High-liquid-absorption antibacterial polyacrylate foam material and preparation method thereof

Abstract

The invention relates to the field of hygienic products, provides a high-liquid-absorptivity antibacterial polyacrylate foam material and a preparation method thereof, and solves the problems that an existing acrylate foam material for hygienic products cannot give consideration to high water absorptivity and does not have a lasting antibacterial function due to insufficient emulsion stability. The foam material is formed by polymerization of a water-in-oil Pickering emulsion under the initiation of ultraviolet light, the Pickering emulsion comprises an oil phase and a water phase, and the oil phase comprises the following raw materials: an acrylate monomer, a cross-linking agent, a photoinitiator, a nonionic emulsifier and hydrophobically modified p-n heterojunction nanoparticles; the water phase comprises deionized water and electrolyte; the hydrophobic modified p-n heterojunction nanoparticles are any one of a heterojunction composed of Cu2O and ZnO, a heterojunction composed of TiO2 and ZnO, and a heterojunction composed of Cu2O and TiO2.

Description

Technical Field

[0001] This invention relates to the field of hygiene products, and more particularly to a highly absorbent antibacterial polyacrylate foam material and its preparation method. Background Technology

[0002] Acrylic (PA) foams, due to their excellent absorbency, softness, and designability, have broad application potential in disposable hygiene products, medical dressings, and environmental absorbent materials. Products such as sanitary napkins, diapers, and incontinence pads place extremely high demands on materials for high absorbency, rapid liquid absorption, water retention, and safety. Compared to traditional cellulose cotton and powdered superabsorbent polymers (SAP), PA foams offer the following advantages: a three-dimensional porous network structure that enhances liquid transport rate while maintaining absorbency; structural stability and softness that improves user comfort; and adjustable formulation design, allowing for customization of pore structure and absorbency through monomers and crosslinking agents.

[0003] However, despite the enormous application potential of PA foam, its industrialization development is still constrained by many factors.

[0004] (1) First, the contradiction between emulsion stability and water absorption: Currently, most PA foams are prepared using emulsion polymerization, where hydrophilic monomers (such as acrylic acid and sodium acrylate) are key to improving water absorption. However, these monomers significantly weaken the interfacial stability of water-in-oil emulsions, leading to emulsion rupture or delamination at high water phase ratios. Therefore, existing processes are generally limited to low water-to-oil ratios (usually below 10:1), failing to fully utilize the role of hydrophilic monomers. This not only limits the water absorption of the foam but also increases the amount of oil phase used, resulting in increased costs and environmental burdens.

[0005] (2) Secondly, the shortcomings of a single emulsifier system: Although traditional nonionic emulsifiers (such as Span 80) can form a water-in-oil system, they are not stable enough under high water content and high hydrophilicity conditions, and cannot support the polymerization process under high water-to-oil ratio conditions. As a result, the foams produced often have uneven pore size distribution and obvious structural defects, which affects the consistency of water absorption ratio and mechanical properties.

[0006] (3) Finally, insufficient antibacterial properties: Hygiene products are in a warm and humid environment for a long time, which easily becomes a breeding ground for bacteria and fungi. Existing products usually rely on introducing a single antibacterial agent (such as silver ions or organic antibacterial agents) into the polymer to achieve the antibacterial effect. However, this method has problems such as narrow antibacterial spectrum, easy migration and loss, and insufficient durability, making it difficult to provide long-term stable protection and even potentially causing safety hazards; in addition, the process of simply blending antibacterial agents into antibacterial PA foam leads to a decrease in the strength of the emulsion interface film, making it difficult to prepare materials with high water absorption ratio; and the antibacterial agent is easily embedded in the polymer matrix, resulting in low utilization.

[0007] Chinese Patent Publication No. CN113289049A discloses a method for preparing an acrylate-based foam absorbent core. This acrylate-based foam absorbent core is composed of emulsion A, emulsion B, and sheet material. Emulsion A and emulsion B include an oil phase, an aqueous phase, and an initiator aqueous solution, prepared using a continuous emulsification device. The invention also prepares a photoinitiator containing multiple NO bonds, which initiates the polymerization of acrylate monomers under common 405nm and 450nm LED light irradiation, avoiding the use of mercury lamps and exhibiting good environmental performance. The foam absorbent core prepared by this invention has good toughness and mechanical strength, moderate pore size, fast absorption speed, and high absorption rate, making it suitable for dispersing and storing aqueous fluids and applicable to the field of hygiene products. However, this patent uses traditional small-molecule emulsifiers and co-emulsifiers to stabilize the emulsion, which has limited stability and is difficult to withstand high water-to-oil ratios, leading to emulsion breakage or delamination. Furthermore, this foam material lacks antibacterial properties.

[0008] Chinese Patent Publication No. CN108084330A discloses an acrylate-based porous polymer and its preparation method. The acrylate-based porous polymer is composed of emulsion products, wherein the emulsion products are composed of emulsion 1 and emulsion 2 polymers. Emulsion 1 and emulsion 2 are continuously emulsified using a continuous emulsification device. The polymer is in sheet form, rather than the granular form of traditional acrylic superabsorbent polymers. It can be directly composited with film or sheet materials to form two layers of foam-like porous materials with significantly different pore sizes. It is particularly suitable for blood absorption products. The use of a continuous emulsification device for emulsification has high production efficiency. The different average diameters of the aqueous phase droplets in the two emulsions can be precisely controlled by controlling the W / O ratio of the aqueous phase and the reflux ratio. The emulsion products directly enter the next process, which has the advantage of preventing partial demulsification and uneven polymerization during the stagnation of the high internal phase emulsion. This continuous emulsification process significantly shortens the emulsification cycle. The linoleic acid glyceride, triglyceride stearate, and diglyceride dioleate used in this application are traditional small molecule emulsifier compound systems with low upper limits of emulsion stability; although the water phase ratio (20:1 and 32:1) is not low, it does not have antibacterial properties.

[0009] Based on the above problems, there is an urgent need for a PA foam preparation technology that can maintain emulsion stability under high water-to-oil ratio conditions. This technology would enable the foam to achieve both higher water absorption rates and more uniform pore structures, while reducing the amount of oil phase used to meet the trend of green environmental protection. Simultaneously, the foam should also possess long-lasting and broad-spectrum antibacterial capabilities to meet the dual requirements of safety and comfort in hygiene products. Summary of the Invention

[0010] Therefore, in view of the above problems, the present invention provides a highly absorbent antibacterial polyacrylate foam material and its preparation method, which solves the problem that existing acrylate foam materials for hygiene products cannot achieve high water absorption ratio and do not have long-lasting antibacterial function due to insufficient emulsion stability.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A highly absorbent antibacterial polyacrylate foam material, wherein the foam material is formed by ultraviolet light-initiated polymerization of a water-in-oil Pickering emulsion, the Pickering emulsion comprising an oil phase and an aqueous phase, the oil phase comprising the following raw materials: acrylate monomers, crosslinking agents, photoinitiators, nonionic emulsifiers, and hydrophobically modified pn heterojunction nanoparticles; the aqueous phase comprising deionized water and an electrolyte.

[0013] The mass ratio of the aqueous phase to the oil phase is (10-36):1, and the hydrophobically modified pn heterojunction nanoparticles are any one of the following: a heterojunction composed of Cu2O and ZnO, a heterojunction composed of TiO2 and ZnO, or a heterojunction composed of Cu2O and TiO2.

[0014] On the one hand, the hydrophobically modified pn heterojunction nanoparticles, as Pickering stabilizers, work synergistically with nonionic emulsifiers to steadily increase the water-oil ratio from 15:1 to over 35:1 and the water absorption rate from 10g / g to 22g / g, overcoming the problem of hydrophilic monomers damaging the interfacial film.

[0015] On the other hand, the hydrophobically modified pn heterojunction nanoparticles can exhibit certain antibacterial effects under light-free conditions. Metal ions in the pn heterojunction dissolve, and Cu2O and ZnO release trace amounts of Cu even in darkness. 2+ and Zn 2+ These metal ions are positively charged and can adsorb onto the negatively charged bacterial cell walls, disrupting cell membrane permeability and causing bacterial death; this is a classic inorganic antibacterial mechanism that does not require light; at the same time, the surface of nanoparticles has roughness and static charge, which can physically destroy the structure of bacteria by direct contact.

[0016] In dark environments, such as during use, the pn heterojunction utilizes metal elements such as Cu and Zn to disrupt the bacterial cell membrane potential through the release of trace metal ions and electrostatic adsorption, achieving efficient and rapid contact sterilization in light-free usage scenarios.

[0017] In bright environments, such as during storage and disposal, under visible light or weak ultraviolet light (such as during production lines, shelf life, or waste disposal), the heterojunction structure excites photogenerated electron-hole pairs to produce reactive oxygen species (ROS), which can not only deeply sterilize but also oxidize and decompose volatile organic compounds in urine / blood, exhibiting significant antibacterial and deodorizing functions.

[0018] Therefore, heterojunction nanoparticles can continuously generate reactive oxygen species in dark or bright environments, achieving long-lasting, broad-spectrum, and low-drug-resistance photocatalytic antibacterial effects.

[0019] Meanwhile, the antibacterial effect is stronger in bright environments than in dark environments. In dark environments, metal ions primarily damage cell membrane structures; however, reactive oxygen species (ROS) generated by photocatalysis are strong oxidizing agents that can indiscriminately attack bacterial cell membranes, proteins, enzymes, and even DNA, causing irreversible damage to their structures. This multi-faceted attack makes it harder for bacteria to survive and develop drug resistance. Studies have shown that reactive oxygen species can destroy the cell structure of microorganisms, thereby achieving bactericidal effects.

[0020] A stable emulsion system enables more uniform foam formation and narrower pore size distribution, thus balancing water absorption ratio and mechanical strength.

[0021] Furthermore, the foam material has an absorption rate of ≥22 times for deionized water and ≥19 times for physiological saline.

[0022] Furthermore, the acrylate monomers include isooctyl acrylate, butyl acrylate, and hydroxyethyl acrylate.

[0023] Furthermore, the aqueous phase also contains 0.1%-1% by mass of acrylic acid and / or sodium acrylate.

[0024] Furthermore, the electrolyte is CaCl2.

[0025] Furthermore, the nonionic emulsifier is Span 80.

[0026] The preparation method of the above-described highly absorbent antibacterial polyacrylate foam material includes the following steps:

[0027] S1. Preparation of oil phase: The raw materials for oil phase are ultrasonically mixed and stirred evenly to obtain the oil phase;

[0028] S2. Preparation of aqueous phase: Mix all raw materials for aqueous phase and stir evenly to obtain aqueous phase;

[0029] S3. Under high-speed stirring conditions, the aqueous phase obtained in step S2 is gradually added dropwise to the oil phase to form a water-in-oil Pickering emulsion.

[0030] S4. The Pickering emulsion is irradiated under ultraviolet light to initiate a polymerization reaction and form a porous foam preform.

[0031] S5. The porous foam preform obtained in step S4 is sequentially washed, dried and hydrophilic post-treated to obtain a highly absorbent antibacterial polyacrylate foam material.

[0032] Furthermore, the speed of the high-speed stirring condition is 800-2000 rpm.

[0033] Furthermore, in step S5, the hydrophilic post-treatment is as follows: the dried foam material is immersed in sodium alginate solution, taken out, rolled, and then dried again.

[0034] By adopting the aforementioned technical solution, the beneficial effects of the present invention are as follows:

[0035] 1. By hydrophobically modifying composite nanoparticles such as Cu2O / ZnO and TiO2 / ZnO and introducing them into the oil phase, they act as a Pickering stabilizer, synergistically with Span 80 to significantly improve the stability of the water-oil ratio, which can reach over 30:1. On the other hand, they form pn heterojunctions, and the built-in electric field at the interface promotes the separation of photogenerated electrons and holes, achieving bactericidal effects through different mechanisms in both dark and bright environments. In the absence of light, such as when worn, they achieve efficient contact sterilization through ion dissolution and electrostatic adsorption. In the presence of light, such as during production, storage, and disposal, active oxygen is generated, achieving deep sterilization and deodorization of organic matter. This dual-mechanism antibacterial effect overcomes the defect of single photocatalytic materials failing in light-protected environments, achieving a broad-spectrum, long-lasting antibacterial effect with low risk of drug resistance.

[0036] 2. Utilizing the self-assembly properties of Pickering emulsion, the polymerized nanoparticles are naturally anchored to the inner wall surface of the microporous channels. Compared with the traditional blending method where the antibacterial agent is embedded in the matrix, this structure ensures that the antibacterial sites are exposed to the liquid absorption channels to the greatest extent, which greatly improves the utilization efficiency and sterilization speed of the antibacterial agent.

[0037] 3. Introducing hydroxyethyl acrylate into the oil phase improves hydrophilicity; further controlling the addition of acrylic acid / sodium acrylate into the aqueous phase achieves increased water absorption ratio without compromising emulsion stability. Excessive use will lead to demulsification and structural inhomogeneity; therefore, this range has critical optimization potential.

[0038] 4. By impregnating and rolling the foam material in sodium alginate solution, a stable hydrophilic layer is formed on the foam surface, which further improves the liquid diffusion and absorption rate, and improves the absorption performance and comfort of the material in complex media such as urine and blood. Attached Figure Description

[0039] Figure 1 This is a SEM image of the highly absorbent antibacterial polyacrylate foam material prepared in Example 1 of the present invention at a magnification of 2000x.

[0040] Figure 2 This is a SEM image of the highly absorbent antibacterial polyacrylate foam material prepared in Example 1 of the present invention at a magnification of 5000x.

[0041] Figure 3 The infrared spectrum of the highly absorbent antibacterial polyacrylate foam material prepared in Example 1 of this invention;

[0042] Figure 4 This is a SEM image of the foam material prepared in Comparative Example 1 of this invention.

[0043] Figure 5 The graph shows the antibacterial test results of the highly absorbent antibacterial polyacrylate foam material prepared in Example 1 of this invention. Detailed Implementation

[0044] Example 1

[0045] A highly absorbent antibacterial polyacrylate foam material is disclosed. The foam material is formed by UV-initiated polymerization of a water-in-oil Pickering emulsion, exhibiting an absorption rate of up to 22 times for deionized water and up to 19 times for physiological saline. The Pickering emulsion comprises an oil phase and an aqueous phase. The oil phase comprises the following raw materials in parts by weight: 4 parts isooctyl acrylate, 1 part butyl acrylate, 0.3 parts hydroxyethyl acrylate, 1 part crosslinking agent, 0.5 parts photoinitiator, 0.5 parts nonionic emulsifier, and 1 part hydrophobically modified pn heterojunction nanoparticles. The aqueous phase comprises the following raw materials: 150 parts deionized water and 0.15 parts electrolyte.

[0046] The mass ratio of the aqueous phase to the oil phase is 30:1; the hydrophobically modified pn heterojunction nanoparticles are heterojunctions composed of Cu2O and ZnO.

[0047] The aqueous phase also contains 1% acrylic acid and sodium acrylate by mass of the total aqueous phase; the electrolyte is CaCl2; the nonionic emulsifier is Span 80; the foam material can continuously generate active oxygen under visible light or weak ultraviolet light irradiation, and has a broad-spectrum antibacterial effect against bacteria and fungi.

[0048] The preparation method of the above-described highly absorbent antibacterial polyacrylate foam material includes the following steps:

[0049] (1) Preparation of hydrophobically modified pn heterostructure nanoparticles

[0050] The hydrophobically modified pn heterojunction nanoparticles are selected from heterojunctions composed of Cu2O and ZnO;

[0051] (1-1) Preparation of Cu2O nanocube powder

[0052] Weigh 0.5 parts by weight of CuSO4·5H2O and 1.0 parts by weight of sodium citrate, dissolve them in 100 parts by weight of deionized water, and stir magnetically until completely dissolved. Add 1 part by weight of NaOH solution dropwise to adjust the pH of the system to 10. At this point, the solution turns into a light blue turbidity. Heat the solution to 55℃ and maintain the temperature. Quickly add 0.36 parts by weight of ascorbic acid and continue to stir at the temperature for 30 minutes. Observe that the solution color gradually turns brick red, indicating that Cu2O has been generated. The reaction is complete. Allow it to cool naturally to room temperature. Centrifuge at 8000 rpm for 5 minutes to collect the brick red precipitate. Wash it three times each with deionized water and anhydrous ethanol to remove residual reactants and byproducts. Place the washed product in a vacuum drying oven at 60℃ and dry for 6 hours to obtain Cu2O nanocube powder.

[0053] (1-2) In-situ growth of ZnO

[0054] Weigh 0.9 parts by weight of Zn(NO3)2·6H2O and 0.9 parts by weight of HMTA, dissolve them in 200 parts by weight of deionized water, and add 0.1 parts by weight of PVP as a morphology control agent to form a mixture. Take 0.1 parts by weight of the Cu2O nanocube powder obtained in step (1-1), disperse it in the above mixture, sonicate it for 15 minutes to make it uniformly dispersed, react it at 90°C for 3 hours, and observe a white or light yellow precipitate, indicating that ZnO has grown on the Cu2O surface. Centrifuge at 8000 rpm for 5 minutes, collect the precipitate, wash it thoroughly with deionized water and anhydrous ethanol, and dry the product at 60°C for 6 hours to obtain Cu2O / ZnO pn heterojunction nanoparticles, that is, heterojunctions composed of Cu2O and ZnO.

[0055] (1-3) Hydrophobic modification treatment

[0056] Take 0.5 parts by weight of nano-Cu2O / ZnO pn heterojunction nanoparticles, add 50 parts by weight of ethanol, 5 parts by weight of ammonia and 5 parts by weight of silane coupling agent methyltrimethoxysilane, stir at room temperature for about 2 hours, then centrifuge and dry for later use to obtain hydrophobically modified pn heterojunction nanoparticles.

[0057] (2) Preparation of oil phase

[0058] According to the weight proportions, isooctyl acrylate, butyl acrylate, hydroxyethyl acrylate, crosslinking agent, photoinitiator, nonionic emulsifier and pn heterojunction nanoparticles are ultrasonically mixed and stirred evenly to obtain an oil phase; the stirring speed is 1200 rpm.

[0059] (3) Preparation of aqueous phase

[0060] Add the electrolyte to the deionized water according to the weight proportions, stir well, and obtain the aqueous phase;

[0061] The aqueous phase also contains 1% acrylic acid and sodium acrylate by mass of the total aqueous phase, which further enhances the water absorption capacity of the material. This range has been experimentally verified to optimize the water absorption ratio of the material without damaging the emulsion structure. If the amount exceeds 1%wt, the hydrophilicity of the aqueous phase will be too strong, which will weaken the interfacial film strength of the water-in-oil emulsion, causing the emulsion to break down during the reaction. After photopolymerization, the material structure will be uneven, the pore size distribution will be widened, and the water absorption performance and mechanical strength of the final product will decrease.

[0062] (4) Preparation of Pickering emulsion

[0063] Under high-speed stirring conditions, the aqueous phase obtained in step (3) is gradually added dropwise to the oil phase to form a stable water-in-oil Pickering emulsion;

[0064] (5) Preparation of porous foam preform

[0065] The Pickering emulsion was irradiated under ultraviolet light to initiate a polymerization reaction and form a porous foam preform.

[0066] (6) Preparation of highly absorbent antibacterial polyacrylate foam material

[0067] (6-1) The porous foam blank obtained in step (5) is immersed in ethanol, squeezed several times to replace the internal moisture, and then washed and dried in sequence.

[0068] (6-2) Preparation of sodium alginate solution

[0069] Add 1 part by weight of sodium alginate to 99 parts by weight of deionized water and stir until the powder is completely dispersed to obtain a sodium alginate solution.

[0070] (6-3) Post-hydration treatment

[0071] The dried foam sheet is completely immersed in the prepared sodium alginate solution. After 30 minutes, it is taken out and rolled evenly with rollers. After drying, it is taken out and cooled to obtain a highly absorbent antibacterial polyacrylate foam material.

[0072] refer to Figure 1 and Figure 2, Figure 1 The magnification is 2.00KX (2000 times), reflecting the overall morphology of the material and the overall distribution and connectivity of the pores; Figure 2 The magnification is 5.00KX (5000x), reflecting local details of the material, such as the surface morphology of the pore walls and the specific structure of the pore throats. From Figure 1 and Figure 2 It can be seen that the foam material prepared in Example 1 has a regular microporous structure and slightly smaller pore throats, and is three-dimensionally interconnected inside.

[0073] refer to Figure 3 At approximately 3500cm -1 The broad absorption peak at approximately 1730 cm⁻¹ corresponds to the stretching vibration of the hydroxyl group (-OH), confirming the successful introduction of the hydroxyethyl acrylate monomer; at approximately 1730 cm⁻¹... -1 The strong absorption peak observed is due to the stretching vibration of the carbonyl group (C=O) in the ester group, a characteristic functional group of polyacrylate. This spectrum confirms the successful synthesis of the target polymer and the successful incorporation of the hydrophilic functional group.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that hydrophobically modified pn heterojunction nanoparticles are not added, and Span 80 is used as a nonionic emulsifier. All other technical aspects are the same as in Example 1.

[0076] refer to Figure 4 As can be seen, the foam material prepared in Comparative Example 1 has an irregular microporous structure. The distribution of these irregular micropores is highly uneven, with significant differences in size, and some pores even collapse. The pores are not connected, resulting in numerous structural defects. This irregular structure directly leads to a decrease in the material's water absorption capacity, mechanical strength, and other properties.

[0077] The water absorption and liquid absorption ratio of the highly absorbent antibacterial polyacrylate foam material prepared in Example 1 and the foam material prepared in Comparative Example 1 were tested, and the test results are shown in Table 1.

[0078] Table 1

[0079] Test Project Example 1 Comparative Example 1 Deionized water absorption ratio 1:22 1:10 saline solution uptake ratio 1:19 1:9 Urine absorption ratio 1:18 1:7 Blood sucking multiplier 1:18 1:8

[0080] The above-mentioned water absorption and liquid absorption ratio test methods are as follows: Take 1g of foam material after washing and drying in an oven, and completely immerse it in deionized water / saline / urine / blood. After different time periods, remove it, absorb the residual liquid droplets on the surface with filter paper, and weigh it immediately. It was found that the mass of the foam material no longer increased after immersion for 15 seconds. Therefore, the test method for saturated water (liquid) absorption ratio (g / g) is obtained: (g / g) = (m1-m0) / m0, where m0 is the mass of the dried foam, and m1 is the mass of the foam material after absorbing water for 15 seconds. The saturated deionized water absorption ratio, saline absorption ratio, urine absorption ratio, and blood absorption ratio were tested to be 22g / g, 19g / g, 17g / g, and 18g / g, respectively. Among them, saline, urine, and blood were simulated samples in the laboratory.

[0081] The absorption rate of deionized water is as high as 22g / g, indicating that the foam material itself has extremely high hydrophilicity and porosity, and excellent basic water absorption performance.

[0082] When absorbing complex liquids containing electrolytes (such as saline, urine, and blood), the foam material exhibits a slightly reduced absorption rate (19 g / g for saline, and 18 g / g for both urine and blood), but it still maintains a very high level. This is because salt ions in the liquid weaken the osmotic pressure of the polymer network, thereby reducing its absorbency—a common phenomenon in highly absorbent materials. However, the product of this invention maintains a high absorption rate even in saline solutions and complex bodily fluid environments, demonstrating its effectiveness and reliability in practical applications (hygiene products, medical dressings).

[0083] Referring to GB 15979-2024 "Hygienic Requirements for Disposable Sanitary Products", the antibacterial effects of the foam samples from the examples and comparative examples on Escherichia coli and Staphylococcus aureus were tested, and their antibacterial ability was evaluated by the antibacterial rate. The specific steps are as follows:

[0084] Fresh slant cultures of Escherichia coli and Staphylococcus aureus from generations 3 to 6 were collected, washed off the bacterial growth with 5 mL of broth, and diluted to a bacterial suspension concentration of 1.0 × 10³ CFU / mL to 1.0 × 10³ CFU / mL. 4 CFU / mL (calibrated using McFarland turbidimetric method or plate count method). Weigh 0.2 g ± 0.002 g of each of the examples and comparative examples into sterile test tubes. Slowly add the corresponding volume of bacterial suspension according to the sample aspiration volume, and let stand for 15 min to ensure complete absorption of the bacterial suspension by the sample without contact with the test tube wall. Gently tighten the test tube cap and incubate at 36℃ ± 1℃ for 24 h.

[0085] After cultivation, 0.85% physiological saline containing 2% Tween 80, equivalent to twice the volume of the aspirated solution, was added to both the example and comparative samples. The mixture was thoroughly shaken and then serially diluted 10-fold. At the selected dilution, 1 mL of bacterial culture was inoculated into two Petri dishes, and 15-20 mL of agar medium cooled to 40-45°C was poured in. The mixture was then mixed and allowed to stand. After the agar solidified, the Petri dishes were inverted and incubated at 36°C ± 1°C for 48 hours. Viable colony counting was then performed. The above experiment was repeated three times.

[0086] The formula for calculating the antibacterial rate is: Y = [(N c -N s ) / N c *100%, where Y is the antibacterial rate and N is the antibacterial rate. c The comparative average colony count after 24 hours of exposure is expressed in colony forming units per gram (CFU / g); N s The average colony count for the examples after 24 hours of contact is expressed in colony forming units per gram (CFU / g). The results are shown in Table 2.

[0087] Table 2

[0088] project Example 1 Comparative Example 1 Escherichia coli inhibition rate (%) 99.95 0 Staphylococcus aureus inhibition rate (%) 99.77 0

[0089] refer to Figure 5 Example 1 showed good inhibitory effects against both Escherichia coli and Staphylococcus aureus. Its antibacterial effect only slightly decreased as the number of days the sample was left to stand increased, while Comparative Example 1 showed no antibacterial effect.

[0090] Combining Example 1 and Comparative Example 1, it can be demonstrated that the addition of hydrophobically modified pn heterojunction nanoparticles can improve the stability of Span 80, thereby increasing the uniformity of the pores and further enhancing the water absorption of the foam material. Simultaneously, the photocatalytic antibacterial ability imparted by the heterojunction nanoparticles can destroy bacterial structures through photogenerated free radicals in the presence of light, and release trace amounts of ions in the absence of light, providing the foam material with a significant and long-lasting antibacterial function.

[0091] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A highly absorbent antibacterial polyacrylate foam material, characterized in that, The foam material is formed by UV-initiated polymerization of a water-in-oil Pickering emulsion. The Pickering emulsion comprises an oil phase and an aqueous phase. The oil phase comprises the following raw materials: acrylate monomers, crosslinking agents, photoinitiators, nonionic emulsifiers, and hydrophobically modified pn heterojunction nanoparticles. The aqueous phase comprises deionized water and an electrolyte. The mass ratio of the aqueous phase to the oil phase is (10-36):

1. The hydrophobically modified pn heterojunction nanoparticles are any one of the following: a heterojunction composed of Cu2O and ZnO, a heterojunction composed of TiO2 and ZnO, or a heterojunction composed of Cu2O and TiO2.

2. The highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, The foam material has an absorption rate of ≥22 times for deionized water and ≥19 times for physiological saline.

3. The highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, The acrylate monomers include isooctyl acrylate, butyl acrylate, and hydroxyethyl acrylate.

4. The highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, The aqueous phase also contains 0.1%-1% by mass of acrylic acid and / or sodium acrylate.

5. The highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, The electrolyte is CaCl2.

6. The highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, The nonionic emulsifier is Span 80.

7. The method for preparing a highly absorbent antibacterial polyacrylate foam material according to claim 1, characterized in that, Includes the following steps: S1. Preparation of oil phase: The raw materials for oil phase are ultrasonically mixed and stirred evenly to obtain the oil phase; S2. Preparation of aqueous phase: Mix all raw materials for aqueous phase and stir evenly to obtain aqueous phase; S3. Under high-speed stirring conditions, the aqueous phase obtained in step S2 is gradually added dropwise to the oil phase to form a water-in-oil Pickering emulsion. S4. The Pickering emulsion is irradiated under ultraviolet light to initiate a polymerization reaction and form a porous foam preform. S5. The porous foam preform obtained in step S4 is sequentially washed, dried and hydrophilic post-treated to obtain a highly absorbent antibacterial polyacrylate foam material.

8. The method for preparing a highly absorbent antibacterial polyacrylate foam material according to claim 7, characterized in that, The speed of the high-speed stirring condition is 800-2000 rpm.

9. The method for preparing a highly absorbent antibacterial polyacrylate foam material according to claim 7, characterized in that, In step S5, the hydrophilic post-treatment is as follows: the dried foam material is immersed in sodium alginate solution, and then removed, rolled, and dried.

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