Thermal interface materials and methods

Abstract

Composite materials that may include a matrix material, an adhesive, a first plurality of particles, and a second plurality of particles. The first plurality of particles and the second plurality of particles may include particles having different shapes, such as shapes that may facilitate the formation of an interconnected network of the particles. Methods for forming composite materials, and methods of using composite materials, such as using the composite materials to improve heat transfer.

Description

THERMAL INTERFACE MATERIALS AND METHODSCross-Reference to Related Applications

[0001] This application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 640,327, filed April 30, 2024, which is incorporated herein by reference.Field of the Disclosure

[0002] This disclosure relates to thermal interface materials, such as pastes, that may include particles of different shapes, and methods for forming and using thermal interface materials.Background

[0003] Thermal interface materials (TIM) are substances that can be configured to bridge gaps between two surfaces having different temperatures, thereby providing one or more improvements, such as an improved heat transfer rate, effective adhesion, etc. Therefore, TIMs can play an important role in reducing or minimizing energy loss, and, in some instances, enhancing the overall performance of a system.

[0004] TIMs can have various forms, including, but not limited to, thermal pads, thermal grease, gap fillers, thermal paste, thermal gels, etc. Generally, TIMs may include a matrix phase, a filler material, and other additives. The matrix phases typically include viscoelastic polymers, and the filler materials can include a wide range of materials, such as metals, ceramics, and hybrid materials.

[0005] There remains a need for improved composite materials, such as TIMs, that have or provide one or more improved properties, such as an improved thermal conductivity and an enhanced heat transfer rate.Brief Summary

[0006] Provided herein are methods of forming or using composite materials, and composite materials, embodiments of which have one or more of the foregoing properties, such as improved thermal conductivities.

[0007] In one aspect, composite materials are provided. In some embodiments, the composite materials include a matrix material, a first plurality of particles, a second plurality of particles, and an adhesive. In some embodiments, a shape of the first plurality of particles differs from a shape of the second plurality of particles. The shape of the second plurality of particles may be effective to reducethe Gibbs energy barrier for nucleation (e.g., heterogeneous nucleation) of an adhesive from a liquid to surfaces of the second plurality of particles. The first plurality of particles and the second plurality of particles may form an interconnected network in the composite material due to points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles.

[0008] In another aspect, methods of forming composite materials are provided. In some embodiments, the methods include providing a first plurality of particles; providing a second plurality of particles, an adhesive, and a liquid, wherein the second plurality of particles and the adhesive are dispersed in the liquid, and the second plurality of particles is at least partially coated with the adhesive; disposing the first plurality of particles in the liquid, and mixing the first plurality of particles, the second plurality of particles, and the liquid; and disposing a matrix material in the liquid, and mixing the matrix material, the first plurality of particles, the second plurality of particles, and the liquid to form the composite material. The providing of the second plurality of particles, the adhesive, and the liquid may include contacting the adhesive and the liquid, and mixing the adhesive and the liquid; and contacting the second plurality of particles, the adhesive, and the liquid, and mixing the second plurality of particles, the adhesive, and the liquid for a time effective to coat at least a portion of the second plurality of particles with the adhesive. In some embodiments, the methods include providing a first plurality of particles and an adhesive, wherein the first plurality of particles is at least partially coated with the adhesive; providing a second plurality of particles; contacting the first plurality of particles, the second plurality of particles, and the adhesive, and optionally mixing the first plurality of particles, the second plurality of particles, and the adhesive; and contacting the first plurality of particles, the second plurality of particles, the adhesive, and a matrix material, and optionally mixing the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive. The methods also may include separating a portion of the adhesive from the first plurality of particles before contacting the first plurality of particles, the second plurality of particles, and the adhesive, or before contacting the first plurality of particles, the second plurality of particles, the adhesive, and the matrix material.

[0009] In yet another aspect, methods of using composite materials are provided, such as using composite materials to improve heat transfer. In some embodiments, the methods include providing a composite material described herein, and arranging the composite material between and in contact with a surface of a first object and a surface of a second object. The surface of the firstobject and the surface of the second object may be at different temperatures prior to the arranging of the composite material.

[0010] Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the aspects described herein. The advantages described herein may be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.Brief Description of the Drawings

[0011] FIG. 1A is a schematic of an embodiment of a composite material.

[0012] FIG. IB is a schematic of an embodiment of a composite material.

[0013] FIG. 2A depicts the thermal conductivity of a reference composite material.

[0014] FIG. 2B depicts the thermal conductivity of an embodiment of a composite material.

[0015] FIG. 3A depicts a Fourier transform infrared (FTIR) spectrum of a reference composite material.

[0016] FIG. 3B depicts a FTIR spectrum of an embodiment of a composite material.

[0017] FIG. 3C depicts peak assignments of the spectrum of FIG. 3A.

[0018] FIG. 4A depicts an X-ray diffraction (XRD) pattern for a reference composite material.

[0019] FIG. 4B depicts an XRD pattern for an embodiment of a composite material.

[0020] FIG. 5A depicts further thermal conductivity results of a reference composite material.

[0021] FIG. 5B depicts further thermal conductivity results of an embodiment of a composite material.

[0022] FIG. 6 depicts the thermal conductivity of an embodiment of a composite material.

[0023] FIG. 7A depicts rheological characteristics of an embodiment of a composite material at a shear rate of 0.01 s'1.

[0024] FIG. 7B depicts rheological characteristics of an embodiment of a composite material at a shear rate of 0. 1 s'1.

[0025] FIG. 7C depicts rheological characteristics of an embodiment of a composite material at a shear rate of 100 s'1.

[0026] FIG. 7D depicts rheological characteristics of an embodiment of a composite material at a shear rate of 300 s'1.

[0027] FIG. 8 depicts an FTIR spectrum of an embodiment of a composite material.

[0028] FIG. 9 depicts an XRD pattern for an embodiment of a composite material.

[0029] FIG. 10 depicts a differential scanning calorimetry (DSC) plot collected for an embodiment of a composite material.Detailed Description

[0030] Provided herein are composite materials, such as pastes, methods of forming composite materials, and methods of using composite materials, such as using composite materials to improve heat transfer among two or more objects.Composite Materials

[0031] Composite materials are provided herein, which may include a matrix material, a first plurality of particles, a second plurality of particles, and an adhesive. A shape of the first plurality of particles may differ from a shape of the second plurality of particles. The first plurality of particles and the second plurality of particles may be dispersed evenly or unevenly in the matrix materials.

[0032] The first plurality of particles and the second plurality of particles may form an interconnected network in the composite material due to points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles. An embodiment of a composite material 100 that features an interconnected network 110 of the first and second pluralities of particles is depicted at FIG. 1A. In the embodiment depicted at FIG. 1A, the first plurality of particles are flake particles 120, and the second plurality of particles are rod-shaped particles 130 (also referred to as fiber materials). The first and second pluralities of particles are dispersed in a matrix material 140 and physically contact each other at multiple points. Although each end of the rod-shaped particles contact a flake-shaped particle in FIG. 1A, it should be noted that FIG. 1A is merely a schematic, and it is envisioned that, in some instances, not every particle will be in physical contact with another particle and / or or in the manner depicted at FIG. 1A. For example, one or more of the first plurality of particles may be in direct contact with one or more others of the first plurality of particles (e.g., flake particles in contact with other flake particles). Likewise, one or more of the second plurality of particles may be in direct contact with one or more others of the second plurality of particles (e.g., rod particles in contact with other rod particles). Also, one or more of the first plurality of particles and / or one or more of the second plurality ofparticles may be physically isolated and not in contact with other particles, regardless of whether they are the same type or different type of particle.

[0033] Another embodiment of a composite material 200 that features an embodiment of an interconnected network 210 of the first and second pluralities of particles is depicted at FIG. IB. In the embodiment depicted at FIG. IB, the first plurality of particles are flake particles 220, and the second plurality of particles are rod-shaped particles 230 (also referred to as fiber materials). In contrast to the embodiment depicted at FIG. 1A, flake particles of different sizes are featured in the embodiment of the composite material depicted at FIG. IB. The first and second pluralities of particles are dispersed in a matrix material 240 and physically contact each other at multiple points. Although each end of the rod-shaped particles contact a flake-shaped particle in FIG. IB, it should be noted that FIG. IB is merely a schematic, and it is envisioned that, in some instances, not every particle will be in physical contact with another particle and / or or in the manner depicted at FIG. IB. For example, one or more of the first plurality of particles may be in direct contact with one or more others of the first plurality of particles (e.g., flake particles in contact with other flake particles). Likewise, one or more of the second plurality of particles may be in direct contact with one or more others of the second plurality of particles (e.g., rod particles in contact with other rod particles). Also, one or more of the first plurality of particles and / or one or more of the second plurality of particles may be physically isolated and not in contact with other particles, regardless of whether they are the same type or different type of particle.

[0034] Due to their shapes and / or other features described herein, the first plurality of particles and the second plurality of particles may provide conductive pathways in a composite material, due at least in part to the points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles, such as those depicted at FIG. 1A and FIG. IB. The conductive pathways may be thermally conductive pathways.

[0035] The composite materials may be in any physical form and / or any phase of matter, for example, a solid, semi-solid, or fluid. In some embodiments, the composite material is a paste.

[0036] In some embodiments, the composite materials have thermal conductivities that exceed, to a surprising extent, the thermal conductivities of comparative composite materials. For example, embodiments of the composite materials described herein may have a thermal conductivity (W / m'1K’1) that is at least 30 %, at least 40 %, at least 50 %, or at least 60 % greater than a thermal conductivity (W / m^K-1) of a comparative composite material. For example, if a comparative composite material has a thermal conductivity of 10 units, and a composite material has a thermalconductivity of 16 units, then the composite material has a thermal conductivity that is 60 % greater than the thermal conductivity of the comparative composite material.

[0037] The phrase “comparative composite material”, as used herein, refers to a material that includes a first plurality of particles but not a second plurality of particles (see, e.g., the reference composite material of Example 1), wherein the first plurality of particles is present in a comparative composite material at a concentration that is within about 10 wt%, about 5 wt%, or about 1 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material. For example, if a comparative composite material includes about 35 wt% to about 45 wt% of the first plurality of particles, and a composite material includes about 30 wt% of the first plurality of particles and about 10 wt% of the second plurality of particles, then the comparative composite material includes the first plurality of particles at a concentration that is within about 5 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material.

[0038] When an embodiment of a composite material described herein and a comparative composite material are compared, then the embodiment of the composite material and the comparative composite material may include (i) the same matrix material or similar matrix materials, and (ii) the same adhesive or similar adhesives.

[0039] In some embodiments, the composite materials described herein unexpectedly have a thermal impedance (K m2W-1) that is at least 30 %, at least 40 %, at least 50 %, or at least 60 % less than a thermal impedance (K m2W-1) of a comparative composite material. For example, if a comparative composite material has a thermal impedance of 10 units, and a composite material has a thermal impedance of 6 units, then the composite material has a thermal conductivity that is 40 % less than the thermal impedance of the comparative composite material.Methods of Forming Composite Materials

[0040] Also provided herein are methods of forming composite materials. In some embodiments, the methods include providing a first plurality of particles, and providing a second plurality of particles, an adhesive, and a liquid. The second plurality of particles and the adhesive may be dispersed in the liquid, and the second plurality of particles may be at least partially coated with the adhesive. The methods also may include disposing the first plurality of particles in the liquid, and optionally mixing the first plurality of particles, the second plurality of particles, and the liquid. The methods also may include disposing a matrix material in the liquid, and optionallymixing the matrix material, the first plurality of particles, the second plurality of particles, and the liquid to form the composite material.

[0041] The providing of the second plurality of particles, the adhesive, and the liquid may be achieved using any technique known in the art. In some embodiments, the providing of the second plurality of particles, the adhesive, and the liquid includes contacting the adhesive and the liquid, and optionally mixing (e.g., via stirring or otherwise) the adhesive and the liquid; and contacting the second plurality of particles, the adhesive, and the liquid, and optionally mixing (e.g., via stirring or otherwise) the second plurality of particles, the adhesive, and the liquid for a time effective to coat at least a portion of the second plurality of particles with the adhesive.

[0042] When the adhesive is soluble in the liquid, the mixing of the adhesive and the liquid may occur for any time effective to dissolve, completely or partially, the adhesive in the liquid. In some embodiments, the mixing of the adhesive and the liquid occurs for a time of about 5 to about 20 minutes, or about 10 minutes to about 15 minutes. At least a portion of the liquid may be separated from the second plurality of particles before disposing the first plurality of particles in the liquid. The liquid may be separated using any known technique, such as filtration, evaporation, heating, etc. In some embodiments, the liquid is a super-saturated solution of the adhesive (i .e., the adhesive is present in the liquid at an amount that exceeds the maximum amount of the adhesive that is soluble in the liquid at a temperature at which the method is performed).

[0043] The mixing of the first plurality of particles, the second plurality of particles, and the liquid may be achieved using any known technique. The technique may include dynamic and / or static mixing. The mixing may be achieved with a dynamic mixer, for example, a rotary mixer. The mixing of the first plurality of particles, the second plurality of particles, and the liquid may be performed in a manner that imparts a force that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles. The force may be effective to preserve, to a desired extent, an interconnected network that may be formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles. The force may be controlled by limiting the time of mixing, the intensity of mixing, the mixing apparatus, etc. In some embodiments, the mixing of the first plurality of particles, the second plurality of particles, and the liquid includes stirring with a rotary mixer at about 5 rpm to about 50 rpm, about 10 rpm to about 50 rpm, about 20 rpm to about 50 rpm, about 30 rpm to about 50 rpm, about 40 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm. In some embodiments, the mixing of the firstplurality of particles, the second plurality of particles, and the liquid occurs for about 30 seconds to about 5 minutes, about 1 minute to about 5 minutes, about 2 minutes to about 5 minutes, about 3 minutes to about 5 minutes, about 4 minutes to about 5 minutes, about 30 seconds to about 4 minutes, about 30 seconds to about 3 minutes, about 30 seconds to about 2 minutes, or about 30 seconds to about 1 minute.

[0044] The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid may be achieved using any known technique. The technique may include dynamic and / or static mixing. The mixing may be achieved with a dynamic mixer, for example, a rotary mixer. The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid may be performed in a manner that imparts a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles. The force may be effective to preserve, to a desired extent, an interconnected network that may be formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles. The force may be controlled by limiting the time of mixing, the intensity of mixing, the mixing apparatus, etc. In some embodiments, the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid includes stirring with a rotary mixer at about 5 rpm to about 60 rpm, about 10 rpm to about 60 rpm, about 20 rpm to about 60 rpm, about 30 rpm to about 60 rpm, about 40 rpm to about 60 rpm, about 50 rpm to about 60 rpm, about 5 rpm to about 60 rpm, about 5 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm. In some embodiments, the mixing of the first plurality of particles, the second plurality of particles, and the liquid occurs for about 10 minutes to about 30 minutes, about 10 minutes to about 25 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 15 minutes, about 15 minutes to about 30 minutes, about 20 minutes to about 30 minutes, or about 25 minutes to about 30 minutes.

[0045] In some embodiments, the methods include providing a first plurality of particles and an adhesive, wherein the first plurality of particles is at least partially coated with the adhesive, providing a second plurality of particles, contacting the first plurality of particles, the second plurality of particles, and the adhesive, and optionally mixing (e.g., via stirring or otherwise) the first plurality of particles, the second plurality of particles, and the adhesive. The methods also may include contacting the first plurality of particles, the second plurality of particles, the adhesive, and a matrixmaterial, and optionally mixing (e.g., via stirring or otherwise) the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive.

[0046] The providing of the first plurality of particles and the adhesive may include contacting the adhesive and the first plurality of particles, and optionally mixing (e.g., via stirring or otherwise) the adhesive and the first plurality of particles for a time effective to coat at least a portion of the first plurality of particles with the adhesive. The methods may include separating a portion of the adhesive, such as an excess portion of the adhesive, from the first plurality of particles (such as via filtration or otherwise) before contacting the first plurality of particles, the second plurality of particles, and the adhesive, or before contacting the first plurality of particles, the second plurality of particles, the adhesive, and the matrix material.

[0047] The mixing of the first plurality of particles, the second plurality of particles, and the adhesive may be achieved using any technique, such as stirring. The stirring may be performed with a dynamic mixer, for example, a rotary mixer.

[0048] The mixing of the first plurality of particles, the second plurality of particles, and the adhesive may impart a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles. In some embodiments the mixing of the first plurality of particles, the second plurality of particles, and the adhesive includes stirring with a rotary mixer at about 5 rpm to about 50 rpm, about 10 rpm to about 50 rpm, about 20 rpm to about 50 rpm, about 30 rpm to about 50 rpm, about 40 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm. In some embodiments, the mixing of the first plurality of particles, the second plurality of particles, and the adhesive occurs for about 30 seconds to about 5 minutes, about 1 minute to about 5 minutes, about 2 minutes to about 5 minutes, about 3 minutes to about 5 minutes, about 4 minutes to about 5 minutes, about 30 seconds to about 4 minutes, about 30 seconds to about 3 minutes, about 30 seconds to about 2 minutes, or about 30 seconds to about 1 minute.

[0049] The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive may include stirring, such as with a dynamic mixer, for example, a rotary mixer. The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive may impart a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between thefirst plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles. The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive may include stirring with a rotary mixer at about 5 rpm to about 60 rpm, about 10 rpm to about 60 rpm, about 20 rpm to about 60 rpm, about 30 rpm to about 60 rpm, about 40 rpm to about 60 rpm, about 50 rpm to about 60 rpm, about 5 rpm to about 60 rpm, about 5 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm. The mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive may occur for about 10 minutes to about 30 minutes, about 10 minutes to about 25 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 15 minutes, about 15 minutes to about 30 minutes, about 20 minutes to about 30 minutes, or about 25 minutes to about 30 minutes.Methods of Using Composite Materials

[0050] Also provided herein are methods of using composite materials, such as any of those described herein. In some embodiments, the methods include providing a composite material, such as any of those described herein; and arranging the composite material between and in contact with a surface of a first object and a surface of a second object. The surface of the first object and the surface of the second object may be at different temperatures prior to the arranging of the composite material. The temperature difference between the different temperatures of the surface of the first object and the surface of the second object may be at least 5 °C, at least 10 °C, at least 20 °C, at least 30 °C, at least 40 °C, or at least 50 °C.

[0051] The first object and the second object generally may be formed of any material (e.g., metal, ceramic, plastic, glass, etc.) and have any shape. The first object and / or the second object may be part of an appliance, such as an appliance configured for heating and / or cooling a space (e g., a furnace, boiler, air conditioner, heat pump, etc.), a tanked or tankless water heater, etc. The first object, for example, may be a pipe, channel, or other heat exchanger component. In some implementations, the first object is a condenser in a refrigeration circuit, such as for a heat pump water heater. For example, the first object may be a microchannel condenser in the refrigeration circuit. The second object may be a tank. For example, the tank may be a hot water tank arranged for heat exchange with the first object (e.g., microchannel condenser of a heat pump water heater).First Plurality of Particles

[0052] In some embodiments, the first plurality of particles includes flake-shaped particles, which may be referred to as “flake particles”. Each particle of the first plurality of particles may have a first surface, a second surface opposite the first surface, and a thickness.

[0053] The first plurality of particles may include particles having different dimensions (see, for example, FIG. IB) or one or more substantially uniform dimensions (i.e., thicknesses (and / or other dimension) within ± 5 % of each other) (see, for example, FIG. 1A). Dimensions are “substantially uniform” herein when the dimensions are within ± 5 % or ± 1 % of each other. When the first plurality of particles have a first surface, a second surface opposite the first surface, and a thickness, the first plurality of particles may have an average thickness of about 10 pm to about 200 pm, about 10 pm to about 150 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 50 pm to about 200 pm, about 100 pm to about 200 pm, or about 150 pm to about 200 pm, and / or an average largest dimension of the first surface of about 1 pm to about 200 pm, about 10 pm to about 200 pm, about 10 pm to about 150 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 50 pm to about 200 pm, about 100 pm to about 200 pm, or about 150 pm to about 200 pm. The first plurality of particles may feature any ratio of the average largest dimension of the first surface to the average thickness. In some embodiments, a ratio of the average largest dimension of the first surface to the average thickness is about 100: 1 to about 1 :1, about 50: 1 to about 1 : 1, about 40: 1 to about 1 : 1, about 30: 1 to about 1 : 1, about 20: 1 to about 1 : 1, about 10: 1 to about 1 : 1, about 100: 1 to about 2: 1, about 50: 1 to about 2: 1, about 40: 1 to about 2: 1, about 30: 1 to about 2:1, about 20: 1 to about 2: 1, or about 10: 1 to about 2: 1 (average largest dimension of the first surface : average thickness).

[0054] The first plurality of particles generally may be formed of any one or more materials that imparts one or more desired properties to a composite material. In some embodiments, the first plurality of particles is formed at least in part of a first metal, a first ceramic, or a combination thereof. The first metal may include aluminum, silver, or a combination thereof. The first ceramic may include alumina, aluminum nitride, zinc oxide, silicon carbide, silicon nitride, beryllium oxide, or a combination thereof. In some embodiments, the first plurality of particles is formed at least in part of graphene, carbon nanotubes (e.g., a buckypaper, a nanoribbon, etc.), or a combination thereof.

[0055] A first plurality of particles generally may be present in a composite material at any concentration, such as a concentration that provides an interconnected network of particles, as described herein. In some embodiments, the first plurality of particles is present in a compositematerial at an amount of about 0.1 wt% to about 50 wt%, about 5 wt% to about 45 wt%, about 10 wt% to about 40 wt%, about 20 wt% to about 40 wt%, about 20 wt% to about 30 wt%, or about 24 wt% to about 26 wt%, based on the weight of the composite material.Second Plurality of Particles

[0056] The second plurality of particles may be at least partially coated with an adhesive, as described herein. The selected shape of the second plurality of particles may be effective to reduce the Gibbs energy barrier for nucleation (e.g., heterogeneous nucleation) of the adhesive from a liquid (e g., a solution of the adhesive) to surfaces of the second plurality of particles, which may result in a substantially uniform deposition of the adhesive on the surfaces. In some embodiments, the second plurality of particles includes rod-shaped particles.

[0057] The second plurality of particles may include particles having different dimensions or substantially uniform dimensions (e g., lengths within ± 5 % of each other). When the second plurality of particles includes rod-shaped particles, each particle of the second plurality of particles may have a length (or height) and a width (or diameter when the rod-shaped particles are cylindrical). In some embodiments, the second plurality of particles has an average width (or diameter) of about 1 pm to about 400 pm, about 40 pm to about 400 pm, about 1 pm to about 300 pm , about 40 pm to about 300 pm, about 1 pm to about 200 pm, about 40 pm to about 200 pm, about 1 pm to about 100 pm, about 40 pm to about 100 pm, about 100 pm to about 400 pm, about 200 pm to about 400 pm, or about 300 pm to about 400 pm, and / or an average length (or height) of about 1 pm to about 2,000 pm , about 1 pm to about 1,500 pm, about 1 pm to about 1,000 pm, about 1 pm to about 500 pm, about 10 pm to about 500 pm, about 10 pm to about 400 pm, about 10 pm to about 300 pm, about 10 pm to about 200 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 50 pm to about 500 pm, about 100 pm to about 500 pm, about 200 pm to about 500 pm, about 300 pm to about 500 pm, or about 400 pm to about 500 pm.

[0058] When the second plurality of particles includes rod-shaped particles, the rod-shaped particles generally may feature any ratio of length to width, including a ratio that achieves an effective reduction of the Gibbs energy barrier, as described herein. In some embodiments, a ratio of the average length (or height) to the average width (or diameter) is about 50: 1 to about 1 : 1, about 40: 1 to about 1:1, about 30:1 to about 1 : 1, about 20: 1 to about 1 : 1, about 10: 1 to about 1 : 1, about 5: 1 to about 1 : 1, about 50: 1 to about 2: 1, about 40: 1 to about 2: 1, about 30: 1 to about 2: 1, about 20: 1 to about 2: 1, about 10: 1 to about 2: 1, about 5: 1 to about 2: 1, about 50: 1 to about 5: 1, about 40: 1 toabout 5: 1 , about 30: 1 to about 5: 1, about 20:1 to about 5:1, about 12: 1 to about 5: 1, about 10: 1 to about 5:1, or about 5: 1 to about 5:1 (average length (or height) : average width (or diameter)).

[0059] The second plurality of particles generally may be formed of any one or more materials that imparts one or more desired properties to a composite material. In some embodiments, the second plurality of particles is formed at least in part of a second metal, a second ceramic, or a combination thereof. The first metal of the first plurality of particles and the second metal of the second plurality of particles may be the same or different. The first ceramic of the first plurality of particles and the second ceramic of the second plurality of particles may be the same or different.

[0060] The second metal may include aluminum, silver, or a combination thereof. The second plurality of particles may be formed at least in part from a wool, such as a metal wool (e.g., aluminum wool), that has been processed to reduce the dimensions of the wool, particularly the lengths of each strand of the wool. The second ceramic may include alumina, aluminum nitride, zinc oxide, silicon carbide, silicon nitride, beryllium oxide, or a combination thereof. In some embodiments, the second plurality of particles is formed at least in part of graphene, carbon nanotubes (e.g., a buckypaper, a nanoribbon, etc.), or a combination thereof.

[0061] A second plurality of particles generally may be present in a composite material at any concentration, such as a concentration that provides an interconnected network of particles, as described herein. In some embodiments, the second plurality of particles is present in the composite material at an amount of about 0.001 wt% to about 30 wt%, about 0.1 wt% to about 25 wt %, about 0.1 wt% to about 20 wt%, about 5 wt% to about 15 wt%, or about 8 wt% to about 12 wt%.

[0062] The first plurality of particles and the second plurality of particles generally may be present in a composite material at any ratio, including a ratio that provides an interconnected network of particles, as described herein. In some embodiments, a ratio of the concentrations (wt%) of the first plurality of particles to the second plurality of particles in the composite material is about 2: 1 to about 4: 1, about 2: 1 to about 3 : 1, or about 2.5: 1 (first plurality of particles (wt%) : second plurality of particles (wt%)).Adhesive

[0063] The adhesive generally may include any known adhesive, including adhesives that are capable of effectively adhering to surfaces of the second plurality of particles. In some embodiments, the adhesive includes a surfactant. The adhesive may include a fatty acid, such as a saturated fatty acid. In some embodiments, the adhesive includes a compound of the following formula:

[0064] H3C(CH2)nCOOH;

[0065] wherein n is 10 to 30, 10 to 20, or 12 to 18.

[0066] In some embodiments, the adhesive includes stearic acid, myristic acid, lauric acid, or a combination thereof. In some embodiments, adhesive includes enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, tridecyl acid, pentadecyl acid, nonadecanoic acid, arachidic acid, or behenic acid, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, cetoleic acid, brassidic acid, erucic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, or a combination thereof.

[0067] In some embodiments, the adhesive includes a silicone oil. The silicone oil may have a viscosity that ensures or encourages wetting of particles, such as flake-shaped particles, and / or facilitates at least some adhesion of the silicone oil to particles, such as flake-shaped particles, through capillary force. The silicone oil may be a low-viscosity silicone oil. As used herein, the phrase “low- viscosity silicone oil” refers to a silicone oil having a viscosity at 25 °C that does not exceed 100 centistokes (cSt), 75 cSt, 50 cSt, 25 cSt, 10 cSt, or 5 cSt.

[0068] A composite material generally may include any amount of adhesive. The amount of adhesive that is present in a composite material may be determined, at least in part, by the surface area of the first plurality of particles and / or the second plurality of particles, which may be at least partially coated by the adhesive. In some embodiments, the adhesive is present in the composite material at a concentration of about 0.1 wt% to about 20 wt%, about 0.5 wt% to about 15 wt%, about 5 wt% to about 15 wt%, or about 8 wt% to about 12 wt%, based on the weight of the composite material.Liquid

[0069] The composite materials provided herein also may include a liquid, such as a liquid used in the methods to prepare the composite materials. The liquid may include any liquid in which the adhesive is at least partially soluble (i.e., a solubility of at least 0.1 g of adhesive per 100 mL of the liquid) or soluble (i.e., a solubility of at least 1 g of adhesive per 100 mL of the liquid). The liquid may include an organic liquid, such as a C5-C12 organic liquid. The liquid may include hexane.

[0070] The liquid may be present in a composite material at any amount. An amount of liquid in a composite material may decrease over time for one or more reasons, such as the volatility of the liquid, the temperature at which the composite material is stored and / or used, etc.

[0071] In some embodiments, the liquid is present in the composite material at an initial amount of about 0.1 wt% to about 15 wt%, about 1 wt% to about 15 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 5 wt%, or about 1 wt% to about 3 wt%, based on the weight of thecomposite material. The “initial amount” of liquid that is present in the composite material is the amount that is present in a newly-produced composite material (i.e., within one hour of production and before the composite material is exposed to a temperature of at least 100 °C). The amount of liquid in a composite material may decrease after production for one or more reasons, such as the volatility of the liquid, the conditions in which a composite material is used and / or stored, etc. For example, when a composite material is exposed to a temperature of 125 °C for 48 hours, an amount of liquid in the composite material, such as the initial amount, may decrease by at least 1, at least 3, or at least 5 weight percentage points.Matrix Material

[0072] The matrix material generally may include any matrix material, such as any matrix material that is capable of withstanding the conditions at which a composite material may be used, and / or preserving, to a desired extent, an interconnected network of particles, as described herein.

[0073] The matrix material may be a thixotropic matrix material. The thixotropic matrix material may resist flow, or not flow, under one or more operating conditions of objects with which the compositions herein are used, and / or to which the compositions herein are applied. The thixotropic matrix material, however, may flow, to a desired extent, under manufacturing or other processing conditions, thereby facilitating application of the compositions herein to an object, a gap between objects, etc. In some embodiments, the matrix material is stable (e.g., chemically stable) at temperatures less than 100 °C, less than 90 °C, less than 80 °C, less than 70 °C, or less than 60 °C.

[0074] In some embodiments, the matrix material includes a hydrocarbon, such as a polymeric hydrocarbon. In some embodiments, the matrix material is a lithium-based hydrocarbon. In some embodiments, the matrix material includes a paraffinic material. In some embodiments, the matrix material includes a silicon-based polymer, such as a polysiloxane (e.g., polydimethylsiloxane (PDMS), polymethylhydrogensiloxane (PMHS), polydiethylsiloxane (PDES), polyphenylmethylsiloxane (PMPS), polydiphenylsiloxane (PDPS) etc.), which may be a component of a silicone grease. Therefore, the matrix material may include a silicone grease.

[0075] In some embodiments, the matrix material is present in the composite material at an amount of about 10 wt% to about 98 wt%, about 10 wt% to about 90 wt%, about 20 wt% to about 80 wt%, about 30 wt% to about 70 wt%, about 40 wt% to about 60 wt%, about 50 wt% to about 60 wt%, or about 50 wt% to about 55 wt%, based on the weight of the composite material.

[0076] All referenced publications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by referenceherein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0077] While certain aspects of conventional technologies have been discussed to facilitate disclosure of various embodiments, applicants in no way disclaim these technical aspects, and it is contemplated that the present disclosure may encompass one or more of the conventional technical aspects discussed herein.

[0078] The present disclosure may address one or more of the problems and deficiencies of known methods and processes. However, it is contemplated that various embodiments may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the present disclosure should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.

[0079] In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

[0080] In the descriptions provided herein, the terms “includes,” “is,” “containing,” “having,” and “comprises” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” When composite materials or methods are claimed or described in terms of “comprising” various components or steps, the composite materials or methods can also “consist essentially of’ or “consist of’ the various components or steps, unless stated otherwise.

[0081] The terms “a,” “an,” and “the” are intended to include plural alternatives, e.g., at least one. For instance, the disclosure of “an adhesive”, “a liquid”, and the like, is meant to encompass one, or mixtures or combinations of more than one adhesive, liquid, and the like, unless otherwise specified.

[0082] Various numerical ranges may be disclosed herein. When Applicant discloses or claims a range of any type, Applicant’s intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein, unless otherwise specified. Moreover, all numerical end points of ranges disclosed herein are approximate. As a representative example, Applicant discloses, in some embodiments, that the matrix material is present in thecomposite material at an amount of about 50 wt% to about 60 wt%. This range should be interpreted as encompassing about 50 wt% and about 60 wt%, and further encompasses “about” each of 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt% 57 wt%, 58 wt%, and 59 wt%, including any ranges and sub-ranges between any of these values.

[0083] As used herein, the term “about” means plus or minus 10 % of the numerical value of the number with which it is being used.EXAMPLES

[0084] The present invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations upon the scope thereof. On the contrary, it is to be clearly understood that resort may be had to various other aspects, embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to one of ordinary skill in the art without departing from the spirit of the present invention or the scope of the appended claims. Thus, other aspects of this invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.Example 1 - Preparation and Testing of Composite Material

[0085] In this example, an embodiment of a composite material was prepared. The rod particles used in this example were prepared by chopping an aluminum wool to produce the rod particles. The rod particles then were placed in a super- saturated solution of stearic acid in hexane in order to coat the rod particles with the adhesive.

[0086] Aluminum flakes then were added to the rod-containing mixture, and the rodcontaining mixture was mixed with a rotary mixer at a speed not exceeding 50 rpm for a time not exceeding 5 minutes. Then, a lithium-based hydrocarbon was added to the mixture, followed by mixing with the rotary mixer at a speed not exceeding 60 rpm and a time not exceeding 30 minutes.

[0087] The components were added in amounts that resulted in an embodiment of a composite material having the following characteristics:Table 1. Characteristics of Tested Embodiment of a Composite Material

[0088] For comparison purposes, a reference composite material was prepared that included aluminum flakes, but not aluminum rods. The aluminum flakes were present in the reference composite material at a concentration of about 35 wt%, which was comparable to the combined concentration of aluminum flakes (24.9 wt%) and aluminum rods (10.1 w%) in the embodiment of the composite material prepared in this example (Table 1). The reference composite material was prepared in the same manner as the composite material of this example, except aluminum flakes were added to the super-saturated solution of stearic acid in hexane, and no aluminum rods were added.

[0089] The thermal conductivities of the reference composite material (FIG. 2A) and the embodiment of the composite material (FIG. 2B) was measured. The reference composite material had a thermal conductivity of 1.6 ± 0.1 W / mk, and the embodiment of the composite material had a thermal conductivity of 2.4 ± 0.1 W / mk.

[0090] Fourier transform infrared (FTIR) spectra also were collected for the reference composite material (FIG. 3A) and the embodiment of the composite material (FIG. 3B). The similarity of the spectra of FIG. 3A and FIG. 3B indicated that the materials have the same, or similar, chemical composition. FIG. 3C depicts FTIR peak assignments for FIG. 3A, and the wavenumbers of FIG. 3C are assigned as shown in the following table.Table 2. Assignment of Wave Numbers

[0091] X-ray diffraction patterns of the reference composite material (FIG. 4A) and the embodiment of the composite material (FIG. 4B) also were collected, and the data indicated the same, or similar, composition of the crystalline phases of the materials.

[0092] Further thermal conductivity results for the reference composite material (FIG. 5A) and the embodiment of the composite material (FIG. 5B) were collected, and the results are depicted at the following table.Table 3. Thermal Conductivity ResultsExample 2 - Preparation and Testing of Composite Material

[0093] In this example, an embodiment of a composite material was prepared. The composite material prepared in this example included flake particles of varying dimensions (see, for example, FIG. IB) The flake particles were contacted with a low-viscosity silicone oil (5 cSt at 25 °C), which promoted wetting of the flake particles, and facilitated at least some adhesion through capillary force. To enhance interconnectivity among the particles, rod-shaped particles (also referred to as fiber particles) were added to the mixture that included the flake particles and silicone oil. Samples were made that included a concentration of rod-shaped particles ranging from about 0.001 wt% to about 30 wt%, based on the weight of the final composite material.

[0094] The flake particles and rod-shaped particles were then contacted with a matrix material, and the components were mixed in a manner that preserved, to a desired extent, the integrity of the interconnections between at least a portion of the particles.

[0095] The thermal conductivities of the composite materials prepared in this example were then assessed in compliance with ASTM D5470-17. FIG. 6 depicts the temperature responses of the composite material prepared in this example. Table 4 provides tabulated results that showcase the measured thermal impedance and thermal conductivity derived from the steady-state temperature response.Table 4. Thermal Conductivity Results

[0096] FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7D depict rheological characteristics of the composite material prepared in this example at shear rates of 0.01 s-1, 0.1 s-1, 100 s-1, and 300 s-1, respectively. The results are depicted at Table 5.Table 5. Dynamic Viscosities

[0097] FTIR spectra also were collected for the embodiment of the composite material prepared in this example (FIG. 8). The wavenumbers of FIG. 8 are assigned as shown in the following table.Table 6. Assignment of Wave Numbers

[0098] An XRD pattern (FIG. 9) also was collected for the embodiment of the composite material prepared in this example. The XRD pattern suggested that aluminum was the only crystalline phase in the material. DSC data (FIG. 10) also was collected for the composite material prepared in this example.EMBODIMENTSComposite Materials

[0099] Embodiment 1. A composite material comprising, consisting essentially of, or consisting of a matrix material, a first plurality of particles, a second plurality of particles, and an adhesive.

[0100] Embodiment 2. The composite material of any of the preceding Embodiments, wherein a shape of the first plurality of particles differs from a shape of the second plurality of particles.

[0101] Embodiment 3. The composite material of any of the preceding Embodiments, wherein the shape of the second plurality of particles is effective to reduce the Gibbs energy barrier for nucleation (e.g., heterogeneous nucleation) of the adhesive from a liquid (e.g., a solution of the adhesive) to surfaces of the second plurality of particles, which may result in a substantially uniform deposition of the adhesive on the surfaces.

[0102] Embodiment 4. The composite material of any of the preceding Embodiments, wherein the first plurality of particles and the second plurality of particles are dispersed, evenly or unevenly, in the matrix material.

[0103] Embodiment 5. The composite material of any of the preceding Embodiments, wherein the first plurality of particles and the second plurality of particles provide pathways (e.g., conductive pathways, such as thermally conductive pathways) in the composite material, due at least in part to points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles.

[0104] Embodiment 6. The composite material of any of the preceding Embodiments, wherein at least a portion of the first plurality of particles and at least a portion of the second plurality of particles form an interconnected network in the composite material due to points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles.

[0105] Embodiment 7. The composite material of any of the preceding Embodiments, wherein (i) the first plurality of particles is at least partially coated with the adhesive, (ii) the second plurality of particles is at least partially coated with the adhesive, or (iii) the first plurality of particles and the second plurality of particles are at least partially coated with the adhesive.

[0106] Embodiment 8. The composite material of any of the preceding Embodiments, wherein the composite material is a paste.Methods of Forming Composite Materials

[0107] Embodiment 9. A method of forming a composite material, the method comprising, consisting essentially of, or consisting of (i) providing a first plurality of particles, (ii) providing a second plurality of particles, an adhesive, and a liquid, wherein the second plurality of particles and the adhesive are dispersed in the liquid, and the second plurality of particles is at least partially coated with the adhesive; (iii) disposing the first plurality of particles in the liquid, and optionally mixing (e.g., via stirring or otherwise) the first plurality of particles, the second plurality of particles, and the liquid; and (iv) disposing a matrix material in the liquid, and optionally mixing (e.g., via stirring or otherwise) the matrix material, the first plurality of particles, the second plurality of particles, and the liquid.

[0108] Embodiment 10. The method of any of the preceding Embodiments, wherein the providing of the second plurality of particles, the adhesive, and the liquid comprises, consists essentially of, or consists of (a) contacting the adhesive and the liquid, and optionally mixing (e.g.,via stirring or otherwise) the adhesive and the liquid; and (b) contacting the second plurality of particles, the adhesive, and the liquid, and optionally mixing (e.g., via stirring or otherwise) the second plurality of particles, the adhesive, and the liquid for a time effective to coat at least a portion of the second plurality of particles with the adhesive.

[0109] Embodiment 11. The method of any of the preceding Embodiments, wherein when the adhesive is soluble in the liquid, the mixing of the adhesive and the liquid occurs for a time effective to dissolve, completely or partially, the adhesive in the liquid, such as a time of about 5 to about 20 minutes, or about 10 minutes to about 15 minutes.

[0110] Embodiment 12. The method of any of the preceding Embodiments, further comprising, consisting essentially of, or consisting of separating a portion of the liquid from the second plurality of particles (such as via filtration, evaporation, or otherwise) before disposing the first plurality of particles in the liquid.[0U1] Embodiment 13. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the liquid comprises, consists essentially of, or consists of stirring, such as with a dynamic mixer, for example, a rotary mixer.

[0112] Embodiment 14. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the liquid imparts a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles.

[0113] Embodiment 15. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the liquid comprises, consists essentially of, or consists of stirring with a rotary mixer at about 5 rpm to about 50 rpm, about 10 rpm to about 50 rpm, about 20 rpm to about 50 rpm, about 30 rpm to about 50 rpm, about 40 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm.

[0114] Embodiment 16. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the liquid occurs for about 30 seconds to about 5 minutes, about 1 minute to about 5 minutes, about 2 minutes to about 5 minutes, about 3 minutes to about 5 minutes, about 4 minutes to about 5 minutes, about 30 seconds toabout 4 minutes, about 30 seconds to about 3 minutes, about 30 seconds to about 2 minutes, or about 30 seconds to about 1 minute.

[0115] Embodiment 17. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid comprises, consists essentially of, or consists of stirring, such as with a dynamic mixer, for example, a rotary mixer.

[0116] Embodiment 18. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid imparts a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles.

[0117] Embodiment 19. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid comprises, consists essentially of, or consists of stirring with a rotary mixer at about 5 rpm to about 60 rpm, about 10 rpm to about 60 rpm, about 20 rpm to about 60 rpm, about 30 rpm to about 60 rpm, about 40 rpm to about 60 rpm, about 50 rpm to about 60 rpm, about 5 rpm to about 60 rpm, about 5 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm.

[0118] Embodiment 20. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid occurs for about 10 minutes to about 30 minutes, about 10 minutes to about 25 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 15 minutes, about 15 minutes to about 30 minutes, about 20 minutes to about 30 minutes, or about 25 minutes to about 30 minutes.

[0119] Embodiment 21. A method of forming a composite material, the method comprising, consisting essentially of, or consisting of (i) providing a first plurality of particles and an adhesive, wherein the first plurality of particles is at least partially coated with the adhesive; (ii) providing a second plurality of particles; (iii) contacting the first plurality of particles, the second plurality of particles, and the adhesive, and optionally mixing (e.g., via stirring or otherwise) the first plurality of particles, the second plurality of particles, and the adhesive; and (iv) contacting the first plurality of particles, the second plurality of particles, the adhesive, and a matrix material, and optionally mixing(e g., via stirring or otherwise) the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive.

[0120] Embodiment 22. The method of any of the preceding Embodiments, wherein the providing of the first plurality of particles and the adhesive comprises, consists essentially of, or consists of contacting the adhesive and the first plurality of particles, and optionally mixing (e.g., via stirring or otherwise) the adhesive and the first plurality of particles for a time effective to coat at least a portion of the first plurality of particles with the adhesive.

[0121] Embodiment 23. The method of any of the preceding Embodiments, further comprising, consisting essentially of, or consisting of separating a portion of the adhesive from the first plurality of particles (such as via filtration or otherwise) before contacting the first plurality of particles, the second plurality of particles, and the adhesive, or before contacting the first plurality of particles, the second plurality of particles, the adhesive, and the matrix material.

[0122] Embodiment 24. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the adhesive comprises, consists essentially of, or consists of stirring, such as with a dynamic mixer, for example, a rotary mixer.

[0123] Embodiment 25. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the adhesive imparts a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles.

[0124] Embodiment 26. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the adhesive comprises, consists essentially of, or consists of stirring with a rotary mixer at about 5 rpm to about 50 rpm, about 10 rpm to about 50 rpm, about 20 rpm to about 50 rpm, about 30 rpm to about 50 rpm, about 40 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm.

[0125] Embodiment 27. The method of any of the preceding Embodiments, wherein the mixing of the first plurality of particles, the second plurality of particles, and the adhesive occurs for about 30 seconds to about 5 minutes, about 1 minute to about 5 minutes, about 2 minutes to about 5 minutes, about 3 minutes to about 5 minutes, about 4 minutes to about 5 minutes, about 30 seconds toabout 4 minutes, about 30 seconds to about 3 minutes, about 30 seconds to about 2 minutes, or about 30 seconds to about 1 minute.

[0126] Embodiment 28. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive comprises, consists essentially of, or consists of stirring, such as with a dynamic mixer, for example, a rotary mixer.

[0127] Embodiment 29. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive imparts a force to the first plurality of particles and the second plurality of particles that does not undesirably reduce and / or alter the points of contact between the first plurality of particles and the second plurality of particles, or the interconnected network formed by the at least a portion of the first plurality of particles and the at least a portion of the second plurality of particles.

[0128] Embodiment 30. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive comprises, consists essentially of, or consists of stirring with a rotary mixer at about 5 rpm to about 60 rpm, about 10 rpm to about 60 rpm, about 20 rpm to about 60 rpm, about 30 rpm to about 60 rpm, about 40 rpm to about 60 rpm, about 50 rpm to about 60 rpm, about 5 rpm to about 60 rpm, about 5 rpm to about 50 rpm, about 5 rpm to about 40 rpm, about 5 rpm to about 30 rpm, about 5 rpm to about 20 rpm, or about 5 rpm to about 10 rpm.

[0129] Embodiment 31. The method of any of the preceding Embodiments, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive occurs for about 10 minutes to about 30 minutes, about 10 minutes to about 25 minutes, about 10 minutes to about 20 minutes, about 10 minutes to about 15 minutes, about 15 minutes to about 30 minutes, about 20 minutes to about 30 minutes, or about 25 minutes to about 30 minutes.

[0130] Methods of Using Composite Materials

[0131] Embodiment 32. A method of improving heat transfer, the method comprising, consisting essentially of, or consisting of (i) providing a composite material of any of the preceding Embodiments; and (ii) arranging the composite material between and in contact with a surface of a first object and a surface of a second object.

[0132] Embodiment 33. The method of Embodiment 32, wherein the surface of the first object and the surface of the second object are at different temperatures prior to the arranging of the composite material.

[0133] Embodiment 34. The method of Embodiment 33, wherein a temperature difference between the different temperatures of the surface of the first object and the surface of the second object is at least 5 °C, at least 10 °C, at least 20 °C, at least 30 °C, at least 40 °C, or at least 50 °C.

[0134] Embodiment 35. The method of any of the preceding Embodiments, wherein the first object is a pipe, channel, other heat exchanger component, or a condenser in a refrigeration circuit, such as for a heat pump water heater; for example, the first object may be a microchannel condenser in the refrigeration circuit.

[0135] Embodiment 36. The method of any of the preceding Embodiments, wherein the second object is a tank; for example, the tank may be a hot water tank arranged for heat exchange with the first object (e g., a microchannel condenser of a heat pump water heater).First Plurality of Particles

[0136] Embodiment 37. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles comprises, consists essentially of, or consists of flake-shaped particles.

[0137] Embodiment 38. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles comprises, consists essentially of, or consists of particles having different dimensions or one or more substantially uniform dimensions (e.g., thicknesses (or other dimensions) within ± 5 % of each other).

[0138] Embodiment 39. The composite material or method of any of the preceding Embodiments, wherein each particle of the first plurality of particles has a first surface, a second surface opposite the first surface, and a thickness.

[0139] Embodiment 40. The composite material or method of Embodiment 39, wherein the first plurality of particles has an average thickness of about 1 pm to about 200 pm, about 10 pm to about 200 pm, about 10 pm to about 150 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 50 pm to about 200 pm, about 100 pm to about 200 pm, or about 150 pm to about 200 pm.

[0140] Embodiment 41. The composite material or method of Embodiment 39 or 40, wherein the first plurality of particle has an average largest dimension of the first surface of about 10 pm to about 200 pm, about 10 pm to about 150 pm, about 10 pm to about 100 pm, about 10 pm to about 50pm, about 50 pm to about 200 pm, about 100 pm to about 200 pm, or about 1 0 pm to about 200 pm.

[0141] Embodiment 42. The composite material or method of any one of Embodiments 39 to 41, wherein a ratio of the average largest dimension of the first surface to the thickness is about 100: 1 to about 1 : 1, about 50: 1 to about 1 :1, about 40: 1 to about 1 : 1, about 30: 1 to about 1 : 1, about 20: 1 to about 1 : 1, about 10: 1 to about 1 : 1, about 100: 1 to about 2: 1, about 50: 1 to about 2: 1, about 40: 1 to about 2: 1, about 30: 1 to about 2: 1, about 20: 1 to about 2: 1, or about 10:1 to about 2:1 (largest dimension of the first surface : thickness).

[0142] Embodiment 43. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles is formed at least in part of a first metal.

[0143] Embodiment 44. The composite material or method of any of the preceding Embodiments, wherein the first metal is aluminum, silver, or a combination thereof.

[0144] Embodiment 45. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles is formed at least in part of a first ceramic.

[0145] Embodiment 46. The composite material or method of any of the preceding Embodiments, wherein the first ceramic comprises alumina, aluminum nitride, zinc oxide, silicon carbide, silicon nitrides, and beryllium oxides.

[0146] Embodiment 47. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles is formed at least in part of graphene, carbon nanotubes (e.g., a buckypaper, a nanoribbon, etc ), or a combination thereof.

[0147] Embodiment 48. The composite material or method of any of the preceding Embodiments, wherein the first plurality of particles is present in the composite material at an amount of about 0.1 wt% to about 50 wt%, about 5 wt% to about 45 wt%, about 10 wt% to about 40 wt%, about 20 wt% to about 40 wt%, about 20 wt% to about 30 wt%, or about 24 wt% to about 26 wt%, based on the weight of the composite material.Second Plurality of Particles

[0148] Embodiment 49. The composite material or method of any of the preceding Embodiments, wherein the shape of the second plurality of particles comprises, consists essentially of, or consists of rod-shaped particles.

[0149] Embodiment 50. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles comprises, consists essentially of, or consistsof particles having different dimensions or one or more substantially uniform dimensions (e.g., lengths within ± 5 % of each other).

[0150] Embodiment 51. The composite material or method of any of the precedingEmbodiments, wherein each particle of the second plurality of particles has a length (or height) and a width (or diameter when the rod-shaped particles are cylindrical).

[0151] Embodiment 52. The composite material or method of Embodiment 51, wherein the second plurality of particles has an average width (or diameter) of about 1 pm to about 400 pm, about 40 pm to about 400 pm, about 1 pm to about 300 pm , about 40 pm to about 300 pm, about 1 pm to about 200 pm, about 40 pm to about 200 pm, about 1 pm to about 100 pm, about 40 pm to about 100 pm, about 100 pm to about 400 pm, about 200 pm to about 400 pm, or about 300 pm to about 400 pm.

[0152] Embodiment 53. The composite material or method of Embodiment 51 or 52, wherein the second plurality of particle has an average length (or height) of about 1 pm to about 2,000 pm , about 1 pm to about 1,500 pm, about 1 pm to about 1,000 pm, about 1 pm to about 500 pm, about 10 pm to about 500 pm, about 10 pm to about 400 pm, about 10 pm to about 300 pm, about 10 pm to about 200 pm, about 10 pm to about 100 pm, about 10 pm to about 50 pm, about 50 pm to about 500 pm, about 100 pm to about 500 pm, about 200 pm to about 500 pm, about 300 pm to about 500 pm, or about 400 pm to about 500 pm

[0153] Embodiment 54. The composite material or method of any one of Embodiments 51 to 53, wherein a ratio of the average length (or height) to the average width (or diameter) is about 50: 1 to about 1 : 1, about 40: 1 to about 1 :1, about 30: 1 to about 1: 1, about 20: 1 to about 1 : 1, about 10: 1 to about 1 : 1, about 5: 1 to about 1 : 1, about 50: 1 to about 2: 1, about 40: 1 to about 2: 1, about 30:1 to about 2: 1, about 20: 1 to about 2: 1, about 10:1 to about 2:1, about 5: 1 to about 2:1, about 50: 1 to about 5: 1, about 40: 1 to about 5: 1, about 30:1 to about 5:1, about 20: 1 to about 5: 1, about 12:1 to about 5: l, or about 10: 1 to about 5:l (average length (or height) : average width (or diameter)).

[0154] Embodiment 55. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles is formed at least in part of a second metal.

[0155] Embodiment 56. The composite material or method of any of the preceding Embodiments, wherein the first metal and the second metal are the same or different.

[0156] Embodiment 57. The composite material or method of any of the preceding Embodiments, wherein the second metal is aluminum, silver, or a combination thereof.

[0157] Embodiment 58. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles comprises, consists essentially of, or consists of a wool, such as a metal wool (e.g., aluminum wool), that has been processed to reduce the dimensions of the wool, particularly the lengths of each strand of the wool.

[0158] Embodiment 59. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles is formed at least in part of a second ceramic.

[0159] Embodiment 60. The composite material or method of any of the preceding Embodiments, wherein the first ceramic or the second ceramic are the same or different.

[0160] Embodiment 61. The composite material or method of any of the preceding Embodiments, wherein the second ceramic comprises alumina, aluminum nitride, zinc oxide, silicon carbide, silicon nitrides, beryllium oxides, or a combination thereof.

[0161] Embodiment 62. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles is formed at least in part of graphene, carbon nanotubes, or a combination thereof.

[0162] Embodiment 63. The composite material or method of any of the preceding Embodiments, wherein the second plurality of particles is present in the composite material at an amount of about 0.001 wt% to about 30 wt%, about 0.1 wt% to about 25 wt %, about 0.1 wt% to about 20 wt%, about 5 wt% to about 15 wt%, or about 8 wt% to about 12 wt%.

[0163] Embodiment 64. The composite material or method of any of the preceding Embodiments, wherein a ratio of the concentrations (wt%) of the first plurality of particles to the second plurality of particles in the composite material is about 2: 1 to about 4: 1, about 2:1 to about 3: 1, or about 2.5: 1 (first plurality of particles (wt%) : second plurality of particles (wt%)).Adhesive

[0164] Embodiment 65. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of a surfactant.

[0165] Embodiment 66. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of a fatty acid.

[0166] Embodiment 67. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of a saturated fatty acid.

[0167] Embodiment 68. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of a compound of the following formula:

[0168] H3C(CH2)nCOOH;

[0169] wherein n is 10 to 30, 10 to 20, or 12 to 18.

[0170] Embodiment 69. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of stearic acid, myristic acid, lauric acid, or a combination thereof.

[0171] Embodiment 70. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, tridecyl acid, pentadecyl acid, nonadecanoic acid, arachidic acid, or behenic acid, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, cetoleic acid, brassidic acid, erucic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, or a combination thereorf.

[0172] Embodiment 71. The composite material or method of any of the preceding Embodiments, wherein the adhesive comprises, consists essentially of, or consists of a silicone oil, such as a low- viscosity silicone oil.

[0173] Embodiment 72. The composite material or method of any of the preceding Embodiments, wherein the adhesive is present in the composite material at a concentration of about 0.1 wt% to about 20 wt%, about 0.5 wt% to about 15 wt%, about 5 wt% to about 15 wt%, or about 8 wt% to about 12 wt%, based on the weight of the composite material.Liquid

[0174] Embodiment 73. The composite material or method of any of the preceding Embodiments, wherein the composite material further comprises, consists essentially of, or consists of a liquid.

[0175] Embodiment 74. The composite material or method of any of the preceding Embodiments, wherein the liquid comprises, consists essentially of, or consists of an organic liquid.

[0176] Embodiment 75. The composite material or method of any of the preceding Embodiments, wherein the liquid comprises, consists essentially of, or consists of hexane.

[0177] Embodiment 76. The composite material or method of any of the preceding Embodiments, wherein the adhesive is soluble in the liquid.

[0178] Embodiment 77. The composite material or method of any of the preceding Embodiments, wherein the adhesive is completely or partially dissolved or soluble in the liquid.

[0179] Embodiment 78. The composite material or method of any of the preceding Embodiments, wherein the liquid is a super-saturated solution of the adhesive (i.e., the adhesive is present in the liquid at an amount that exceeds the maximum amount of the adhesive that is soluble in the liquid at a temperature at which the method is performed).

[0180] Embodiment 79. The composite material or method of any of the preceding Embodiments, wherein the liquid is present in the composite material at an amount of about 0.1 wt% to about 15 wt%, about 1 wt% to about 15 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 5 wt%, or about 1 wt% to about 3 wt%.Matrix Material

[0181] Embodiment 80. The composite material or method of any of the preceding Embodiments, wherein the matrix material comprises, consists essentially of, or consists of a hydrocarbon, a silicone, or a combination thereof.

[0182] Embodiment 81. The composite material or method of any of the preceding Embodiments, wherein the hydrocarbon is a polymeric hydrocarbon.

[0183] Embodiment 82. The composite material or method of any of the preceding Embodiments, wherein the matrix material comprises, consists essentially of, or consists of a lithium- based hydrocarbon, a paraffinic material, and / or a silicon-based polymer, which may be a component of a silicone grease.

[0184] Embodiment 83. The composite material or method of any of the preceding Embodiments, wherein the matrix material is present in the composite material at an amount of about 10 wt% to about 98 wt%, about 10 wt% to about 90 wt%, about 20 wt% to about 80 wt%, about 30 wt% to about 70 wt%, about 40 wt% to about 60 wt%, about 50 wt% to about 60 wt%, or about 50 wt% to about 55 wt%.Relative Properties

[0185] Embodiment 84. The composite material or method of any of the preceding Embodiments, wherein the composite material has a thermal conductivity (W / m^K-1) that is at least 30 %, at least 40 %, at least 50 %, or at least 60 % greater than a thermal conductivity (W / nr’K'1) of a comparative composite material that includes the first plurality of particles but not the second plurality of particles (see, e.g., the reference composite material of Example 1), wherein the first plurality of particles is present in the comparative composite material at a concentration that is withinabout 10 wt%, about 5 wt%, or about 1 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material. (For example, if a comparative composite material has a thermal conductivity of 10 units, and a composite material has a thermal conductivity of 16 units, then the composite material has a thermal conductivity that is 60 % greater than the thermal conductivity of the comparative composite material.) (As a further example, if a comparative composite material includes about 35 wt% to about 45 wt% of the first plurality of particles, and a composite material includes about 30 wt% of the first plurality of particles and about 10 wt% of the second plurality of particles, then the comparative composite material includes the first plurality of particles at a concentration that is within about 5 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material.)

[0186] Embodiment 85. The composite material or method of any of the preceding Embodiments, wherein the composite material has a thermal impedance (K m2W-1) that is at least 30 %, at least 40 %, at least 50 %, or at least 60 % less than a thermal impedance (K m2W-1) of a comparative composite material that includes the first plurality of particles but not the second plurality of particles (see, e.g., the reference composite material of Example 1), wherein the first plurality of particles is present in the comparative composite material at a concentration that is within about 10 wt%, about 5 wt%, or about 1 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material. (For example, if a comparative composite material has a thermal impedance of 10 units, and a composite material has a thermal impedance of 6 units, then the composite material has a thermal conductivity that is 40 % less than the thermal impedance of the comparative composite material.)Provisos

[0187] Embodiment 86. The composite material or method of any of the preceding Embodiments, wherein the composite material does not include graphene, or graphene is present at an amount not exceeding 10 wt%, 5 wt%, 1 wt%, or 0. 1 wt%, based on the weight of the composite material.

[0188] Embodiment 87. The composite material or method of any of the preceding Embodiments, wherein the composite material does not include carbon nanotubes (e.g., singlewalled, multi-walled, metal coated carbon nanotubes, or a combination thereof), or carbon nanotubes are present at an amount not exceeding 10 wt%, 5 wt%, 1 wt%, or 0.1 wt%, based on the weight of the composite material.

[0189] Embodiment 88. The composite material or method of any of the preceding Embodiments, wherein the composite material does not include carbon fibers, or carbon fibers are present at an amount not exceeding 10 wt%, 5 wt%, 1 wt%, or 0.1 wt%, based on the weight of the composite material.

Claims

Claims1. A composite material comprising: a matrix material; a first plurality of particles, wherein the first plurality of particles comprises flakeshaped particles; a second plurality of particles, wherein the second plurality of particles comprises rodshaped particles; and an adhesive; wherein the first plurality of particles and the second plurality of particles are dispersed in the matrix material, wherein the first plurality of particles or the second plurality of particles is at least partially coated with the adhesive, and wherein the first plurality of particles and the second plurality of particles form an interconnected network in the composite material due to points of physical contact between at least a portion of the first plurality of particles and at least a portion of the second plurality of particles.

2. The composite material of claim 1, wherein the composite material has a thermal conductivity (W / nT1K'1) that is at least 30 % greater than a thermal conductivity (W / nr'K'1) of a comparative composite material that includes the first plurality of particles but not the second plurality of particles, wherein the first plurality of particles is present in the comparative composite material at a concentration that is within about 10 wt% of the total concentration of the first plurality of particles and the second plurality of particles in the composite material.

3. The composite material of claim 1, wherein each particle of the first plurality of particles has a first surface, a second surface opposite the first surface, and a thickness, and wherein the first plurality of particles has an average thickness of about 10 pm to about 200 pm, and an average largest dimension of the first surface of about 10 pm to about 200 pm.

4. The composite material of claim 3, wherein a ratio of the average largest dimension of the first surface to the average thickness is about 20: 1 to about 2: 1 (average largest dimension of the first surface : average thickness).

5. The composite material of claim 1, wherein each particle of the second plurality of particles has a length and a width, and wherein the second plurality of particles has an average width about 40 pm to about 400 pm, and an average length of about 100 pm to about 500 pm.

6. The composite material of claim 5, wherein a ratio of the average length to the average width is about 12: 1 to about 5: 1 (average length : average width).

7. The composite material of claim 1, wherein the first plurality of particles is present in the composite material at an amount of about 10 wt% to about 40 wt %, and the second plurality of particles is present in the composite material is present in the composite material at an amount of about 5 wt% to about 15 wt%, based on the weight of the composite material.

8. The composite material of any one of claims 1 to 7, wherein the adhesive comprises a fatty acid or a low-viscosity silicone oil.

9. The composite material of any one of claims 1 to 7, wherein the adhesive comprises a compound of the following formula:H3C(CH2)nCOOH; wherein n is 10 to 30, 10 to 20, or 12 to 18.

10. The composite material of claim 1, wherein the adhesive is present in the composite material at a concentration of about 5 wt% to about 15 wt%, based on the weight of the composite material.

11. The composite material of claim 1, further comprising an organic liquid, wherein the organic liquid is present in the composite material at an amount of about 1 wt% to about 5 wt%, based on the weight of the composite material.

12. The composite material of claim 1, wherein the first plurality of particles is at least partially coated with the adhesive, and the adhesive comprises a fatty acid.

13. The composite material of claim 1, wherein the second plurality of particles is at least partially coated with the adhesive, and the adhesive comprises a silicone oil.

14. A method of forming a composite material, the method comprising: providing a first plurality of particles; providing a second plurality of particles, an adhesive, and a liquid, wherein the second plurality of particles and the adhesive are dispersed in the liquid, and the second plurality of particles is at least partially coated with the adhesive; disposing the first plurality of particles in the liquid, and mixing the first plurality of particles, the second plurality of particles, and the liquid; and disposing a matrix material in the liquid, and mixing the matrix material, the first plurality of particles, the second plurality of particles, and the liquid to form the composite material.

15. The method of claim 14, wherein the providing of the second plurality of particles, the adhesive, and the liquid comprises: contacting the adhesive and the liquid, and mixing the adhesive and the liquid; contacting the second plurality of particles, the adhesive, and the liquid, and mixing the second plurality of particles, the adhesive, and the liquid for a time effective to coat at least a portion of the second plurality of particles with the adhesive.

16. The method of claim 14, wherein the mixing of the first plurality of particles, the second plurality of particles, and the liquid comprises stirring with a rotary mixer at about 5 rpm to about 50 rpm for about 30 seconds to about 5 minutes.

17. The method of claim 14, wherein the mixing of the matrix material, the first plurality of particles, the second plurality of particles, and the liquid comprises stirring with a rotary mixer at about 5 rpm to about 60 rpm for about 10 minutes to about 30 minutes.

18. The method of any one of claims 14 to 17, wherein the first plurality of particles comprises flake-shaped particles, and the second plurality of particles comprises rod-shaped particles.

19. The method of claim 14, wherein the adhesive comprises a surfactant.

20. A method of forming a composite material, the method comprising: providing a first plurality of particles and an adhesive, wherein the first plurality of particles is at least partially coated with the adhesive;providing a second plurality of particles; contacting the first plurality of particles, the second plurality of particles, and the adhesive, and mixing the first plurality of particles, the second plurality of particles, and the adhesive; and contacting the first plurality of particles, the second plurality of particles, the adhesive, and a matrix material, and mixing the matrix material, the first plurality of particles, the second plurality of particles, and the adhesive.

21. The method of claim 20, further comprising separating a portion of the adhesive from the first plurality of particles before contacting the first plurality of particles, the second plurality of particles, and the adhesive, or before contacting the first plurality of particles, the second plurality of particles, the adhesive, and the matrix material.

22. The method of claim 20, wherein the first plurality of particles comprises flake-shaped particles, and the second plurality of particles comprises rod-shaped particles.

23. The method of any one of claims 20 to 22, wherein the adhesive comprises a low-viscosity silicone oil, optionally wherein the silicone oil has a viscosity at 25 °C of 5 cSt or less.

24. A method of improving heat transfer, the method comprising: providing a composite material of claim 1; arranging the composite material between and in contact with a surface of a first object and a surface of a second object; wherein the surface of the first object and the surface of the second object are at different temperatures prior to the arranging of the composite material.

25. The method of claim 24, wherein a temperature difference between the different temperatures of the surface of the first object and the surface of the second object is at least 20 °C.

26. The method of claim 24, wherein the first object is a pipe, a heat exchanger component, or a condenser.

27. The method of any one of claims 24 to 26, wherein the second object is a tank.

Images