Polyvinyl alcohol-hollow microsphere composite aerogel as well as preparation method and application thereof

Abstract

The invention discloses polyvinyl alcohol-hollow microsphere composite aerogel as well as a preparation method and application thereof, and belongs to the technical field of high polymer material preparation. The aerohydrogel is prepared from the following raw materials in percentage by weight: 5 to 35 percent of polyvinyl alcohol, 1 to 70 percent of polymer hollow microspheres and the balance of water. The preparation method comprises the following steps: adding polymer hollow microspheres into a polyvinyl alcohol aqueous solution under a water bath condition, carrying out dispersion and defoaming treatment on a composite solution, and finally, carrying out freezing-unfreezing treatment to obtain the aerogel. By adjusting the content of the polyvinyl alcohol and the polymer hollow microspheres, the freezing treatment time and the number and time of bubbles, the wide-range adjustable density, heat-insulating property and mechanical property of the aerogel can be realized. The aerogel has the advantages of high elasticity, ultralow density, better heat insulation property, simple and non-toxic components, greenness and environmental protection, expands the application range of gel materials, and can be applied to the fields of children space mud toys, buffer materials, heat insulation materials, sound insulation materials, antibacterial materials and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and specifically relates to a polyvinyl alcohol-hollow microsphere composite aerogel and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Hydrogel has the advantages of high water content, good water retention, non-toxicity, good biodegradability and compatibility, and has great application value in the fields of flexible sensing, smart health, soft robots, etc.; aerogel has extremely high thermal insulation performance and low density due to its special hollow microporous structure. The new aerohydrogel material is expected to overcome the existing high-density disadvantage of hydrogel and realize the combination of the dual advantages of aerogel and hydrogel, providing a new matrix material for multiple fields such as buffer materials, aerospace materials, thermal insulation materials, and antibacterial materials. However, most gel materials currently have difficulty in taking into account the advantages of both. This is because the current existing gel preparation technology can only realize the independent preparation of hydrogel and aerogel, and it is difficult to construct an interpenetrating structure of gas phase hollow micropores and water phase gel, and it is even more difficult to control the content of the two (water phase and gas phase).

[0004] The research on traditional polyvinyl alcohol hydrogel composite fillers is committed to the advancement of mechanical properties, and has a large unit density, ignoring the research on its lightweight. However, its large unit mass has great limitations in application. For example, as a building thermal insulation material, it not only requires good strength but also a low unit mass to reduce the load. Therefore, it is urgent to develop a new type of aerogel hydrogel material that integrates the lightweight of aerogel into hydrogel with good mechanical properties.

[0005] A Chinese patent with application number 202211403578.2 discloses a porous double-network air hydrogel and its preparation and application. It uses a biomacromolecule grafted conductive polymer copolymer as a matrix material, introduces air bubbles and fixes the air bubbles through high-speed stirring to obtain a porous double-network air hydrogel. The introduced air bubbles reduce the refractive index of the incident light and increase the energy input for water evaporation. At the same time, air bubbles can reduce heat conduction, concentrate heat energy inside the double-network air hydrogel, and effectively reduce the heat energy loss of the double-network air hydrogel. The preparation process of this method is complicated, and air bubbles are introduced through high-speed stirring, and the content of the water phase and the gas phase is difficult to control.

[0006] The Chinese patent application number 202010333422.6 discloses a method for preparing a modified acrylic acid-based degradable hydrogel with high strength, which is a composite hydrogel obtained by mixing silica-modified olefinic chitosan, acrylic acid, acrylamide, an initiator, and a cross-linking agent. The composite hydrogel modified silica microspheres of the invention undergo chemical cross-linking with chitosan, which improves the tensile and compressive properties of the composite gel and gives it good mechanical properties. However, the preparation process of this method ignores the research on lightweighting, which limits its scope of application. In addition, the preparation process of this method is relatively complicated and the raw material mixing process is relatively cumbersome.

[0007] The Chinese patent application number 201910940977.4 discloses a method for preparing an organic-inorganic composite thermal insulation material, which is prepared by spraying an inorganic filler onto a release film, and then spraying a mixture of liquid phenolic resin, anhydrous ethanol, and low-density hollow microspheres onto the other side to obtain a composite gel. The composite gel of the invention is light and has good thermal insulation properties, but its strength is low, its mechanical properties are poor, and its preparation process is relatively complicated. Summary of the invention

[0008] In view of the problem that it is difficult to construct an aerogel that can control the content of the gas phase and the water phase with the traditional gel preparation technology, and it is difficult to integrate the lightweight of the aerogel into the hydrogel with good mechanical properties, the purpose of the present invention is to provide a polyvinyl alcohol-hollow microsphere composite aerogel and its preparation method and application. The present invention uses a composite process, polyvinyl alcohol hydrogel as the water phase, and a low-density polymer hollow microsphere as the gas phase. With the help of the very rich physical groups on the surfaces of the two, the interpenetrating distribution and strong interface construction of the two phases are achieved, and a new type of aerogel material that has the advantages of both aerogel and hydrogel and can regulate the structure of the two is developed. It has lightweight and excellent mechanical properties, which is of great significance to expand its application in the fields of children's space mud toys, cushioning materials, sound insulation materials, heat insulation materials, antibacterial materials, etc.

[0009] Specifically, the present invention provides the following technical features, and the combination of one or more of the following technical features constitutes the technical solution of the present invention.

[0010] The first aspect of the present invention provides a polyvinyl alcohol-hollow microsphere composite aerohydrogel, comprising polyvinyl alcohol hydrogel and polymer hollow microspheres, wherein the polymer hollow microspheres are dispersed in the polyvinyl alcohol hydrogel.

[0011] The polyvinyl alcohol-hollow microsphere composite aerohydrogel provided by the present invention has the dual advantages of aerogel and hydrogel, has unique advantages such as low density, high resilience, and thermal insulation, and has simple ingredients and is non-toxic. It can be applied to children's space mud toys, cushioning materials, thermal insulation materials, sound insulation materials, buoyancy materials and other fields.

[0012] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-35wt%, high molecular hollow microspheres 1-70wt%, and the balance is water.

[0013] In some embodiments of the present invention, in the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel, the amount of polyvinyl alcohol can be selected from the following ranges or any value in the following ranges: 6-35wt%, 8-35wt%, 10-35wt%, 15-35wt%, 18-35wt%, 20-35wt%, 25-35wt%, 30-35wt%, 5-30wt%, 5-20wt%, 10-30wt%, 10-20wt%, 10-15wt%, 10-17wt%, 13-18wt%, 10-16wt%, 15-16wt%, and the like.

[0014] In an embodiment of the present invention, in the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel, the amount of the polymer hollow microspheres can be selected from the following range or any value in the following range: 5-70wt%, 5-60wt%, 5-50wt%, 5-40wt%, 5-30wt%, 5-20wt%, 10-70wt%, 20-70wt%, 30-70wt%, 10-60wt%, 15-60wt%, 15-50wt%, 15-40wt%, 15-30wt%, 15-20wt%, 18-23wt%, 15-25wt%, and the like.

[0015] In some embodiments of the present invention, the polyvinyl alcohol-hollow microsphere composite aerohydrogel further comprises 5-15 wt % of an auxiliary agent; the auxiliary agent comprises one or more of a functional filler, a dye, a foaming agent and a moisturizing agent.

[0016] Preferably, the functional filler includes at least one of graphene, carbon nanotubes and MXene.

[0017] Preferably, the dye comprises at least one of Congo red, methyl orange, rhodamine B, methylene blue and crystal violet.

[0018] Preferably, the foaming agent includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate and sodium lauryl alcohol polyoxyethylene ether carboxylate.

[0019] Preferably, the humectant includes at least one of glycerin, propylene glycol, butylene glycol, polyethylene glycol and sorbitol.

[0020] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, high molecular hollow microspheres 1-50wt%, and the balance is water.

[0021] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 10-20wt%, high molecular hollow microsphere 1-50wt%, and the balance is water.

[0022] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-25wt%, and the balance is water.

[0023] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, high molecular hollow microspheres 1-20wt%, and the balance is water.

[0024] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, and the balance is water.

[0025] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: 15wt% polyvinyl alcohol, 20wt% polymer hollow microspheres, and the balance is water.

[0026] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, auxiliary agent 5-15wt%, and the balance is water.

[0027] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, functional filler 5-15wt%, and the balance is water.

[0028] In some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, MXene 5-15wt%, and the balance is water.

[0029] In some embodiments of the present invention, the number average molecular weight of the polyvinyl alcohol is 7000-200000, and the alcoholysis degree is 80-99.9%.

[0030] In some embodiments of the present invention, the particle size of the polymer hollow microspheres is 1-100 microns and the density is 5-100 kg / m 3 .

[0031] In some embodiments of the present invention, the polymer hollow microspheres are acrylic hollow microspheres or polyacrylic acid hollow microspheres. The polyvinyl alcohol hydrogel in the raw material and the surface of the polymer hollow microspheres have very rich physical groups, and the two produce a strong interface effect when compounded, so that the polymer hollow microspheres are more evenly dispersed in the hydrogel, and the interpenetrating distribution and strong interface construction of the two phases are achieved, so that the obtained aerohydrogel has light weight and excellent mechanical properties.

[0032] It should be noted that the acrylic hollow microspheres or polyacrylic acid hollow microspheres described in the present invention are conventional commercial products, which can be purchased or made at home. For example, they can be purchased from Shanghai Tuojia Printing Materials Co., Ltd., and their model is em30 wet powder.

[0033] In some embodiments of the present invention, the polyvinyl alcohol-hollow microsphere composite aerohydrogel further comprises one or more of a functional filler, a dye, a foaming agent and a moisturizing agent. The addition of additives such as a functional filler, a dye, a foaming agent and a moisturizing agent can give the polyvinyl alcohol-hollow microsphere composite aerohydrogel multifunctionality or aesthetics.

[0034] In some embodiments of the present invention, the functional filler includes but is not limited to graphene, carbon nanotubes or MXene. The functional filler is preferably MXene. In an embodiment of the present invention, the functional filler can give the polyvinyl alcohol-hollow microsphere composite aerohydrogel multiple functions after addition, such as conductivity, fluorescence, etc.

[0035] In some embodiments of the present invention, the dye includes but is not limited to Congo red, methyl orange, rhodamine B, methylene blue or crystal violet. In an embodiment of the present invention, the addition of the dye makes the polyvinyl alcohol-hollow microsphere composite aerohydrogel have an aesthetic appearance.

[0036] In some embodiments of the present invention, the foaming agent includes but is not limited to sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate or sodium lauryl alcohol polyoxyethylene ether carboxylate. In an embodiment of the present invention, the addition of the foaming agent makes the polyvinyl alcohol-hollow microsphere composite aerohydrogel more flexible, softer and easier to stretch.

[0037] In some embodiments of the present invention, the humectant includes but is not limited to glycerin, propylene glycol, butylene glycol, polyethylene glycol or sorbitol.

[0038] In a second aspect of the present invention, a method for preparing the above-mentioned polyvinyl alcohol-hollow microsphere composite aerohydrogel is provided, comprising the following steps:

[0039] mixing polyvinyl alcohol with water to obtain a polyvinyl alcohol aqueous solution;

[0040] Adding the polymer hollow microspheres into the polyvinyl alcohol aqueous solution and mixing to obtain a blended solution;

[0041] The blended solution is subjected to defoaming treatment and freezing-thawing treatment to obtain a polyvinyl alcohol-hollow microsphere composite aerohydrogel.

[0042] In some embodiments of the present invention, the method for preparing the polyvinyl alcohol aqueous solution is specifically: swelling polyvinyl alcohol in water, and then dissolving it at high temperature to obtain polyvinyl alcohol gel, that is, polyvinyl alcohol aqueous solution.

[0043] It should be noted that the high temperature is generally 90-95°C. After polyvinyl alcohol is dissolved in water, it swells. Under high temperature conditions, the molecular chain activity of polyvinyl alcohol itself is enhanced, the molecular gap is enlarged, and water molecules are easy to penetrate, which makes it easier to swell and dismember. Keep it under high temperature conditions for a period of time until it is completely dissolved, and then you can get a polyvinyl alcohol aqueous solution.

[0044] In some embodiments of the present invention, the polyvinyl alcohol includes but is not limited to polyvinyl alcohol 1799, polyvinyl alcohol 2099, polyvinyl alcohol 2299, polyvinyl alcohol 2499, polyvinyl alcohol 2699, and polyvinyl alcohol 1788.

[0045] In some embodiments of the present invention, the polyvinyl alcohol aqueous solution further includes one or more of a functional filler, a dye, a foaming agent and a moisturizing agent. The addition of additives such as functional fillers, dyes, foaming agents and moisturizing agents can give the polyvinyl alcohol-hollow microsphere composite aerogel multifunctionality or aesthetics. The functional filler includes but is not limited to graphene, carbon nanotubes or MXene; the dye includes but is not limited to Congo red, methyl orange, rhodamine B, methylene blue or crystal violet; the foaming agent includes but is not limited to sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate or sodium lauryl alcohol polyoxyethylene ether carboxylate; the moisturizing agent includes but is not limited to glycerol, propylene glycol, butylene glycol, polyethylene glycol or sorbitol.

[0046] In some embodiments of the present invention, the functional filler, dye, foaming agent, humectant and other additives may be added when the polyvinyl alcohol is mixed with water, or may be added when the polyvinyl alcohol is swollen and dissolved under high temperature conditions.

[0047] In some embodiments of the present invention, the preparation method comprises: heating the polyvinyl alcohol aqueous solution, adding the polymer hollow microspheres in batches while the polyvinyl alcohol aqueous solution has fluidity, and stirring the mixture evenly.

[0048] In some embodiments of the present invention, in order to achieve uniform dispersion of the polymer hollow microspheres in the solution, the polymer hollow microspheres are added in batches when the fluidity of the polyvinyl alcohol aqueous solution is strong.

[0049] In some embodiments of the present invention, the batch method refers to that when adding the polymer hollow microspheres to the polyvinyl alcohol aqueous solution, the polymer hollow microspheres to be added are divided into multiple portions (such as 5 portions, 10 portions or 15 portions, etc.), and each portion of the polymer hollow microspheres is added while stirring to make them evenly dispersed in the polyvinyl alcohol aqueous solution. The stirring time is 5-120 min, and can be specifically 5-100 min, 10-80 min, 15-70 min, 15-30 min, 5-10 min, 5-50 min, 25-30 min, 50-70 min, 30-90 min, 40-80 min, 45-85 min, and the like.

[0050] In some embodiments of the present invention, as the content of the polymer hollow microspheres in the blended solution increases, the polymer hollow microspheres added subsequently are not easy to be evenly dispersed in the solution, and external force can be used to fully disperse them.

[0051] It should be noted that when the content of the polymer hollow microspheres is so high that the solution cannot be stirred, it can be evenly dispersed by external force such as squeezing, kneading, folding, pinching, etc.

[0052] In some embodiments of the present invention, the defoaming treatment includes three steps: ultrasonic defoaming, puncture defoaming, and pressure filling defoaming;

[0053] The ultrasonic defoaming is specifically as follows: heating the blended solution and ultrasonicating it for 2-120 minutes under the condition that the blended solution has fluidity;

[0054] The puncture defoaming specifically comprises: puncturing bubbles in the blended solution after ultrasonic defoaming;

[0055] The pressure filling defoaming specifically includes: applying pressure to the blended solution after puncture defoaming to eliminate bubbles.

[0056] It should be noted that the purpose of the defoaming treatment is to eliminate the large bubbles introduced during the stirring process. The presence of large bubbles affects the performance of the obtained polyvinyl alcohol-hollow microsphere composite aerohydrogel, such as reducing its mechanical properties, reducing its flexural strength, affecting its strain resilience, and causing the polyvinyl alcohol-hollow microsphere composite aerohydrogel to break easily. After the defoaming treatment, the large bubbles generated during the stirring process are fully eliminated, and the polymer hollow microspheres are evenly dispersed in the polyvinyl alcohol-hollow microsphere composite aerohydrogel, ensuring that the polyvinyl alcohol-hollow microsphere composite aerohydrogel has light weight and excellent mechanical properties.

[0057] In some embodiments of the present invention, the defoaming treatment is as follows: subjecting the fluid blended solution to ultrasound to eliminate bubbles, the ultrasound is performed for 2-120 minutes to complete the first step of defoaming; after the ultrasound is completed, the fluid blended solution is introduced into the mold, and the bubbles inside and on the surface of the blended solution are punctured by a puncture method to complete the second step of defoaming; the blended solution after puncture and defoaming is repeatedly pressurized to fully fill the mold to complete the third step of defoaming.

[0058] In some embodiments of the present invention, the blended solution after defoaming treatment is cooled to 0-40°C before freeze-thawing treatment. The blended solution after defoaming treatment can be placed at 0-40°C for 1-12 hours to achieve cooling. After defoaming treatment, the temperature of the solution is still at a relatively high level. If it is placed in a -20°C environment for a short time, a large temperature difference may cause the microspheres to rupture, causing the gas inside the microspheres to be released, thereby generating new bubbles. In order to ensure the excellent performance of the polyvinyl alcohol-hollow microsphere composite aerohydrogel, freeze-thawing treatment is performed after cooling.

[0059] In some embodiments of the present invention, the freeze-thaw treatment is specifically: freezing at a temperature of -80 to 10°C for 1 to 48 hours, and then thawing at a temperature of 10 to 90°C for 1 to 48 hours.

[0060] In an embodiment of the present invention, the freeze-thaw treatment is specifically: freezing at a temperature of -30 to -10°C for 6 to 20 hours, and then thawing at a temperature of 20 to 40°C for 1 to 12 hours.

[0061] In some embodiments of the present invention, the freeze-thaw process has a repetition number of at least 2, preferably 2-3 times. In the present invention, the term repetition number refers to the number of additional executions in addition to the initial execution. For example, if the freeze-thaw process has a "repetition number of 2", then the freeze-thaw process is performed 3 times, that is, the number of cycles is 3.

[0062] In the third aspect of the present invention, there is provided the use of the above-mentioned polyvinyl alcohol-hollow microsphere composite aerohydrogel or the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared by the above-mentioned preparation method as a toy material, a cushioning material, a heat insulation material, a sound insulation material, an antibacterial material and / or a buoyancy material.

[0063] In some embodiments of the present invention, the toy is a space clay toy.

[0064] The beneficial effects of the present invention are:

[0065] (1) The present invention discloses a polyvinyl alcohol-hollow microsphere composite aerohydrogel, the raw materials of which are polyvinyl alcohol, polymer hollow microspheres and water, the raw materials do not involve any toxic cross-linking agent, and the preparation process is simple and efficient. The mechanical characteristics of the polyvinyl alcohol-hollow microsphere composite aerohydrogel provided by the present invention show high elasticity, ultra-low density and good thermal insulation, and also have antibacterial properties. At the same time, by adjusting the content of polyvinyl alcohol and polyacrylic acid hollow microspheres, freezing treatment time, bubble number and time, the aerohydrogel can achieve a wide range of adjustable density, thermal insulation and mechanical properties.

[0066] (2) The present invention composites polyvinyl alcohol hydrogel with polymer hollow microspheres. The surfaces of polyvinyl alcohol hydrogel and polyacrylic acid hollow microspheres (or acrylic hollow microspheres) have a large number of physical groups, which produce a strong interface effect when composited, making the hollow microspheres more evenly dispersed in the hydrogel.

[0067] (3) The polyvinyl alcohol-hollow microsphere composite aerogel disclosed in the present invention has simple ingredients, is non-toxic, and is green and environmentally friendly, which expands its application in different fields. For example, it can be applied to children's space mud toys, cushioning materials, heat insulation materials, sound insulation materials, antibacterial materials and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0069] Figure 1 The diagram shows the aerohydrogels obtained in Examples 1, 3 and Comparative Example 1 of the present invention placed in water, wherein the aerohydrogels obtained in Examples 1 and 3 float on the water surface, while the hydrogel obtained in Comparative Example 1 sinks into the water;

[0070] Figure 2 is the density of the aerogel obtained in Examples 1 and 3 of the present invention and Comparative Example 1. The density of the aerogel prepared in the present invention is lower than that of the traditional hydrogel. Compared with the traditional hydrogel prepared in Comparative Example 1 which sinks to the bottom of the water, it can float on the water surface;

[0071] Figure 3The elastic recovery rate of the aerogel obtained in Examples 1 and 3 of the present invention and Comparative Example 1; the aerogel prepared in the present invention has better elasticity, and the deformation rate of the aerogel is smaller after 90% strain compression;

[0072] Figure 4 The infrared thermal images of the aero-hydrogels obtained in Examples 1 and 3 of the present invention and Comparative Example 1 are shown; the aero-hydrogels prepared in the present invention have excellent thermal insulation properties and have significant thermal insulation effects in an environment of 100°C;

[0073] Figure 5 The structures of the aerogels obtained from the hollow microspheres (A), comparative example 1 (B), and example 1 (C) show that the hollow microspheres are evenly distributed in the gel;

[0074] Figure 6 The antibacterial performance of the novel aero-hydrogel samples obtained in Example 1 (A) and Comparative Example 1 (B) of the present invention after being placed for 120 days is shown; the aero-hydrogel obtained in Example 1 shows little change after being placed for 120 days, while the traditional hydrogel prepared in Comparative Example 1 grows hair and deteriorates significantly. DETAILED DESCRIPTION

[0075] The present application is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0076] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in this application can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in this application are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar to or equivalent to the content described herein can be applied to the method of this application. The preferred implementation methods and materials described in the text are for demonstration purposes only.

[0077] The present invention provides a polyvinyl alcohol-hollow microsphere composite aerohydrogel, comprising polyvinyl alcohol hydrogel and polymer hollow microspheres, wherein the polymer hollow microspheres are dispersed in the polyvinyl alcohol hydrogel;

[0078] The raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-35wt%, high molecular hollow microsphere 1-70wt%, and the balance is water;

[0079] The number average molecular weight of the polyvinyl alcohol is 7000-200000, and the alcoholysis degree is 80-99.9%;

[0080] The particle size of the polymer hollow microspheres is 1-100 microns and the density is 5-100 kg / m3 ; The polymer hollow microspheres are acrylic hollow microspheres or polyacrylic acid hollow microspheres.

[0081] For example, in some embodiments of the present invention, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microsphere 1-50wt%, and the balance is water. Or further, its composition is: polyvinyl alcohol 5-20wt%, polymer hollow microsphere 1-20wt%, and the balance is water. Or further, its composition is: polyvinyl alcohol 5-20wt%, polymer hollow microsphere 10-20wt%, and the balance is water. Or further, its composition is: polyvinyl alcohol 15wt%, polymer hollow microsphere 20wt%, and the balance is water.

[0082] For example, in some embodiments of the present invention, the raw materials of the polyvinyl alcohol-hollow microsphere composite aerogel also include 5-15wt% of auxiliary agents; the auxiliary agents include one or more of functional fillers, dyes, foaming agents and moisturizers. Preferably, the functional filler includes at least one of graphene, carbon nanotubes and MXene; preferably, the dye includes at least one of Congo red, methyl orange, rhodamine B, methylene blue and crystal violet; preferably, the foaming agent includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate and sodium lauryl polyoxyethylene ether carboxylate; preferably, the moisturizer includes at least one of glycerol, propylene glycol, butylene glycol, polyethylene glycol and sorbitol. Further, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerogel is: the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, functional filler 5-15wt%, and the balance is water. Furthermore, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, MXene 5-15wt%, and the balance is water.

[0083] The present invention also provides a method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel, comprising the following steps:

[0084] mixing polyvinyl alcohol with water to obtain a polyvinyl alcohol aqueous solution;

[0085] Adding the polymer hollow microspheres into the polyvinyl alcohol aqueous solution and mixing to obtain a blended solution;

[0086] The blended solution is subjected to a defoaming treatment and a freeze-thaw treatment to obtain a polyvinyl alcohol-hollow microsphere composite aerohydrogel;

[0087] The polyvinyl alcohol aqueous solution is heated, and the polymer hollow microspheres are added in small amounts in batches while the solution is fluid, and stirred evenly;

[0088] The defoaming treatment includes three steps: ultrasonic defoaming, puncture defoaming and pressure filling defoaming; wherein the ultrasonic defoaming is specifically: heating the blended solution and ultrasonicating it for 2-120 minutes under the condition that it has fluidity; the puncture defoaming is specifically: puncturing the bubbles in the blended solution after ultrasonic defoaming; the pressure filling defoaming is specifically: applying pressure to the blended solution after puncture defoaming to eliminate bubbles;

[0089] The blended solution after defoaming treatment is cooled to 0-40°C and then subjected to freeze-thaw treatment;

[0090] The freeze-thaw treatment is specifically: freezing at a temperature of -80 to 10°C for 1 to 48 hours, and then thawing at a temperature of 10 to 90°C for 1 to 48 hours;

[0091] The freeze-thaw process is repeated at least 2 times, preferably 2-3 times.

[0092] For example, in some embodiments of the present invention, the polyvinyl alcohol aqueous solution further includes one or more of a functional filler, a dye, a foaming agent and a moisturizing agent. The addition of additives such as functional fillers, dyes, foaming agents and moisturizing agents can give the polyvinyl alcohol-hollow microsphere composite aerogel multifunctionality or aesthetics. The functional filler includes but is not limited to graphene, carbon nanotubes or MXene; the dye includes but is not limited to Congo red, methyl orange, rhodamine B, methylene blue or crystal violet; the foaming agent includes but is not limited to sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate or sodium lauryl alcohol polyoxyethylene ether carboxylate; the moisturizing agent includes but is not limited to glycerol, propylene glycol, butylene glycol, polyethylene glycol or sorbitol.

[0093] The polyvinyl alcohol-hollow microsphere composite aerogel prepared by the present invention has high elasticity, ultra-low density and high thermal insulation performance, and the composition is simple, non-toxic, green and environmentally friendly, which can expand the application of gel materials in different fields, for example, it can be applied to children's space mud toys, cushioning materials, thermal insulation materials, sound insulation materials, antibacterial materials and other fields.

[0094] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail in conjunction with specific embodiments. Unless otherwise specified, the polyvinyl alcohol (1750±50) used in the following embodiments has a degree of alcoholysis of 99%; the type of polymer microspheres used is polyacrylic acid hollow microspheres (Shanghai Tuojia Printing Materials Co., Ltd., em30 wet powder), with an average particle size of 35 microns and a density of 35±4 kg / m 3 .

[0095] Example 1

[0096] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel comprises the following steps:

[0097] Add polyvinyl alcohol to deionized water to prepare a polyvinyl alcohol aqueous solution, stir at high temperature, add hollow microspheres in batches and mix evenly to obtain a blended solution. The composition is as follows: by weight, 10% hollow microspheres, polyvinyl alcohol (M w =70000) 15%, deionized water 75%.

[0098] Under high temperature and fluidity conditions, the blended solution is ultrasonicated for 30 minutes to complete the first step of defoaming. After the ultrasonic blended solution is introduced into the mold, the new bubbles generated during stirring are punctured using the puncture method to complete the second step of defoaming. After filling the mold, repeated pressure (about 750N) is applied to fill and complete the third step of defoaming. The blended solution after the three steps of defoaming is placed at 25°C for cooling and cooling for 25 minutes.

[0099] The cooled blended solution was frozen in an environment at a temperature of -20°C for 12 hours, and then thawed in an environment at 25°C for 12 hours. The number of repetitions of the freeze-thaw process was 2.

[0100] Example 2

[0101] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel, which is different from Example 1 in that the composition is: 10% by weight of hollow microspheres, polyvinyl alcohol (M w =70000) 20%, deionized water 70%. The remaining steps are consistent with those of Example 1.

[0102] Example 3

[0103] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel, which is different from Example 1 in that the composition is: 20% by weight of hollow microspheres, polyvinyl alcohol (M w =70000) 15%, deionized water 65%. The remaining steps are consistent with those of Example 1.

[0104] Example 4

[0105] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from Example 1 in that only the second and third steps of defoaming are performed. The remaining steps are consistent with those of Example 1.

[0106] Example 5

[0107] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from Example 1 in that only the first defoaming step and the third defoaming step are performed. The remaining steps are consistent with those of Example 1.

[0108] Example 6

[0109] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from Example 1 in that only the first defoaming step and the second defoaming step are performed. The remaining steps are consistent with those of Example 1.

[0110] Example 7

[0111] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from that of Example 1 in that the cooled blended solution is frozen in an environment at a temperature of -20°C for 6 hours and then thawed in an environment at 25°C for 6 hours. The remaining steps are consistent with those of Example 1.

[0112] Example 8

[0113] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from that of Example 1 in that after the defoaming treatment is completed, the defoaming process is not cooled, but directly subjected to a freeze-thaw process. The remaining steps are the same as those of Example 1.

[0114] Example 9

[0115] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel comprises the following steps:

[0116] The composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is as follows: by weight, 10% hollow microsphere, polyvinyl alcohol (M w =70000) 15%, anhydrous calcium chloride 10%, deionized water 65%.

[0117] Polyvinyl alcohol, anhydrous calcium chloride and deionized water are mixed to prepare a solution, stirred at high temperature, and hollow microspheres are added and mixed evenly.

[0118] Under high temperature and fluidity conditions, the blended solution is ultrasonicated for 30 minutes to complete the first step of defoaming. After the ultrasonic blended solution is introduced into the mold, the new bubbles generated during stirring are punctured using the puncture method to complete the second step of defoaming. After filling the mold, repeated pressure (about 750N) is applied to fill and complete the third step of defoaming. The blended solution after the three steps of defoaming is placed at 25°C for cooling and cooling for 30 minutes.

[0119] The cooled blended solution was frozen in an environment at a temperature of -20°C for 12 hours, and then thawed in an environment at 25°C for 12 hours. The number of repetitions of the freeze-thaw process was 2.

[0120] Example 10

[0121] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerohydrogel is different from Example 1 in that: 5 wt% MXene is added when the gel is dissolved under high temperature stirring, and the hollow microspheres are mixed uniformly. The remaining steps are consistent with Example 1.

[0122] The polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in the above embodiment was tested. The density, elastic recovery rate at 90% strain and internal temperature of the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in Examples 1 to 10 are shown in Table 1. As shown in Table 1, the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in the present invention has high elasticity, low density and good thermal insulation performance. And these polyvinyl alcohol-hollow microsphere composite aerohydrogels were placed in the air for 120 days, and the changes were small, and there was no hair growth and deterioration, showing good stability and antibacterial properties.

[0123] Table 1 Performance test statistics of Examples 1-10

[0124]

[0125]

[0126] in, Figure 1 and Figure 2 The density of the materials obtained in Examples 1, 3 and Comparative Example 1 is shown. The polyvinyl alcohol hydrogel prepared in Comparative Example 1 sinks in water and has a large density. The density of the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in Examples 1 and 3 is significantly lower than that of the gel material prepared in Comparative Example 1, and can float on the water surface. As the content of the polymer hollow microspheres increases, the density of the obtained polyvinyl alcohol-hollow microsphere composite aerohydrogel gradually decreases, and the addition of the polymer hollow microspheres makes the polyvinyl alcohol-hollow microsphere composite aerohydrogel lighter.

[0127] Figure 3 The elastic recovery rates of the materials obtained in Examples 1, 3 and Comparative Example 1 are shown. As can be seen from the figure, the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in the embodiment of the present invention has better elasticity, and the deformation rate is small after 90% strain compression, and the elastic recovery rate increases with the increase of the content of the polymer hollow microspheres. This shows that the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in the present invention has high elasticity.

[0128] Figure 4Infrared thermal imaging images of the materials obtained in Examples 1 and 3 and Comparative Example 1 are shown. The ambient temperature is 100°C, and the thermal insulation of the gel material obtained in Comparative Document 1 is lower than that of the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in Examples 1 and 3 of the present invention. And with the increase of the content of polymer hollow microspheres, the thermal insulation of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is also significantly improved. The polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared by the present invention has excellent thermal insulation, and the thermal insulation effect is significant in an environment of 100°C.

[0129] Figure 5 The structures of the hollow microspheres (A), comparative example 1 (B) and the materials obtained in example 1 (C) are shown, and it can be seen that the hollow microspheres are uniformly distributed in the polyvinyl alcohol-hollow microsphere composite aerohydrogel.

[0130] Figure 6 The antibacterial performance of the samples of the materials obtained in Example 1 (A) and Comparative Example 1 (B) after being placed at room temperature for 120 days is shown. As can be seen from the figure, the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in Example 1 has little change after being placed for 120 days, while the traditional hydrogel prepared in Comparative Example 1 has obvious hair growth and deterioration. This shows that the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared in the embodiment of the present invention has high stability and antibacterial properties.

[0131] Comparative Example 1

[0132] A method for preparing a polyvinyl alcohol hydrogel comprises the following steps:

[0133] Prepare a solution of 15% polyvinyl alcohol (Mw=70000) and 85% deionized water, stir at high temperature, mix evenly, and put into a mold. Freeze the resulting solution in an environment at a temperature of -20°C for 12 hours, and then thaw it in an environment at 25°C for 12 hours. The number of repetitions of the freeze-thaw process is 2.

[0134] Comparative Example 2

[0135] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerogel, which is different from Example 1 in that: its components are: weight percentage, polyvinyl alcohol (M w =70000) 10%, hollow microspheres 20%, deionized water 70%. No defoaming treatment was performed during the preparation process. The remaining steps were consistent with those of Example 1.

[0136] The density of the polyvinyl alcohol-hollow microsphere composite aerogel obtained in this comparative example 2 is 0.25 g / cm 3 , the elastic recovery rate under 90% strain is 60%, and its internal temperature is 44.7℃ under 100℃ environment.

[0137] Comparative Example 3

[0138] A method for preparing a polyvinyl alcohol-hollow microsphere composite aerogel, which is different from Example 1 in that: its components are: weight percentage, polyvinyl alcohol (M w =70000) 10%, hollow microspheres 20%, deionized water 70%. No freezing-thawing treatment was performed during the preparation process. After cooling, the obtained solution was placed at room temperature. The remaining steps were consistent with those of Example 1.

[0139] The density of the polyvinyl alcohol-hollow microsphere composite aerogel obtained in this comparative example 3 is 0.17 g / cm 3 , the elastic recovery rate under 90% strain is 0%, and its internal temperature is 30°C in a 100°C environment.

[0140] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polyvinyl alcohol-hollow microsphere composite aerohydrogel, characterized in that: The invention comprises polyvinyl alcohol hydrogel and macromolecular hollow microspheres, wherein the macromolecular hollow microspheres are dispersed in the polyvinyl alcohol hydrogel.

2. The polyvinyl alcohol-hollow microsphere composite aerohydrogel according to claim 1, characterized in that: The raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-35wt%, high molecular hollow microsphere 1-70wt%, and the balance is water; Preferably, the polyvinyl alcohol-hollow microsphere composite aerogel further comprises 5-15wt% of an auxiliary agent; the auxiliary agent comprises one or more of a functional filler, a dye, a foaming agent and a moisturizing agent; Preferably, the functional filler comprises at least one of graphene, carbon nanotubes and MXene; Preferably, the dye comprises at least one of Congo red, methyl orange, rhodamine B, methylene blue and crystal violet; Preferably, the foaming agent includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate and sodium lauryl alcohol polyoxyethylene ether carboxylate; Preferably, the humectant includes at least one of glycerin, propylene glycol, butylene glycol, polyethylene glycol and sorbitol.

3. The polyvinyl alcohol-hollow microsphere composite aerohydrogel according to claim 2, characterized in that: The raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, high molecular hollow microsphere 1-50wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microsphere 1-20wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 15wt%, polymer hollow microsphere 20wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, auxiliary agent 5-15wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, functional filler 5-15wt%, and the balance is water; Preferably, the raw material composition of the polyvinyl alcohol-hollow microsphere composite aerohydrogel is: polyvinyl alcohol 5-20wt%, polymer hollow microspheres 10-20wt%, MXene 5-15wt%, and the balance is water.

4. The polyvinyl alcohol-hollow microsphere composite aerohydrogel according to claim 1, characterized in that: The number average molecular weight of the polyvinyl alcohol is 7000-200000, and the alcoholysis degree is 80-99.9%; Preferably, the particle size of the polymer hollow microspheres is 1-100 microns and the density is 5-100 kg / m 3 ; Preferably, the polymer hollow microspheres are acrylic hollow microspheres or polyacrylic acid hollow microspheres.

5. A method for preparing the polyvinyl alcohol-hollow microsphere composite aerohydrogel according to any one of claims 1 to 4, characterized in that: The steps include: mixing polyvinyl alcohol with water to obtain a polyvinyl alcohol aqueous solution; Adding the polymer hollow microspheres into the polyvinyl alcohol aqueous solution and mixing to obtain a blended solution; The blended solution is subjected to defoaming treatment and freezing-thawing treatment to obtain a polyvinyl alcohol-hollow microsphere composite aerohydrogel.

6. The preparation method according to claim 5, characterized in that: The polyvinyl alcohol aqueous solution further comprises one or more of a functional filler, a dye, a foaming agent and a moisturizing agent; Preferably, the functional filler comprises graphene, carbon nanotubes or MXene; Preferably, the dye comprises Congo red, methyl orange, rhodamine B, methylene blue or crystal violet; Preferably, the foaming agent includes sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, triethanolamine lauryl sulfate or sodium lauryl alcohol polyoxyethylene ether carboxylate; Preferably, the humectant comprises glycerin, propylene glycol, butylene glycol, polyethylene glycol or sorbitol.

7. The preparation method according to claim 5, characterized in that: The preparation method comprises: Heat the polyvinyl alcohol aqueous solution, add the polymer hollow microspheres in batches while the solution has fluidity, and stir evenly.

8. The preparation method according to claim 5, characterized in that: The defoaming treatment includes three steps: ultrasonic defoaming, puncture defoaming and pressure filling defoaming; The ultrasonic defoaming is specifically as follows: heating the blended solution and ultrasonicating it for 2-120 minutes under the condition that the blended solution has fluidity; The puncture defoaming specifically comprises: puncturing bubbles in the blended solution after ultrasonic defoaming; The pressure filling defoaming specifically includes: applying pressure to the blended solution after puncture defoaming to eliminate bubbles.

9. The preparation method according to claim 5, characterized in that: The blended solution after defoaming treatment is cooled to 0-40°C and then subjected to freeze-thaw treatment; Preferably, the freeze-thaw treatment is specifically: freezing at a temperature of -80 to 10°C for 1 to 48 hours, and then thawing at a temperature of 10 to 90°C for 1 to 48 hours; Further preferably, the freeze-thaw treatment is specifically: freezing at a temperature of -30 to -10°C for 6 to 20 hours, and then thawing at a temperature of 20 to 40°C for 1 to 12 hours; Preferably, the freeze-thaw process is repeated at least 2 times, preferably 2-3 times.

10. Use of the polyvinyl alcohol-hollow microsphere composite aerohydrogel according to any one of claims 1 to 4 or the polyvinyl alcohol-hollow microsphere composite aerohydrogel prepared by the preparation method according to any one of claims 5 to 9 as a toy material, a cushioning material, a heat insulation material, a sound insulation material, an antibacterial material and / or a buoyancy material; Preferably, the toy is a space mud toy.

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