Process for producing graphene foam laminate based sealing materials

#The present invention relates generally to the field of sealing materials and elements (e.g. O-rings, gaskets, etc.) and, more particularly, to a new class of graphene foam laminate-based sealing materials.

#A sealing material (e.g. an O-ring) must have a high elastic deformation and high yield strength, the two mechanical properties that are often mutually exclusive. For example, a successful O-ring joint design requires a rigid mechanical mounting that applies a large deformation to the O-ring, which introduces a mechanical stress at the O-ring contacting surfaces. Leaking will not occur as long as the pressure of the fluid being contained does not exceed the contact stress of the O-ring. The contact stress rises with increasing pressure and an O-ring can seal high pressure as long as the contact stress does not exceed the yield strength of the O-ring.

#The seal is often designed to have a point contact between the O-ring and sealing faces. The O-ring must be able to contain high pressure without exceeding the yield stress of the O-ring body. The flexible (elastic) nature of O-ring materials accommodates imperfections in the mounting parts. Rubbers or elastomers are the most commonly used O-ring materials due to their high elastic deformation and moderate yield strength under compression. However, rubbers and elastomers alone are typically not mechanically strong and do not withstand high temperatures.

#FIG. 1(A) Schematic drawing illustrating the processes for producing conventional paper, mat, film, and membrane of simply aggregated graphite flakes or NGP platelets. All processes begin with intercalation and/or oxidation treatment of graphitic materials (e.g. natural graphite particles).

#FIG. 1(B) A SEM image of a graphite worm sample after thermal exfoliation of graphite intercalation compounds (GICs) or graphite oxide powders.

#FIG. 2 Schematic of some cross-sectional view of a presently invented 3-layer laminate according to some embodiments of the instant invention.

#The present invention provides a graphene foam laminate for use as a sealing material The laminate comprises: (a) a layer of graphene foam having a thickness from 100 nm to 10 cm and comprising pores and pore walls having a 3D network of interconnected graphene planes or graphene sheets; and (b) a permeation-resistant polymer layer disposed on a primary surface of the graphene foam to form a two-layer laminate or two permeation-resistant polymer layers disposed on the two primary surfaces of the graphene foam to form a three-layer sandwich laminate, wherein the permeation-resistant polymer layer has a thickness preferably from 10 nm to 1 cm. Such a laminated material exhibits an unprecedented combination of high elastic deformation, high yield strength, high permeation resistance, high-temperature durability, and good thermal conductivity (for fast heat dissipation).

#The 3D network of interconnected graphene sheets or planes provides the needed high elasticity, high strength, high thermal conductivity, high yield strength, and improved thermal stability of the sealing material. The graphene sheets in the graphene foam layer may be selected from pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, or a combination thereof.

#The solid graphene foam (prior to being laminated with a protecting polymer layer) for use in the presently invented sealing material typically has a density from 0.01 to 1.7 g/cm3 (more typically from 0.1 to 1.5 g/cm3, and even more typically from 0.1 to 1.0 g/cm3, and most typically from 0.2 to 0.75 g/cm3), or a specific surface area from 50 to 2,600 m2/g (more typically from 200 to 2,000 m2/g, and most typically from 500 to 1,500 m2/g).