A highly absorbent polymer hollow microsphere and its concrete moisturizing curing film

Abstract

The present invention relates to highly water-absorbent hollow polymer microspheres and their concrete moisturizing and curing membranes. The hollow polymer microspheres are formed by photoinitiated Pickering emulsion polymerization. The Pickering emulsion comprises an emulsifier, water, and an oil phase. The emulsifier is a photopolymerizable amphiphilic copolymer particle, and the oil phase comprises a photocurable monomer and a photoinitiator. Under light, the photopolymerizable amphiphilic copolymer particle and the photocurable monomer undergo separate polymerization reactions to form hollow polymer microspheres having a hydrophilic shell. The shell's strong hydrophilicity allows for rapid absorption of large amounts of water and storage in its internal cavity. Compared to conventional water-absorbent resins, the cavity structure within the hollow polymer microspheres of the present invention significantly increases water storage capacity. The concrete moisturizing and curing membrane prepared using the hollow polymer microspheres of the present invention has extremely strong water retention. The internally absorbed water can be released into the concrete through capillary action on the rough surface of the base fabric layer, ensuring the required moisture for the concrete during its curing period.

Description

Technical Field

[0001] The invention belongs to the technical field of functional polymer materials, and particularly relates to highly water-absorbent hollow polymer microspheres and a concrete moisturizing curing film thereof. Background Art

[0002] Concrete curing is crucial in highway construction. Traditional methods typically employ curing agents, films, wet tarpaulins, and spraying. These methods not only consume significant water and human resources, but also, due to the limitations of traditional water-retaining coverings or curing agents, can result in uneven pavement dryness and shrinkage, ultimately impacting the quality of concrete construction and leading to lower concrete quality. This can lead to safety hazards, high maintenance costs, and short maintenance cycles. Therefore, developing new, efficient, and environmentally friendly concrete curing materials to improve curing quality and reduce costs is crucial for ensuring the safety and long-term effectiveness of transportation projects.

[0003] Some patents have developed some curing membranes using high-absorbent resin materials. During the concrete curing period, watering is only required once when the membrane is laid. The water consumption is about one twentieth of the traditional method, which greatly saves water resources and significantly reduces costs. For example, Chinese patent CN201677393U discloses a composite concrete water-saving and moisturizing curing membrane, which is composed of a single-layer impermeable membrane, a controllable polymer water-absorbing material layer and a hollow plastic film in sequence. This composite curing membrane has a large water absorption capacity, a long water-retention time, a good curing effect, and is easy to construct. Chinese patent CN201784030U discloses a grafted modified concrete water-saving and moisturizing curing membrane, which is composed of a single-layer impermeable membrane layer and a grafted modified fiber cloth layer with high water absorption and water retention properties. The two layers are bonded by an adhesive or hot pressed to form an integral structure. The grafted modified fiber cloth used is chemically grafted to become a highly water-absorbing and water-retaining material. Chinese patent CN105965679B discloses a concrete curing membrane production process and production equipment, in which a covering layer with super water absorption and water retention properties is coated on a plastic film. The covering layer includes a super polymer water-absorbing material and an adhesive. The super polymer water-absorbing material is selected from one or more copolymer powders selected from starch, methyl methacrylate, kaolin, cellulose, ammonium bicarbonate, acrylonitrile, acrylamide, and acrylic acid.

[0004] Compared to traditional curing methods, these curing films are economical and practical, with excellent water conservation and water retention. However, the highly absorbent resins used are primarily hydrophilic polymer materials with a certain degree of crosslinking, formed by polymerizing hydrophilic monomers. While these polymers have a certain water absorption rate, their water absorption is limited by their own crosslinking, resulting in significant limitations on their maximum water absorption rate and water retention. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a water-absorbing polymer hollow microsphere with better water absorption and water retention, which has higher water absorption and longer water retention time when used on the curing membrane, in order to solve the problem that the existing concrete moisturizing curing membrane using super absorbent resin has poor water absorption and water retention.

[0006] The second object of the present invention is to provide a concrete moisturizing curing membrane with better water absorption and water retention.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A polymer hollow microsphere is prepared by photoinitiated Pickering emulsion polymerization, wherein the Pickering emulsion comprises an emulsifier, water and an oil phase, the emulsifier is a photopolymerizable amphiphilic copolymer particle, and the oil phase comprises a photocurable monomer and a photoinitiator.

[0009] In the present invention, the Pickering emulsion is also referred to as Pickering emulsion.

[0010] According to some embodiments of the present invention, the photopolymerizable amphiphilic copolymer particles are obtained by polymerization of a hydrophilic monomer, a hydrophobic photosensitive monomer and a crosslinking agent via an initiator, wherein the hydrophobic photosensitive monomer is 7-(4-vinylbenzyloxy)-4-methylcoumarin.

[0011] In the present invention, if the hydrophilic monomer is added too much, the prepared photopolymerizable amphiphilic copolymer particles are prone to hydrophilic swelling, making the structure loose and more hydrophilic. However, this will also lead to a decrease in the stability of the subsequent Pickering emulsion, difficulty in forming the polymer hollow microspheres, and easy rupture. If the hydrophilic monomer is added too little, the prepared photopolymerizable amphiphilic copolymer particles become more hydrophobic, resulting in poor emulsification effect, difficulty in forming a stable oil-in-water emulsion, and even failure to emulsify. Therefore, the ratio of hydrophilic monomer to hydrophobic photosensitive monomer needs to be controlled within a certain range. Preferably, the molar ratio of the hydrophilic monomer to the hydrophobic photosensitive monomer is 1 to 5:1.

[0012] Furthermore, the hydrophilic monomer is one or a combination of acrylamide, N-isopropylacrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, and methacrylic acid.

[0013] Furthermore, the cross-linking agent is N,N'-methylenebisacrylamide, and the molar amount of the cross-linking agent is 3-4% of the total molar amount of the hydrophilic monomer and the hydrophobic photosensitive monomer.

[0014] Furthermore, the initiator is a combination of one or more of ammonium persulfate, sodium persulfate, and potassium persulfate, and the molar amount of the initiator is 0.5-1.5% of the total molar amount of the hydrophilic monomer and the hydrophobic photosensitive monomer.

[0015] Furthermore, the hydrophobic photosensitive monomer is obtained by reacting 7-hydroxy-4-methylcoumarin and p-chloromethylenestyrene.

[0016] According to some embodiments of the present invention, the particle size of the photopolymerizable amphiphilic copolymer particles is 100 to 600 nm.

[0017] According to some embodiments of the present invention, the method for preparing the photopolymerizable amphiphilic copolymer particles includes adding a hydrophilic monomer, a hydrophobic photosensitive monomer, a crosslinker, an initiator and water into a reactor, and reacting at 60 to 80° C. under the protection of an inert gas to obtain a reaction solution containing the photopolymerizable amphiphilic copolymer particles.

[0018] Furthermore, the method for preparing the photopolymerizable amphiphilic copolymer particles further comprises the steps of centrifuging, washing, and drying the reaction solution containing the photopolymerizable amphiphilic copolymer particles to obtain the photopolymerizable amphiphilic copolymer particles.

[0019] According to some embodiments of the present invention, the oil phase further comprises an organic solvent. Preferably, the mass ratio of the photocurable monomer to the organic solvent is 10-100:0-35.

[0020] Furthermore, the organic solvent is a combination of one or more of toluene, xylene, dichloromethane, cyclohexane, cyclopentane, ethyl acetate, tung oil, and linseed oil.

[0021] According to some implementation aspects of the present invention, the mass ratio of the photocurable monomer to the photoinitiator is 10-100:0.2-3.

[0022] According to some embodiments of the present invention, the photocurable monomer is a combination of one or more of dimethylaminoethyl methacrylate, glycidyl methacrylate, methyl methacrylate, 1,6-hexanediol diacrylate, methacrylic acid, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, lauryl acrylate, butyl acrylate, isobornyl acrylate, ethoxylated 1,6-hexanediol diacrylate, and divinylbenzene, and 7-(4-vinylbenzyloxy)-4-methylcoumarin, and the mass ratio of the 7-(4-vinylbenzyloxy)-4-methylcoumarin to the photocurable monomer is 1 to 5:100.

[0023] An appropriate amount of 7-(4-vinylbenzyloxy)-4-methylcoumarin is added to the photocurable monomer. During the photocuring process, the 7-(4-vinylbenzyloxy)-4-methylcoumarin can also undergo a photocuring reaction with the photopolymerizable amphiphilic copolymer particles, so that the photopolymerizable amphiphilic copolymer particles can be more firmly embedded in the shell layer.

[0024] According to some embodiments of the present invention, the photoinitiator is a combination of one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, methyl benzoylformate, 2,4-diethylthiazolone, and 2-isopropylthioxanthone.

[0025] According to some embodiments of the present invention, the method for preparing the Pickering emulsion includes ultrasonically dispersing an emulsifier and water to form an aqueous phase, and then mixing the aqueous phase with an oil phase and homogenizing and emulsifying to obtain the oil-in-water type Pickering emulsion.

[0026] Furthermore, the concentration of the emulsifier in the water phase is 15 to 30 g / L, the mass ratio of the oil phase to the water phase is 1 to 3:1, and the rotation speed used for the homogenization emulsification is 5000 to 20000 rpm.

[0027] In some specific embodiments, the particle size of the polymer hollow microspheres is 10-60 μm and the wall thickness is 0.7-3 μm. The size of the polymer hollow microspheres can be controlled by changing the concentration of the photopolymerizable amphiphilic copolymer particles, the oil-water ratio and the emulsification speed.

[0028] The second technical solution adopted by the present invention is: the preparation method of the above-mentioned hollow polymer microspheres comprises the following steps:

[0029] (1) Preparation of photopolymerizable amphiphilic copolymer particles

[0030] Adding a hydrophilic monomer, a hydrophobic photosensitive monomer, a crosslinking agent, an initiator and water into a reactor, reacting at 60-80° C. under the protection of an inert gas to obtain the photopolymerizable amphiphilic copolymer particles;

[0031] (2) Preparation of polymer hollow microspheres

[0032] The photopolymerizable amphiphilic copolymer particles are dispersed in water to form an aqueous phase, the aqueous phase is mixed with an oil phase, and homogenized to form an oil-in-water Pickering emulsion. The oil-in-water Pickering emulsion is then irradiated with UV light to form the polymer hollow microspheres.

[0033] Furthermore, in step (1), the hydrophobic photosensitive monomer is dissolved and dispersed in water by precipitation polymerization, and then the crosslinking agent and initiator are added. The mixture is sealed and stirred under nitrogen protection for 6 to 10 hours, and the reaction temperature is controlled to be 60 to 80° C. and the stirring speed is 1000 to 1500 rpm. After the reaction is completed, the precipitate is obtained by centrifugation, and the precipitate is washed with water multiple times and dried to obtain the photopolymerizable amphiphilic copolymer particle powder.

[0034] Furthermore, in step (2), the homogenization and emulsification is carried out using a high-speed homogenizer, the stirring speed of the homogenization and emulsification is 5000 to 20000 rpm, and the emulsification time is 1 to 5 minutes.

[0035] Furthermore, in step (2), the UV irradiation time is 15 to 30 minutes. After the UV irradiation is completed, the system is washed with deionized water and ethanol separately and sequentially, and centrifuged to obtain the polymer hollow microspheres.

[0036] The third technical solution adopted by the present invention is: a concrete moisturizing curing membrane, comprising a base fabric layer and a plastic film layer, the concrete moisturizing curing membrane also comprising a water-absorbing layer arranged between the base fabric layer and the plastic film layer, the water-absorbing layer comprising an adhesive and polymer hollow microspheres distributed in the adhesive, the polymer hollow microspheres being the above-mentioned polymer hollow microspheres or polymer hollow microspheres prepared by the above-mentioned method for preparing polymer hollow microspheres.

[0037] Furthermore, the base fabric layer is a hydrophilic non-woven fabric with a gram weight of 15 to 25 g / m 2 .

[0038] Furthermore, the adhesive is polyvinyl alcohol, and the mass ratio of the adhesive to the polymer hollow microspheres is 1:5-15.

[0039] Furthermore, the plastic film layer is PE, PP, PVC or PET film with a thickness of 0.008 to 0.1 mm.

[0040] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0041] The present invention uses photopolymerizable amphiphilic copolymer particles as an emulsifier, which has excellent hydrophilicity. Under light, the photopolymerizable amphiphilic copolymer particles and the photocurable monomers are polymerized to obtain polymer hollow microspheres with a hydrophilic shell. The strong hydrophilicity of the shell layer can quickly absorb a large amount of water and store it in the internal cavity. Compared with traditional water-absorbing resins, the cavity structure inside the polymer hollow microspheres of the present invention can greatly increase the water storage capacity. The concrete moisturizing curing film prepared using the polymer hollow microspheres of the present invention has extremely strong water retention capacity. The internally adsorbed water can be released to the concrete through the capillary phenomenon of the rough surface of the base fabric layer, ensuring the required moisture for the concrete during the curing period.

[0042] The concrete moisturizing curing membrane prepared by using the polymer hollow microspheres of the present invention has uniform water supply and a water retention time of more than 60 days, which can significantly improve the quality of concrete hydration curing and enable curing to be carried out under optimal conditions. In addition, the curing membrane is light in weight and reusable. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a scanning electron micrograph of the photopolymerizable amphiphilic copolymer particles of Example 1;

[0044] Figure 2 This is a microscope photograph of the Pickering emulsion of Example 1;

[0045] Figure 3 This is a scanning electron microscope image of the highly water-absorbent polymer hollow microspheres of Example 1. DETAILED DESCRIPTION

[0046] To address the problem that the water absorption and water retention rates of existing concrete moisturizing and curing membranes are still not high enough, the present invention synthesizes a photopolymerizable amphiphilic copolymer particle by using a hydrophilic monomer and a specific hydrophobic photosensitive monomer, and uses the photopolymerizable amphiphilic copolymer particle as an emulsifier, and emulsifies it with water and an oil phase to form an oil-in-water Pickering emulsion, wherein the oil phase contains a photocurable monomer and a photoinitiator. Under light, the photocurable monomer undergoes an interfacial photopolymerization reaction to form a shell layer. At the same time, the photopolymerizable amphiphilic copolymer particle undergoes photodimerization with the shell layer, embeds into the shell layer, imparts hydrophilicity to the shell layer, and forms a protruding structure on the surface to increase the hydrophilic surface area. After washing, the polymer hollow microspheres are obtained. The polymer hollow microspheres have a highly hydrophilic rough outer surface that can absorb water and store it in the internal cavity to achieve the water absorption function. It is applied to the preparation of a controllable water absorption / release concrete moisturizing and curing membrane, which has the advantages of high water absorption, continuous water release, and long water retention time.

[0047] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solutions of the present invention, but the present invention is not limited to the scope of the examples.

[0048] Example 1

[0049] The highly absorbent polymer hollow microspheres provided in this embodiment are prepared using the following preparation method:

[0050] (1) Preparation of hydrophobic photosensitive monomer

[0051] 7-Hydroxy-4-methylcoumarin was dissolved in an alkaline solution of polyethylene glycol (pH = 14, polyethylene glycol mass concentration of 20 g / L), and then 4-chloromethylene styrene was added after heating to 40°C. The molar ratio of 7-hydroxy-4-methylcoumarin to 4-chloromethylene styrene was 1.05:1. After reacting for 48 hours, the product was precipitated in a methanol / water mixed solution (volume ratio of 3:1). The obtained solid was dissolved in tetrahydrofuran and the precipitation was repeated 3 times. After drying, the hydrophobic photosensitive monomer 7-(4-vinylbenzyloxy)-4-methylcoumarin was obtained.

[0052] (2) Preparation of photopolymerizable amphiphilic copolymer particles

[0053] Acrylamide and 7-(4-vinylbenzyloxy)-4-methylcoumarin were dissolved and dispersed in water at a molar ratio of 1:1, and then 3% of the total molar number of the monomers, N,N'-methylenebisacrylamide, and 1.0% of the total molar number of the monomers, were added. After nitrogen was passed through, the mixture was sealed and stirred at 70°C for 6 hours at a stirring speed of 1000 rpm. After the reaction was completed, the precipitate was centrifuged to obtain a precipitate, which was washed three times with water and dried to obtain a photopolymerizable amphiphilic copolymer particle powder. The particle size of the photopolymerizable amphiphilic copolymer particles was approximately 100 nm as measured by a nanoparticle size analyzer. The scanning electron microscopy image is shown in FIG. Figure 1 shown.

[0054] (3) Preparation of highly absorbent polymer hollow microspheres

[0055] The photopolymerizable amphiphilic copolymer particles were ultrasonically dispersed in water to form a dispersion as the aqueous phase, with a concentration of 30 g / L;

[0056] Then, glycidyl methacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and toluene were mixed in a feed mass ratio of 10:0.2:35, and 7-(4-vinylbenzyloxy)-4-methylcoumarin was added, with a mass ratio of 7-(4-vinylbenzyloxy)-4-methylcoumarin to glycidyl methacrylate being 1:100, and this was used as the oil phase;

[0057] The water phase and the oil phase were mixed at a mass ratio of 1:1, and then emulsified at a speed of 20,000 rpm for 3 minutes using a high-speed homogenizer to form an oil-in-water Pickering emulsion. The microscope photo is shown in FIG. Figure 2 As shown;

[0058] The Pickering emulsion was irradiated under a UV light source at 365 nm for 15 min, and then washed repeatedly with deionized water and ethanol, and finally centrifuged to obtain highly absorbent polymer hollow microspheres. Scanning electron microscopy showed that the microspheres Figure 3 As shown, the diameter of the polymer hollow microspheres is about 10 μm, the average wall thickness of the shell is about 700 nm, and protrusion structures formed by photopolymerizable amphiphilic copolymer particles can be observed on the inner and outer surfaces of the shell. This structure gives the microsphere surface good hydrophilicity and water retention.

[0059] Example 2

[0060] The highly absorbent polymer hollow microspheres provided in this embodiment are prepared using the following preparation method:

[0061] (1) Preparation of photopolymerizable amphiphilic copolymer particles

[0062] N-isopropylacrylamide and 7-(4-vinylbenzyloxy)-4-methylcoumarin prepared in Example 1 were dissolved and dispersed in water at a molar ratio of 5:1. Then, 4% of the total molar amount of the monomers was added, and 1.0% of the total molar amount of the monomers was added. After nitrogen was passed through, the mixture was sealed and stirred at 70° C. for 6 hours at a stirring speed of 1000 rpm. After the reaction, the precipitate was centrifuged to obtain a precipitate, which was washed three times with water and dried to obtain a photopolymerizable amphiphilic copolymer particle powder. The particle size of the photopolymerizable amphiphilic copolymer particles was approximately 600 nm as measured by a nanoparticle size analyzer.

[0063] (2) Preparation of highly absorbent polymer hollow microspheres

[0064] The photopolymerizable amphiphilic copolymer particles were ultrasonically dispersed in water to form a dispersion as the aqueous phase with a concentration of 15 g / L;

[0065] Then, glycidyl methacrylate and 2-hydroxy-2-methyl-1-phenyl-1-propanone were mixed at a feed mass ratio of 10:3, and 7-(4-vinylbenzyloxy)-4-methylcoumarin was added, with the mass ratio of 7-(4-vinylbenzyloxy)-4-methylcoumarin to glycidyl methacrylate being 5:100, and this was used as the oil phase;

[0066] The water phase and the oil phase were mixed at a mass ratio of 1:1, and then emulsified using a high-speed homogenizer at 5000 rpm for 3 min to form an oil-in-water Pickering emulsion;

[0067] The Pickering emulsion was irradiated under a UV light source at 365 nm for 15 minutes, then washed repeatedly with deionized water and ethanol separately, and finally centrifuged to obtain highly absorbent polymer hollow microspheres. Scanning electron microscopy showed that the diameter of the polymer hollow microspheres was about 60 μm and the shell wall thickness was about 3 μm.

[0068] Example 3

[0069] The superabsorbent hollow polymer microspheres provided in this embodiment are substantially the same as those in Example 1, except that in step (2), the mass ratio of the oil phase to the water phase is 3:1. Testing revealed that the diameter of the hollow polymer microspheres was approximately 18 μm, and the shell wall thickness was approximately 1.5 μm.

[0070] Comparative Example 1

[0071] The hollow polymer microspheres provided in this comparative example are essentially the same as those in Example 1, except that in step (2), styrene is used as the hydrophobic monomer instead of 7-(4-vinylbenzyloxy)-4-methylcoumarin. The amphiphilic copolymer particles prepared in this example cannot undergo photopolymerization.

[0072] Comparative Example 2

[0073] The hollow polymer microspheres provided in this comparative example are substantially the same as those in Example 1, except that in step (2), the molar ratio of acrylamide to 7-(4-vinylbenzyloxy)-4-methylcoumarin is 1:2. In this example, the amphiphilic copolymer particles contain a relatively high amount of hydrophobic monomers in their synthesis monomers, resulting in a highly hydrophobic surface.

[0074] Comparative Example 3

[0075] The hollow polymer microspheres provided in this comparative example are basically the same as those in Example 1, except that in step (2), lignin sulfonate is used instead of amphiphilic copolymer particles as an emulsifier to prepare the oil-in-water emulsion. The lignin sulfonate in this example is an anionic surfactant.

[0076] The polymer hollow microspheres of Examples 1 to 3 and Comparative Examples 1 to 3 were used to prepare concrete moisturizing curing films respectively:

[0077] Preparation of concrete moisturizing curing film: The polymer hollow microspheres of Examples 1 to 3 and Comparative Examples 1 to 3 were mixed with polyvinyl alcohol adhesive at a mass ratio of 10:1, and then coated with 10 g / m 2Coated on a PE film with a thickness of 0.008mm, and then covered with a 20g / m 2 The hydrophilic non-woven fabric is used to form a concrete moisturizing curing membrane with a structure of a base fabric layer, a water-absorbing layer and a plastic film layer stacked in sequence, wherein the base fabric layer is a hydrophilic non-woven fabric purchased from Zhejiang Guancheng Technology Co., Ltd.; the water-absorbing layer is formed by coating a mixture of polyvinyl alcohol adhesive and polymer hollow microspheres on a PE film, and the polyvinyl alcohol adhesive is purchased from Shanghai Chenqi Huagong Technology Co., Ltd.; the plastic film layer is a PE film purchased from Xi'an Runye Plastic Industry Co., Ltd.

[0078] The above concrete moisturizing curing membrane was subjected to a water absorption test, and the results are shown in Table 1.

[0079] Table 1 shows the water absorption of concrete moisturizing curing membranes prepared using the polymer hollow microspheres of Examples 1 to 3 and Comparative Examples 1 to 3.

[0080] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Water absorption (g / m 2 )]]> 1600 1800 1500 700 300 100

[0081] The test method for water absorption is as follows: weigh the mass M1 of a sample with an area of A, place the sample in a water tank, inject tap water, and leave it at room temperature for a period of time to reach adsorption equilibrium. Then take out the sample and drain it. Weigh the mass M2 of the sample, and the water absorption of the sample is (M2-M1) / A.

[0082] By comparative example 1 and comparative example 1, it is known that the photodimerization reaction of the amphiphilic copolymer particles of photopolymerizable has an important role, and the amphiphilic copolymer particles in comparative example 1 cannot carry out photodimerization reaction, therefore cannot be embedded in polymer microsphere shell, causes microsphere surface hydrophilicity to decline.By comparative example 1 and comparative example 2, it is known that the surface hydrophilicity regulation and control of the amphiphilic copolymer particles of photopolymerizable directly affects the hydrophilicity of polymer hollow microsphere, and in comparative example 2, hydrophobic monomer is more, so prepared particle surface hydrophobicity is higher, and the surface hydrophilicity of the polymer hollow microsphere formed thus declines, and water absorption reduces.By comparative example 1 and comparative example 3, it is known that the amphiphilic copolymer particles of photopolymerizable can improve polymer microsphere water absorption as macromolecular emulsifier, this is because the hollow microsphere prepared by common surfactant type emulsifier is closed-cell microsphere, its shell is relatively smooth and dense, and moisture is difficult to enter inside, and the shell that hydrophilic polymer particles are embedded has open pore structure, and shell can be stored in internal cavity after hydrophilicity, reaches water absorption purpose.

[0083] When the concrete moisturizing curing membrane prepared by using the polymer hollow microspheres of Example 1 is laid on the concrete, the water retention time can reach more than 60 days.

[0084] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0085] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A polymer hollow microsphere, characterized in that: The polymer hollow microspheres are formed by photo-initiated Pickering emulsion polymerization, wherein the Pickering emulsion comprises an emulsifier, water and an oil phase, the emulsifier is a photopolymerizable amphiphilic copolymer particle, and the oil phase comprises a photocurable monomer and a photoinitiator; The photopolymerizable amphiphilic copolymer particles are obtained by polymerization of a hydrophilic monomer, a hydrophobic photosensitive monomer and a crosslinking agent via an initiator, wherein the hydrophobic photosensitive monomer is 7-(4-vinylbenzyloxy)-4-methylcoumarin; The molar ratio of the hydrophilic monomer to the hydrophobic photosensitive monomer is 1 to 5:1; The cross-linking agent is N,N'-methylenebisacrylamide, and the molar amount of the cross-linking agent is 3% to 4% of the total molar amount of the hydrophilic monomer and the hydrophobic photosensitive monomer.

2. The hollow polymer microspheres according to claim 1, characterized in that: The hydrophilic monomer is one or a combination of acrylamide, N-isopropylacrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, and methacrylic acid.

3. The hollow polymer microspheres according to claim 1, characterized in that: The initiator is a combination of one or more of ammonium persulfate, sodium persulfate, and potassium persulfate, and the molar amount of the initiator is 0.5% to 1.5% of the total molar amount of the hydrophilic monomer and the hydrophobic photosensitive monomer; and / or, The hydrophobic photosensitive monomer is obtained by reacting 7-hydroxy-4-methylcoumarin and p-chloromethylenestyrene.

4. The hollow polymer microspheres according to claim 1, wherein: The particle size of the photopolymerizable amphiphilic copolymer particles is 100-600 nm; and / or the particle size of the polymer hollow microspheres is 10-60 μm and the wall thickness is 0.7-3 μm.

5. The hollow polymer microspheres according to any one of claims 1 to 4, characterized in that: The preparation method of the photopolymerizable amphiphilic copolymer particles comprises adding a hydrophilic monomer, a hydrophobic photosensitive monomer, a crosslinking agent, an initiator and water into a reactor, and reacting at 60 to 80° C. under the protection of an inert gas to obtain a reaction solution containing the photopolymerizable amphiphilic copolymer particles.

6. The hollow polymer microspheres according to claim 5, characterized in that: The method for preparing the photopolymerizable amphiphilic copolymer particles further comprises the steps of centrifuging, washing, and drying the reaction solution containing the photopolymerizable amphiphilic copolymer particles to obtain the photopolymerizable amphiphilic copolymer particles.

7. The hollow polymer microspheres according to claim 1, characterized in that: The oil phase further comprises an organic solvent; and / or, The mass ratio of the photocurable monomer to the photoinitiator is 10-100:0.2-3; and / or, the photocurable monomer is a combination of one or more of dimethylaminoethyl methacrylate, glycidyl methacrylate, methyl methacrylate, 1,6-hexanediol diacrylate, methacrylic acid, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, lauryl acrylate, butyl acrylate, isobornyl acrylate, ethoxylated-1,6-hexanediol diacrylate, and divinylbenzene, and 7-(4-vinylbenzyloxy)-4-methylcoumarin, and the mass ratio of 7-(4-vinylbenzyloxy)-4-methylcoumarin to the photocurable monomer is 0.5-5:100; and / or, The photoinitiator is a combination of one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, benzophenone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, methyl benzoylformate, 2,4-diethylthiazolone, and 2-isopropylthioxanthone.

8. The hollow polymer microspheres according to any one of claims 1 to 4 and 7, characterized in that: The preparation method of the Pickering emulsion includes ultrasonically dispersing an emulsifier and water to form an aqueous phase, then mixing the aqueous phase with an oil phase, and homogenizing and emulsifying to obtain the oil-in-water Pickering emulsion, wherein the concentration of the emulsifier in the aqueous phase is 15 to 30 g / L, the mass ratio of the oil phase to the aqueous phase is 1 to 3:1, and the rotation speed used for the homogenization emulsification is 5000 to 20000 rpm.

9. A method for preparing hollow polymer microspheres according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of photopolymerizable amphiphilic copolymer particles Adding a hydrophilic monomer, a hydrophobic photosensitive monomer, a crosslinking agent, an initiator and water into a reactor, reacting at 60-80° C. under the protection of an inert gas to obtain the photopolymerizable amphiphilic copolymer particles; (2) Preparation of polymer hollow microspheres The photopolymerizable amphiphilic copolymer particles are dispersed in water to form an aqueous phase, the aqueous phase is mixed with an oil phase, and homogenized to form an oil-in-water Pickering emulsion. The oil-in-water Pickering emulsion is then irradiated with UV light to form the polymer hollow microspheres.

10. A concrete moisturizing curing membrane comprising a base fabric layer and a plastic film layer, characterized in that: The concrete moisturizing curing membrane also includes a water-absorbing layer arranged between the base fabric layer and the plastic film layer, the water-absorbing layer includes an adhesive and polymer hollow microspheres distributed in the adhesive, and the polymer hollow microspheres are the polymer hollow microspheres described in any one of claims 1 to 8 or the polymer hollow microspheres prepared by the preparation method of the polymer hollow microspheres described in claim 9.

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