Improved hydrophobic aerogel materials

Abstract

The present invention provides an aerogel composition that is durable and easy to handle, has good performance in water environments, and also has good combustion and self-heating properties. The present invention also provides a method of making an aerogel composition that is durable and easy to handle, has good performance in water environments, and also has good combustion and self-heating properties. The present invention further provides a method of improving the hydrophobicity, water absorption, heat of combustion, or onset of thermal decomposition temperature of an aerogel composition.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 059,555, filed October 3, 2014; U.S. Provisional Application No. 62 / 118,864, filed February 20, 2015; and U.S. Provisional Application No. 62 / 232,945, filed September 25, 2015; the contents of which are incorporated herein by reference and any terms are subject to the control of this application. Background Technology

[0003] Low-density aerogel materials are widely considered the best available solid insulators. Aerogels are suitable as insulators primarily because they minimize conductivity (low structural density leads to detours in energy transfer through the solid framework), convection (large pore volume and very small pore size result in minimal convection), and radiation (IR absorption or scattering dopants can be easily dispersed throughout the aerogel matrix). Aerogels can be used in a wide range of applications, including heating and cooling insulation, sound insulation, dielectrics, aerospace, energy storage and production, and filtration. Furthermore, aerogel materials exhibit many other noteworthy acoustic, optical, mechanical, and chemical properties, making them widely applicable in a variety of insulating and non-insulating applications. Summary of the Invention

[0004] In a general aspect, the present invention provides an aerogel composition that is durable and easy to handle, exhibits good performance in aqueous environments, and also possesses good flammability and self-heating properties. In some embodiments, the present invention provides an aerogel composition that is a flexible, elastic, and self-supporting reinforced aerogel composition that exhibits good performance in aqueous environments and also possesses good flammability and self-heating properties.

[0005] In another general aspect, the present invention can provide an aerogel composition comprising a silica-based framework, having the following properties: a) 0.60 g / cm³ 3 or lower density; b) 50mW / m * K or less thermal conductivity; and c) 40 wt% or less water absorption. In some embodiments, the aerogel composition of the present invention has a heat of combustion of 717 cal / g or less. In some embodiments, the aerogel composition of the present invention has a thermal decomposition temperature of hydrophobic organic materials between 300°C and 700°C. In some embodiments, the aerogel composition of the present invention has 0.50 g / cm³. 3 Or even smaller, 0.40 g / cm³ 3 Or even smaller, 0.30 g / cm³ 3 Or even smaller, 0.25 g / cm³ 3Or smaller, or 0.20 g / cm³ 3 Or even lower density. In some embodiments, the aerogel composition of the present invention has a density of 45 mW / M. * K or less, 40mW / M * K or less, 35mW / M * K or less, 30mW / M * K or less, 25mW / M * K or less, 20mW / M * Thermal conductivity of K or less, or 5 mW / M * K to 50mW / M * Thermal conductivity between K and K. In some embodiments, the aerogel composition of the present invention has a water absorption rate of 35 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, or 10 wt% or less. In some embodiments, the aerogel composition of the present invention has a heat of combustion of 650 cal / g or less, 600 cal / g or less, 550 cal / g or less, 500 cal / g or less, 450 cal / g or less, 400 cal / g or less, or between 150 cal / g and 717 cal / g. In some embodiments, the aerogel composition of the present invention has a thermal decomposition temperature of 400°C or higher, 450°C or higher, 475°C or higher, 500°C or higher, 525°C or higher, 550°C or higher, 575°C or higher, 600°C or higher, or between 400°C and 700°C. In a preferred embodiment, the aerogel composition of the present invention has the following properties: a) 0.40 g / cm³ 3 or lower density; b) 40mW / M * The thermal conductivity is K or less; c) water absorption is 40 wt% or less; and d) heat of combustion is between 140 cal / g and 600 cal / g. In some embodiments, the aerogel composition of the present invention has a thermal decomposition temperature starting point of 525°C to 700°C. In some embodiments, the aerogel composition of the present invention has a T0.01 to 0.5. 1-2 :T 3 The ratio of silica species and / or Q between approximately 0.1 and 1.5 2-3 Q 4The ratio of silica species. In some embodiments, the aerogel composition of the present invention is a reinforced aerogel composition, a fiber-reinforced aerogel composition, or an aerogel blanket composition. In some embodiments, the aerogel composition of the present invention has a hydrophobic organic content between about 1 wt% and about 30 wt%, between about 1 wt% and about 25 wt%, between about 1 wt% and about 20 wt%, between about 1 wt% and about 15 wt%, between about 1 wt% and about 10 wt%, or between about 1 wt% and about 5 wt%.

[0006] In another general aspect, the present invention provides a method for preparing an aerogel composition, comprising: a) providing a precursor solution comprising a silica gel precursor material, a solvent, and optionally a catalyst; b) converting the silica gel precursor material in the precursor solution into a gel material or composition; c) extracting at least a portion of the solvent from the gel material or composition to obtain the aerogel material or composition; d) incorporating at least one hydrophobic bound silicon into the aerogel material or composition by one or both of: i) including at least one silica gel precursor material having at least one hydrophobic group in the precursor solution, or ii) exposing the precursor solution, the gel composition, or the aerogel composition to a hydrophobic agent; and e) exposing the aerogel material or composition to an oxygen-reducing atmosphere at a temperature above 300°C. In some embodiments, the method of the present invention includes exposing the aerogel composition to an oxygen-reducing atmosphere at a temperature between 300°C and 650°C for about 30 seconds to about 200 minutes to obtain a treated aerogel material or composition. In some embodiments, the method of the present invention includes incorporating a reinforcing material into the aerogel composition by combining a reinforcing material with the precursor solution before or during the transformation of a silica gel precursor material in a precursor solution into a gel composition. In a preferred embodiment, the reinforcing material comprises a continuous sheet of fiber-reinforced material. In some embodiments, the method of the present invention includes limiting the temperature exposure of the aerogel composition to a temperature below 850°C for heat treatment. In some embodiments, the method of the present invention provides a total time of 30 hours or less for the transformation of at least one gel precursor in the precursor solution into the gel material. In some embodiments, the method of the present invention includes an oxygen-depleting atmosphere comprising 0.1 vol% to 5 vol% oxygen. In some embodiments, the method of the present invention includes a step of incorporating at least one hydrophobic bound silicon into the aerogel material or composition to provide a hydrophobic organic content in the aerogel composition between about 1 wt% and about 25 wt%. In a preferred embodiment, the method of the present invention manufactures the aerogel composition. In some embodiments, the aerogel material or composition manufactured by the method of the present invention has the following properties: a) 0.60 g / cm³ 3 or lower density; b) 50mW / m *K or less thermal conductivity; c) 40 wt% or less water absorption; d) heat of combustion between 150 cal / g and 717 cal / g; and e) thermal decomposition temperature of hydrophobic organic materials between 300 °C and 700 °C.

[0007] In another general aspect, the present invention provides a method for preparing an aerogel composition, comprising: a) manufacturing an aerogel composition comprising at least one hydrophobically bound silica; and b) exposing the aerogel composition to an oxygen-reducing atmosphere at a temperature above 300°C. In another general aspect, the present invention provides a method for exposing a first aerogel composition comprising at least one hydrophobically bound silica to an oxygen-reducing atmosphere at a temperature above 300°C to obtain a second aerogel composition. In some embodiments, the method of the present invention comprises exposing the aerogel composition to an oxygen-reducing atmosphere at a temperature between 300°C and 650°C for about 30 seconds to about 200 minutes to obtain a treated aerogel material or composition. In some embodiments, the method of the present invention includes a temperature exposure for heat treatment of the aerogel material or composition limited to a temperature below 850°C. In some embodiments, the method of the present invention comprises a silica-based aerogel composition. In some embodiments, the method of the present invention includes an aerogel composition that is a reinforced aerogel composition. In some embodiments, the method of the present invention includes an oxygen-reducing atmosphere comprising 0.1 vol% to 5 vol% oxygen. In some embodiments, the method of the present invention includes an aerogel composition having an aerogel content of between about 1 wt% and about 25 wt%. In some embodiments, the method of the present invention produces an aerogel material or composition with improved hydrophobicity compared to the aerogel composition before the treatment method. In some embodiments, the method of the present invention produces an aerogel composition with lower water absorption compared to the aerogel composition before the treatment method. In some embodiments, the method of the present invention produces an aerogel material or composition with lower heat of combustion compared to the aerogel composition before the treatment method. In some embodiments, the method of the present invention produces an aerogel composition with higher thermal decomposition temperature than the aerogel composition before the treatment method. Attached Figure Description

[0008] Figure 1 Examples of aerogel compositions of the present invention 29 Si solid-state NMR spectrum.

[0009] Figure 2 TGA / DSC analysis chromatograms depicting examples of the aerogel composition of the present invention. Detailed Implementation

[0010] Aerogels are open, porous materials comprising a framework of interconnected structures, a corresponding network of pores integrated within the framework, and an interstitial phase within the network of pores primarily containing gases such as air. Aerogels are characterized by low density, high porosity, large surface area, and small pore size. Aerogels are distinguished from other porous materials by their physical and structural properties.

[0011] Within the present invention, the term "aerogel" or "aerogel material" refers to a gel comprising a framework of interconnected structures, a corresponding network of interconnected pores integrated within the framework, and containing a gas such as air as a dispersed interstitial medium; and characterized by the following physical and structural properties attributable to the aerogel (based on nitrogen porosity determination experiments): (a) an average pore diameter of about 2 nm to about 100 nm, (b) a porosity of at least 80% or greater, and (c) about 20 nm. 2 / g or a larger surface area.

[0012] The aerogel material of the present invention therefore includes any aerogel or other open compound that satisfies the defining elements shown in the preceding paragraph; including compounds that can be classified as dry gels, freeze gels, environmentally dried gels, microporous materials, etc.

[0013] Further characteristics of the aerogel material may also include other physical properties, including: (d) a pore volume of about 2.0 mL / g or greater, preferably about 3.0 mL / g or greater; (e) a density of about 0.50 g / cc or less, preferably about 0.25 g / cc or less; and (f) at least 50% of the pore volume comprises pores having a pore diameter of 2 to 50 nm, although satisfying these other properties is not a required characteristic of a compound as an aerogel material.

[0014] Within the scope of this invention, the term "innovative processing and extraction technique" refers to a method of replacing the liquid interstitial phase in a wet gel material with a gas, such as air, in a manner that results in low pore collapse and low shrinkage of the gel's skeletal structure. Drying techniques, such as atmospheric evaporation, often introduce strong capillary pressures and other mass transfer constraints at the liquid-gas interface of the evaporated or removed interstitial phase. The strong capillary forces generated by liquid evaporation or removal can cause significant pore shrinkage and skeletal collapse within the gel material. Innovative processing and extraction techniques used during liquid interstitial phase extraction reduce the negative impact of capillary forces on the pores and skeletal structure of the gel during liquid phase extraction.

[0015] In some embodiments, innovative processing and extraction techniques utilize near-critical or supercritical fluids, or near-critical or supercritical conditions, to extract the interstitial liquid phase from a self-wetting gel material. This can be achieved by removing the interstitial liquid phase from the gel at or above the critical point of the liquid or liquid mixture. Co-solvents and solvent exchange can be used to optimize the near-critical or supercritical fluid extraction process.

[0016] In some embodiments, the innovative processing and extraction techniques include modifying the gel skeleton to reduce the capillary pressure at the liquid-gas interface and other irreversible effects of mass transfer limitations. This embodiment may include treating the gel skeleton with a hydrophobic agent or other functionalizing agent that allows the gel skeleton to withstand or freely recover from any collapse forces during liquid-phase extraction below the critical point of the interstitial phase.

[0017] Within the present invention, the term "skeleton" or "skeleton structure" refers to a network of interconnected oligomers, polymers, or colloidal particles that form a solid structure within a gel or aerogel. The polymers or particles constituting the skeleton structure typically have a diameter of about 100 angstroms. However, the skeleton structure of the present invention may also comprise a network of interconnected oligomers, polymers, or colloidal particles of all diameter sizes forming a solid structure within a gel or aerogel. Furthermore, the term "silica-based aerogel" or "silica-based skeleton" means that the silica comprises at least 50% by weight of the aerogel skeleton of oligomers, polymers, or colloidal particles forming a solid skeleton structure within a gel or aerogel.

[0018] Within the scope of this invention, the term "aerogel composition" refers to any composite material that incorporates aerogel material as a component of a composite. Examples of aerogel compositions include, but are not limited to: fiber-reinforced aerogel composites; aerogel composites containing additive elements such as opacifiers; aerogel-foam composites; aerogel-polymer composites; and composite materials incorporating aerogel microparticles, particles, fine particles, beads, or powders into solid or semi-solid materials such as adhesives, resins, bonding agents, foams, polymers, or similar solid materials.

[0019] Within the scope of this invention, the term "single" refers to an aerogel material in which most (by weight) of the aerogels contained in an aerogel material or composition are in the form of a single interconnected aerogel nanostructure. A single aerogel material comprises an aerogel material initially formed having a single interconnected gel or aerogel nanostructure, but which subsequently breaks, fractures, or fragments into non-single aerogel nanostructures. A single aerogel material differs from a particulate aerogel material. The term "particulate aerogel material" refers to an aerogel material in which most (by weight) of the aerogels contained in an aerogel material are in the form of microparticles, particles, fine grains, beads, or powder, which may be combined or compressed together but lack interconnected aerogel nanostructures between individual particles.

[0020] Within this invention, the term "reinforced aerogel composition" refers to an aerogel composition that includes a reinforcing phase (which is not part of the aerogel skeleton) within an aerogel material. The reinforcing phase can be any material that provides increased flexibility, elasticity, conformability, or structural stability to the aerogel material. Examples of well-known reinforcing materials include, but are not limited to: open-cell foam reinforcing materials, closed-cell foam reinforcing materials, open membrane materials, honeycomb reinforcing materials, polymer reinforcing materials, and fiber-reinforcing materials such as discrete fibers, woven materials, non-woven materials, cotton wadding, mesh fabrics, mats, and felt articles. Furthermore, fiber-based reinforcement can be combined with one or more other reinforcing materials and can be directionally continuous throughout or preferably confined within the composition.

[0021] Within the present invention, the term "fiber-reinforced aerogel composition" refers to a reinforced aerogel composition comprising a fiber-reinforced material as a reinforcing phase. Examples of fiber-reinforced materials include, but are not limited to: discrete fibers, woven materials, non-woven materials, cotton wadding, mesh fabrics, mats, felt articles, or combinations thereof. Fiber-reinforced materials can include many materials, including, but not limited to: polyester, polyterephthalate, polyethylene naphthalate (PET), polycarbonate (e.g., rayon, nylon), cotton (e.g., Lycra from DuPont), carbon (e.g., graphite), polyacrylonitrile (PAN), oxidized PAN, uncarbonized heat-treated PAN (e.g., those produced with SGL carbon), glass fiber-based materials (e.g., S-glass, 901 glass, 902 glass, 475 glass, E-glass), silica-based fibers such as quartz (e.g., Quaetzel from Saint-Gobain), Q-felt products (Johns Manville), Saffil, Durablanket (Unifra DuPont produces x and other silica fibers, Duraback (Carborundum), polyaramid fibers such as Kevlar, Nomex, Sontera (all produced by DuPont), Conex (Taijin), polyolefins such as Tyvek (DuPont), Dyneema (DSM), Spectra (Honeywell), other polypropylene fibers such as Typar, Xavan (both produced by DuPont), fluoropolymers such as polytetrafluoroethylene (PTFE) with trade names such as Teflon (DuPont), Goretex (WLGORE), and silicon carbide fibers such as Nicalon (COI). Ceramics products, ceramic fibers such as Nextel (3M), acrylic polymers, wool, silk, hemp, leather, suede fibers, PBO-Zylon fibers (Tyobo), liquid crystal materials such as Vectan (Hoechst), Cambrelle fibers (DuPont), polyurethane, polyamide, wool fibers, boron, aluminum, iron, stainless steel fibers, and other thermoplastics such as PEEK, PES, PEI, PEK, and PPS.

[0022] Within the scope of this invention, the term "aerogel blanket" or "aerogel blanket composition" refers to an aerogel composition reinforced with a continuous sheet of reinforcing material. Aerogel blanket compositions differ from other reinforced aerogel compositions reinforced with discontinuous fibers or foam networks, such as separated agglomerates or clumps of fibrous materials. Aerogel blanket compositions are particularly suitable for applications requiring flexibility due to their high adaptability, allowing them to be used like blankets to cover surfaces with simple or complex geometries while retaining the excellent thermal insulation properties of aerogel. Aerogel blanket compositions and similar fiber-reinforced aerogel compositions are described in published U.S. Patent Application No. 2002 / 0094426 (paragraphs 12-16, 25-27, 38-58, 60-88), the individual sections and paragraphs of which are incorporated herein by reference.

[0023] Within the present invention, the term "wet gel" refers to a gel in which the mobile interstitial phase within the interconnected network of pores primarily comprises a liquid phase such as a conventional solvent, a liquefied gas such as liquid carbon dioxide, or a combination thereof. Aerogels typically require the initial fabrication of a wet gel, followed by innovative processing and extraction to replace the mobile interstitial phase in the gel with air. Examples of wet gels include, but are not limited to, alcohol gels, hydrogels, ketone gels, carbon gels, and any other wet gels known in the art.

[0024] Within the scope of this invention, the term "additive" or "additive element" refers to a material that may be added to the aerogel composition before, during, or after the manufacture of the aerogel. Additives may be added to alter or improve desired properties of the aerogel, or to counteract undesirable properties of the aerogel. Additives are typically added to the aerogel material before or during gelation. Examples of additives include, but are not limited to: microfibers, fillers, reinforcing agents, stabilizers, thickeners, elastic compounds, light-blocking agents, coloring or dyeing compounds, radiation-absorbing compounds, radiation-reflecting compounds, corrosion inhibitors, thermally conductive components, phase-changing materials, pH adjusters, redox regulators, HCN modifiers, exhaust gas modifiers, conductive compounds, dielectric compounds, magnetic compounds, radar-blocking components, hardeners, anti-shrinkage agents, and other aerogel additives known in the art. Other examples of additives include smoke suppressants and fire extinguishing agents. U.S. Patent Application No. 20070272902A1 (paragraphs

[0008] and

[0010] -

[0039] ) contains teachings on smoke suppressants and fire extinguishing agents, the individual paragraphs of which are incorporated herein by reference.

[0025] Within the scope of this invention, the term "flexible" or "flexible" refers to the property of an aerogel material or composition to bend or flex without macroscopic failure. The aerogel compositions of this invention are preferably capable of bending at least 5°, at least 25°, at least 45°, at least 65°, or at least 85° without macroscopic failure; and / or have a bending radius of less than 4 feet, less than 2 feet, less than 1 foot, less than 6 inches, less than 3 inches, less than 2 inches, less than 1 inch, or less than 1 / 2 inch without macroscopic failure. Similarly, the term "highly flexible" or "highly flexible" refers to an aerogel material or composition capable of bending to at least 90° and / or having a bending radius of less than 1 / 2 inch without macroscopic failure. Furthermore, the terms "classified as flexible" and "classified as flexible" refer to aerogel materials or compositions classified as flexible according to ASTM Classification Standard C1101 (ASTM International, West Conshohocken, PA).

[0026] The aerogel materials or compositions of the present invention may be flexible, highly flexible, and / or classified as flexible. The aerogel materials or compositions of the present invention may also be draped. Within this invention, the terms "draped" or "draping property" refer to the property of an aerogel material or composition to be bent or flexed to a bending radius of 90° or greater and about 4 inches or less without macroscopic failure. The aerogel materials or compositions of the present invention are preferably flexible so that the composition is non-rigid and can be applied to and conform to three-dimensional surfaces or objects, or pre-formed into various shapes and configurations to simplify installation or application.

[0027] Within the scope of this invention, the terms "elastic" or "flexible" refer to the property of an aerogel material or composition to at least partially recover its original shape or size after being compressed, flexed, or bent. Elasticity can be complete or partial, and it can be expressed as a percentage recovery. The aerogel materials or compositions of the present invention preferably have an elasticity of more than 25%, more than 50%, more than 60%, more than 70%, more than 75%, more than 80%, more than 85%, more than 90%, or more than 95% recovery to their original shape or size after deformation. Similarly, the terms "classified as elastic" and "classified as elastic" refer to the aerogel materials or compositions of the present invention classified as elastic according to ASTM Classification Standard C1101 (ASTM International, West Conshohocken, PA).

[0028] Within the scope of this invention, the term "self-supporting" refers to the flexible and / or elastic properties of an aerogel material or composition primarily based on the physical properties of the aerogel and any reinforcing phase within the aerogel composition. The self-supporting aerogel materials or compositions of this invention differ from other aerogel materials, such as coatings (which rely on an underlying substrate to provide flexibility and / or elasticity to the material).

[0029] Within the scope of this invention, the term "shrinkage rate" refers to: 1) the difference between the measured final density of a dried aerogel material or composition, or a similar aerogel material or composition, and the target density calculated from the solid content of the sol-gel precursor solution, relative to 2) the target density calculated from the solid content of the sol-gel precursor solution. Shrinkage rate can be calculated using the following formula: Shrinkage rate = [Final density (g / cm³)] 3 ) - Target density (g / cm³) 3 )] / [Target density (g / cm³) 3 The shrinkage rate of the aerogel material of the present invention is preferably 50% or less, 25% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.1% or less, about 0.01% or less, or in any range between these values.

[0030] Within the scope of this invention, the term "thermal conductivity" or "TC" refers to a measure of the ability of a material or composition to transfer heat between two surfaces on either side of the material or composition under a temperature difference between the two surfaces. Thermal conductivity is specifically measured as the amount of heat transferred per unit time and per unit surface area, divided by the temperature difference. It is typically recorded in SI units mW / m*K (milliwatts per meter of absolute temperature). The thermal conductivity of a material can be determined by methods known in the art, including, but not limited to: steady-state heat transfer properties test method by heat flow meter apparatus (ASTM C518, ASTM International, West Conshohocken, PA); steady-state heat flux measurement and heat transfer properties test method by protective heating plate apparatus (ASTM C177, ASTM International, West Conshohocken, PA); steady-state heat transfer properties test method for pipe insulation (ASTM C335, ASTM International, West Conshohocken, PA); thermal conductivity test of thin heaters (ASTM C1114, ASTM International, West Conshohocken, PA); determination of heat resistance by protective heating plate apparatus and heat flow meter method (EN12667, British Standardsinstitution); or determination of steady-state heat resistance and related properties by protective heating plate apparatus (ISO8203, International Organization for Standardization, Switzerland). Throughout this invention, thermal conductivity measurements were obtained at a temperature of approximately 37.5°C and a compression of approximately 2 psi, in accordance with ASTM C177 or ASTM C518 standards, unless otherwise stated. The aerogel materials or compositions of the present invention preferably have a thermal conductivity of approximately 50 mW / mK or less, approximately 40 mW / mK or less, approximately 30 mW / mK or less, approximately 25 mW / mK or less, approximately 20 mW / mK or less, approximately 18 mW / mK or less, approximately 16 mW / mK or less, approximately 14 mW / mK or less, approximately 12 mW / mK or less, approximately 10 mW / mK or less, approximately 5 mW / mK or less, or within any two of these values.

[0031] Within the scope of this invention, the term "density" refers to a measure of mass per unit volume of an aerogel material or composition. The term "density" generally refers to the actual density of the aerogel material, as well as the overall density of the aerogel composition. Density is typically expressed in kg / m³. 3Or recorded in g / cc. The density of the aerogel material or composition can be determined by methods known in the art, including, but not limited to: standard test methods for the dimensional and density measurements of preformed block and sheet insulation (ASTM C303, ASTM International, West Conshohocken, PA); standard test methods for the thickness and density of felt or wadding insulation (ASTM C167, ASTM International, West Conshohocken, PA); or determination of the apparent density of preformed pipe insulation (ISO 18098, International Organization for Standardization, Switzerland). Within the scope of this invention, density measurements are obtained according to ASTM C167 unless otherwise stated. The aerogel material or composition of the present invention preferably has a density of about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.25 g / cc or less, about 0.20 g / cc or less, about 0.18 g / cc or less, about 0.16 g / cc or less, about 0.14 g / cc or less, about 0.12 g / cc or less, about 0.10 g / cc or less, about 0.05 g / cc or less, about 0.01 g / cc or less, or a range between any two of these values.

[0032] In this document, the term "hydrophobic" refers to a measure of the water-repellent properties of an aerogel material or composition.

[0033] The hydrophobicity of aerogel materials or compositions can be expressed as water absorption rate. Within the scope of this invention, the term "water absorption rate" refers to the potential energy of an aerogel material or composition to absorb or retain water. Water absorption rate can be expressed as the percentage (by weight or volume) of water absorbed or retained by an aerogel material or composition when exposed to water under certain measurement conditions. The water absorption rate of an aerogel material or composition can be determined by methods known in the art, including, but not limited to: standard test methods for measuring the water retention (drainage) properties of fiberglass insulation (ASTM C1511, ASTM International, West Conshohocken, PA); standard test methods for water absorption by immersion in insulation materials (ASTM C1763, ASTM International, West Conshohocken, PA); and for insulation products used in building applications: measurements of short-term water absorption by partial immersion (EN 1609, British Standardsinstitution). Within the scope of this invention, water absorption rate measurements are obtained according to ASTM C1511 at normal pressure and temperature, unless otherwise stated. The aerogel material or composition of the present invention preferably has a water absorption rate according to ASTM C1511 within the range of about 100 wt% or less, about 80 wt% or less, about 60 wt% or less, about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or any two of these values. The aerogel material or composition of the present invention may have a water absorption rate according to ASTM C1763 within the range of about 100 wt% or less, about 80 wt% or less, about 60 wt% or less, about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or any two of these values. An aerogel material or composition having an improved water absorption rate relative to another aerogel material or composition will have a lower percentage of water absorption than a reference aerogel material or composition.

[0034] The hydrophobicity of aerogel materials or compositions can be expressed as water vapor absorption rate. Within the scope of this invention, the term "water vapor absorption rate" refers to the potential energy of an aerogel material or composition to absorb or retain water. The water vapor absorption rate can be expressed as the percentage (by weight) of water vapor absorbed or retained by an aerogel material or composition when exposed to water vapor under certain measurement conditions. The water vapor absorption rate of an aerogel material or composition can be determined by methods known in the art, including, but not limited to, standard test methods for measuring the water vapor absorption of unprocessed mineral fiber insulation surfaces (ASTM C1104, ASTM International, West Conshohocken, PA). Within the scope of this invention, water vapor absorption rate measurements are obtained at normal pressure and temperature according to ASTM C1104, unless otherwise stated. The aerogel material or composition of the present invention preferably has a water vapor absorption rate of about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or in any range between these values. An aerogel material or composition having an improved water vapor absorption rate relative to another aerogel material or composition will have a lower water vapor absorption rate / water vapor retention percentage than a reference aerogel material or composition.

[0035] The hydrophobicity of an aerogel material or composition can be represented by measuring the equilibrium contact angle of a water droplet at the interface with the material surface. The aerogel material or composition of the present invention may have a water contact angle of about 90° or greater, about 120° or greater, about 130° or greater, about 140° or greater, about 150° or greater, about 160° or greater, about 170° or greater, about 175° or greater, or a range between any two of these values.

[0036] Within the scope of this invention, the term "heat of combustion" or "HOC" refers to a measure of the thermal energy released by the combustion of an aerogel material or composition. Heat of combustion is typically recorded in calories (cal / g) of thermal energy released per gram of aerogel material or composition, or megajoules (MJ / kg) of thermal energy released per kilogram of aerogel material or composition. The heat of combustion of an aerogel material or composition can be determined by methods known in the art, including, but not limited to, fire test reaction of the product – measurement of total heat of combustion (calorific value) (ISO 1716, International Organization for Standardization, Switzerland). Within the scope of this invention, heat of combustion measurements are obtained according to conditions comparable to ISO 1716, unless otherwise stated. The aerogel material or composition of the present invention preferably has a heat of combustion of about 750 cal / g or less, about 717 cal / g or less, about 700 cal / g or less, about 650 cal / g or less, about 600 cal / g or less, about 575 cal / g or less, about 550 cal / g or less, about 500 cal / g or less, about 450 cal / g or less, about 400 cal / g or less, about 350 cal / g or less, about 300 cal / g or less, about 250 cal / g or less, about 200 cal / g or less, about 150 cal / g or less, about 100 cal / g or less, about 50 cal / g or less, about 25 cal / g or less, about 10 cal / g or less, or in any two of these values. An aerogel composition having an improved heat of combustion relative to another aerogel composition will have a lower heat of combustion value than a reference aerogel composition.

[0037] Within the scope of this invention, the terms "thermal decomposition initiation of hydrophobic organic materials," "thermal decomposition initiation," and "T" are used. d The term "thermal decomposition initiation" refers to the lowest temperature measure of the environment from the rapid exothermic reaction of a hydrophobic organic material decomposing within a material or composition. The thermal decomposition initiation of a material or composition can be measured using thermogravimetric analysis (TGA). A TGA curve of a material depicts the weight loss (% mass) of the material when exposed to increasing ambient temperature. The thermal decomposition initiation of a material is related to the intersection of the following tangents to the TGA curve: the line tangent to the bottom line of the TGA curve, and the line tangent to the TGA curve at the point of maximum slope during the rapid decomposition event associated with the hydrophobic organic material. Within the scope of this invention, the measurement of the thermal decomposition initiation of the hydrophobic organic material is obtained using TGA analysis as described in this paragraph, unless otherwise stated.

[0038] The thermal decomposition initiation point of a material can also be measured using differential scanning calorimetry (DSC). The DSC curve of a material depicts the heat energy (mW / mg) released by the material when exposed to a gradually increasing ambient temperature. The thermal decomposition temperature initiation point of a material can be correlated with the DSC curve, where ΔmW / mg (the change in heat output) increases most significantly, thus representing the exothermic heat production from the aerogel material. Within the scope of this invention, measurements of the thermal decomposition initiation point using DSC are obtained at a temperature rise / fall rate of 20°C or less, unless otherwise stated.

[0039] The aerogel material or composition of the present invention preferably has a thermal decomposition initiation temperature of about 100°C or greater, about 150°C or greater, about 200°C or greater, about 250°C or greater, about 300°C or greater, about 350°C or greater, about 400°C or greater, about 450°C or greater, about 500°C or greater, about 550°C or greater, about 600°C or greater, about 650°C or greater, about 700°C or greater, about 750°C or greater, about 800°C or greater, or a range between any two of these values. An aerogel material or composition having an improved thermal decomposition initiation temperature relative to another aerogel material or composition will have a higher thermal decomposition temperature initiation temperature than a reference aerogel material or composition.

[0040] In this document, the term "self-heating temperature" refers to a measure of the lowest ambient temperature at which an exothermic reaction occurs within an insulating system, such as an insulating system comprising an aerogel material or composition, under specific measurement conditions. In this document, the self-heating temperature of the insulating system is measured according to the following procedure, unless otherwise stated: a) providing an insulating system having a geometric cube with a 20 mm dimension on each side; b) placing a thermocouple measuring device at the center of the insulating system; and c) exposing the insulating system to a series of increasing temperatures until a self-heating exothermic event occurs, expressed as a quantity significantly sufficient to indicate a self-heating exothermic event within the insulating system by the temperature of the thermocouple measuring device exceeding the external exposure temperature of the sample. Preferably, the aerogel material or composition of the present invention preferably has an autothermal temperature of about 100°C or higher, about 150°C or higher, about 200°C or higher, about 250°C or higher, about 300°C or higher, about 350°C or higher, about 400°C or higher, about 450°C or higher, about 500°C or higher, about 550°C or higher, about 600°C or higher, about 650°C or higher, about 700°C or higher, about 750°C or higher, about 800°C or higher, or a range between any two of these values. An aerogel material or composition having an improved autothermal temperature relative to another aerogel material or composition will have a higher autothermal temperature than a reference aerogel material or composition.

[0041] Aerogels are described as having a framework, most commonly comprising interconnected oligomers, polymers, or colloidal particles. The aerogel framework can be made from a variety of precursor materials, including: inorganic precursor materials (such as those used to manufacture silica-based aerogels); organic precursor materials (such as those used to manufacture carbon-based aerogels); mixed inorganic / organic precursor materials; and combinations thereof. Within the scope of this invention, the term "hybrid aerogel" refers to an aerogel made from a combination of two or more different gel precursors.

[0042] Inorganic aerogels are typically formed from metal oxides or metal alkoxides. These metal oxides or metal alkoxides can be oxides or alkoxides of any metal that can form oxides. Such metals include, but are not limited to, silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, cerium, etc. Inorganic silica aerogels are conventionally manufactured through the hydrolysis and condensation of silica-based alkoxides (such as tetraethoxysilanes), or through gelation via silicic acid or water glass. Other related inorganic precursor materials for the synthesis of silica-based aerogels include, but are not limited to: metal silicates such as sodium silicate or potassium silicate, alkoxysilanes, partially hydrolyzed alkoxysilanes, tetraethoxysilanes (TEOS), partially hydrolyzed TEOS, condensation polymers of TEOS, tetramethoxysilanes (TMOS), partially hydrolyzed TMOS, condensation polymers of TMOS, tetra-n-propoxysilanes, partially hydrolyzed and / or condensation polymers of tetra-n-propoxysilanes, polyethyl silicate, partially hydrolyzed polyethyl silicate, monoalkylalkoxysilanes, bis-trialkoxyalkyl or arylsilanes, polyhedral silsesquioxanes, or combinations thereof.

[0043] In some embodiments of the invention, pre-hydrolyzed TEOS, such as Silbond H-5 (SBH5, Silbond Corporation), which is hydrolyzed at a water / silica ratio of about 1.9-2, is commercially available or may be further hydrolyzed before being incorporated into the gelation process. Partially hydrolyzed TEOS or TMOS, such as polyethylene silicate (Silbond 40) or polymethyl silicate, is also commercially available or may be further hydrolyzed before being incorporated into the gelation process.

[0044] Inorganic aerogels may also contain gel precursors comprising at least one hydrophobic group, such as alkyl metal alkoxides, cycloalkyl metal alkoxides, and aryl metal alkoxides, which can impart or modify certain properties of the gel, such as stability and hydrophobicity. Inorganic silica aerogels may specifically contain hydrophobic precursors such as alkylsilanes or arylsilanes. Hydrophobic gel precursors can be used as primary precursor materials to form the framework of the gel material. However, hydrophobic gel precursors are more often used as co-precursors in combination with simple metal alkoxides that form hybrid aerogels. Hydrophobic inorganic precursor materials synthesized from silica-based aerogels include, but are not limited to: trimethylmethoxysilane [TMS], dimethyldimethoxysilane [DMS], methyltrimethoxysilane [MTMS], trimethylethoxysilane, dimethyldiethoxysilane [DMDS], methyltriethoxysilane [MTES], ethyltriethoxysilane [ETES], diethyldiethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane [PhTES], hexamethyldisilazane, and hexaethyldisilazane, etc.

[0045] Aerogels can be treated to impart or modify hydrophobicity. Hydrophobic treatment can be applied to a sol-gel solution, a wet gel, or an aerogel after liquid-phase extraction. Hydrophobic treatment is particularly common in the manufacture of metal oxide aerogels, such as silica aerogels. Examples of hydrophobic treatment of gels are detailed below, particularly in the treatment of silica wet gels. However, the specific examples and descriptions provided herein are not intended to limit the scope of the invention to any particular type of hydrophobic treatment procedure or aerogel substrate. The invention may encompass any gel or aerogel known in the art, and related methods for hydrophobic treatment of aerogels (in wet or dry aerogel form).

[0046] Hydrophobic treatment is performed by reacting the hydroxyl groups on the gel, such as the silanol groups (Si-OH) present on the backbone of the silica gel, with the functional groups of a hydrophobicating agent. The resulting reaction transforms the silanol groups and the hydrophobicating agent into hydrophobic groups on the backbone of the silica gel. The hydrophobicating agent compound reacts with the hydroxyl groups on the gel according to the following reaction: R N MX 4-N (Hydrophobic agent) + MOH (silanol) → MOMR N (Hydrophobic group) + HX. Hydrophobic treatment can occur on both the large outer surface of the silica gel and the inner pore surfaces within the porous network of the gel.

[0047] The gel can be immersed in a mixture of a hydrophobic agent and an optional hydrophobic treatment solvent in which the hydrophobic agent is soluble, and it is also miscible with the gel solvent in the wet gel. A wide range of hydrophobic treatment solvents can be used, including solvents such as methanol, ethanol, isopropanol, xylene, toluene, benzene, dimethylformamide, and hexane. The hydrophobic agent in liquid or gaseous form can also be in direct contact with the gel to impart hydrophobicity.

[0048] The hydrophobic treatment process may include mixing or stirring to help the hydrophobic agent penetrate the wet gel. The hydrophobic treatment process may also include altering other conditions such as temperature and pH to further enhance or optimize the treatment reaction. After the reaction is complete, the wet gel is rinsed to remove unreacted compounds and reaction byproducts.

[0049] The hydrophobicating agents used for hydrophobic treatment of aerogels are typically of the formula: R N MX 4-N The compound; wherein M is a metal; R is a hydrophobic group such as CH3, CH2CH3, C6H6, or similar hydrophobic alkyl, cycloalkyl, or aryl moiety; and X is a halogen, usually Cl. Specific examples of hydrophobic agents include, but are not limited to: trimethylchlorosilane [TMCS], triethylchlorosilane [TECS], triphenylchlorosilane [TPCS], dimethylchlorosilane [DMCS], dimethyldichlorosilane [DMDCS], etc. Hydrophobic agents may also have the formula: Y(R3M)2; wherein M is a metal; Y is a bridging group such as NH or O; and R is a hydrophobic group such as CH3, CH2CH3, C6H6, or similar hydrophobic alkyl, cycloalkyl, or aryl moiety. Specific examples of such hydrophobic agents include, but are not limited to: hexamethyldisilazane [HMDZ] and hexamethyldisiloxane [HMDSO]. Hydrophobic agents may further include the formula: R N MV 4-N Compounds in which V is a reactive or leaving group other than a halogen. Specific examples of such hydrophobic agents include, but are not limited to, vinyltriethoxysilane and vinyltrimethoxysilane.

[0050] Within the present invention, the term "hydrophobic-bonded silicon" refers to silicon atoms within the framework of a gel or aerogel comprising at least one hydrophobic group covalently bonded to silicon atoms. Examples of hydrophobic-bonded silicon include, but are not limited to, silicon atoms in silica groups within a gel framework formed from a gel precursor comprising at least one hydrophobic group (such as MTES or DMDS). Hydrophobic-bonded silicon may also include, but is not limited to, silicon atoms in the gel framework or on the gel surface treated with a hydrophobicating agent (such as HMDZ) that impart or modify hydrophobicity by incorporating other hydrophobic groups into the composition. The hydrophobic groups of the present invention include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, octyl, phenyl, or other substituted or unsubstituted hydrophobic organic groups known in the art. In this invention, the terms "hydrophobic group", "hydrophobic organic material", and "hydrophobic organic content" specifically exclude readily hydrolyzable organically bound silanoxy groups on the gel material skeleton of the reaction product between organic solvents and silanol groups.

[0051] Within the scope of this invention, the terms "aliphatic hydrophobic group," "aliphatic hydrophobic organic material," and "aliphatic hydrophobic organic content" refer to hydrophobic groups limited to those on a hydrophobically bonded silicon of an aliphatic hydrocarbon, including, but not limited to, hydrocarbon moieties containing 1-40 carbon atoms (but not aromatic), which may be saturated or unsaturated, and may include straight-chain, branched, cyclic moieties (including fused, bridged, and spiro-fused polycyclic rings), or combinations thereof, such as alkyl, alkenyl, alkynyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl, or (cycloalkyl)alkenyl moieties, and hetero-aliphatic moieties (wherein one or more carbon atoms are independently substituted by one or more atoms selected from the group consisting of oxygen, sulfur, nitrogen, and phosphorus). In some embodiments of the invention, at least 50% of the hydrophobic organic material in the aerogel composition comprises aliphatic hydrophobic groups.

[0052] NMR spectra, such as CP / MAS, can be used. 29 Solid-state NMR analysis of Si indicates the amount of hydrophobic bound silicon contained in aerogels. NMR analysis of aerogels can identify characteristic and relatively quantifiable types of hydrophobic bound silicon: M-type hydrophobic bound silicon (monofunctional silica, such as TMS derivatives); D-type hydrophobic bound silicon (bifunctional silica, such as DMDS derivatives); T-type hydrophobic bound silicon (trifunctional silica, such as MTES derivatives); and Q-type hydrophobic bound silicon (tetrafunctional silica, such as TEOS derivatives). NMR analysis can also classify hydrophobic bound silicon into subtypes based on specific types (e.g., T-type hydrophobic bound silicon is classified into T...). 1 Species, T 2 Species, and T 3(Species) and used to analyze the bonding chemistry of hydrophobic bound silicon contained in aerogels. Specific details on NMR analysis of silica materials can be found in Geppi et al.'s paper "Study on solid-state NMR applications of organic / inorganic multi-component materials", specifically pp. 7-9 (Appl. Spec. Rev. (2008), 44-1: 1-89), which are incorporated herein by reference according to the specific page numbers cited.

[0053] CP / MAS 29 The characteristics of hydrophobic bound silicon in SiNMR analysis can be based on the following chemical shift peaks: M 1 (30 to 10 ppm); D 1 (10 to -10 ppm), D 2 (-10 to -20 ppm); T 1 (-30 to -40 ppm), T 2 (-40 to -50 ppm), T 3 (-50 to -70ppm); Q 2 (-70 to -85ppm), Q 3 (-85 to -95ppm), Q 4 (-95 to -110 ppm). These chemical shift peaks are approximate and illustrative, and are not intended to limit or define. Precise chemical shift peaks attributable to various silicon species within a material depend on the specific chemical composition of the material and can generally be decoded by routine experiments and analyses in the art.

[0054] The aerogel material of the present invention may have a T0.01 to a value between about 0.5, between about 0.01 and about 0.3, or between about 0.1 and about 0.3. 1-2 :T 3 The ratio of T. 1-2 :T 3 The ratio represents T 1 With T 2 Species combination relative to T 3 The ratio of species. T 1 T 2 and T 3 The amount can be obtained by separately connecting with 29 T as defined above in Si NMR analysis 1 Species, T 2 Species or T 3 The integral of individual chemical shift peaks related to the species is used for quantification. The aerogel material of the present invention may have a Q value between about 0.1 and 2.5, between about 0.1 and 2.0, between about 0.1 and 1.5, between about 0.1 and 1.0, or between about 0.5 and 1.0. 2-3 Q 4 The ratio. Q2-3 Q 4 The ratio represents Q 2 With Q 3 The combination of species relative to Q 4 The ratio of species. Q 2 Q 3 and Q 4 The amount can be obtained by separately connecting with 29 In Si NMR analysis, Q as defined above... 2 Species, Q 3 Species or Q 4 The integrals of individual chemical shift peaks related to species are used to quantify the data.

[0055] Within the scope of this invention, the term "hydrophobic organic content" refers to the amount of hydrophobic organic material incorporated into the framework of an aerogel material or composition. The hydrophobic organic content of an aerogel material or composition can be expressed as a weight percentage of the amount of hydrophobic organic material on the aerogel framework relative to the total amount of material in the aerogel material or composition. The hydrophobic organic content can be calculated by those well known in the art based on the nature and relative concentration of the materials used to manufacture the aerogel material or composition. The hydrophobic organic content can also be measured using thermogravimetric analysis (TGA) in an inert atmosphere. More specifically, the percentage of hydrophobic organic material in the aerogel can be correlated with the percentage weight loss of the aerogel material or composition when a combustion heat temperature is applied during TGA analysis, adjusted for moisture loss, residual solvent loss, and loss of readily hydrolyzable alkoxy groups during TGA analysis.

[0056] The aerogel material or composition of the present invention may have a hydrophobic organic content of 50 wt% or less, 40 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, 10 wt% or less, 8 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or any two of these values.

[0057] The term "fuel content" refers to the total amount of combustible material in an aerogel material or composition, which can be correlated with the total weight loss of the aerogel material or composition after adjusting for moisture loss when the heat of combustion is applied during TGA or TG-DSC analysis. The fuel content of an aerogel material or composition may include hydrophobic organic content, as well as other combustible materials such as residual alcohol solvents, filler materials, reinforcing materials, and readily hydrolyzable alkoxy groups.

[0058] Organic aerogels are typically formed from carbon-based polymer precursors. Such polymer materials include, but are not limited to: resorcinol aldehyde (RF), polyimide, polyacrylate, polymethacrylate, acrylate oligomers, polyepoxide, polyurethane, polyphenol, polybutane, terminal trialkoxysilyl polydimethylsiloxane, polystyrene, polyacrylonitrile, polyfurfural, melamine-formaldehyde, cresol-formaldehyde, phenol-furfural, polyether, polyol, polyisocyanate, polyhydroxybenzene, polyvinyl alcohol dialdehyde, polycyanate, polyacrylamide, various epoxides, agar, agarose, chitosan, and combinations thereof. As an example, organic RF aerogels are typically manufactured by the sol-gel polymerization of resorcinol or melamine with formaldehyde under alkaline conditions.

[0059] Organic / inorganic hybrid aerogels primarily include organosiloxane film aerogels (organically modified silica). These organosiloxane film materials contain organic components covalently bonded to a silica network. Organosiloxane films are typically formed through the hydrolysis and condensation of organically modified silanes, R-Si(OX)3, and conventional alkoxide precursors, Y(OX)4. In these formulas, X can represent, for example, CH3, C2H5, C3H7, C4H9; Y can represent, for example, Si, Ti, Zr, or Al; and R can be any organic segment such as methyl, ethyl, propyl, butyl, isopropyl, methacrylate, acrylate, vinyl, epoxide, etc. The organic components in organosiloxane film aerogels can also be dispersed throughout the silica network or chemically bonded to it.

[0060] Within the present invention, the term "organosiloxane film" refers to ceramics comprising the aforementioned materials and other organically modified materials, sometimes referred to as "ormocer". Organosiloxane films are frequently used as coatings, wherein the organosiloxane film is cast onto a substrate via, for example, a sol-gel process. Other examples of organic-inorganic hybrid aerogels of the present invention include, but are not limited to, silica-polyether, silica-PMMA, silica-chitosan, carbides, nitrides, and other combinations of the aforementioned organic and inorganic aerogel forming compounds. U.S. Patent Application Publication No. 20050192367 (paragraphs

[0022] -

[0038] and

[0044] -

[0058] ) contains teachings on such hybrid organic-inorganic materials, which are incorporated herein by reference in accordance with the individual referenced sections and paragraphs.

[0061] The aerogel of the present invention is preferably an inorganic silica aerogel formed primarily of an alcohol solution of hydrolyzed silicate esters (formed from silane oxides). However, the present invention can be implemented with any other aerogel composition known in the art, and is not limited to any one precursor material or mixture of precursor materials.

[0062] The manufacture of aerogels typically involves the following steps: i) forming a sol-gel solution; ii) forming a gel from the sol-gel solution; and iii) obtaining a dried aerogel material through innovative processing and extraction of the solvent from the gel material. This process is detailed below, particularly in the section on the formation of inorganic aerogels such as silica aerogels. However, the specific examples and descriptions provided herein are not intended to limit the scope of the invention to any particular type of aerogel and / or preparation method. The invention may include any aerogel formed by any relevant preparation method known in the art.

[0063] The first step in forming inorganic aerogels typically involves the hydrolysis and condensation of metal alkoxide precursors in an alcohol-based solvent to form a sol-gel solution. Key variables in inorganic aerogel formation include the type of alkoxide precursor contained in the sol-gel solution, the nature of the solvent, the processing temperature and pH of the sol-gel solution (which can be altered by adding acid or base), and the precursor / solvent / water ratio within the sol-gel solution. Controlling these variables in sol-gel formation allows for the control of gel skeleton growth and aggregation during the subsequent transition of the gel material from a "sol" to a "gel" state. While the properties of the resulting aerogel are affected by the pH of the precursor solution and the molar ratio of the reactants, any pH and molar ratio at which gel formation can occur can be used in this invention.

[0064] Sol-gel solutions are formed by combining at least one gelation precursor with a solvent. Suitable solvents for forming sol-gel solutions include lower alcohols having 1 to 6, preferably 2 to 4, carbon atoms, although other solvents known to those skilled in the art may be used. Examples of solvents that can be used include, but are not limited to, methanol, ethanol, isopropanol, ethyl acetate, ethyl acetoacetate, acetone, dichloromethane, tetrahydrofuran, etc. Multiple solvents may also be combined to achieve the desired degree of dispersion and optimize the properties of the gel material. The selection of the optimized solvent and gelation step for the sol-gel is therefore dependent on the specific precursor, the fillers and additives incorporated into the sol-gel solution, the target processing conditions for gelation and liquid-phase extraction, and the desired properties of the final aerogel material.

[0065] Water can also be present in the precursor-solvent solution. Water can dissolve metal alkoxide precursors into metal hydroxide precursors. The hydrolysis reaction can be (using TEOS in ethanol solvent as an example): Si(OC2H5)4 + 4H2O → Si(OH)4 + 4(C2H5OH). The resulting hydrolyzed metal hydroxide precursor remains in a "sol" state, with individual molecules or small polymeric (or oligomeric) colloidal clusters suspended in the solvent solution. For example, the polymerization / condensation reaction of the Si(OH)4 precursor can occur as follows: 2Si(OH)4 = (OH)3Si-O-Si(OH)3 + H2O. This polymerization reaction can continue until colloidal clusters of polymeric (or oligomeric) SiO2 (silicon dioxide) molecules are formed.

[0066] Acids and bases can be incorporated into sol-gel solutions to control the pH of the solution and catalyze the hydrolysis and condensation reactions of precursor materials. While any acid can be used to catalyze precursor reactions and obtain solutions with lower pH values, preferred acids include HCl, H₂SO₄, H₃PO₄, oxalic acid, and acetic acid. Similarly, any base can be used to catalyze precursor reactions and obtain solutions with higher pH values; preferred bases include NH₄OH.

[0067] The sol-gel solution may contain other co-gelation precursors, as well as filler materials and other additives. The filler materials and other additives may be dispensed into the sol-gel solution at any point before or during gel formation. The filler materials and other additives may also be incorporated into the gel material after gelation via various techniques known in the art. The sol-gel solution comprising gelation precursors, solvents, catalysts, water, filler materials, and other additives is preferably a homogeneous solution capable of effectively forming a gel under suitable conditions.

[0068] Once the sol-gel solution is formed and optimized, the gel-forming components in the sol-gel can be transformed into a gel material. The process of transforming the gel-forming components into a gel material includes an initial gel-forming step, in which the gel is solidified until the gel point of the gel material. The gel point of the gel material can be considered as the point where the gelled solution exhibits resistance to flow and / or forms a substantially continuous polymer backbone throughout its volume. Many gel-forming techniques are known in the art. Examples include, but are not limited to: maintaining the mixture in a static state for a sufficient period of time; adjusting the pH of the solution; adjusting the temperature of the solution; directing an energy form onto the mixture (ultraviolet light, visible light, infrared light, microwaves, ultrasound, particle radiation, electromagnetic waves); or combinations thereof.

[0069] The process of transforming gel-forming components into gel materials may also include an aging step (also known as curing) before liquid-phase extraction. Aging the gel material after it reaches its gel point can further strengthen the gel skeleton by increasing the number of crosslinks within the network. The aging period can be adjusted to control various properties within the resulting aerogel material. This aging process can be used to prevent potential volume loss and shrinkage during liquid-phase extraction. Aging can encompass: holding the gel in a static state (before extraction) for an extended period; maintaining the gel at elevated temperatures; adding crosslinking-promoting compounds; or any combination thereof. The preferred aging temperature is typically between about 10°C and about 100°C. The aging of the gel material usually continues until the liquid-phase extraction of the wet gel material.

[0070] The time it takes for the gel-forming component to transform into the gel material includes the initial gel formation period (from the start of gelation to the gel point) and any subsequent curing and aging of the gel material before liquid-phase extraction (from the gel point to the start of liquid-phase extraction). The total time for the gel-forming component to transform into the gel material is typically from about 1 minute to several days, preferably about 30 hours or less, about 24 hours or less, about 15 hours or less, about 10 hours or less, about 6 hours or less, about 4 hours or less, about 2 hours or less, about 1 hour or less, about 30 minutes or less, or about 15 minutes or less.

[0071] The resulting gel material can be rinsed with a suitable second solvent to replace the first reaction solvent present in the wet gel. The second solvent may be a straight-chain unit alcohol having one or more aliphatic carbon atoms, a diol having two or more carbon atoms, a branched-chain alcohol, a cyclic alcohol, an alicyclic alcohol, an aromatic alcohol, a polyol, an ether, a ketone, a cyclic ether, or a derivative thereof.

[0072] Once the gel material is formed and processed, extraction methods (including innovative processing and extraction techniques) can be used to at least partially extract the liquid phase of the gel from the wet gel to form an aerogel material. Liquid phase extraction plays a crucial role in the engineering of aerogel characteristics, such as porosity and density, and related properties such as thermal conductivity. Typically, aerogels are obtained by extracting the liquid phase from the gel in a manner that causes minimal shrinkage to the porous network and framework of the wet gel.

[0073] Aerogels are typically formed by removing the liquid mobile phase from the gel material at temperatures and pressures near or above the critical point of the liquid mobile phase. Once the critical point is reached (near critical) or exceeded (supercritical) (i.e., the system pressure and temperature are at or above the critical pressure and critical temperature, respectively), a new supercritical phase appears in the liquid, distinct from the liquid or gas phase. The solvent can then be removed without introducing capillary pressure, or any associated mass transfer limitations typically associated with the liquid-gas boundary. Furthermore, the supercritical phase is generally more miscible with organic solvents, thus exhibiting better extraction capabilities. Co-solvents and solvent exchange are also commonly used to optimize supercritical fluid drying processes.

[0074] If evaporation or extraction occurs below the supercritical point, the capillary forces generated by liquid evaporation can cause pore shrinkage and skeletal collapse within the gel material. Maintaining the mobile phase at near or above the critical pressure and temperature during solvent extraction processes reduces the negative impact of these capillary forces. In some embodiments of the invention, near-critical conditions just below the critical point of the solvent system can produce aerogel materials or compositions with sufficiently low shrinkage, thus yielding commercially viable end products.

[0075] Several other aerogel extraction techniques are known in the art, encompassing many different methods using supercritical fluids to dry aerogels. For example, Kistler (J. Phys. Chem. (1932) 36: 52-64) describes a simple supercritical extraction process in which the gel solvent is maintained above its critical pressure and temperature, thus reducing capillary forces of evaporation and maintaining the structural integrity of the gel network. U.S. Patent No. 4,610,863 describes an extraction process in which the gel solvent is exchanged with liquid carbon dioxide and subsequently extracted under conditions where the carbon dioxide is in a supercritical state. U.S. Patent No. 6,670,402 teaches the production of aerogels by rapidly exchanging the liquid phase from the gel via solvent exchange through injection of supercritical (not liquid) carbon dioxide into an extractor preheated and pre-pressurized to substantially supercritical conditions or above. U.S. Patent No. 5,962,539 describes a process for obtaining aerogels from polymeric materials in sol-gel form in an organic solvent by exchanging an organic solvent with a fluid having a critical temperature below the polymer decomposition temperature and supercritically extracting the fluid / sol-gel. U.S. Patent No. 6,315,971 discloses a process for manufacturing a gel composition, comprising: drying a wet gel including a gel solid and a desiccant to remove the desiccant under drying conditions sufficient to reduce gel shrinkage during drying. U.S. Patent No. 5,420,168 describes a process in which resorcinol / formaldehyde aerogels can be manufactured using a simple air-drying procedure. U.S. Patent No. 5,565,142 describes a drying technique in which the gel surface is modified to be stronger and more hydrophobic, such that the gel framework and pores resist collapse during environmental drying or subcritical extraction. Other examples of extracting liquid phases from aerogel materials can be found in U.S. Patents Nos. 5,275,796 and 5,395,805.

[0076] A preferred embodiment of a self-wetting gel extraction of the liquid phase using supercritical carbon dioxide includes, for example: firstly, substantially exchanging a first solvent present in the pore network of the gel with liquid carbon dioxide; then heating the wet gel (typically in an autoclave) above the critical temperature of carbon dioxide (approximately 31.06°C) and increasing the system pressure to a pressure greater than the critical pressure of carbon dioxide (approximately 1070 psig). The pressure around the gel material can be slightly varied to facilitate the self-gel removal of supercritical carbon dioxide. The carbon dioxide can be circulated through the extraction system to facilitate the continued removal of the first solvent by the self-wetting gel. Finally, the temperature and pressure are slowly returned to ambient conditions to produce a dry aerogel material. The carbon dioxide can also be pre-processed to a supercritical state before being injected into the extraction chamber.

[0077] An example of an alternative method for forming aerogels involves acidifying an alkaline metal oxide precursor (such as sodium silicate) in water to produce a hydrogel. Salt byproducts can be removed from the silicate precursor by ion exchange and / or rinsing the subsequently formed gel with water. Water removal from the pores of the gel can be carried out by exchange with a polar organic solvent such as ethanol, methanol, or acetone. The liquid phase in the gel is then at least partially extracted using innovative processing and extraction techniques.

[0078] Another example of alternative methods for forming aerogels includes chemically modifying a matrix material in a wet hydrogel state by converting surface hydroxyl groups to hydrophobic trimethylsilyl ethers to reduce harmful capillary pressure at the solvent / pore interface, thus enabling extraction of the liquid phase from the gel material at temperatures and pressures below the solvent's critical point.

[0079] The large-scale production of aerogel materials or compositions is complicated by the difficulty of large-scale continuous formation of gel materials and the difficulty of using innovative processing and extraction techniques to extract the liquid phase from the gel material in large volumes. The aerogel materials or compositions of the present invention are preferably suitable for large-scale production. In some embodiments, the gel materials of the present invention can be mass-produced via a continuous casting and colloidal process. In some embodiments, large-scale production of the gel materials or compositions of the present invention requires the use of a large-scale extraction vessel. The large-scale extraction vessel of the present invention may contain a diameter of approximately 0.1 m... 3 Or larger, approximately 0.25m 3 Or larger, approximately 0.5m 3 Or larger, or about 0.75m 3 Or a larger extraction container.

[0080] The gel composition of the present invention may have a thickness of 15 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less, or 1 mm or less.

[0081] Dry aerogel materials or compositions can be further processed to optimize their target properties. In some embodiments, the dry aerogel composition may be subjected to one or more heat treatments, such as pyrolysis, to produce a heat-treated aerogel composition. Careful control of heat treatment can be used to reduce or stabilize the hydrocarbon fuel content of the aerogel material or composition, which can improve the corresponding HOC and T of the aerogel material or composition. d Properties. In some embodiments, the heat treatment of the dry aerogel composition can occur within a range of temperature, pressure, duration, and atmospheric conditions.

[0082] In some embodiments of the invention, the dry aerogel composition may be subjected to a treatment temperature of 200°C or higher, 250°C or higher, 300°C or higher, 350°C or higher, 400°C or higher, 450°C or higher, 500°C or higher, 550°C or higher, 600°C or higher, 650°C or higher, 700°C or higher, 750°C or higher, 800°C or higher, or a range between any two of said values.

[0083] In some embodiments of the invention, the dry aerogel composition may be applied for a duration of 3 hours or longer, between 10 seconds and 3 hours, between 10 seconds and 2 hours, between 10 seconds and 1 hour, between 10 seconds and 45 minutes, between 10 seconds and 30 minutes, between 10 seconds and 15 minutes, between 10 seconds and 5 minutes, between 10 seconds and 1 minute, between 1 minute and 3 hours, between 1 minute and 1 hour, between 1 minute and 45 minutes, between 1 minute and 30 minutes, between 1 minute and 15 minutes, between 1 minute and 5 minutes, 10 One or more heat treatments within the range of 10 minutes to 3 hours, 10 minutes to 1 hour, 10 minutes to 45 minutes, 10 minutes to 30 minutes, 10 minutes to 15 minutes, 30 minutes to 3 hours, 30 minutes to 1 hour, 30 minutes to 45 minutes, 45 minutes to 3 hours, 45 minutes to 90 minutes, 45 minutes to 60 minutes, 1 hour to 3 hours, 1 hour to 2 hours, or 1 hour to 90 minutes, or any two of the values ​​mentioned.

[0084] In some embodiments of the invention, the dry aerogel composition may be subjected to a treatment temperature of 200°C to 750°C for 10 seconds to 3 hours.

[0085] Heat treatment of aerogel materials or compositions can occur in an oxygen-depleted environment. Within the scope of this invention, the term "oxygen-depleted environment" refers to an atmosphere comprising a volume concentration of 10 vol% oxygen or less (which is lower than the amount of oxygen in ambient air under standard conditions). An oxygen-depleted environment may include a positively pressurized atmosphere having an increased concentration of inert gases (including, but not limited to, nitrogen, argon, helium, neon, and xenon). An oxygen-depleted environment may also include a vacuum atmosphere having a reduced oxygen concentration, including vacuum and partial vacuum. An oxygen-depleted environment may further include an atmosphere contained within a sealed container in which a portion of the oxygen content of the sealed atmosphere consumed by combustion is limited. An oxygen-depleted environment may include 10 vol% oxygen or less, 8 vol% oxygen or less, 6 vol% oxygen or less, 5 vol% oxygen or less, 4 vol% oxygen or less, 3 vol% oxygen or less, 2 vol% oxygen or less, or 1 vol% oxygen or less. The oxygen-reducing environment may include oxygen levels between 0.1 and 10 vol%, between 0.1 and 5 vol%, between 0.1 and 3 vol%, between 0.1 and 2 vol%, or between 0.1 and 1 vol%. In one embodiment of the invention, the hydrophobic aerogel material or composition is heat-treated in an oxygen-reducing atmosphere comprising between about 85% and about 99.9% of an inert gas (such as nitrogen). In a preferred embodiment of the invention, the dry hydrophobic aerogel composition is heat-treated in an oxygen-reducing atmosphere comprising between about 95% and about 99.9% of an inert gas (such as nitrogen) for between about 1 minute and about 3 hours.

[0086] The heat treatment of aerogel materials or compositions can highly determine various properties of certain aerogel materials. For example, Rao et al. (J. Sol-Gel Sci. Tech., 2004, 30: 141-147) taught an aerogel material made from a TEOS precursor and various hydrophobic agents (including MTMS, MTES, TMES, PhTES, ETES, DMCS, TMCS, and HMDZ) added via co-gelling and surface derivatization to provide hydrophobicity, but all of them lost their hydrophobicity when exposed to temperatures above 310°C (except for DMCS co-gel, which is stable up to 390°C, and PhTES co-gel, which is stable up to 520°C); Liu et al. (J. Sol-Gel Sci. Tech., 2012, 62: 126-133 teaches an aerogel material made from a sodium silicate precursor, which is treated with HMDZ to provide hydrophobicity, but loses its hydrophobicity when exposed to temperatures above 430°C in a standard atmosphere; Zhou et al. (Inorg. Mat., 2008, 44-9: 976-979) teach an aerogel material made from a TEOS precursor, which is treated with TMCS to provide hydrophobicity, but loses its hydrophobicity when exposed to temperatures above 500°C in a standard atmosphere. In one embodiment, the heat treatment of the aerogel material or composition of the present invention is limited to exposure to temperatures below 950°C, below 900°C, below 850°C, below 800°C, below 750°C, below 700°C, below 650°C, or below 600°C.

[0087] In some embodiments, the present invention provides aerogel materials, compositions, and processing methods that allow for controlled heat treatment to reduce or stabilize the hydrocarbon fuel content of the aerogel material (thus improving corresponding properties of the aerogel material such as HOC and T). d Furthermore, it can also enable aerogel materials to maintain a degree of hydrophobicity at high temperatures, including exposure to temperatures of about 550°C or higher, and exposure to temperatures of about 650°C or higher.

[0088] Embodiments of the present invention may be implemented using any of the processing, extraction and treatment techniques described herein, as well as other processing, extraction and treatment techniques known in the art, to manufacture the aerogels, aerogel-like materials, and aerogel compositions as defined herein.

[0089] Aerogel compositions can be reinforced with various fiber-reinforcing materials to achieve more flexible, elastic, and compatible composite products. The fiber-reinforcing materials can be added to the gel at any point during the gelation process of manufacturing a wet, fibrous gel composition. The wet gel composition can then be dried to produce a fiber-reinforced aerogel composition. Fiber-reinforcing materials can be in the form of discrete fibers, woven materials, non-woven materials, cotton wadding, mesh fabrics, mats, and felt products. Fiber-reinforcing materials can be made from organic fiber materials, inorganic fiber materials, or combinations thereof.

[0090] In a preferred embodiment, a non-woven fiber-reinforcing material is incorporated into the aerogel composition as continuous sheets of interconnected or interwoven fiber-reinforcing material. This process involves initially creating continuous sheets of fiber-reinforced gel by casting or pouring a gel precursor solution into continuous sheets of interconnected or interwoven fiber-reinforcing material. The liquid phase can then be at least partially extracted from the fiber-reinforced gel sheets to create a sheet-like, fiber-reinforced aerogel composition.

[0091] Aerogel compositions may also contain light-blocking agents to reduce the radiative components of heat transfer. At any point prior to gel formation, a light-blocking compound or its precursor may be dispersed into a mixture including the gel precursor. Examples of light-blocking compounds include, but are not limited to: boron carbide [B4C], diatomaceous earth, manganese ferroate, MnO, NiO, SnO, Ag2O, Bi2O3, carbon black, titanium oxide, iron-titanium oxide, zirconium silicate, zirconium oxide, iron(I) oxide, iron(II) oxide, manganese dioxide, iron-titanium oxide (ilmenite), chromium oxide, carbides (such as SiC, TiC, or WC), or mixtures thereof. Examples of light-blocking compound precursors include, but are not limited to: TiOSO4 or TiOCl2.

[0092] The aerogel materials and compositions of the present invention have shown to be highly effective as insulating materials. However, the application of the methods and materials of the present invention is not intended to be limited to insulation-related applications. The methods and materials of the present invention can be applied to any system or application that can benefit from the unique combination of properties or procedures provided by the materials and methods of the present invention.

[0093] The following examples provide various non-limiting embodiments and properties of the present invention.

[0094] Example 1 -

[0095] K-grade sodium silicate was used as a precursor, comprising 2.88 wt% SiO2:Na2O and containing 31.7 wt% SiO2 and 11 wt% Na2O. Sodium methylsilanolate was obtained from 30% NaSiO3CH3 in water. The combination of sodium silicate and sodium methylsilanolate resulted in 31.4% of the resulting aerogel mass being derived from sodium methylsilanolate (SiO2 from NaSiO3CH3). 1.5CH3), the aerogel material contains 7.0 wt% of the expected hydrophobic organic content.

[0096] Dilute this mixture with water before adding it to 32% H2SO4 so that the acidified sol contains 9.68 wt% silica solids (6.64 wt% SiO2 and 3.04 wt% SiO2). 1.5 CH3). Cool both H2SO4 and Na2SiO3 to 10°C in an ice bath. Add Na2SiO3 slowly to H2SO4 with rapid stirring. Perform this exothermic addition at a rate never exceeding 12°C to avoid gelation. Cool the sol to 4°C to induce some precipitation of Na2SO4·10H2O. Maintain the solution temperature at 4°C. To further precipitate sodium sulfate, add ethanol equivalent to 68.7% by volume of the hydrosol, resulting in a molar ratio of Si (from water glass): Si (from methylsilyl alkoxide): EtOH: H2O: H2SO4 of 1:0.409:2.34:6.97:0.156. Remove Na2SO4 immediately by vacuum filtration.

[0097] The aerogel was cast at a target aerogel density of 0.07-0.08 g / cc by adding dilute ammonium hydroxide (10 vol% of 28% NH4OH in water) as a catalyst. An 85 vol% sol, 5 vol% EtOH, and 10 vol% catalyst were used (added in increments of several seconds). After catalyst addition, the sol was stirred at 300 rpm for 30 seconds, then cast into a fiber-reinforced phase and allowed to gel. After curing for approximately 1 hour, the aerogel material was placed in an EtOH bath for 6 hours at a 3:1 EtOH:gel volume ratio to reduce water content before aging. It was then aged at 68°C for 14 hours in an aging fluid containing 0.8 wt / vol% NH3 in an ethanol solution at a 3:1 fluid:gel ratio. The sample was subjected to solvent extraction with supercritical CO2 and then dried at 110°C for 2 hours.

[0098] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0099] Example 2-

[0100] A sol was prepared by co-hydrolyzing TEOH and MTES in EtOH and H₂O using an acid catalyst. The molar ratio of the sol materials was adjusted to obtain an aerogel with an organic content of approximately 7.0 wt%. The sol was stirred at 60°C for 4 hours and then cooled to room temperature. During hydrolysis, approximately 3% of the sol volume was lost; EtOH was added to restore the sol to its original volume.

[0101] 0.5 M NH4OH was added to the combined sol to achieve a target aerogel density of 0.07–0.08 g / cc. The sol was cast into a fiber-reinforced phase and gelled. After curing for approximately 1 hour, the aerogel material was aged at 68 °C for approximately 16 hours in an aging fluid containing 0.8 wt / vol% NH3 at a fluid:gel ratio of 3:1. The sample was subjected to solvent extraction with supercritical CO2 and then dried at 110 °C for 2 hours.

[0102] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0103] Example 3-

[0104] A sol was prepared by co-hydrolyzing TEOH and MTES in EtOH and H2O using an acid catalyst. The molar ratio of the sol materials was adjusted to obtain an aerogel with an organic content of approximately 7.0 wt%. The sol was stirred at 60°C for 4 hours and then cooled to room temperature. Boron carbide [B4C], carbon black, manganese dioxide, titanium dioxide, or zirconium silicate were incorporated into batches of the combined sol, and then stirred for at least 1 hour.

[0105] 0.5 M NH4OH was added to the combined sol to achieve a target aerogel density of 0.07–0.08 g / cc. The sol was cast into a fiber-reinforced phase and gelled. After curing for approximately 1 hour, the aerogel material was aged at 68 °C for approximately 16 hours in an aging fluid containing 0.8 wt / vol% NH3 at a fluid:gel ratio of 3:1. The sample was subjected to solvent extraction with supercritical CO2 and then dried at 110 °C for 2 hours.

[0106] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0107] Example 4-

[0108] Polyethyl silicate sol was prepared by hydrolyzing TEOS in EtOH and H2O with an acid catalyst, followed by stirring at room temperature for at least 6 hours. Polymethylsilsesquioxane sol was prepared by hydrolyzing MTES in EtOH and H2O with an acid catalyst, followed by stirring at room temperature for at least 6 hours. Polyethyl silicate (TEOS) and polymethylsilsesquioxane (MTES) were combined to obtain an aerogel with an organic content of approximately 10-11 wt%. Silicon carbide powder (F1200Grit) or titanium dioxide powder was incorporated into batches of the combined sol at a sol-to-powder weight ratio of approximately 15:1. The combined sol was stirred for at least 1 hour.

[0109] 0.5 M NH4OH was added to the combined sol to achieve a target aerogel density of 0.07–0.08 g / cc. The sol was cast into a nonwoven, glass fiber-reinforced phase and gelled. The aerogel material was aged in an aging fluid containing 0.5 wt / vol% NH3 in ethanol for at least 10 hours. The sample was subjected to solvent extraction with supercritical CO2 and then dried with conventional heat at approximately 180 °C.

[0110] The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (resulting in an aerogel density of 0.07-0.08 g / cc).

[0111] Example 5 -

[0112] Polyethyl silicate sol was prepared by hydrolyzing TEOS in EtOH and H2O with an acid catalyst, followed by stirring at room temperature for at least 6 hours. Polymethylsilsesquioxane sol was prepared by hydrolyzing MTES in EtOH and H2O with an acid catalyst, followed by stirring at room temperature for at least 6 hours. The polyethyl silicate (TEOS) and polymethylsilsesquioxane (MTES) sols were combined to obtain an aerogel with an organic content of approximately 10-11 wt%. Iron oxide, titanium carbide, diatomaceous earth, manganese ferroate, or iron-titanium dioxide were incorporated into the batches of combined sols. The combined sols were stirred for at least 1 hour.

[0113] 0.5 M NH4OH was added to the combined sol to achieve a target aerogel density of 0.07–0.08 g / cc. The sol was cast into a nonwoven, glass fiber-reinforced phase and gelled. The aerogel material was aged in an aging fluid containing 0.5 wt / vol% NH3 in ethanol for at least 10 hours. The sample was subjected to solvent extraction with supercritical CO2 and then dried with conventional heat at approximately 180 °C.

[0114] The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (resulting in an aerogel density of 0.07-0.08 g / cc).

[0115] Example 6-

[0116] A sol was prepared by co-hydrolyzing TEOS and an organosilane hydrophobic in EtOH and 1 mM aq oxalic acid. The organosilane hydrophobic co-precursor could be selected from the following: methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), trimethylethoxysilane (TMES), ethyltriethoxysilane (ETES), and phenyltriethoxysilane (PhTES). In this embodiment, PhTES was used as the organosilane hydrophobic. The molar ratio of EtOH:H₂O:oxalic acid was kept constant at 5:7:1.26 x 10⁻⁶. -4 Oxalic acid and water were introduced together with 1 mM oxalic acid. The molar ratio of TEOS to PhTES was provided to obtain aerogels with 8.0 and 9.0 wt% hydrophobic organic content in each case, and a target density of 0.07-0.08 g / cc. The molar ratios of the sol components in these two formulations were 0.0719:1:8.98:12.57:2.26x10⁻¹, respectively. -4 and 0.0825:1:9.18:12.85:2.3x10 - 4 PhTES: TEOS: EtOH: H2O: Oxalic acid.

[0117] The sol was stirred for 15 minutes, then cast into a fiber-reinforced phase and gelled in a 60°C oven. After curing at 60°C for 21-33 hours, the aerogel material was aged at 68°C for 22 hours in an aging fluid containing 0.8 wt / vol% NH3 at a fluid:gel ratio of 3:1. The sample was then subjected to solvent extraction with supercritical CO2 and dried at 110°C for 2 hours.

[0118] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0119] Example 7-

[0120] A sol was prepared by co-hydrolyzing TEOS and PhTES in MeOH with 1 mM aq oxalic acid catalyst. The molar ratio of MeOH:H2O:oxalic acid was kept constant at 66:7:1.26 x 10⁻⁶. -4Oxalic acid was introduced into the solution along with water at a concentration of 1 mM oxalic acid. The target density for all formulations was 0.07-0.08 g / cc. PhTES content was varied to achieve aerogels with target organic contents of 7.0, 11.0, or 19.0 wt%. The molar ratios of the sol components in these formulations were 1:0.062:16.57:1.76:3.16x10⁻¹⁰. -5 ,1:0.105:18.15:1.93:3.47x10 -5 , and 1:0.217:22.18:2.35:4.24x10 -5 TEOS: PhTES: MeOH: H2O: Oxalic acid. Stir the sol at 28°C for 24 hours.

[0121] To gel the hydrolyzed sol, 1 M NH4OH was added at an additional 1 mole of H2O per mole of H2O as in the previous step. This resulted in 0.0316, 0.0347, or 0.0424 moles of NH4OH per mole of TEOS for 7.0, 11.0, and 19.0 wt% organic formulations, respectively. The sol was stirred for 3 minutes, then cast into a fiber-reinforced phase and gelled at 28 °C. The gel was allowed to cure at room temperature for 2 days, then soaked in an ethanol bath with fresh ethanol every 24 hours for 4 days. The sample was subjected to solvent extraction with supercritical CO2 and then dried at 110 °C for 2 hours.

[0122] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0123] Example 8-

[0124] A sol was prepared by co-hydrolyzing tetramethyl orthosilicate (TMOS) and PhTES in MeOH using an 86 mM NH4OH catalyst. The molar ratio of solvent to catalyst was kept constant at 11:5:3.7 x 10⁻⁶. -3 MeOH:H2O:NH4OH, with NH4OH introduced into the solution along with water at 86 mM NH4OH. The final density of all formulations was 0.07-0.08 g / cc. PhTES content was varied to achieve aerogels with target organic contents of 7.0, 11.0, or 19.0 wt%. The molar ratios of the sol components in these formulations were 1:0.062:16.61:7.55:5.59 x 10⁻⁶. -3 ,1:0.105:18.04:8.20:6.07x10 -3, and 1:0.217:21.78:9.90:7.33x10 -3 TMOS: PhTES: MeOH: H2O: NH4OH.

[0125] The sol was stirred for 15 minutes, then cast into a fiber-reinforced phase and gelled. The gel was allowed to cure at room temperature for 3 days, then soaked in an ethanol bath with fresh ethanol every 24 hours for 4 days. The sample was subjected to solvent extraction with supercritical CO2, and then dried at 110°C for 2 hours.

[0126] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0127] Example 9-

[0128] A sol was prepared by co-hydrolyzing TEOS and 1,2-bis(triethoxysilyl)ethane (BTESE) in EtOH and water using 1M HCl catalyst. The sol was prepared by using a ratio of 1:0.223:13.84:3.46:2.42x10⁻¹. -3 ,1:0.275:15.04:3.76:2.63x10 -3 , and 1:0.334:16.24:4.06:2.84x10 -3 Aerogels with organic contents of 7.0, 8.0, or 9.0 wt% were obtained using a TEOS:BTESE:EtOH:H2O:HCl molar ratio. In each case, the solvent-catalyst ratio remained constant at 8:2:1.4 x 10⁻⁶. -3 The reaction mixture was prepared using EtOH, H₂O, and HCl, which simultaneously altered the BTESE content. The sol was stirred at 60°C for 4 hours and then cooled to room temperature. Approximately 3% of the sol volume was lost during hydrolysis; EtOH was added to restore the sol to its original volume.

[0129] To gel the hydrolyzed sol, dilute NH4OH was added so that the final cast sol contained 8.0 vol% 0.5 M NH4OH, and the target density of the final aerogel was 0.07-0.08 g / cc. The sol was cast into a fiber-reinforced phase and gelled. After curing for about 1 hour, the aerogel material was aged at 68°C for about 16 hours in an aging fluid containing 0.8 wt / vol% NH3 at a fluid:gel ratio of 3:1. The sample was solvent-extracted with supercritical CO2 and then dried at 110°C for 2 hours.

[0130] The fiber-reinforcing phase consisted of silica PD filaments with 9-micron diameter fibers, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material comprised approximately 45 wt% aerogel and 55 wt% fibers, yielding a desired material density of approximately 0.16–0.20 g / cc (resulting in an aerogel density of 0.07–0.08 g / cc).

[0131] Example 10-

[0132] K-grade sodium silicate was used as a precursor, comprising 2.88 wt% SiO2:Na2O, and containing 31.7 wt% SiO2 and 11 wt% Na2O. The sodium silicate precursor was first diluted with water, then added to 32% H2SO4. The resulting solution, in the acidified sol, contained 10.34 wt% SiO2 and 1.34 M Na2O. + and 1.50MH + Cool both H₂SO₄ and Na₂SiO₃ to 10°C in an ice bath. Add Na₂SiO₃ slowly to H₂SO₄ with rapid stirring. Perform this exothermic addition at a rate not exceeding 12°C to avoid gelation. Cool the sol to 4°C to promote some precipitation of Na₂SO₄·10H₂O. Maintain the solution temperature at 4°C.

[0133] THF was added until the final sol contained 6.72 wt% SiO2, thus further precipitating Na2SiO4. Na2SO4 was immediately removed by vacuum filtration, and NaCl was added to the filtered sol solution until the sol was saturated. NaCl initiated the separation of the aqueous and organic phases. 95% H2O was removed from the organic phase, and 100% SiO2 separated into the organic phase. The organic phase was isolated, with a desired solids content of approximately 0.18 g SiO2 / mL. Ethanol was added in an amount equivalent to 104% of the volume of the THF layer, resulting in a molar ratio of 1(Si):6.256(EtOH):0.975(H2O):4.115(THF) in the sol.

[0134] A sol solution of MTES precursor was prepared comprising: 69.4 wt% MTES with a 2.7 H₂O:Si (molar ratio) and 70 mM acetic acid (99.7%) diluted with EtOH, which provided the expected 26 wt% solids content [SiO₂]. 1.5 (CH3)]. The molar ratio of MTES:EtOH:H2O:HOAc was 1:0.624:2.703:0.0199. The sol was stirred in a thermos flask for 5 hours and then quenched by cooling.

[0135] Combine 85.9 vol% silica sol (1a) and 14.1 vol% MTES sol (1b), and stir for another 2 hours to obtain a product containing hydrophobic components (SiO2 from MTES). 1.5 The expected final aerogel mass is 31.4 wt% (CH3), and the expected hydrophobic organic content is 7.0 wt%.

[0136] The aerogel was cast to a target aerogel density of 0.07-0.08 g / cc by adding EtOH and dilute ammonium hydroxide (2.5 vol% of 28% NH4OH in water) as a catalyst. A 67 vol% sol solution, 21 vol% EtOH, and 12 vol% catalyst were added (over several seconds). After catalyst addition, the sol was stirred at 300 rpm for 30 seconds, then cast into a fiber-reinforced phase and allowed to gel. After curing for approximately 1 hour, the aerogel material was aged at 68°C for approximately 16 hours in an aging fluid containing 0.8 wt / vol% NH3 at a fluid:gel ratio of 3:1. The sample was subjected to solvent extraction with supercritical CO2 and then dried at 110°C for 2 hours.

[0137] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc).

[0138] Example 11-

[0139] K-grade sodium silicate was used as a precursor, having a SiO2:Na2O ratio of 2.88 by weight, containing 31.7 wt% SiO2 and 11 wt% Na2O, and a density of 1.48 g / mL. It was first diluted with water to obtain a solution containing 22.1 wt% original water glass (7.0 wt% SiO2). This solution was then passed through an amberlite Na... + The diluted sodium silicate was ion-exchanged with resin. The resulting silica was then gelled by adding H₂O and 1M NH₄OH catalyst, resulting in H₂O and catalyst comprising 6.9 vol% and 0.4 vol% of the final hydrosol, respectively. The sol was stirred at 300 rpm for 30 seconds before casting into a fiber-reinforced phase and gelling. The molar ratio of Si:H₂O:NH₃ was 1:47.8:0.0016, and the target silica aerogel density was 0.07-0.08 g / cc. The gel was aged at 50°C for 3 hours. Solvent exchange was performed three times with ethanol over 36 hours, followed by three times with hexane over 36 hours.

[0140] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc, excluding hydrophobic treatment).

[0141] Hydrophobic treatment of the wet gel was performed using one of the following hydrophobic silylating agents: methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), vinyltrimethoxysilane (VTMS), phenyltrimethoxysilane (PhTMS), phenyltriethoxysilane (PhTES), or dimethyldimethoxysilane (DMDMS). The silanization of the gel was carried out for 24 hours at 50°C in a hexane bath containing 20 vol% hydrophobic agent, using a fluid-to-gel ratio of 4:1. The molar ratio of the hydrophobic agent in the fluid to Si in the gel was 2.8–5.0, depending on the hydrophobic agent used. The gel was washed twice with hexane after 24 hours, followed by solvent extraction with supercritical CO2, and then dried at 110°C for 2 hours.

[0142] Example 12-

[0143] Silica gel was prepared by hydrolysis and condensation of TEOS in the presence of oxalic acid catalyst, diluted with EtOH. The molar ratio of TEOS:EtOH:H2O:oxalic acid was 1:7.60:10.64:1.92x10⁻⁶. -4 Oxalic acid and water were introduced together with 1 mM oxalic acid. The target silica aerogel had a density of 0.07-0.08 g / cc. The sol was stirred for 15 minutes, then cast into a fiber-reinforced phase and gelled in a 60°C oven.

[0144] The fiber-reinforcing phase is silica PD wadding with fibers of 9 micrometer diameter, approximately 10 mm thickness, and a density of approximately 3.8 oz / sq ft. The resulting aerogel material is approximately 45 wt% aerogel and 55 wt% fiber, resulting in a desired material density of approximately 0.16-0.20 g / cc (yielding an aerogel density of 0.07-0.08 g / cc, excluding hydrophobic treatment).

[0145] The gel was transferred to a bath containing 20 vol% hydrophobic agent in methanol using a 4:1 fluid:gel ratio and heated at 45°C for 24 hours. The hydrophobic agent was one of the following: methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), ethyltriethoxysilane (ETES), or phenyltriethoxysilane (PhTES). The molar ratio of the hydrophobic agent in the fluid to Si in the gel was 2.8–4.8, depending on which hydrophobic agent was used. The gel was washed three times with EtOH at 45°C for 6 hours each time, followed by solvent extraction with supercritical CO2 and drying at 110°C for 2 hours.

[0146] Example 13-

[0147] Examples 1, 2, 6, 7, 8, and 9 yielded aerogel compositions with an expected hydrophobic organic content of about 7.0-9.0 wt% in the aerogel material (3.0-5.0 wt% of the composite). Example 4 yielded an aerogel composition with an aerogel material with an aerogel content of about 9.0-11.0 wt% (4.0-6.0 wt% of the composite). Examples 7 and 8 also yielded aerogel compositions with an aerogel material content of about 11.0 wt% and 19.0 wt% PhTES hydrophobic organic content (6.0-9.0 wt% of the composite), respectively. Examples 3 and 5, by adjusting the manufacturing conditions (amount of hydrophobic material, time, temperature, etc.), yielded aerogel compositions with an aerogel material content of about 9.0-11.0 wt%. Examples 10-12 show that aerogel compositions with approximately 7.0-9.0 wt% hydrophobic organic content in the aerogel material can be prepared by adjusting the manufacturing conditions (amount of hydrophobic material, time, temperature, etc.).

[0148] The samples prepared in Examples 1, 2, 6, 7, 8, and 9, as well as the sample prepared in Example 4 including silicon carbide powder, were subjected to heat treatment in a tube furnace under N2 at a temperature rise / fall rate of 10°C / min until the selected treatment temperature reached 200°C to 700°C. After the treatment was completed, the tube furnace was allowed to cool to room temperature before the samples were removed.

[0149] The treated samples included: 7% MTES sample from Example 2; 7% NaSiO3CH3 sample from Example 1; 7%, 8%, and 9% BTESE samples from Example 9; 8% and 9% PhTES samples from Example 6; 7%, 11%, and 19% PhTES samples from Example 7; and 7%, 11%, and 19% PhTES samples from Example 8. The samples were heat-treated at temperatures ranging from 200°C to 700°C for 10 seconds to 1 hour. Samples treated at 475°C for 10 minutes and at 525°C for 10 minutes were selected for further testing.

[0150] The samples prepared in Example 4, comprising titanium dioxide powder, were heat-treated by sealing each batch of samples in stainless steel foil bags and then placing the foil bags in an inert furnace preheated to various temperatures from 450°C to 800°C for no more than 60 minutes. The treated samples of Example 4 were identified in this invention based on the powder material (S = silicon carbide; T = titanium dioxide), the heat treatment temperature (450-800°C), and the treatment time (0-60 minutes).

[0151] Heat treatment of samples containing 7%, 8%, and 9% BTESE showed signs of decomposition starting at approximately 475°C. Heat treatment of samples containing PhTES showed signs of unstable phenyl species at temperatures above 400°C.

[0152] Example 14-

[0153] Table 1 shows the density measurements of the treated aerogel composite samples from Example 13. Density measurements were performed according to ASTM C167. All composite aerogel samples had a measured density of less than 0.216 g / cc.

[0154] Example 15 -

[0155] Table 1 shows the thermal conductivity (TC) measurements of the treated aerogel composite specimens from Example 13. TC measurements were performed according to ASTM C177 at a temperature of approximately 37.5°C and compression of 2 psi (8x8 specimens) or 8 psi (4x4 specimens).

[0156] All treated aerogel composite samples were measured to have thermal conductivity values ​​at or below 31.6 mW / mK.

[0157] Example 16-

[0158] Aerogel compositions with approximately 7.0–8.0 wt% hydrophobic organic content are generally expected to be hydrophilic when prepared, with an expected C1511 water absorption value of approximately 350 wt% or higher (after immersion in ambient conditions for 15 minutes).

[0159] Table 1 shows the water absorption measurements of the treated aerogel composite samples before and after the deoxygenation heat treatment of Example 13. All measurements were performed according to ASTM C1511 (immersion in ambient conditions for 15 minutes).

[0160] Both the 7% MTES and 7% NaSiO3CH3 pretreated samples showed water absorption rates greater than 400 wt%. The 7%, 8%, and 9% BTESE pretreated samples all showed water absorption rates greater than 340 wt%. The PhTES pretreated samples all showed water absorption rates greater than 280 wt%.

[0161] The post-treated specimens with 7% MTES showed a water absorption rate of approximately 0.0 wt%, lower than the pre-treated specimens with 7% MTES. The post-treated specimens with 7% NaSiO3CH3 showed a water absorption rate of approximately 81% (specimens heat-treated at 475°C for 10 minutes). All post-treated specimens with BTESE showed a water absorption rate greater than 290 wt%. All post-treated specimens with PhTES showed a water absorption rate greater than 275 wt%.

[0162] Example 17-

[0163] Table 1 shows the heat of combustion (HOC) measurements of the treated aerogel composite samples before and after the oxygen-reducing heat treatment in Example 13. The HOC measurements were performed under conditions comparable to the ISO 1716 measurement standard.

[0164] The pretreated sample of 7% MTES had an HOC of approximately 600 cal / g; the post-treated sample (heat-treated at 525°C for 10 minutes) had an HOC of approximately 425 cal / g. The pretreated sample of 7% NaSiO3CH3 had an HOC of approximately 415 cal / g; the post-treated sample (heat-treated at 525°C for 10 minutes) had an HOC of approximately 140 cal / g. The pretreated sample of 9% BTESE had an HOC of approximately 780 cal / g; the post-treated sample of 9% BTESE (heat-treated at 525°C for 10 minutes) had an HOC of approximately 285 cal / g. The pretreated sample of 9 wt% PhTES (from Example 3-1) had an HOC of approximately 437 cal / g; the post-treated sample (heat-treated at 525°C for 10 minutes) had an HOC of approximately 144 cal / g. The pretreated sample of 7 wt% PhTES (from Examples 3-3) had an HOC of approximately 351 cal / g; the post-treated sample (heat-treated at 400°C for 10 minutes) had an HOC of approximately 120 cal / g. The pretreated sample of 11 wt% PhTES (from Examples 3-3) had an HOC of approximately 403 cal / g; the post-treated sample (heat-treated at 400°C for 10 minutes) had an HOC of approximately 110 cal / g.

[0165] Example 18-

[0166] Figure 1 This shows the CP / MAS of the 7% MTES sample from Example 13 before and after the deoxygenated heat treatment at 525°C for 10 minutes. 29 Si solid-state NMR analysis.

[0167] Pretreated samples with 7% MTES showed a T0.463. 1-2 :T3 The ratio, and Q of approximately 1.961. 2-3 Q 4 Ratio. Post-treated samples with 7% MTES showed a T ratio of approximately 0.272. 1-2 :T 3 The ratio, and Q is approximately 0.842. 2-3 Q 4 Ratio. The ratio is obtained by individually integrating the overlapping peaks.

[0168] Example 19

[0169] Figure 2 This shows the TGA / DSC analysis of the 7% MTES sample, 7% NaSiO3CH3 sample, 9% BTESE sample, and 9% PhTES (from Example 3-1) sample before and after deoxygenated heat treatment at 525°C for 10 minutes. The TGA / DSC analysis was performed at a rate of 20°C / min from room temperature to 1000°C.

[0170] Table 1 shows the data based on... Figure 2 The starting point (°C) of the thermal decomposition temperature of the post-processed sample shown in the TGA / DSC analysis plot.

[0171] Post-treated specimens with 7% MTES (heat-treated at 525°C for 10 minutes) exhibit a T0 of approximately 545°C. d Measurement. The post-treated sample of 7% NaSiO3CH3 (heat-treated at 525°C for 10 minutes) has a T0 of approximately 600°C. d Measurement. Post-treated specimens of 9% BTESE (heat-treated at 525°C for 10 minutes) have a T0 of approximately 460°C. d Measurement. Post-treated specimens of 9% PhTES (heat-treated at 525°C for 10 minutes) have a T0 of approximately 595°C. d Measurement.

[0172] Table 1

[0173]

[0174] The conjunction "and" as used in this article indicates inclusion, while the conjunction "or" does not indicate exclusion unless otherwise stated. For example, the phrase "or" or "or" indicates exclusion.

[0175] The terms “a,” “an,” or other similar terms used in the text describing the invention (particularly in the claims) are to be interpreted as both singular and plural, unless otherwise stated or obviously contradicted in the text.

[0176] Terms such as "including," "having," "containing," and "containing" are interpreted as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise stated.

[0177] The term "approximately" as used in this article usually refers to the degree of deviation from the identified properties, composition, dosage, value, or parameter; such as based on experimental error, measurement error, approximation error, calculation error, standard deviation from the average value, routine fine adjustments, etc.

[0178] The numerical ranges described herein are merely shorthand notations intended for individual reference to the individual values ​​falling within the range, unless otherwise stated herein, and each individual value is incorporated herein as it is individually described herein.

[0179] All methods described herein may be performed in any suitable order unless otherwise stated or obviously contradicted herein. Any and all embodiments or exemplary language (e.g., "as," "for example") provided herein are intended to better illustrate the invention and not to limit the scope of the invention, unless otherwise claimed in the patent claims.

Claims

1. A method for preparing a reinforced aerogel composite, comprising: a) Provide a precursor solution including silica gel precursor material and solvent; b) Combining the precursor solution and the reinforcing material; c) Transform the silica gel precursor material in the precursor solution into a gel composition through a reinforcing material to form a reinforced, silica-based gel complex. d) Extracting at least a portion of the solvent from the reinforced, silica-based gel complex to obtain a first reinforced, silica-based aerogel complex; and e) Expose the first reinforced silica-based aerogel composite to one or more heat treatments in an oxygen-reducing atmosphere at a temperature between 500°C and 700°C for at least 1 minute to obtain a second reinforced silica-based aerogel composite. The method further includes, prior to step e), incorporating at least one hydrophobic bound silicon into the first reinforced, silica-based aerogel composite, and The second reinforced silica-based aerogel composite has the following properties: 1) a water absorption rate of 40 wt% or less and 2) a thermal decomposition temperature of 500 °C or higher for hydrophobic organic materials.

2. A method for preparing a reinforced aerogel composite, comprising: A first reinforced silica-based aerogel composite, comprising at least one hydrophobic bonded silicon, is exposed to one or more heat treatments in an oxygen-reducing atmosphere at a temperature between 500°C and 700°C for at least 1 minute to obtain a second reinforced silica-based aerogel composite; wherein the second reinforced silica-based aerogel composite has the following properties: i) a water absorption rate of 40 wt% or less; and ii) a thermal decomposition initiation of a hydrophobic organic material at 500°C or higher.

3. The method of claim 2, wherein the second reinforced, silica-based aerogel composite has the following properties: iii) heat of combustion of 717 cal / g or less; and iv) 5 mW / M * K up to 40mW / M * Thermal conductivity between K.

4. The method of any one of claims 1 to 3, wherein the second reinforced, silica-based aerogel composite comprises a sheet of fiber-reinforced material.

5. The method according to any one of claims 1 to 3, wherein the second reinforced, silica-based aerogel composite has a hydrophobic organic content between 1 wt% and 15 wt%.

6. The method of any one of claims 1 to 3, wherein the second reinforced silica-based aerogel composite has a lower water absorption rate relative to the first reinforced silica-based aerogel composite.

7. The method as described in any one of claims 1 to 3, wherein, The second reinforced, silica-based aerogel composite has a water absorption rate of 40 wt% or less; and has one or more of the following properties: ii) thermal decomposition initiation of hydrophobic organic materials between 500°C and 636°C, or iii) heat of combustion between 265 cal / g and 717 cal / g.

8. The method as claimed in any one of claims 1 to 3, wherein, The second reinforced, silica-based aerogel composite has a water absorption rate of 40 wt% or less; and has one or more of the following properties: ii) thermal decomposition initiation of hydrophobic organic materials between 525°C and 636°C, or iii) heat of combustion between 265 cal / g and 600 cal / g.

9. The method as claimed in any one of claims 1 to 3, wherein, The second reinforced, silica-based aerogel composite has a water absorption rate of 40 wt% or less; and has one or more of the following properties: ii) thermal decomposition initiation of hydrophobic organic materials between 550°C and 636°C, or iii) heat of combustion between 265 cal / g and 550 cal / g.

10. The method as claimed in any one of claims 1 to 3, wherein, The second reinforced, silica-based aerogel composite has a water absorption rate of 40 wt% or less; and has one or more of the following properties: ii) thermal decomposition initiation of hydrophobic organic materials between 575°C and 636°C, or iii) heat of combustion between 265 cal / g and 500 cal / g.

11. The method of any one of claims 1 to 3, wherein the reinforced aerogel composite comprises a single aerogel material.

Images