阅读说明：本技术 六方氮化硼/水泥/聚合物复合物及合成法 (Hexagonal boron nitride/cement/polymer composite and synthesis method ) 是由 鲁兹贝赫·沙赫萨瓦里 马赫什·巴特 于 2018-08-06 设计创作，主要内容包括：六方氮化硼(hBN)是一种合成材料,由于其化学惰性、热稳定性和其它有益性质,其可用于多种应用中。本文描述了hBN复合材料和用于制备这样的复合物的方法。特别地,讨论了既包括官能化的hBN又包括水泥或胶凝材料的复合材料及其制备方法。这样的材料可用于建筑、固井(初次注水泥和补注水泥)、核工业、先进多功能复合物的3D打印和耐火材料。(Hexagonal boron nitride (hBN) is a synthetic material that can be used in a variety of applications due to its chemical inertness, thermal stability, and other beneficial properties. hBN composite materials and methods for making such composites are described herein. In particular, composites comprising both functionalized hBN and cement or cementitious materials and methods of making the same are discussed. Such materials can be used for construction, cementing (primary and secondary cementing), nuclear industry, 3D printing of advanced multi-functional composites, and refractory materials.)

1. A composition comprising cement and hexagonal boron nitride, wherein the hexagonal boron nitride is functionalized.

2. The composition of claim 1, wherein the functionalized hexagonal boron nitride is exfoliated.

3. The composition of claim 1, wherein the composition is substantially free of added graphite or graphite oxide.

4. The composition of claim 1, wherein the hexagonal boron nitride is embedded between calcium silicate hydrate layers or cement hydration products.

5. The composition of claim 1, wherein the composition comprises at least about 1 wt% hexagonal boron nitride, and wherein the composition has at least a 20% reduction in viscosity as compared to the same composition without hexagonal boron nitride.

6. The composition of claim 1, wherein the hexagonal boron nitride is functionalized such that it increases the compressive strength of the composition by at least about 10% as compared to the same material without the functionalized hexagonal boron nitride.

7. The composition of claim 1, wherein the composition has a thermal conductivity at least about 10% greater than the same material without the functionalized hexagonal boron nitride.

8. The composition of claim 1, wherein the functionalized hexagonal boron nitride and cement are mixed in water or sodium hydroxide and then dried to form a composite.

9. The composition of claim 1, wherein the functionalized hexagonal boron nitride and cement are mixed by shear mixing, screw mixing, or rotary mixing.

10. The composition of claim 1, wherein the hexagonal boron nitride is functionalized by heating with sodium hydroxide.

11. The composition of claim 1, wherein the composition has an increase in surface resistivity of at least about 30% as measured with a durability tester, as compared to the same composition without the functionalized hexagonal boron nitride.

12. The composition of claim 1, wherein the hexagonal boron nitride is less than or about 1 μ ι η in lateral dimension.

13. The composition of claim 1, further comprising a polymer selected from the group consisting of: poly (methyl methacrylate), acrylics, polyamides, polyethylene, polystyrene, polycarbonates, methacrylics, phenols, polypropylene, polyolefins, polyolefin plastomers, polyolefin elastomers, copolymers of ethylene, epoxies, polyurethanes, unsaturated polyester resins, and combinations thereof.

14. The composition of claim 1, wherein the complex substantially retains hardness after radiation exposure.

15. The composition of claim 1, wherein the composition is in the form of a coating.

16. The composition of claim 1, wherein the composition is in the form of a well casing.

17. A method of manufacturing a composite material comprising the steps of:

mixing hexagonal boron nitride with a solvent to produce functionalized hexagonal boron nitride;

removing the solvent from the hexagonal boron nitride solution;

the functionalized hexagonal boron nitride is mixed with cement.

18. The method of claim 17, wherein the solvent is selected from the group consisting of: water, isopropanol, sodium hydroxide, t-butanol, 1-butanol and 2-butanol, 1-propanol and 2-propanol, ethanol, methanol, acetone, dimethylformamide, sodium cholate, polyethylene glycol, N-methyl-2-pyrrolidone, pyridine, cetyltrimethylammonium bromide, sodium cholate, soaps, ethers, ketones, amines, nitrated hydrocarbons, halogenated hydrocarbons, and combinations thereof.

19. The method of claim 17, further comprising, prior to mixing the functionalized hexagonal boron nitride with the cement, the steps of: centrifuging the hexagonal boron nitride solvent solution to obtain a supernatant;

separating the supernatant; and

the supernatant was dried to give a sample of chemically exfoliated and functionalized hexagonal boron nitride.

20. A composition comprising cement and treated hexagonal boron nitride, wherein the composition comprises less than about 0.5 wt% hexagonal boron nitride, and wherein the composition increases compressive strength by at least 20% compared to a cement composition without hexagonal boron nitride.

Technical Field

The present application relates to hexagonal boron nitride (hBN) doped composites. The present application also encompasses formulations and methods for preparing such composites.

Background and summary of the invention

Boron nitride is a synthetic material made of boric acid or boron trioxide. Among its various crystal forms, its hexagonal allotrope, hexagonal boron nitride (h-BN), may resemble graphite in structure and layered form, but with alternating B and N atoms. h-BN has beneficial thermodynamic (up to 1000 ℃ air stable) and chemical stability, extraordinary hardness and large thermal conductivity while being electrically insulating. These properties make hBN suitable for many technical applications. hBN can also exhibit characteristics such as high thermal conductivity and mechanical strength as well as chemical stability. The hydrophobic nature of hBN can be used for non-wetting surface or underwater construction. hBN can also be used for corrosion resistant surfaces. Current commercial products of hBN include various thermal management materials such as thermal pads, thermal greases, thermal coatings and various cosmetics (due to their role as solid lubricants). Furthermore, the high neutron absorption cross section of boron and the advantage of multi-layer nanostructured materials (i.e., many interfaces) to reduce radiation make h-BN a suitable candidate for an insert in a ceramic for nuclear shielding.

Porous cement composites comprising hBN are described in Hexagonal Boron Nitride and Graphiteoxide Reinforced (Advanced Functional Materials, Vol.25, No. 45, p.5621-. This reference describes cement and concrete composites utilizing non-functionalized, non-exfoliated hBN and graphite oxide.

We describe herein a class of multifunctional hexagonal boron nitride (hBN) -cement composites that utilize treated, functionalized and/or exfoliated hBN. Embodiments described herein relate to synthesis, exfoliation, functionalization, hydrolysis, agitation, sonication, mixing, and/or intercalation methods for developing composites comprising treated hBN that exhibit enhanced properties. In some embodiments, these properties include, but are not limited to, strength, toughness, stiffness, ductility, heat resistance, radiation resistance, rheology, viscosity, low permeability, durability, and/or acid resistance. In some embodiments, the material may be a protective coating. Enhanced properties may also include compatibility with a variety of functional groups including, but not limited to, hydroxyl, amine, and/or thiol groups. In certain embodiments, the disclosed composites include various cementitious materials, including but not limited to portland cement, oil well cement, calcium aluminate cement, polymers, and/or other binders. In some embodiments, due to the unique properties of the treated hexagonal boron nitride, the final composite is resistant to degradation at much higher temperatures than typical gelling materials and other similar hybrid composites.

Other embodiments disclosed herein relate to construction, transportation, cementing (primary and secondary cementing), drilling fluids, nuclear industry applications, radiation rich environments such as space, aviation or medical applications, 3D printing of composites, refractories, lubricants, scaffolds for high temperature combustion sensors, removal of harmful oxyanions such as arsenate, chromate, phosphate from contaminated water, and other applications of the disclosed composites.

Certain embodiments relate to composites, mixtures, and/or crystal structures comprising hBN, calcium silicate hydrate, tobermorite, and/or other products involved in cement hydration. These embodiments may further be combined with cement and/or concrete materials and/or other composites.

In some embodiments, the synthesis methods include, but are not limited to, solid state reactions and/or solution-based treatments of hBN sheets, tapes, tubes, and/or particles. These processes can be carried out at elevated temperatures or at room temperature. The synthesis of treated, exfoliated, hydrolyzed and/or functionalized boron nitride sheets, ribbons, tubes and/or particles may be performed first, with or without post-treatment, filtration and/or additional chemical reactions. In some embodiments, the hBN material may then be incorporated into a cement or cementitious material, resulting in the creation of a new composite material. Functionalization can include, but is not limited to, various functional groups such as hydroxyl, carboxylate, carbonyl, amine, and the like. The composites can take advantage of several properties of hBN, such as high thermal conductivity and/or thermal stability, low coefficient of thermal expansion, high chemical stability, lubricity, radiation resistance, and/or acid resistance, to provide a class of hybrid materials that provide enhanced properties including, but not limited to, structural and rheological properties, and resistance to extreme conditions. In some embodiments, our composite will (1) allow for the construction of high strength and/or more durable hybrid cement/concrete structures that provide enhanced material properties over conventional cement/concrete, including (but not limited to) cement in construction applications, oil well cement (including but not limited to grade G and H oil well cement and primary and secondary cementing cement) and concrete for nuclear power plants, and/or transport infrastructure, (2) provide materials that can be used for both general infrastructure and high temperature applications, eliminating the need for separate materials, and (3) reduce overall costs through lower replacement costs (increased durability) and excess material costs due to (1) and (2).

Drawings

Fig. 1 shows embodiments of hBN before and after stripping the sample.

Figure 2 depicts a graph of compressive strength versus setting time obtained from a composite cement sample comprising 1.2 w% hBN.

Fig. 3 depicts a graph showing the weight percent of hBN versus compressive strength.

Fig. 4 shows SEM images of regular hBN (left) and hBN peeled using a strong base in a shear mixer (right).

Fig. 5 shows SEM images of regular hBN (left) and hBN stripped using a strong base in a rotary mixer (right).

Fig. 6 shows SEM images of regular hBN (left) and hBN stripped using a strong base in the mixer (right).

Fig. 7 shows SEM images of regular hBN (left) and hBN stripped using a strong base in a rotary mixer (right).

Fig. 8 shows SEM images of regular hBN (left) and hBN stripped using NMP in the mixer (right).

Fig. 9 shows SEM images of normal hBN (left) and exfoliated hBN (right) using a molten hydroxide method followed by centrifugation.

Fig. 10a depicts a representative TEM image of exfoliated hBN.

Fig. 10b depicts a representative TEM image of an ultra-thin exfoliated hBN sheet (1-5 atomic layers).

FIG. 10d depicts a representative TEM image of hBN/C-S-H (I).

FIGS. 10e-f depict representative TEM images of hBN/C-S-H (II) at two different scales.

FIG. 10g depicts representative XRD spectra of hBN/C-S-H and control samples.

FIG. 10H depicts representative FTIR spectra of hBN/C-S-H and control samples.

Detailed Description

In the following description, certain details are set forth, such as specific quantities, dimensions, etc., in order to provide a thorough understanding of the present embodiments disclosed herein. It will be apparent, however, to one skilled in the art that the present disclosure may be practiced without these specific details. In many instances, details concerning such considerations and the like have been omitted inasmuch as such details are not necessary to obtain a complete understanding of the present disclosure and are within the skills of persons of ordinary skill in the relevant art.

Note that the word "cement" in this patent refers to all types of cement, including but not limited to each and combinations of the following: types I to IV cements, and (including but not limited to) G and/or H grade oil well cements, rapid hardening cements, rapid setting cements, calcium aluminate cements, low heat cements, sulfate resistant cements, slag cements, high alumina cements, white cements, colored cements, pozzolana cements, aerated cements, fly ash based cements, bottom ash based cements from incineration waste, fly ash based cements from incineration waste, cements or hydrologic cements from dolomite (whallostonite) or pseudo dolomite (psuedowhallostonite), and/or other binders with cementitious properties.

In this application, unless specifically stated otherwise, use of the singular includes the plural, the words "a" or "an" mean "at least one", and use of "or" means "and/or". Furthermore, the use of the term "including" as well as other forms, such as "includes" and "included", is not limiting. Furthermore, unless specifically stated otherwise, terms such as "element" or "component" encompass an element or component comprising one unit as well as an element or component comprising more than one unit.

From a mechanical perspective, 2D h-BN sheets can be an excellent reinforcement material similar to or superior to graphene or graphite oxide. A potential factor in fracture toughness is the mechanism by which the graphene platelet filler is anchored and encapsulated under the silica particles, forming a continuous wall of graphene platelet filler along the particle boundaries. This arrangement may effectively prevent crack propagation in 3D rather than 2D. With relatively similar structures, graphite and BN can also be used to synthesize various forms of Carbon Nanotubes (CNTs) and Boron Nitride Nanotubes (BNNTs), respectively. Although the electrical properties of CNTs and BNNTs differ, they possess similar mechanical properties, particularly in terms of young's modulus, which demonstrates their potential application as mechanical reinforcement. A potential advantage of 2D nanomaterials such as hBN compared to 1D materials such as BNNT is that they have double the surface area for equal mass. This property results in extremely high surface area, providing excellent functionalization and the ability to bond to the surrounding matrix. In some embodiments, the exfoliated monolayer hBN may have at least about 50m²Per g, or at least about 100m²Per g, or at least about 500m²Per g, or at least about 1000m²Per gram, or at least about 1500m²In g, or at least about 2000m²In g, or at least about 2500m²Surface area in g. . In some embodiments, the exfoliated monolayer hBN may have less than about 1000m²A/g, or less than about 1500m²A/g, or less than about 2000m²A/g, or less than about 2500m²Surface area in g. In a particular embodimentIn one embodiment, the exfoliated monolayer hBN has a thickness of about 2200m²Surface area in g.

Ultra-thin hBN sheets can be used to improve the mechanical properties of BN-based polymer composites. In some embodiments, the polymer composition comprises at least about 0.01 wt% hBN, or at least about 0.05 wt% hBN, or at least about 0.1 wt% hBN, or at least about 0.3 wt% hBN, or at least about 0.5 wt% hBN, or at least about 0.7 wt% hBN, or at least about 1.0 wt% hBN, or at least about 1.2 wt% hBN, or at least about 1.5 wt% hBN, or at least about 2.0 wt% hBN. In some embodiments, the polymer composition comprises up to about 0.3 wt% hBN, or up to about 0.5 wt% hBN, or up to about 0.7 wt% hBN, or up to about 1.0 wt% hBN, or up to about 1.2 wt% hBN, or up to about 1.5 wt% hBN, or up to about 2.0 wt% hBN. The hBN may be in the form of sheets, ribbons, tubes and/or particles. The polymer may include, but is not limited to, poly (methyl methacrylate), polyacrylics, polyamides, polyethylene, polystyrene, polycarbonate, methacrylic, polyphenols, polypropylene, polyolefins such as polyolefin plastomers and elastomers, EPDM, copolymers of polyalkylene glycols and ethylene, epoxy resins, polyurethanes, unsaturated polyester resins, or combinations thereof. In a certain embodiment, the addition of about 0.3 wt% hBN nanoplatelets to Polymethylmethacrylate (PMMA) increases the elastic modulus by about 22% and the strength by about 11%.

Infrastructure materials can benefit from the properties of hBN. As the most widely used material on earth, concrete is a brittle material with strong compressive strength but relatively weak tensile, flexural and fracture toughness. While reinforcing bars may partially overcome these problems, they generally do not prevent localized cracking and do not allow the material to resist high bending loads. This encourages the incorporation of several additives into the cement paste, which is a known binder in concrete. Some examples include polymer-modified cements to enhance ductility and fiber-reinforced cements for micro-reinforcement.

The firm B-N combination in the BN layer enables the BN nanosheets to be highly heat-conducting. The disclosed nanoplatelets can have a single layer, two layers, less than five layers, less than 10 layers, less than 50 layers, or a plurality of layers.

In some embodiments, the disclosed composites have a thermal conductivity of at least about 0.1W/mK, or at least about 10W/mK, or at least about 500W/mK, or at least about 1000W/mK, or at least about 1500W/mK, or at least about 2000W/mK. The disclosed embodiments may also be mechanically strong and elastic as well as thermally and chemically stable. The disclosed embodiments may also have a low viscosity when in the slurry phase, thereby facilitating pumping. The disclosed embodiments may also have low permeability (to liquids and gases) and are useful in applications related to spills and leaks. Unlike pure covalent bonds in graphene, the partial ionic B-N bonds make BN nanoplates an intrinsic electrical insulator with a wide band gap (about 5.5eV), which can be valuable for dielectric applications and deep ultraviolet luminescence. The disclosed embodiments may have beneficial thermal conductivity, heat resistance, corrosion resistance, dielectric applications, deep ultraviolet light emission, induction, sealing or soldering operations in vacuum and atmospheric furnaces, and/or electrical insulation properties.

hBN sheets can be used as additives in various types of matrices. In one embodiment, exfoliated hBN is mixed and/or embedded between calcium silicate hydrate (C-S-H) layers and in bulk cement. Without being bound by theory, it is believed that hBN is embedded between C-S-H layers as described in interconnected Hexagonal Boron Nitride/silicas as a bilayer multifunctional ceramic (ACS application. mater. interfaces,2018,10(3), page 2203-. The entire disclosure of which is incorporated herein by reference.

Certain disclosed embodiments include the use of sonochemical techniques as an alternative or in addition to conventional chemical methods to obtain hBN. Nanomaterials are effective fillers for nanocomposites due to their developed surface and high aspect ratio. In some embodiments, hBN may have a nanometer thickness and lateral dimensions of up to micrometers. In some embodiments, the functionalized and/or exfoliated hBN may have a lateral dimension of at least about 10nm, at least about 50nm, at least about 100nm, at least about 500nm or at least about 1 μm or at least about 3 μm or at least about 5 μm, or at least about 10 μm, or at least about 25 μm, or at least about 50 μm. In some embodiments, the functionalized and/or exfoliated hBN may have a lateral dimension of less than about 10nm, less than about 50nm, less than about 100nm, less than about 500nm or less than about 1 μm or less than about 3 μm or less than about 5 μm, or less than about 10 μm, or less than about 25 μm, or less than about 50 μm.

In some embodiments, hBN may have an aspect ratio (width to thickness) of at least about 20, or at least about 50, or at least about 100, or at least about 500, or at least about 1000, or at least about 3000, or at least about 5000, or at least about 10000. In some embodiments, hBN may have an aspect ratio (width to thickness) of no more than about 100, or no more than about 500, or no more than about 1000, or no more than about 3000, or no more than about 5000, or no more than about 10000.

In some embodiments, hBN may have a thickness of less than about 0.3nm, or less than about 0.5nm, or less than about 1nm, or less than about 10nm, or less than about 50nm, or less than about 100nm, or less than about 500nm, or less than about 1 μm, or less than about 5 μm, or less than about 10 μm, or less than about 15 μm, or less than about 20 μm, or less than about 25 μm.

Described herein is a method of synthesizing hBN/cement composites that result in cementitious materials with desirable properties. In certain embodiments, these composites may have properties including, but not limited to, mechanical, thermal, rheological, and radiation properties, high durability, solvent and acid resistance, rapid thermal diffusion properties, protective coatings, low permeability, resistance to harmful ions, and/or good adhesion to metal, ceramic, glass, porcelain, and other surfaces.

Applications of