390 results about "Supercritical drying" patented technology

The invention discloses a heat-insulating and high-temperature-resistant metal core fireproof plate and a preparation method thereof, belongs to the technical field of plate processing, and is used for solving the technical problem that the structural stability and fireproof performance of a fireproof plate in the prior art need to be further improved. The fireproof board comprises the two composite framework layers and the metal plate core layer arranged between the composite framework layers, in the process of preparing the fireproof board, aerogel and honeycomb polyimide resin are closely crosslinked through chemical bonds, in the supercritical drying process, the aerogel invades into gaps of a felt board to be solidified and closely combined with the felt board, and the fireproof board is formed. The aerogel layer serves as a heat insulation and sound insulation layer and is connected with all the layers at the same time, the honeycomb layer enhances the pressure resistance of the fireproof plate, all the layers are matched with one another in structure, and the fireproof plate which is flame-retardant, heat-insulation, bending-resistant, high-temperature-resistant, impact-resistant and stable is obtained.

The invention discloses a method for preparing hydrophobic SiO2 aerogel through in-situ polymerization. The method comprises the following steps: (1) uniformly mixing and stirring an alcohol solvent, a silicon source, water, an in-situ modifier and a catalyst to obtain a mixed solution; (2) adding an acid adjusting solution into the obtained mixed sol solution to hydrolyze the mixed sol solution, and adding an alkali adjusting solution to polymerize the mixed sol solution; (3) gum dipping: dipping the silica sol solution into the inorganic fiber material through a gum dipping process to obtain a compound of the silica sol and the inorganic fiber material, and standing to obtain a gel composite material; (4) aging: adding the obtained composite gel material into an aging liquid mixed solution; and (5) immersing the aged wet gel in an organic solvent, and then feeding into a supercritical drying kettle for supercritical drying treatment to obtain the SiO2 aerogel composite material. By adopting an in-situ polymerization method, the use of a hydrophobic modifier is reduced, the aerogel preparation process period is shortened, and the production process is simple.

The invention provides quantum dot aerogel, a quantum dot light-emitting device and a preparation method thereof, and the preparation method comprises the following steps: adding a silane coupling agent into quantum dots to form modified quantum dots with silanol groups on the surfaces; uniformly stirring a silicon dioxide precursor and absolute ethyl alcohol, slowly adding deionized water and a catalyst, and stirring to form silicon dioxide sol; adding the modified quantum dots into silicon dioxide sol to form a mixed solution; placing the mixed solution in a closed container, and standing to form gel; putting the gel into absolute ethyl alcohol for aging treatment; and carrying out supercritical drying treatment on the aged gel to obtain the quantum dot aerogel composite material. The light-emitting performance of the quantum dots and the heat insulation performance of the aerogel are perfectly combined, the high temperature resistance and blue light resistance of the quantum dot aerogel composite material film layer can be greatly improved, the preparation method is simple, and the application range of the quantum dots can be greatly widened.

The invention relates to the technical field of porous material preparation processes, in particular to a preparation method of light low-thermal-conductivity lutetium silicate aerogel, which comprises the following steps: preparing composite sol; preparing and aging wet gel; drying the gel; preparing the aerogel; the lutetium silicate aerogel is prepared by combining in-situ sol-gel with a supercritical drying process, and the lutetium silicate aerogel has relatively high porosity, can be in a light, crack-free and complete block shape, and can be used for near-net size forming; the method is simple to operate, can realize fluidized production, and is easy to industrialize; the lutetium silicate ceramic aerogel prepared by adopting an in-situ synthesis mode has higher porosity, better thermal stability and lower thermal conductivity, and can tolerate the extreme temperature of 1500 DEG C.

The invention discloses a wear-resistant hard alloy material and a preparation method thereof, and particularly relates to the field of alloy materials.The wear-resistant hard alloy material comprises tungsten carbide, cobalt powder, graphene aerogel fragments, coconut shell carbonized porous carbon, yttrium oxide and auxiliaries, and a multi-scale reinforcing system is constructed by optimizing the proportion. According to the preparation method, supercritical drying is combined with a microwave reaction sintering process, and material densification is realized through gradient temperature control and steam concentration accurate regulation and control in a specific atmosphere. Graphene aerogel fragments and porous carbon form a three-dimensional interpenetrating network, so that the wear resistance and the conductivity are synergistically improved; yttrium oxide is segregated at a grain boundary to form a high-temperature anti-oxidation barrier; the gradient sintering process effectively eliminates internal stress and inhibits abnormal growth of grains. The technical bottleneck that wear resistance and toughness of traditional hard alloy are difficult to synergistically improve is broken through, excellent conductivity and high-temperature stability are achieved, and the industrial problems that wear resistance / toughness is inverted, a conductive network is low in efficiency, and the high-temperature stability is poor are solved.

The invention belongs to the field of preparation processes of nano-porous materials, and relates to a method for preparing a silicon-based elastic aerogel phase-change thermal insulation material by an in-situ chemical method. A phase-change material with an oxygen-containing functional group on the surface is selected as a phase-change core material, a surfactant, deionized water, ethanol, a silicon precursor, acid, alkali and the phase-change core material are uniformly mixed and subjected to hydrolysis, polycondensation and other reactions, meanwhile, the phase-change core material and silicon-based aerogel are subjected to in-situ grafting combination in the process, and the silicon-based aerogel is prepared. The silicon-based elastic aerogel phase change thermal insulation material is prepared through sol-gel and supercritical drying. The invention innovatively provides an in-situ grafting method, and the constructed silicon-based elastic aerogel phase-change thermal insulation material integrates multiple functions of high thermal insulation property, elasticity, leakage prevention, high response rate and the like, has the advantages of low material cost and convenient preparation process, and is low in energy consumption and easy to realize large-scale production.

The invention relates to the related field of heat insulation composite material processing, in particular to an aerogel heat insulation pipe shell and a preparation method and application thereof, and the aerogel heat insulation pipe shell is composed of a fiber needled felt without a binder and silicon dioxide aerogel. The manufacturing method comprises the steps of fibrofelt cutting and pre-rolling, sol preparation, rotary dynamic gel forming, supercritical drying, two-end trimming and opening treatment, and the tubular prefabricated part which is accurate in size, convenient and fast to install and capable of replacing aerogel felt is mainly applied to various pipelines and cylindrical equipment needing heat insulation and insulation. Loss of on-site construction materials and consumption of auxiliary materials can be effectively reduced, the construction period is shortened, and the heat insulation engineering quality is improved.

The invention provides a secondary battery, which comprises a pole piece, a diaphragm and an electrolyte, the pole piece comprises a current collector and an active material layer arranged on at least one side of the current collector, and the active material layer comprises an active material, a conductive agent and a binder; the value range of the effective ion migration rate of the pole piece is 0.02 to 0.5; according to the invention, the pole piece prepared under high solid content is subjected to freeze drying or supercritical drying, so that the solvent in the pole piece leaves the pole piece, and meanwhile, the adhesive does not migrate along with the solvent, and the uniform distribution of the adhesive in the pole piece is maintained; meanwhile, under the condition that the electrode plate has higher surface density and higher compaction density, distribution of a pore structure in the electrode plate is maintained, due to the special process effect of freeze drying or supercritical drying, the high pore structure of the electrode plate can be maintained, or pores in the electrode plate can be further improved through pore forming, the migration rate of ions in the electrode is increased, and the service life of the electrode plate is prolonged. Therefore, the battery has relatively high energy density and better electrochemical performance.

The invention discloses a catalyst applicable to preparation of methanol by hydrogenation of carbon dioxide and a preparation method of the catalyst, relates to the technical field of hydrogenation catalysts, and aims to solve the problems that active sites are few and sintering is easy at high temperature. The preparation method comprises the following steps: taking a Fe and Zn doped metal precursor and a main body Zr precursor as raw materials, preparing a gel catalyst intermediate product through a sol-gel method, carrying out supercritical drying, and then carrying out high-temperature calcination to prepare the Fe-Zn co-doped ZrO2 catalyst, and the activity of the Fe-Zn co-doped ZrO2 catalyst comes from rich oxygen vacancies and asymmetric active sites brought by metal doping; according to the invention, asymmetric active sites are constructed through metal doping to activate CO2, the prepared catalyst can realize more efficient reaction for preparing methanol through carbon dioxide hydrogenation at high space velocity in a high-temperature region, and the space-time rate of methanol can be directly increased by one order of magnitude.

The invention discloses a polyimide aerogel fiber as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: 1, synthesizing a polyamide acid solution; 2, adding acrylic acid, polyethylene glycol, a photoinitiator and a cationic surfactant into the polyamide acid solution, and mixing to form a spinning solution; step 3, carrying out wet spinning on the spinning solution, and then entering a coagulating bath to form initial gel fibers; step 4, performing ultraviolet light curing on the initial gel fibers to form gel fibers; and 5, carrying out chemical imidization treatment on the gel fiber, then carrying out stretching treatment, and carrying out supercritical CO2 drying after solvent replacement so as to obtain the polyimide aerogel fiber. Under the synergistic effect of multiple components of the spinning solution, the polyimide aerogel fiber is endowed with excellent mechanical properties and high porosity in cooperation with gelation and ultraviolet curing in a coagulating bath, and the polyimide aerogel fiber can be applied to preparation of heat insulation materials.

The invention relates to the technical field of thermal insulation material preparation, and discloses an aerogel composite metal film thermal insulation material and a preparation method thereof, and the preparation method comprises the following steps: metal film surface treatment; performing fiber-metal film needling; through mold forming and porosity control, a fiber-metal film prefabricated part with a specific shape and a high-porosity structure is prepared; soaking and aging the sol, realizing efficient permeation and filling of the sol in the fiber-metal film prefabricated member through staged pressure control, and completing conversion from the sol to gel in a low-temperature aging stage, so that a uniform and stable nano-particle continuous phase is constructed in the fiber-metal film prefabricated member, and a gel-containing fiber-metal film prefabricated member is formed; the preparation method comprises the following steps: preparing a fiber-metal film preform, performing supercritical drying, thoroughly removing a solvent under the condition of not damaging a gel network structure by utilizing the characteristic that alcohol fluid has no gas-liquid interface surface tension in a supercritical state aiming at the fiber-metal film preform containing gel, and further preparing the aerogel composite metal film heat insulation material.

The invention discloses a method for increasing the phase transition temperature of Al2O3 aerogel through grain boundary pinning and nano-structure strengthening, which comprises the following steps: co-hydrolyzing an aluminum source, yttrium salt, a silicon source and magnesium salt to form sol through the coordination of double mechanisms of grain boundary pinning and nano-domain isolation, and carrying out gradient heating aging, mixed medium supercritical drying and two-stage sintering to obtain the phase transition temperature of the Al2O3 aerogel. The gamma-alpha phase transition temperature of the Al2O3 aerogel is greater than or equal to 1300 DEG C. The specific surface area of the aerogel after heat treatment at 1300 DEG C is larger than 100 m / g, the process cost is controllable, and the aerogel is suitable for industrial production and can be applied to extreme environments such as a spacecraft thermal protection system and a high-temperature industrial furnace lining.

The invention relates to a covalent organic framework modified cellulose nanofiber composite diaphragm which is characterized in that cellulose nanofiber is used as a matrix, an amide type or amine type covalent organic framework layer is grown on the surface in situ, the loading capacity of a covalent organic framework is regulated and controlled, and a hierarchical pore structure with gradient pore diameter is constructed; the preparation method comprises the following steps: synthesizing a covalent organic framework precursor bonded with an imine bond on the surface of cellulose nanofiber in situ by a one-pot method under an acidic mixed solution and a heating condition, and regulating and synchronously reducing to convert into an amine type covalent organic framework; or after the imine bond bonded covalent organic framework is synthesized in two stages, the imine bond bonded covalent organic framework is selectively converted into an amide type covalent organic framework through oxidation modification; the obtained cellulose nanofiber compound coated with the covalent organic framework is subjected to the processes of film forming, solvent replacement, supercritical drying and the like, and the composite diaphragm is obtained; the diaphragm has excellent electrolyte wettability, high liquid absorption rate, good ionic conductivity and thermal stability, and can promote uniform transmission of lithium ions and inhibit growth of lithium dendrites.

The invention belongs to the technical field of coatings, and discloses a 600 DEG C heat insulation coating containing In2O3 and rutile type TiO2 aerogel and a preparation method of the 600 DEG C heat insulation coating. The coating is composed of an organic-inorganic compound adhesive, In2O3 at rutile type TiO2 aerogel, hollow glass beads, HAP ultra-long nanowires and auxiliaries, the aerogel is prepared by combining sol-gel with CO2 supercritical drying, and the aerogel is calcined at 800 DEG C to form a rutile crystal form. The compound adhesive is prepared from alkaline silica sol, modified organic silicon emulsion and a silane coupling agent through hydro-thermal synthesis. The coating is prepared by dispersing all the components at a high speed, heat conduction is inhibited by using aerogel nanopores, infrared radiation is reflected synergistically by rutile TiO2 and In2O3, and heat convection is blocked by a lock catch structure formed by hollow glass beads and HAP nanowires. The thermal conductivity of the obtained coating at 600 DEG C is as low as 0.035-0.044 W / (m.K), the coating has excellent temperature resistance, thermal shock resistance and full-wave band heat reflection capacity, and the technical problems of high-temperature phase change, structural collapse and poor thermal stability of a traditional coating are solved.

The present invention discloses a gradient aerogel composite material and its preparation method. The gradient aerogel composite material is prepared by preparing a sunscreen slurry, applying the slurry, hot-pressing fibers, impregnating and aging the sol, supercritical drying, and heat treating. The gradient aerogel composite material prepared using the present invention is ultra-lightweight, high-temperature resistant, exhibits ultra-low thermal conductivity over a wide temperature range, and can be formed into large-scale thermal insulation components. It can be used as a thermal insulation material in aerospace, nuclear power, shipbuilding, and other fields.

The invention discloses an all-solid-waste-based aerogel adsorbent material and a preparation method and application thereof.According to the all-solid-waste-based aerogel adsorbent material, fly ash, coal gangue, steel slag and other bulk solid waste serve as main raw materials, proportioning is conducted according to the raw material composition of the solid waste, Si, Al and Na elements in multiple solid waste are fully utilized, it is avoided that traditional solid-waste-based aerogel uses NaOH, Na2CO3 and other alkaline chemical reagents, and the preparation method is simple and environmentally friendly; and high-value utilization of the solid waste is realized. The all-solid-waste-based aerogel prepared through sol-gel, surface hydrophobic modification and CO2 supercritical drying technologies has good adsorption performance on various VOCs, the preparation process of an adsorbent is mild and controllable and environmentally friendly, and a new scheme is provided for adsorption of VOCs in a complex industrial environment.

The invention belongs to the technical field of aerogel, and relates to a method for preparing aerogel by carbon dioxide supercritical drying based on gradient drying control, which comprises the following steps: preparing basic catalytic liquid, preparing silica sol, gelatinizing and aging, performing surface modification, pretreating a drying system, placing and sealing materials, replacing and boosting carbon dioxide, and performing gradient depressurization and material taking. After pressure reduction is completed, aerogel is obtained; by accurately controlling the temperature, the pressure and the pressure increasing and decreasing rate in the carbon dioxide supercritical drying process, skeleton collapse and size shrinkage caused by capillary stress are effectively avoided, and the morphology retentivity and the structural integrity of the aerogel are remarkably improved. The obtained aerogel is light blue and semitransparent, has no cracks on the surface, has the specific surface area of more than or equal to 850m < 2 > / g and the heat conductivity of less than or equal to 0.020 W / (m.K), has excellent heat insulation performance, structural stability and mechanical strength, and is suitable for the fields of building energy conservation, aerospace, microelectronic packaging, flexible heat management and the like.

The invention relates to a chitosan-collagen synergistic self-assembly fiber material and a preparation method thereof, and belongs to the technical field of biological fiber materials. According to the method, the mass ratio of chitosan to collagen is controlled, co-assembly is induced through hydrogen bonds and electrostatic interaction in a low-temperature PBS solution, and then glutaraldehyde crosslinking, gradient dehydration and supercritical drying are performed to prepare the freeze-dried fiber. The obtained material completely retains the triple helix conformation of collagen, and has excellent conformation stability and enzymolysis resistance. The mechanical strength of the composite fiber is remarkably improved, and the composite fiber has excellent antibacterial property and cell affinity. The process does not need a toxic cross-linking agent, the operation is simple and convenient, and the prepared fiber is suitable for the high-end biomedical fields of tissue engineering scaffolds, intelligent antibacterial dressings, degradable nerve conduits and the like.

The invention discloses a preparation method of a 1200 DEG C temperature-resistant thermal insulation coating containing ATO-Nb2O5-coated Al2O3 aerogel, and belongs to the technical field of coatings. According to the method, the ATO-Nb2O5-coated Al2O3 aerogel is prepared through a gradient coating technology, nanometer ATO particles form an infrared reflection barrier, Nb2O5 inhibits Al2O3 high-temperature crystal form transformation through a pinning effect, and CO2 supercritical drying (11-14 MPa, 30-45 DEG C and 4-6 h) is combined to obtain the aerogel with high porosity and the alpha phase transition temperature larger than or equal to 1200 DEG C. An organic-inorganic compound adhesive (alkaline silica sol, potassium silicate and modified organic silicon emulsion) is used as a matrix and cooperates with hollow ceramic microbeads and superfine mullite fibers to construct a multi-scale heat insulation system, and the coating is prepared through high-speed dispersion. The heat conductivity coefficient of the coating at 25 DEG C is as low as 0.039 W / (m.K), the temperature resistance reaches 1225 DEG C, the coating has thermal shock resistance and low heat conductivity, the problems of high-temperature phase change densification and coating cracking of traditional Al2O3 aerogel are solved, and the coating is suitable for ultrahigh-temperature heat insulation protection of industrial equipment.

The invention discloses a high-toughness thermal bridge blocking material and a preparation method thereof, namely a metal fibrofelt reinforced aerogel composite material and a preparation method thereof, and belongs to the technical field of thermal insulation materials. The preparation of the metal fibrofelt reinforced aerogel composite material is realized by adopting the processes of metal fibrofelt modification, fiber prefabricated part forming, sol dipping and aging, supercritical drying, heat treatment and the like. The composite material prepared by the invention has the characteristics of light weight, low thermal conductivity, high temperature resistance, high pressure bearing capacity, high toughness and the like, and can be used as a thermal bridge blocking material in the fields of aerospace, thermal equipment and the like.

The invention provides a hollow fiber reinforced aerogel composite material and a preparation method thereof, and relates to the field of aerogel materials. The preparation method of the hollow fiber reinforced aerogel composite material comprises the following steps: preparation of aluminum silica sol, modification compounding, vacuum impregnation, gel aging and supercritical drying. According to the hollow fiber reinforced aerogel composite material and the preparation method thereof, the sound insulation performance of the aerogel material can be effectively improved on the premise of overcoming the existing defects (the defect of a porous structure of aerogel, weak binding force among aerogel particles and thermal stress caused by mismatching of thermal expansion coefficients of aluminum and silicon components) of the aerogel material; the strength, the toughness and the heat insulation performance of the aerogel material are synchronously improved.

The invention relates to the technical field of aerogel materials, in particular to a four-side elastic aerogel thermal insulation material and a preparation method thereof. The invention relates to a four-side elastic aerogel thermal insulation material, which comprises the following substances by weight: 20-30 parts of TPU resin; and 0.5 to 2.0 parts of ethyl silicate. According to the preparation method, TPU resin and ethyl silicate are preferably selected as main materials, TPU is taken as a spinning aid, ethyl silicate is taken as a silicon source, different proportions of ethyl silicate are added in the TPU drying process, the TPU enters a screw rod for melt spinning after being dried, and the porous thin film material is prepared by adopting rotor spinning. And soaking the film in absolute ethyl alcohol, adding a catalyst to prepare gel, and performing super-hydrophobic and nitrogen dioxide supercritical drying to prepare the elastic aerogel film. The elastic aerogel thermal insulation material prepared by the method disclosed by the invention has high transverse and longitudinal elasticity and air permeability, does not drop powder and has good thermal insulation performance.

The invention relates to aerogel with high heat insulation performance and a preparation method thereof, and belongs to the technical field of aerogel materials. The aerogel is prepared from a silicon source, nano heat insulation particles, a surface modifier, a catalyst and a solvent. The nano heat insulation particles are a compound of zirconium dioxide and hollow glass beads, and the surface modifier is a mixture of trimethylchlorosilane and gamma-aminopropyltriethoxysilane. The preparation method comprises the steps of sol preparation, modification treatment, gelation, aging and supercritical drying. Through compounding and synergistic effects of specific components, the mesoporous network structure of the aerogel is remarkably optimized, so that the aerogel has ultralow normal-temperature thermal conductivity, relatively high compression strength and excellent thermal stability, and the problem that heat insulation performance and mechanical strength of traditional aerogel are difficult to consider at the same time is solved; the method is suitable for the fields of building insulation, industrial pipelines and aerospace.

The invention discloses a core-shell structure aerogel and a preparation method and application thereof in refractory bricks, and belongs to the technical field of thermal insulation materials, and the preparation method comprises the following steps: adding zirconium oxychloride into an ethanol water solution at room temperature for hydrolysis, then adding carboxylated silicon dioxide aerogel, stirring and mixing, then adding a gelling agent to form a sol solution, and carrying out vacuum drying to obtain the core-shell structure aerogel. Performing sealed aging to obtain wet gel, and performing solvent replacement, supercritical drying and crushing to obtain core-shell structure aerogel; the method for applying the aerogel to the refractory brick comprises the following steps: adding the aerogel with the core-shell structure into an organic solvent for soaking, then adding the refractory brick raw materials with the particle size of 0.05-0.2 mm for mixing, then adding the refractory brick raw materials with the remaining particle size for mixing, and finally adding a bentonite solution for uniformly mixing to obtain a refractory brick mixture; and carrying out compression molding, high-temperature calcination and cooling to obtain the refractory brick. The prepared refractory brick has the characteristics of high strength, high temperature resistance and low heat conductivity, and the problem that the strength and heat insulation of a traditional refractory brick cannot be considered at the same time is solved.

The invention discloses a preparation method of an aerogel laminated composite heat insulation pad, and relates to the technical field of aerogel heat insulation pads, and the preparation method comprises the following steps: mixing and dispersing a silane precursor and absolute ethyl alcohol, adding a basic catalyst, hydrolyzing to generate sol, and aging to form prefabricated sol; adding a flame retardant, a smoke retardant and reinforced fibers, dispersing and gelatinizing, and carrying out supercritical drying to obtain an aerogel block; and coating basalt fiber non-woven fabric with the aerogel slurry to form a base layer, laminating a plurality of layers, and carrying out hot-pressing curing, cooling, post-curing, cutting and edge covering to obtain the composite heat insulation pad. According to the invention, by optimizing the ratio of silane and a drying process, the pore structure and the thermal stability of the aerogel are obviously improved; the flame-retardant, mechanical and heat-insulating properties are improved through multi-component collaborative design, and the obtained heat-insulating pad has the characteristics of low heat conductivity, high strength, excellent flame retardance and light weight, and is suitable for multiple heat-insulating and flame-retardant fields.

The invention relates to the technical field of preparation of high polymer materials and intelligent response materials, in particular to a preparation method of polyacrylamide for treatment. And constructing a quaternary polymerization system with acrylamide, a temperature-sensitive monomer and a zirconium-based metal organic framework-graphene quantum dot composite material. Magnetic response interpenetrating network gel is formed by induction of a photo-magnetic synergistic field, bacterial cellulose nanofibrils and a calcium silicate layered structure are introduced through a biomimetic mineralization technology, and the hierarchical porous carrier is prepared by combining a microfluidic crushing technology and a supercritical drying technology. Finally, through an intelligent regeneration mechanism of bimetal coordination activation and high-frequency magnetic field triggering, the material is endowed with multiple stimulation response characteristics, high adsorption capacity and in-situ regeneration capacity, and the mechanical strength and the salt resistance are remarkably improved through a pearl-layer-like micro-nano laminated structure. The method is suitable for industrial wastewater advanced treatment and emergency pollution repair scenes.

The invention relates to a composite aerogel for water treatment and a preparation method thereof, and the preparation method comprises the following steps: activating graphene oxide, and then carrying out amidation reaction on the activated graphene oxide, aminated beta-cyclodextrin and hexamethylenediamine to obtain modified graphene; then carrying out hydrothermal reaction on the GO / BiOCOOH composite material, a Bi < 3 + > solution and formamide to obtain a modified GO / BiOCOOH composite material; crosslinking in a lignin aqueous solution to obtain hydrogel; and finally, performing supercritical drying to obtain the composite aerogel. The preparation method has the beneficial effects that by constructing macroscopic blocky aerogel, the problems that a powder material is easy to lose and difficult to recycle are effectively solved; the high photocatalytic activity is still kept under the condition that iodine doping is not used, and the possibility of secondary pollution of free iodine to a water body due to instability of the material is reduced; under the synergistic effect of the aerogel and the photocatalytic reaction, the efficient proceeding of the adsorption and desorption-photocatalytic reaction is realized; the material is high in stability, easy to recover, capable of being recycled through simple desorption, high in cycle index and long in service life.

The invention relates to a flame-retardant composite aerogel and a preparation method and application thereof, and the preparation method comprises the following steps: uniformly mixing a chitosan aqueous solution with an MXene dispersion liquid to obtain a mixed solution, dropwise adding an alkali liquid to obtain a black first suspension, and concentrating to obtain a second suspension; adding a cross-linking agent into the second suspension, and performing freezing cross-linking to obtain chitosan / MXene frozen gel; the chitosan / MXene frozen gel is subjected to unfreezing, solvent replacement and drying, and the flame-retardant composite aerogel is obtained. The composite aerogel obtained by the invention is good in mechanical stability and has excellent flame retardant property and oil absorption property; the preparation method is simple, no ultralow-temperature freeze drying equipment or supercritical drying equipment is needed, the preparation cost is low, the size is not limited, and large-scale production can be achieved.

The invention discloses a polyimide polymer as well as a preparation method and application thereof, and the preparation method comprises the following steps: carrying out condensation polymerization on dianhydride and diamine, and then carrying out crosslinking, gel aging, solvent replacement and supercritical drying to obtain a polyimide microporous foam material. The dianhydride disclosed by the invention is a commercial product; the diamine comprises novel diphenylmethylene fluorene-based diamine prepared by a two-step method, and other diamines are commercial products; the preparation route of the polyimide microporous foam is simple, and the synthesis method has universality. The polymer chain rigidity of the polyimide microporous foam is moderate, the shrinkage rate is as low as 7.7%, the specific surface area exceeds 670 m < 2 > g <-1 >, the glass-transition temperature reaches 376 DEG C, the polyimide microporous foam has excellent thermal properties, and the thermal conductivity at 150 DEG C is as low as 41.5 mW m <-1 > K <-1 >.

The invention discloses a preparation method of an aerogel composite material uniformly doped with an opacifying agent, and belongs to the technical field of aerogel composite materials. Comprising the following steps: mixing a precursor solution with ethanol in a ratio of 1: (0.5-20), and stirring for 20 minutes to obtain a shading modified solution; a base material is put into the shading modification liquid, at the moment, the base material is completely soaked in the shading modification liquid, the base material is taken out after being soaked for 2 min, sent into a steam box to be soaked and then taken out to be dried, a dried base material is obtained, and the dried base material is subjected to heat treatment to obtain a shading base material; the preparation method comprises the following steps: preparing silica sol from ethyl silicate, ethanol, deionized water, ammonium fluoride and ammonia water in a mass ratio of 1: (1.5-15): (0-0.3): (0.01-0.05): (0.01-0.05); a shading base material is completely soaked in silica sol, and the aerogel composite material is obtained through gelation, aging, hydrophobic modification and supercritical drying. The prepared aerogel composite material uniformly doped with the opacifying agent can provide excellent heat insulation performance in a high-temperature environment.