-00009 TABLE 9 Storage stability of MEK Dispersions Sample Reference Stability Comment (4 weeks) at 40 C. MEK1 Significant Hard Sediment MEK2 Soft Sediment MEK3 Soft Sediment

TABLE-US-00010 TABLE 10 Sample: MEK1 MEK2 MEK3 TSI Index 1.5 0.55 0.1 Clear layer development 5 days none none (days) Clear layer thickness (at 5 mm 0 0 35 d)

[0069] The use of a wetting agent provides improvement to a graphene dispersion in Methyl Ethyl Ketone. Use of a grinding resin however significantly improves dispersion stability as demonstrated in the resulting TSI and no significant destabilisation. No impact on final performance characteristics was observed.

Example 3: Dispersion of Graphitic Material A-GNP10 in Xylene

[0070] Samples of dispersions referenced as X1 to X3 were made up including graphitic material A-GNP10 and xylene as shown in Table 11.

TABLE-US-00011 TABLE 11 Graphene/ Sample Graphitic Reference material Grinding resin Wetting agent Solvent X1 10 wt % AGNP-10 — — Xylene X2 10 wt % AGNP-10 — DISPERBYK-2150 Xylene X3 10 wt % AGNP-10 Laropal A81 — Xylene

[0071] Each of samples X1 to X3 was made up using the same steps as used in connection with samples BA1 to BA3 as set out above.

TABLE-US-00012 TABLE 12 Particle Size Distribution of Xylene Dispersions Sample Particle Size Distribution (μm) Reference GNP Type D × 10 D × 50 D × 90 X1 A-GNP10 1.05 2.36 6.67 X2 A-GNP10 0.43 3.61 14.4 X3 A-GNP10 0.94 3.13 15.3

TABLE-US-00013 TABLE 13 Viscosity of MEK Dispersions measured on manufacture at a shear rate ({dot over (γ)}) of 10 s.sup.−1 at 23° C. Sample Initial Viscosity Reference GNP Type (Pa.s) X1 A-GNP10 0.1453 X2 A-GNP10 0.00337 X3 A-GNP10 0.2846

[0072] FIG. 3 provides a graph showing the relationship between viscosity and shear rate for samples X1 to X3 of table 11

TABLE-US-00014 TABLE 14 Storage stability of Xylene Dispersions Sample Reference Stability Comment (4 weeks) X1 Significant Sedimentation X2 Significant Sedimentation X3 Thin wall of Sediment on glass

TABLE-US-00015 TABLE 15 Sample: X1 X2 X3 TSI Index 1 0.8 0.15 Clear layer development 2 days 6 days none (days) Clear layer thickness (at 8 mm 2 mm 0 35 d)

[0073] The use of a wetting agent provides marginal improvement to a graphene dispersion in Xylene. Use of a grinding resin however significantly reduces sedimentation and synereisis as demonstrate, while the resulting TSI indicates no significant destabilisation. No impact on final performance characteristics was observed.