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1. WO2018051095 - METHOD OF FORMING GRAPHENE NANOPLATELETS, GRAPHENE NANOPLATELETS SO-OBTAINED AND COMPOSITES COMPRISING SAID NANOPLATELETS

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[ EN ]

CLAIMS

1. A method of forming graphene nanoplatelets, comprising:

(a) providing an aqueous suspension comprising expanded graphite;

(b) subjecting the suspension to exfoliation, wherein the exfoliation comprises sequential treatments of sonication and high shear mixing, thereby forming graphene nanoplatelets; and

(c) optionally isolating the graphene nanoplatelets from the suspension.

2. The method of claim 1 , wherein the aqueous suspension comprises no organic solvents.

3. The method of claim 1 or claim 2, wherein the aqueous suspension is a surfactant free aqueous suspension.

4. The method of any preceding claim, wherein the sonication comprises treatment with at least one volumetric sonicator (T) and/or at least one high power sonicator (F).

5. The method of any preceding claim, wherein the high shear mixing comprises mixing with a high shear mixer (S).

6. The method of claim 4 or claim 5, wherein the at least one volumetric sonicator (T)

provides a pretreatment prior to treatment with at least one high power sonicator (F) and/or at least one high shear mixer (S).

7. The method of any of claims 4 to 6, wherein the exfoliation comprises sequential

treatment with at least one volumetric sonicator (T), at least one high power sonicator (F), and at least one high shear mixer (S), optionally wherein the exfoliation comprises a sequential treatment selected from the following STFFS, TFF, TFFS, STSFF, TSFF, TTSFF, TFSTF, STFF, TFFSTFF.

8. The method of any of claims 4 to 7, wherein the at least one volumetric sonicator (T) comprises an output with an amplitude of not more than 50 μηι, optionally of not more than 40 μι ι.

9. The method of any of claims 4 to 8, wherein the at least one volumetric sonicator (T) comprises a power output of at least 250 W and not more than 3500 W, optionally a power output of at least 500 W and not more than 2500 W.

10. The method of any of claims 4 to 9, wherein the at least one high power sonicator (F) comprises an output with an amplitude of at least 40 μηι and not more than 150 μηι, optionally with an amplitude of at least 50 μηι and not more than 100 μηι.

1 1. The method of any of claims 4 to 10, wherein the at least one high power sonicator (F) comprises a power output of at least 1500 W and not more than 20000 W, optionally a power output of at least 2000 W and not more than 16000 W.

12. The method of any of claims 4 to 1 1 , wherein the at least one volumetric sonicator (T) and / or at least one high power sonicator (F) each independently provide a frequency field for sonication of at least 20 and not more than 40 kHz.

13. The method of any preceding claim, wherein the expanded graphite is provided at a concentration of about 0.1 % w/w to about 10% w/w of the aqueous suspension of step (a).

14. The method of claim 13, wherein the expanded graphite is provided at a concentration of about 2% w/w to about 8% w/w of the aqueous suspension of step (a), optionally wherein the expanded graphite is provided at a concentration of about 3% w/w to about 7% w/w of the aqueous suspension of step (a), further optionally wherein the expanded graphite is provided at a concentration of about 4% w/w to about 6% w/w of the aqueous suspension of step (a).

15. The method of any of claims 1 to 13, wherein the expanded graphite is provided at a concentration of about 2% w/w, about 3% w/w, about 4% w/w, about 5% w/w, about 6% w/w, about 7% w/w, or about 8% w/w of the aqueous suspension of step (a).

16. The method of any preceding claim, wherein the exfoliation is performed at a pressure of from about 1 to about 10 bar, optionally wherein the pressure is from about 2 to about 7 bar, further optionally wherein the pressure is from about 3 to about 5 bar.

17. The method of any preceding claim, wherein the exfoliation is performed for a period of from at least 1 hour to not more than 10 hours, optionally for a period of from at least 2 hours to not more than 8 hours, further optionally for a period of from at least 3 hours to not more than 6 hours.

18. The method of any of any proceeding claim, wherein the exfoliation is performed until the suspension reaches a viscosity of not more than about 500 cP.

19. The method of any preceding claim, comprising isolating the graphene nanoplatelets from the suspension and optionally drying the graphene nanoplatelets.

20. The method of any preceding claim, wherein the graphene nanoplatelets have a

thickness of not more than 30 nm, optionally a thickness of not more than 20 nm, further optionally a thickness of not more than 10 nm.

21. The method of any proceeding claim, wherein the graphene nanoplatelets have a lateral size of at least 0.5 μηι and not more than 100 μηι, optionally wherein the graphene nanoplatelets have a lateral size of at least 1 μηι and not more than 50 μηι.

22. The method of any preceding claim, wherein the graphene nanoplatelets have an aspect ratio (thickness / lateral size) of not more than 0.01 , optionally of not more than 0.005, further optionally of not more than 0.002, still further optionally of not more than 0.001.

23. The method of any preceding claim, wherein the graphene nanoplatelets have a high platelet planarity.

24. The method of any proceeding claim, wherein the graphene nanoplatelets have a

specific surface area of from 40 m2/g to 100 m2/g, optionally wherein the graphene nanoplatelets have a specific surface area of from 60 m2/g to 80 m2/g.

25. The method of any proceeding claim, wherein the method is a continuous flow process.

26. A method of forming an expanded graphite, comprising obtaining an expandable

graphite and heating the expandable graphite in flowing gas at a temperature of at least 600 °C.

27. The method of claim 26, wherein the expandable graphite that is converted to expanded graphite has an expansion ratio of at least 200 cm3/g and not more than 400 cm3/g.

28. The method of claim 26 or claim 27, wherein the flowing gas is selected from air and nitrogen.

29. The method of any of claims 26 to 28, wherein the expandable graphite is an

intercalated expandable graphite, optionally a sulphuric intercalated expanded graphite.

30. The method of any of claims 26 to 29, wherein the method is a continuous flow process.

31. The method of any of claims 1 to 25, wherein the expanded graphite is formed according to a method of any of claims 26 to 30.

32. Graphene nanoplatelets having the properties of graphene nanoplatelets produced

according to the method of any of claims 1 to 25 or 31.

33. Graphene nanoplatelets obtainable by a method of any of claims 1 to 25 or 31.

34. Graphene nanoplatelets obtained by a method of any of claims 1 to 25 or 31.

35. A plastics composite comprising the graphene nanoplatelets of any of claims 32 to 34 in an amount of at least 0.1 %wt.

36. The plastics composite of claim 35, wherein:

the graphene nanoplatelets are present in an amount of at least 0.2 %wt, optionally 0.5 %wt, further optionally at least 1 %wt or at least 2 %wt; and/or

the graphene nanoplatelets are present in an amount of not more than 10 %wt, optionally of not more than 8 %wt, further optionally of not more than 6 %wt or of not more than 5 %wt; and/or

the graphene nanoplatelets are present in an amount of from 0.2 %wt to 8 %wt, optionally in an amount of from 0.5 %wt to 7 %wt, further optionally in an amount of from 1 %wt to 6 %wt, still further optionally in an amount of from 2 %wt to 5 %wt.

37. The plastics composite of claim 35 or 36, comprising a structural polymer selected from a thermoplastic, a thermoset, and a mixture thereof.

38. The plastics composite of claim 37, wherein the thermoplastic is or comprises a

polyamide or polyether sulfone, optionally wherein the polyamide is polyamide 6.

39. The plastics composite of claim 37 or claim 38, wherein the thermoset is or comprises an epoxy resin, optionally wherein the epoxy resin comprises bisphenol A epoxy, bisphenol

F epoxy, phenol novolak epoxy resin and/or polyfunctional epoxy resin.

40. The plastics composite of any of claims 35 to 39, wherein the composite further

comprises a reinforcing agent.

41. The composite of claim 40, wherein the reinforcing agent is a fibre reinforcing agent. 42. The composite of claim 40 or 41 , wherein the reinforcing agent is selected from glass fibre, carbon fibre, aramid fibre and basalt fibre.

43. The composite of any of claims 40 to 42, wherein the reinforcing agent is present in an amount of from 5 %wt to 70 %wt, optionally 10 %wt to 40 %wt.

44. A vehicle or structure comprising a composite of any of claims 35 to 43.

45. Use of graphene nanoplatelets of any of claims 32 to 34 in a plastics composite.

46. The use of claim 45, wherein the plastics composite has the features of any of claims 35 to 43.