CN114835941A - Polymer porous material and preparation method and application thereof - Google Patents

Polymer porous material and preparation method and application thereof Download PDF

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CN114835941A
CN114835941A CN202210389483.3A CN202210389483A CN114835941A CN 114835941 A CN114835941 A CN 114835941A CN 202210389483 A CN202210389483 A CN 202210389483A CN 114835941 A CN114835941 A CN 114835941A
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emulsion
porous material
crosslinked
monomer
emulsifier
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柏浩
李德文
高微微
张子倍
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Zhejiang University ZJU
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
    • C08J2201/048—Elimination of a frozen liquid phase
    • C08J2201/0484—Elimination of a frozen liquid phase the liquid phase being aqueous
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2383/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
    • C08J2383/04—Polysiloxanes

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Abstract

The invention provides a method for preparing polymer porous material, which is based on the fact that active pre-crosslinking emulsion not only has ready-made polymer network, is highly oriented and extended under the extrusion of ice crystals, but also has unreacted parts, so as to react and fix the characteristics of highly oriented and extended pore wall structure at low temperature, and combines the advantages of the ice template method to obtain high porosity (up to 99.0 percent, and the density as low as 0.013 g/cm) 3 ) The polymeric porous material of (1). Due to high porosity, compared with the polymer porous material prepared by the traditional method, the thermal conductivity is lower (the lowest value is 18.7 mW/m.K), the thermal insulation performance is better, and the polymer porous material can be used as a high-performance thermal insulation/sound insulation/shock absorption material.

Description

Polymer porous material and preparation method and application thereof
Technical Field
The invention relates to the field of preparation of polymer porous materials, in particular to preparation methods, products and applications of several polymer porous materials.
Background
Compared with a non-porous polymer material, the polymer porous material has the advantages of low density, good heat insulation performance, high specific strength, good sound insulation performance and the like, plays an important role in various fields such as aerospace, land and water traffic, national defense and military, civil engineering and the like, and according to the statistical data of '2021 plus 2027 foam plastic market research analysis and investment strategy analysis prediction report' published by Chinese enterprise and belief international consultation, the accumulated yield of the foam plastic products in our country in 2019 reaches 258.19 ten thousand tons, the product types are various, the market occupation ratio is gradually increased, and the polymer porous material plays an important role in national economy.
At present, the method for preparing the polymer porous material mainly comprises the traditional foaming method, a high inward emulsion method, a salting-out method, a 3D printing method, a freezing casting method and the like, wherein the traditional foaming method adopts a physical or chemical foaming agent as a pore-making template, and the polymer porous material is prepared through the processes of gas dissolution, nucleation, growth and cell shaping, the preparation process is relatively simple, but the regulation and control method for the pore structure is limited, and certain foaming agent residue can be caused; the salting-out method is to mix salt particles of a certain size with resin powder, and wash out the salt particles after melting and cooling, but the method is limited by the dispersion degree of the salt particles, and is difficult to prepare a porous material with ultrahigh porosity, and the salt particles partially remain in the porous material; the high internal emulsion method is to obtain a high molecular porous material by polymerizing continuous phase monomers in emulsion and then drying, but the high internal emulsion method has residual emulsifier and lacks of richer means for regulating and controlling pore shapes; the 3D printing method can design a material structure in advance, but high-precision printing needs very long printing time, and the large-scale application of the printing method is limited.
The ice templating method is a typical method for preparing porous materials. In recent years, many different porous materials, particularly aerogel materials having very high porosity, have been successfully prepared by freezing. The application of the ice templating method is extremely dependent on the water solubility of the starting material or its dispersibility in water. For hydrophobic materials, particularly hydrophobic polymers, the main possible route at present is to imitate the preparation process of porous ceramics, firstly prepare polymer emulsion, make holes through an ice template, and then carry out heat treatment to melt and connect the microspheres on the walls of the holes. The process of the route is complicated, the defects of post-treatment hole walls are large, and the self-supporting polymer porous material with higher porosity cannot be obtained due to the collapse of the hole walls. Therefore, the method for obtaining the self-supporting polymer porous material with high porosity has important significance and value.
Disclosure of Invention
The invention aims to provide a preparation method of a high-porosity polymer porous material aiming at the defects of the prior art. Specifically, the method at least comprises the following steps:
(1) freezing the active pre-crosslinked emulsion, and further reacting the emulsion particles in the emulsion with each other under the freezing condition; the ice crystals formed in the freezing stage extrude and fuse the polymer network in the active pre-crosslinked emulsion; the crosslinking degree of the active polymer emulsion is 10-90%;
and (2) freezing and then drying to obtain the polymer porous material.
On one hand, the invention overcomes the technical prejudice, and applies the ice template method to the hydrophobic polymer system, on the other hand, the invention selects the active pre-crosslinking emulsion, and combines the expansion extrusion of the ice template method to generate the extrusion stress as high as hundreds of megapascals, so as to obtain the polymer porous material with extremely high porosity. This further reactive pre-crosslinked emulsion possesses both a ready polymer network to be highly oriented and extended under the extrusion of ice crystals and an unreacted portion to react at low temperatures to fix the highly oriented and extended pore wall structure. Specifically, in the process of freezing and casting the active pre-crosslinked emulsion, ice crystals growing at low temperature can generate a violent extrusion fusion process on pre-crosslinked emulsion particles, so that polymer particles can be demulsified and fused into a uniform structure, and more importantly:the polymer network is induced to produce a certain orientation due to the large extrusion stress, forming thinner, denser, and uniform pore walls. Because the selected pre-crosslinking emulsion has reaction activity, inter-chain reaction is further carried out after emulsion breaking and fusion to form strong chemical bonds, and the orientation and the pore wall structure are fixed, so that a thin and tough pore wall structure is generated, and the self-supporting elastic porous membrane has high porosity (the highest can reach 99.0 percent and the density is as low as 0.013 g/cm) after unfreezing and freeze-drying 3 ) The polymeric porous material of (1).
Based on the invention, the porosity of the product can be effectively controlled by adjusting the oil phase concentration of the pre-crosslinked emulsion, and the lower the concentration, the higher the porosity.
Preferably, the crosslinking degree of the pre-crosslinked emulsion is 10-90% so as to ensure that the emulsion can be smoothly demulsified and fused and has enough strength after being dried so as to support the hole wall not to collapse;
the freezing in the present invention is to allow the water in the emulsion to form ice crystals, generally at temperatures below 0 ℃ and in some special circumstances above 0 ℃.
The drying mode of the invention can be freeze drying or room temperature drying.
In certain embodiments, the porous material obtained after drying is further treated to enhance its properties or impart functional characteristics thereto, including but not limited to heat treatment, chemical modification, and the like.
In some embodiments, the thermal conductivity is further reduced by multi-stage freezing, which is: the living polymer emulsion was added to the freeze-dried sample and frozen again.
The invention also relates to the polymer porous material prepared by the preparation method, the porosity can reach 99.0 percent at most, and the density is as low as 0.013 g/cm 3 。
Based on the high porosity of the polymer porous material, the invention also relates to the application of the polymer porous material in heat insulation and preservation materials, sound absorption materials and shock absorption materials.
Specifically, the pre-crosslinked emulsion includes, but is not limited to, a pre-crosslinked polysiloxane emulsion, a pre-crosslinked polyepoxy resin emulsion, a pre-crosslinked polyurethane emulsion, and a pre-crosslinked polyacrylate emulsion.
The raw materials of the pre-crosslinked polysiloxane emulsion comprise a siloxane monomer, an emulsifier, a crosslinking agent, a catalyst and water; it is common knowledge in the art to control the ratio of the components and the reaction conditions to achieve a degree of crosslinking of 10-90%. The siloxane monomer can be one or more of octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, hexadecylcyclooctasiloxane, dodecamethylcyclohexasiloxane, 2,4,6, 8-tetramethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane or octaphenylcyclotetrasiloxane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldiethoxysilane and vinyltriethoxysilane; the emulsifier can be one or more of dimethyl dicetyl ammonium chloride, dimethyl dioctadecyl ammonium chloride, dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate or sodium dodecyl sulfate; the cross-linking agent can be one or more of ethyl orthosilicate, methyl hydrogen-containing silicone oil, dibenzoyl peroxide or dicumyl peroxide; the catalyst can be one or more of dodecylbenzene sulfonic acid, hydrochloric acid, sulfuric acid, sodium hydroxide, tetramethyl sodium hydroxide, ammonia water, dioctyltin dilaurate, dibutyltin dilaurate, polyalkoxy titanate or chloroplatinic acid or platinum-vinyl siloxane complex.
The raw materials of the pre-crosslinked polyepoxy resin emulsion comprise an epoxy resin monomer, an emulsifier, a crosslinking agent, a catalyst and water. It is common knowledge in the art to control the ratio of the components and the reaction conditions to achieve a degree of crosslinking of 10-90%. The epoxy resin monomer can be one or more of bisphenol A epoxy resin monomers (E51, E54, E44 and E29), bisphenol F epoxy resin monomers and epoxy organic silicon resin; the emulsifier can be one or more of dodecylbenzene sulfonic acid, tween-80, sodium dodecylbenzene sulfonate, triton, 3-allyloxy-2 hydroxy-1-propane sulfonic acid sodium salt and ethoxylated alkyl ether ammonium sulfate; the cross-linking agent can be one or more of trifunctional epoxy resin triglycidyl m-aminophenol, 2,4, 6-tri (dimethylaminomethyl) phenol, diisocyanate, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, maleic anhydride and phthalic anhydride; the catalyst can be one or more of potassium persulfate, tertiary amine, imidazole and boron trifluoride complex.
The raw materials of the pre-crosslinking polyurethane emulsion can be isocyanate monomer, oligomeric polyol or micromolecular polyol, hydrophilic chain extender, crosslinking agent, catalyst and water. It is common knowledge in the art to control the ratio of the components and the reaction conditions to achieve a degree of crosslinking of 10-90%. The isocyanate monomer can be one or more of toluene diisocyanate, diphenylmethane-4, 4' -diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate and naphthalene-1, 5-diisocyanate; the oligo-polyol and the micromolecular polyol can be one or more of polyethylene glycol, polypropylene glycol, polyester polyol, acrylic polyol, polycarbonate polyol, ethylene glycol and 1, 4-butanediol; the hydrophilic chain extender can be one or more of N-methyldiethanolamine, bis-hydroxymethyl propionic acid, bis-hydroxymethyl butyric acid and ethylene diamine ethyl sodium sulfonate; the cross-linking agent can be one or more of ethylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, ethylenediamine, polyethylene polyamine, piperazine, trimethylolmelamine, and polyisocyanate cross-linking agents (Desmodur DA, Desmodur XP-7007, Desmodur XO-671, Desmodur XO-672, PBA 2236LX CR-60N); the catalyst can be one or more of 1, 4-diazabicyclo [2,2,2] octane and dibutyltin dilaurate.
The raw materials of the pre-crosslinked polyacrylate emulsion comprise a main monomer, a functional crosslinking monomer, an emulsifier, an initiator and water. It is common knowledge in the art to control the ratio of the components and the reaction conditions to achieve a degree of crosslinking of 10-90%. The main monomer can be one or more of methyl acrylate, methyl methacrylate, butyl acrylate and ethyl acrylate; the functional crosslinking monomer can be one or more of ethylene glycol dimethacrylate, hydroxyethyl methacrylate, diallyl phthalate, trimethylolpropane triacrylate and acetoacetoxyethyl methacrylate; the emulsifier can be one or more of sodium dodecyl sulfate, ER-10 emulsifier, disodium hydrogen phosphate dodecahydrate and OP-10 emulsifier; the initiator can be one or more of ammonium persulfate, potassium persulfate, azobisisobutyronitrile and N, N-dimethylaniline.
The invention has the beneficial effects that: the invention overcomes the technical prejudice, applies the ice template method to a hydrophobic polymer system, selects the active pre-crosslinking emulsion, and combines the expansion extrusion of the ice template method to generate extrusion stress as high as hundreds of megapascals to obtain the polymer porous material with extremely high porosity. The active polymer emulsion has a ready polymer network to be highly oriented and extended under the extrusion of ice crystals, and an unreacted part to react and fix a highly oriented and extended pore wall structure at low temperature, and brings unexpected technical effects: the porosity of the porous material skeleton can reach 99.0% at most, and the density is as low as 0.013 g/cm 3 Self-supporting can be realized, and the elasticity is excellent.
The silicon rubber porous material prepared by the preparation method has high porosity, and compared with the silicon rubber porous material prepared by the traditional method, the silicon rubber porous material has lower thermal conductivity (the lowest 18.7 mW/m.K) and better heat insulation performance.
Compared with the traditional chemical foaming process, the preparation method of the invention uses water or ice as a pore-foaming agent, and is more environment-friendly.
The preparation method can prepare the polymer porous materials with different apertures and different structures by adjusting the freezing temperature field, and can be applied to other specific fields.
Drawings
FIG. 1 is a photograph of the extrusion fusion and extensional orientation of ice crystals to emulsion particles during the preparation of a polymer emulsion ice template.
FIG. 2 is a photograph of the effect of ice crystals on particles during the preparation of an ice template for a comparative example monomer emulsion.
Fig. 3 is a diagram of a finished product of the silicone rubber porous material.
Figure 4 is a graph comparing the thermal stability of silicone rubber porous material and commercial polystyrene foam.
Fig. 5 is a graph of surface temperature contrast for silicone rubber porous material and commercial polystyrene foam.
Fig. 6 is an SEM picture of a cross section of the silicone rubber porous material.
Detailed Description
Example 1: the preparation process of the pre-crosslinking emulsion ice template method comprises the following steps:
(1) 1-2 g of ER-10 emulsifier, 2-5 g of sodium dodecyl sulfate and 0.4 g of disodium hydrogen sulfate dodecahydrate are dissolved in 180 ml of deionized water.
(2) And (3) uniformly mixing 10 ml of methyl methacrylate monomer, 10 ml of butyl acrylate monomer and 1-5 ml of functional crosslinking monomer trimethylolpropane triacrylate, adding the mixture into the solution, and performing ultrasonic dispersion for 15 min to obtain the acrylic monomer pre-emulsion.
(3) And adding 1 g of ammonium persulfate into the pre-emulsion to initiate reaction, reacting for 1-4 h at 85 ℃, and cooling to room temperature. The degree of crosslinking was found to be 54%.
(4) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(5) Calculating the density and porosity of the porous polyacrylate material, wherein the density is 26.4-27.2 mg/cm 3 Drying the emulsion to obtain a transparent film, and calculating the density (bulk density) of the film to be 1178 mg/cm 3 The porosity of the porous material (1-porous material density/bulk density) was found to be about 97.69-97.76%.
(6) And (3) placing the dried porous material in an oven at 90 ℃ for heating for 1-4 h.
(7) The thermal conductivity of the polyacrylate porous material is tested by a steady-state flat plate method, and the thermal conductivity at room temperature is 24.6-25.3 mW/(m × K).
Comparative example 1: different from the embodiment 1, after monomer methyl methacrylate, butyl acrylate and cross-linking agent trimethylolpropane triacrylate are mixed uniformly, initiator ammonium persulfate is added, after emulsification with water added with emulsifier in the same proportion, the mixture is directly frozen in liquid nitrogen without pre-reaction, after freezing, the mixture is placed in a refrigerator at 15 ℃ below zero for 24 hours to react, then the porous material is obtained by freeze drying, and after drying, the mixture is heated in an oven at 90 ℃ for 1 to 4 hours to completely react. At the same emulsion concentration, i.e. 2.86% (v/v%), the porous material obtained after freezing of the monomer was unable to support itself after freeze-drying, collapsing appeared, and the final porosity was only 47.51%.
As shown in fig. 1, which is an assembly extrusion extension image of a pre-crosslinked emulsion ice template, the freezing process of the single emulsion ice template method in fig. 2 is compared with fig. 1 and fig. 2, it can be seen that, for the pre-crosslinked emulsion ice template method, emulsion particles are subjected to emulsion breaking fusion and extrusion extension orientation processes under the extrusion action of ice crystals, and the freezing of the single emulsion ice template only fixes the position morphology of the emulsion, and the extrusion extension orientation process does not exist, so that the mechanical property is poor, and the higher porosity cannot be supported.
In the widely used silicon rubber aerogel system prepared by the sol-gel method, cyclic monomers such as octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, hexadecylcyclooctasiloxane, decadimethylcyclohexasiloxane and the like cannot form a sol system due to poor solubility in water, hydrolysis ring-opening reaction is difficult to occur, the silicon rubber aerogel with high porosity cannot be prepared by using the traditional sol-gel method, the application of low-cost and easily-obtained materials is limited, and the manufacturing cost of the materials is higher. According to the invention, the high-porosity silicone rubber aerogel can be obtained by using the monomer which is poor in water solubility and cannot form a sol system, and the octamethylcyclotetrasiloxane monomer is taken as an example for explanation:
example 2
(1) 0.1-1 g of dodecyl benzene sulfonic acid, 0.1-1 g of octadecane and 10 g of octamethylcyclotetrasiloxane are mixed, heated to 60-90 ℃ and stirred uniformly.
(2) 90 ml of deionized water is added into the mixture, and after being uniformly mixed, the mixture is subjected to ultrasonic dispersion for 5 min to obtain siloxane monomer emulsion.
(3) And heating and stirring the siloxane monomer emulsion at 80 ℃ for 1-9 h to obtain the polysiloxane emulsion.
(4) Adding 1-5 ml of ethyl orthosilicate, and continuing to heat and stir at 80 ℃ for 1-8 h. The degree of crosslinking was found to be 64%.
(5) And (5) taking 10 ml of the emulsion obtained in the step (4), adding 90 ml of deionized water for dilution, and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, wherein the extrusion effect of ice crystal growth on the pre-crosslinked emulsion is shown in figure 1, and after freezing, carrying out vacuum drying for 36 h.
(7) And (3) placing the dried silicone rubber porous material in an oven at 80 ℃, and heating for 1-6 h to obtain the silicone rubber porous material, as shown in figure 3.
(8) Calculating the density of the silicon rubber porous material, wherein the density is 13.0-15.2 mg/cm 3 (ii) a Drying the emulsion to obtain a transparent film, wherein the calculated film density (silicon rubber bulk density) is 1221 mg/cm 3 The porosity (1-porous material density/bulk density) of the obtained silicone rubber is about 98.8-99.0%.
(9) And (3) performing a thermal conductivity test on the silicon rubber porous material by adopting a steady-state flat plate method, wherein the thermal conductivity is 26.6-28.2 mW/(m × K) at room temperature.
(10) Comparing the heat insulating performance of the silicone rubber porous material with that of the conventional commercial PS foam, as shown in fig. 4, and fig. 5 is a temperature change curve of each surface, the silicone rubber porous material exhibits better heat insulating performance than the conventional commercial PS foam.
(11) And (3) testing the sound absorption coefficient by adopting a standing wave tube method, wherein the average sound absorption coefficient of the silicone rubber porous material with the thickness of 15 mm is 0.34-0.36.
(12) And measuring the damping performance at room temperature by using a dynamic thermomechanical analyzer (DMA), and measuring the damping factor to be 0.32-0.35.
Example 3
(1) 0.1-1 g of dodecyl benzene sulfonic acid, 0.1-1 g of octadecane and 10 g of octamethylcyclotetrasiloxane are mixed, heated to 80 ℃ and stirred uniformly.
(2) 90 ml of deionized water is added into the mixture, and the mixture is evenly mixed and then ultrasonically dispersed for 5 min to obtain the siloxane monomer emulsion.
(3) And heating and stirring the siloxane monomer emulsion at 80 ℃ for 1-9 h to obtain the polysiloxane emulsion.
(4) Adding 1-5 ml of ethyl orthosilicate, and continuing to heat and stir at 80 ℃ for 1-8 h. The degree of crosslinking was found to be 10%.
(5) And (5) adding 25 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(7) And (3) placing the dried silicone rubber porous material in an oven at 80 ℃, and heating for 1-6 h.
(8) Calculating the density and porosity of the silicon rubber porous material, wherein the density is 45.3-47.2 mg/cm 3 The porosity was about 96%.
(9) And (3) performing a thermal conductivity test on the silicon rubber porous material by adopting a steady-state flat plate method, wherein the thermal conductivity at room temperature is 29.1-31.1 mW/(m & ltx & gt K).
(10) And (3) observing the microstructure of the silicon rubber porous material by using a Scanning Electron Microscope (SEM), wherein an SEM image of the silicon rubber porous material is shown in figure 6.
(11) And (3) testing the sound absorption coefficient by adopting a standing wave tube method, wherein the average sound absorption coefficient of the silicone rubber porous material with the thickness of 15 mm is 0.35-0.37.
(12) And measuring the damping performance at room temperature by using a dynamic thermomechanical analyzer (DMA), and measuring the damping factor to be 0.29-0.31.
Example 4
(1) 0.1-1 g of dodecyl benzene sulfonic acid, 0.1-1 g of octadecane and 10 g of tetramethyl tetravinylcyclotetrasiloxane are mixed, heated to 80 ℃ and stirred uniformly.
(2) 90 ml of deionized water is added into the mixture, and the mixture is evenly mixed and then ultrasonically dispersed for 5 min to obtain the siloxane monomer emulsion.
(3) And heating and stirring the siloxane monomer emulsion at 80 ℃ for 1-9 h to obtain the polysiloxane emulsion.
(4) Adding 1-5 ml of ethyl orthosilicate, and continuing to heat and stir at 80 ℃ for 1-6 h. The degree of crosslinking was found to be 90%.
(5) And (5) adding 25 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(7) And (3) placing the dried silicone rubber porous material in an oven at 80 ℃, and heating for 1-6 h.
(8) Calculating the density and porosity of the silicon rubber porous material, wherein the density is 42.2-44.2 mg/cm 3 The porosity was 97%.
(9) And (3) performing a thermal conductivity test on the silicon rubber porous material by adopting a steady-state flat plate method, wherein the thermal conductivity is 30.1-32.2 mW/(m × K) at room temperature.
(10) And (3) testing the sound absorption coefficient by adopting a standing wave tube method, wherein the average sound absorption coefficient of the silicone rubber porous material with the thickness of 15 mm is 0.34-0.36.
(11) And measuring the damping performance at room temperature by using a dynamic thermomechanical analyzer (DMA), and measuring the damping factor to be 0.33-0.35.
Example 5
(1) 0.1-1 g of sodium dodecyl benzene sulfonate, 0.1-1 g of tween-80 and 10 g of bisphenol A type epoxy resin (E51) are mixed and stirred uniformly.
(2) 90 ml of deionized water is added into the mixture, and the mixture is evenly mixed and then ultrasonically dispersed for 15 min to obtain the epoxy resin emulsion.
(3) Adding a small amount of potassium persulfate initiator into the monomer emulsion, and uniformly stirring.
(4) 0.5-5 ml of diethylenetriamine is added into the mixture, and the mixture is continuously heated and stirred for 10 min at the temperature of 60 ℃. The degree of crosslinking was found to be 34%.
(5) And (5) adding 25 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(7) And (3) placing the dried epoxy porous material in a 60 ℃ oven, and heating for 1-2 h.
(8) Calculating the density and porosity of the epoxy porous material, wherein the density is 29.6-31.4 mg/cm 3 Drying the emulsion to obtain a transparent film, and calculating the film density (epoxy bulk density) to be 1798 mg/cm 3 The epoxy porosity (1-porous material density/bulk density) obtained was about 98.25-98.35%.
(9) The thermal conductivity of the epoxy resin porous material is tested by a steady-state flat plate method, and the thermal conductivity is 27.6-28.4 mW/(m & ltx & gt K) at room temperature.
(10) And (3) performing sound absorption coefficient test by adopting a standing wave tube method, wherein the average sound absorption coefficient of the epoxy resin porous material with the thickness of 15 mm is 0.42-0.47.
Example 6
(1) 0.1-1 g of dodecyl benzene sulfonic acid, 0.1-1 g of octadecane and 10 g of octamethylcyclotetrasiloxane are mixed, heated to 80 ℃ and stirred uniformly.
(2) 90 ml of deionized water is added into the mixture, and the mixture is evenly mixed and then ultrasonically dispersed for 5 min to obtain the siloxane monomer emulsion.
(3) And heating and stirring the siloxane monomer emulsion at 80 ℃ for 1-9 h to obtain the polysiloxane emulsion.
(4) Adding 1-5 ml of ethyl orthosilicate, and continuing to heat and stir at 80 ℃ for 1-8 h. The degree of crosslinking was found to be 62%.
(5) And (5) adding 40 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(7) The density and porosity of the silicon rubber porous material are calculated, the density is 31.4-33.5 mg/cm3, and the porosity is about 97.4%.
(8) And (5) adding 90 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(9) And (4) putting the freeze-dried sample into a mold again, adding the emulsion obtained in the step (8) into the mold, putting the mold into liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 hours.
(10) And (3) placing the dried silicone rubber porous material in an oven at 80 ℃, and heating for 1-6 h.
(11) The density and porosity of the silicon rubber porous material are calculated, the density is 68.5-73.3 mg/cm3, and the porosity is about 94.1%.
(12) The thermal conductivity of the silicon rubber porous material is tested by a steady-state flat plate method, and the thermal conductivity at room temperature is 18.7-20.6 mW/(m × K).
Example 7
(1) 10-20 g of polypropylene glycol with the molecular weight of 1000, 1-2 g of 1, 4-butanediol and 1-2 g of hydrophilic chain extender dimethylolbutyric acid which are dehydrated are added into a flask, and a small amount of dibutyltin dilaurate is added under the nitrogen atmosphere.
(2) Adding 15-30 g of isophorone diisocyanate into a system at 80 ℃, and reacting for 2-4 h at 80 ℃.
(3) Taking 5 ml of prepolymer, cooling the prepolymer to 30 ℃ after the reaction is finished, adding a small amount of triethylamine for neutralization, adding a certain amount of acetone to reduce the viscosity, adding 45 ml of deionized water, removing the acetone by distillation, uniformly mixing, and dispersing for 15 min by using ultrasonic to obtain the waterborne polyurethane prepolymer emulsion.
(4) Adding 1-5 g of cross-linking agent triethylene diamine into the mixture, and reacting for 1-2 h at 80 ℃. The degree of crosslinking was found to be 79%.
(5) And (5) adding 25 ml of deionized water into 10 ml of the emulsion obtained in the step (4), and uniformly stirring.
(6) Pouring the diluted emulsion into a mold, placing the mold in liquid nitrogen for freezing, and after freezing, carrying out vacuum drying for 36 h.
(7) Calculating the density and porosity of the polyurethane porous material, wherein the density is 30.2-33.6 mg/cm 3 Drying the emulsion to obtain a transparent film, and calculating the film density (polyurethane bulk density) to be 1164 mg/cm 3 The porosity (1-cellular density/bulk density) of the polyurethane cellular material is about 97.11-97.41%.
(8) And placing the obtained porous material in an oven at 80 ℃ and heating for 1-4 h.
(9) The thermal conductivity of the epoxy resin porous material is tested by a steady-state flat plate method, and the thermal conductivity at room temperature is 16.7-18.3 mW/(m × K).
(10) And (3) testing the sound absorption coefficient by adopting a standing wave tube method, wherein the average sound absorption coefficient of the epoxy resin porous material with the thickness of 15 mm is 0.37-0.39.
(11) And measuring the damping performance at room temperature by using a dynamic thermomechanical analyzer (DMA), and measuring the damping factor to be 0.37-0.38.

Claims (12)

1. A method for preparing a polymeric porous material, characterized in that it comprises at least: freezing the active pre-crosslinked emulsion, and further reacting the emulsion particles in the emulsion with each other under the freezing condition; the ice crystals formed in the freezing stage extrude and fuse the polymer network in the active pre-crosslinked emulsion; the crosslinking degree of the active polymer emulsion is 10-90%;
and (2) freezing and then drying to obtain the polymer porous material.
2. The method of claim 1, wherein the pre-crosslinked emulsion is a pre-crosslinked polysiloxane emulsion, a pre-crosslinked polyepoxy resin emulsion, a pre-crosslinked polyurethane emulsion, or a pre-crosslinked polyacrylate emulsion.
3. The method of claim 2, wherein the pre-crosslinked polysiloxane emulsion is prepared from raw materials comprising siloxane monomers, emulsifiers, crosslinking agents, catalysts, and water; the siloxane monomer is selected from one or more of octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, hexadecylcyclooctasiloxane, dodecamethylcyclohexasiloxane, 2,4,6, 8-tetramethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane or octaphenylcyclotetrasiloxane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldiethoxysilane and vinyltriethoxysilane; the emulsifier is selected from one or more of dimethyl dihexadecyl ammonium chloride, dimethyl dioctadecyl ammonium chloride, dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate or sodium dodecyl sulfate; the cross-linking agent is selected from one or more of ethyl orthosilicate, methyl hydrogen-containing silicone oil, dibenzoyl peroxide or dicumyl peroxide; the catalyst is selected from one or more of dodecyl benzene sulfonic acid, hydrochloric acid, sulfuric acid, sodium hydroxide, tetramethyl sodium hydroxide, ammonia water, dioctyltin dilaurate, dibutyltin dilaurate, polyalkoxy titanate or chloroplatinic acid or platinum-vinyl siloxane complex.
4. The method according to claim 2, wherein the raw materials of the pre-crosslinked polyepoxy resin emulsion comprise an epoxy resin monomer, an emulsifier, a crosslinking agent, a catalyst and water; the epoxy resin monomer comprises one or more of bisphenol A epoxy resin monomer, bisphenol F epoxy resin monomer and epoxy organic silicon resin; the emulsifier comprises one or more of dodecylbenzene sulfonic acid, tween-80, sodium dodecylbenzene sulfonate, triton, 3-allyloxy-2 hydroxy-1-propane sulfonic acid sodium salt and ethoxylated alkyl ether ammonium sulfate; the cross-linking agent comprises one or more of trifunctional epoxy resin triglycidyl m-aminophenol, 2,4, 6-tris (dimethylaminomethyl) phenol, diisocyanate, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, maleic anhydride and phthalic anhydride; the catalyst comprises one or more of potassium persulfate, tertiary amine, imidazole and boron trifluoride complex.
5. The method according to claim 2, wherein the raw materials of the pre-crosslinked polyurethane emulsion comprise isocyanate monomer, oligomeric polyol or small molecular polyol, hydrophilic chain extender, crosslinking agent, catalyst and water; the isocyanate monomer comprises one or more of toluene diisocyanate, diphenylmethane-4, 4' -diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate and naphthalene-1, 5-diisocyanate; the oligomeric polyol and micromolecular polyol comprise one or more of polyethylene glycol, polypropylene glycol, polyester polyol, acrylic polyol, polycarbonate polyol, ethylene glycol and 1, 4-butanediol; the hydrophilic chain extender comprises one or more of N-methyldiethanolamine, bis-hydroxymethyl propionic acid, bis-hydroxymethyl butyric acid and ethylene diamine ethyl sodium sulfonate; the cross-linking agent comprises one or more of ethylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, ethylenediamine, polyethylene polyamine, piperazine, trimethylolmelamine, and polyisocyanate cross-linking agents (Desmodur DA, Desmodur XP-7007, Desmodur XO-671, Desmodur XO-672, PBA 2236LX CR-60N); the catalyst comprises one or more of 1, 4-diazabicyclo [2,2,2] octane and dibutyltin dilaurate.
6. The method according to claim 2, wherein the raw materials of the pre-crosslinked polyacrylate emulsion comprise a main monomer, a functional crosslinking monomer, an emulsifier, an initiator and water; the main monomer comprises one or more of methyl acrylate, methyl methacrylate, butyl acrylate and ethyl acrylate; the functional crosslinking monomer comprises one or more of ethylene glycol dimethacrylate, hydroxyethyl methacrylate, diallyl phthalate, trimethylolpropane triacrylate and acetoacetoxyethyl methacrylate; the emulsifier comprises one or more of sodium dodecyl sulfate, an ER-10 emulsifier, disodium hydrogen phosphate dodecahydrate and an OP-10 emulsifier; the initiator comprises one or more of ammonium persulfate, potassium persulfate, azobisisobutyronitrile and N, N-dimethylaniline.
7. The method for preparing a polymeric porous material according to any one of claims 1 to 6, wherein the low temperature field temperature is less than 0 ℃.
8. The method for preparing a polymeric porous material according to claim 1, wherein the drying in the step 2) is freeze-drying or room temperature drying.
9. The method for preparing a polymeric porous material according to any one of claims 1 to 8, further comprising: 3) further heat treating the porous material obtained in the step 2).
10. The method for preparing a polymeric porous material according to any one of claims 1 to 8, further comprising: 3) the living polymer emulsion was added to the freeze-dried sample and frozen again.
11. The polymer porous material prepared by the preparation method according to any one of claims 1 to 10.
12. Use of the polymeric porous material of claim 11 as thermal insulation, sound absorption or vibration damping material.
CN202210389483.3A 2021-04-15 2022-04-13 Polymer porous material and preparation method and application thereof Pending CN114835941A (en)

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CN111423615A (en) * 2020-05-13 2020-07-17 浙江大学杭州国际科创中心 Method for preparing polymer through hole material by emulsion freezing demulsification and application thereof

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JPS5147055A (en) * 1974-10-21 1976-04-22 Toray Industries Takoseihoriuretanno seiho
JP2571881B2 (en) * 1991-07-11 1997-01-16 リグナイト株式会社 Method for producing silicone porous body
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US5362761A (en) * 1991-07-11 1994-11-08 Lignyte Co., Ltd. Process for fabricating porous silicone product
CN105085773A (en) * 2015-08-14 2015-11-25 武汉理工大学 Polyacrylate polybasic copolymer with interpenetrating polymer network structure and preparation method thereof
CN111423615A (en) * 2020-05-13 2020-07-17 浙江大学杭州国际科创中心 Method for preparing polymer through hole material by emulsion freezing demulsification and application thereof

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