A preparation method of high-strength antibacterial acrylic material

Abstract

The present invention relates to the technical field of polymer materials, and specifically to a method for preparing a high-strength antibacterial acrylic material. The method comprises the following steps: preparation of antibacterial nanocellulose; glycyrrhizic acid-modified antibacterial nanocellulose; and preparation of a composite of antibacterial cellulose-PMMA and polymethyl methacrylate. The present invention uses antibacterial nanocellulose as a matrix, reacts hydroxyl groups with α-dibromopropionyl bromide, and then initiates the polymerization of methyl methacrylate, thereby preparing antibacterial cellulose-PMMA. Since cellulose has a polymer structure, it has good mechanical strength and rigidity. By being connected to PMMA, it can also have good compatibility with acrylic materials. When co-polymerized with methyl methacrylate, nano-scale cellulose can be evenly distributed in the acrylic matrix. In summary, the mechanical properties and antibacterial properties of acrylic materials can be significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a method for preparing a high-strength antibacterial acrylic material. Background Art

[0002] Acrylic, also known as polymethyl methacrylate (PMMA), is an important transparent polymer material widely used in architecture, advertising, transportation, medicine, lighting and other fields. Acrylic has many excellent properties, including high light transmittance, high toughness, and high resistance to fragmentation, which has led to an increasing demand for acrylic materials in various fields.

[0003] Acrylic materials are commonly used in the preparation of display screens, sports equipment covers, isolation fences, and bathroom toilets. These items are often placed in places with high traffic, such as gyms, stadiums, and public restrooms. These places are easily touched by people and may cause cross-infection. To avoid this situation, the antibacterial properties of acrylic materials are particularly important. Existing methods of imparting antibacterial properties to acrylic materials almost all involve adding antibacterial agents during the preparation process. These antibacterial agents are mainly inorganic powders such as nanosilver and silver-loaded composite materials. They have poor compatibility with polymethyl methacrylate and easily migrate and aggregate in polymethyl methacrylate, resulting in uneven distribution and affecting product quality. In addition, in order to make acrylic materials more durable in these places with high traffic, the strength and impact resistance of acrylic materials are also crucial. Summary of the Invention

[0004] In order to solve the above technical defects, the present invention has developed a method for preparing a high-strength antibacterial acrylic material. The prepared acrylic material not only has excellent antibacterial properties, but also has high mechanical strength and strong durability.

[0005] A method for preparing a high-strength antibacterial acrylic material comprises the following steps:

[0006] S1: Preparation of antibacterial nanocellulose

[0007] Copper hydroxide and ammonia water are mixed, thiourea and cellulose pulp are added, and the mixture is stirred to obtain a copper ammonia cellulose solution. A polyethylene oxide aqueous solution is prepared and mixed with the copper ammonia cellulose solution, subjected to ultrasonic treatment, and then subjected to electrospinning. The resulting cellulose film layer is scraped off, collected, and dried to obtain antibacterial nanocellulose.

[0008] S2: Glycyrrhizic acid-modified antibacterial nanocellulose

[0009] The ion exchange resin and tetrabutylammonium hydroxide are mixed and stirred, and then filtered and washed to obtain tetrabutylammonium modified resin; disodium glycyrrhizate is dissolved in deionized water, the tetrabutylammonium modified resin is added, stirred, and then filtered and freeze-dried to obtain tetrabutylammonium modified glycyrrhizic acid; the tetrabutylammonium modified glycyrrhizic acid is dissolved in N,N-dimethylformamide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added and stirred, and then an antibacterial nanocellulose solution prepared by mixing antibacterial nanocellulose and N,N-dimethylformamide is added, the mixture is sealed and shaken, and after the temperature reaction, the reaction solution is dialyzed against deionized water, centrifuged, and freeze-dried to obtain glycyrrhizic acid modified nanocellulose;

[0010] S3: Preparation of antibacterial cellulose-PMMA and polymethyl methacrylate composites

[0011] Glycyrrhizic acid-modified nanocellulose is dissolved in N,N-dimethylformamide, and α-dibromopropionyl bromide is added. The mixture is stirred, washed, and then centrifuged to obtain brominated nanocellulose. Under a nitrogen atmosphere, brominated nanocellulose, methyl methacrylate, and pentamethyldipropylenetriamine are dissolved in N,N-dimethylformamide, and CuBr is added to seal the reaction. The mixture is then taken out and added with deionized water for centrifugal separation. The supernatant is collected and freeze-dried to obtain antibacterial cellulose-PMMA. Methyl methacrylate and dibenzoyl peroxide are pre-polymerized by heating and stirring, and then antibacterial cellulose-PMMA, comonomer, cross-linking agent, zinc stearate, and dioctyl phosphate are added. The mixture is heated and stirred for polymerization, and then degassing and hot pressing are performed to obtain a high-strength antibacterial acrylic material.

[0012] Furthermore, step S1 of preparing antibacterial nanocellulose comprises the following steps:

[0013] S1.1: 4-6 parts by mass of copper hydroxide are placed in a container, 80-100 parts by mass of aqueous ammonia are added, and magnetic stirring is performed at a stirring speed of 200-250 rpm for 10-15 minutes to obtain a copper ammonia solution. 2-3 parts by mass of thiourea and 6-8 parts by mass of cellulose pulp are then added, and magnetic stirring is continued at a stirring speed of 300-400 rpm for 20-25 minutes to obtain a copper ammonia cellulose solution;

[0014] S1.2: Mix 2-3 parts by mass of polyethylene oxide and 95-100 parts by mass of deionized water in a container and stir until the polyethylene oxide is completely dissolved to obtain a polyethylene oxide aqueous solution. The cuprammonium cellulose solution prepared in step S1.1 and the polyethylene oxide aqueous solution are mixed in a mass ratio of 1:(1-2), and then placed in an ultrasonic disperser. The ultrasonic frequency is adjusted to 25-30 kHz and ultrasonic treatment is performed for 8-10 minutes to obtain an antibacterial cellulose spinning solution.

[0015] S1.3: Place the antibacterial cellulose spinning solution in the syringe of the electrospinning machine, adjust the distance between the syringe needle and the receiving plate to 1.5-2 cm, and the relative humidity of the environment to 40-60%. Then start the electrospinning machine, and perform electrospinning at a voltage of 15-20 kV and a syringe pushing speed of 15-20 μL / min. Then scrape and collect the cellulose film layer formed on the receiving plate, and place it in an oven at 60-65°C to dry for 2-2.5 hours to obtain antibacterial nanocellulose.

[0016] Furthermore, step S2 of glycyrrhizic acid-modified antibacterial nanocellulose comprises the following steps:

[0017] S2.1: Place an ion exchange resin and 1.2-1.5 mol / L tetrabutylammonium hydroxide in a container at a solid-to-liquid ratio of 1:(1.8-2), stir for 3-3.5 hours, and then filter. Rinse the filtered solid 3-4 times with deionized water to obtain a tetrabutylammonium-modified resin. Place 1-1.5 parts by mass of disodium glycyrrhizate in a container, add 80-100 parts by mass of deionized water, and stir until the disodium glycyrrhizate is completely dissolved. Then, add 35-40 parts by mass of tetrabutylammonium-modified resin, stir for 10-12 hours, and then filter to obtain a filtrate. Place the filtrate in a freeze dryer for freeze-drying to obtain tetrabutylammonium-modified glycyrrhizic acid.

[0018] S2.2: 0.4-0.6 parts by mass of antibacterial nanocellulose and 15-20 parts by mass of N, N-dimethylformamide are mixed in a container and magnetically stirred at a stirring speed of 450-500 rpm for 10-20 minutes to obtain an antibacterial nanocellulose solution. Under a nitrogen atmosphere, 0.2-0.3 parts by mass of tetrabutylammonium-modified glycyrrhizic acid and 12-15 parts by mass of N, N-dimethylformamide are mixed in a container and stirred until the tetrabutylammonium-modified glycyrrhizic acid is completely dissolved. Then, 0.4-0.5 parts by mass of 1-ethyl- (3-dimethylaminopropyl) carbodiimide and 0.3-0.32 parts by mass of N-hydroxysuccinimide were stirred for 30-35 minutes, and then the antibacterial nanocellulose solution was added. After sealing, the mixture was shaken up and down for 6-8 minutes, and then heated to 40-45°C and kept warm for 20-24 hours to obtain a reaction solution. The reaction solution was placed in a dialysis bag and dialyzed against deionized water for 45-50 hours. The solution was then placed in a centrifuge and centrifuged at 4000-4500 rpm for 3-4 minutes. The supernatant was separated and collected for freeze-drying to obtain glycyrrhizic acid-modified nanocellulose.

[0019] Furthermore, step S3 is to prepare the antibacterial cellulose-PMMA and polymethyl methacrylate composite, comprising the following steps:

[0020] S3.1: 0.6-0.8 parts by weight of glycyrrhizic acid-modified nanocellulose and 25-30 parts by weight of N,N-dimethylformamide are mixed and magnetically stirred for 15-20 minutes, followed by the addition of 0.1-0.2 parts by weight of α-dibromopropionyl bromide. The mixture is stirred for 20-24 hours, and then washed with 120-150 parts by weight of deionized water. The supernatant is collected by centrifugation and lyophilized to obtain brominated nanocellulose;

[0021] S3.2: Add 0.6-0.8 parts by mass of brominated nanocellulose, 2-2.5 parts by mass of methyl methacrylate, and 0.4-0.5 parts by mass of pentamethyldipropylenetriamine to a container, then add 50-60 parts by mass of N,N-dimethylformamide under a nitrogen atmosphere and stir until the solid is completely dissolved, then add 0.4-0.45 parts by mass of CuBr and seal the container, heat to 60-65°C and evacuate to a vacuum, maintain the vacuum for 25-30 minutes, then introduce nitrogen to restore the pressure in the container to one atmosphere, keep warm for 22-24 hours, then remove and add 1-2 times the volume of deionized water, centrifuge to collect the supernatant, and freeze-dry to obtain antibacterial cellulose-PMMA;

[0022] S3.3: Mix 90-100 parts by mass of methyl methacrylate and 0.3-0.5 parts by mass of dibenzoyl peroxide, stir at 50-60°C at a stirring speed of 150-200 rpm for 10-15 minutes, then add 8-10 parts by mass of antibacterial cellulose-PMMA, 15-20 parts by mass of comonomer, 2-4 parts by mass of cross-linking agent, 1-3 parts by mass of zinc stearate and 1-1.5 parts by mass of dioctyl phosphate, heat to 80-85°C, continue stirring at a stirring speed of 120-150 rpm for 1-1.5 hours, cool down and perform vacuum degassing, then inject into a tempered glass mold for hot pressing molding, the hot pressing temperature is 120-150°C, the hot pressing pressure is 40-60KPa, and the heat and pressure are maintained for 2-3 hours to obtain a high-strength antibacterial acrylic material.

[0023] Furthermore, the mass fraction of the ammonia water in step S1.1 is 20-25%.

[0024] Furthermore, in step S1.1, the degree of polymerization of the cellulose pulp is 1000-1100, and the α-cellulose content of the cellulose pulp is 90-95%.

[0025] Furthermore, the ion exchange resin in step S2.1 is the strongly acidic cation exchange resin Amberlyst 15.

[0026] Furthermore, the cutoff of the dialysis bag in step S2.2 is 1-1.2 kDa.

[0027] Furthermore, the comonomer in step S3.3 consists of methacrylamide and allyl methacrylate in a molar ratio of 1:(1-2).

[0028] Furthermore, the cross-linking agent in step S3.3 is butanediol dipropylene glycol.

[0029] The beneficial effects are as follows: 1. The present invention prepares a copper ammonia solution by mixing copper hydroxide and ammonia water, then dissolves cellulose pulp to obtain a copper ammonia cellulose solution, and then prepares a polyethylene oxide aqueous solution and the copper ammonia cellulose solution, mixes them by ultrasound, and performs electrostatic spinning. During this process, copper ions with excellent antibacterial properties can coordinate with hydroxyl groups to prepare antibacterial nanocellulose. Subsequently, the antibacterial nanocellulose is used as a matrix, and the hydroxyl groups react with α-dibromopropionyl bromide, and then the polymerization of methyl methacrylate is initiated by atom transfer radical polymerization to prepare antibacterial cellulose-PMMA. Since cellulose has a polymer structure, it itself has good mechanical strength and rigidity. By connecting to PMMA, it can also have good compatibility with acrylic materials. When blended and polymerized with methyl methacrylate, nano-scale cellulose can be evenly distributed in the acrylic matrix. In summary, the mechanical properties and antibacterial properties of the acrylic material can be significantly improved.

[0030] 2. The present invention first performs lipophilic modification on glycyrrhizic acid by tetrabutylammonium hydroxide so that it can be better dissolved in N,N-dimethylformamide and can fully carry out subsequent reactions. Then, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added for mediation, and glycyrrhizic acid is introduced into the antibacterial nanocellulose through a carboxylamino coupling reaction. Glycyrrhizic acid has the ability to scavenge oxygen free radicals and inhibit bacterial metabolism. It can not only provide antioxidant capacity for antibacterial nanocellulose, but also reduce the oxidation of free radicals in the system during subsequent polymerization with MMA, thereby improving the stability of the polymerization, improving the mechanical properties of the acrylic material, and further enhancing the antibacterial properties of the acrylic material.

[0031] 3. The present invention adds thiourea during the process of dissolving cellulose pulp in a copper ammonia solution, which not only ensures that cellulose is not oxidized and degraded, but also allows thiourea to react with NH3 in ammonia water to generate thiosemicarbazide, which can form a complex with copper ions to enhance the antibacterial activity of copper ions. The formed complex can better adhere to cellulose, further enhancing the antibacterial properties and antibacterial stability of the acrylic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of the preparation method of the high-strength antibacterial acrylic material used in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0034] A method for preparing a high-strength antibacterial acrylic material, such as Figure 1 As shown, the following steps are included:

[0035] S1: Preparation of antibacterial nanocellulose

[0036] S1.1: 4 parts by mass of copper hydroxide are placed in a container, 80 parts by mass of 20% aqueous ammonia are added, and the mixture is magnetically stirred at 200 rpm for 10 minutes to obtain a copper ammonia solution. 2 parts by mass of thiourea and 6 parts by mass of cellulose pulp are then added, wherein the cellulose pulp has a degree of polymerization of 1000 and an α-cellulose content of 90%. The mixture is magnetically stirred at 300 rpm for 20 minutes to obtain a copper ammonia cellulose solution.

[0037] S1.2: Mix 2 parts by mass of polyethylene oxide and 95 parts by mass of deionized water in a container and stir until the polyethylene oxide is completely dissolved to obtain a polyethylene oxide aqueous solution. The cuprammonium cellulose solution prepared in step S1.1 and the polyethylene oxide aqueous solution are mixed in a mass ratio of 1:1, and then placed in an ultrasonic disperser at an ultrasonic frequency of 25 kHz. Ultrasonic treatment is performed for 8 minutes to obtain an antibacterial cellulose spinning solution.

[0038] S1.3: Place the antibacterial cellulose spinning solution in the syringe of the electrospinning machine, adjust the distance between the syringe needle and the receiving plate to 1.5 cm, and the relative humidity of the environment to 40%. Then start the electrospinning machine and perform electrospinning at a voltage of 15 kV and a syringe pushing speed of 15 μL / min. Then, scrape and collect the cellulose film layer formed on the receiving plate, and place it in an oven at 60°C to dry for 2 hours to obtain antibacterial nanocellulose.

[0039] S2: Glycyrrhizic acid modified antibacterial nanocellulose

[0040] S2.1: A strong acidic cation exchange resin Amberlyst 15 and 1.2 mol / L tetrabutylammonium hydroxide were placed in a container at a solid-liquid ratio of 1:1.8, stirred for 3 hours, and then filtered. The filtered solid was rinsed three times with deionized water to obtain a tetrabutylammonium-modified resin. 1 part by mass of disodium glycyrrhizate was placed in a container, 80 parts by mass of deionized water was added, and the mixture was stirred until the disodium glycyrrhizate was completely dissolved. Then, 35 parts by mass of the tetrabutylammonium-modified resin was added. After stirring for 10 hours, the mixture was filtered to obtain a filtrate. The filtrate was placed in a freeze dryer and freeze-dried to obtain tetrabutylammonium-modified glycyrrhizic acid.

[0041] S2.2: 0.4 parts by mass of antibacterial nanocellulose and 15 parts by mass of N, N-dimethylformamide were mixed in a container and magnetically stirred at a stirring speed of 450 rpm for 10 minutes to obtain an antibacterial nanocellulose solution. Under a nitrogen atmosphere, 0.2 parts by mass of tetrabutylammonium-modified glycyrrhizic acid and 12 parts by mass of N, N-dimethylformamide were mixed in a container and stirred until the tetrabutylammonium-modified glycyrrhizic acid was completely dissolved. Then, 0.4 parts by mass of 1-ethyl-(3-dimethylformamide) was added. methylaminopropyl)carbodiimide and 0.3 parts by mass of N-hydroxysuccinimide, stirred for 30 minutes, then added with the antibacterial nanocellulose solution, sealed and oscillated up and down for 6 minutes, then heated to 40°C and kept warm for 20 hours to obtain a reaction solution, and the reaction solution was placed in a dialysis bag with a cutoff of 1 kDa and dialyzed against deionized water for 45 hours, then placed in a centrifuge and centrifuged at 4000 rpm for 3 minutes, the supernatant was separated and collected, and freeze-dried to obtain glycyrrhizic acid-modified nanocellulose.

[0042] S3: Preparation of antibacterial cellulose-PMMA and polymethyl methacrylate composites

[0043] S3.1: 0.6 parts by mass of glycyrrhizic acid-modified nanocellulose and 25 parts by mass of N,N-dimethylformamide were mixed and magnetically stirred for 15 minutes, followed by the addition of 0.1 parts by mass of α-dibromopropionyl bromide. The mixture was stirred for 20 hours and then washed with 120 parts by mass of deionized water. The supernatant was collected by centrifugation and lyophilized to obtain brominated nanocellulose.

[0044] S3.2: Add 0.6 parts by mass of brominated nanocellulose, 2 parts by mass of methyl methacrylate, and 0.4 parts by mass of pentamethyldipropylenetriamine to a container, then add 50 parts by mass of N,N-dimethylformamide under a nitrogen atmosphere and stir until the solid is completely dissolved, then add 0.4 parts by mass of CuBr and seal the container, heat to 60°C and evacuate to a vacuum, maintain the vacuum for 25 minutes, then introduce nitrogen to restore the pressure in the container to 1 atmosphere, keep warm for 22 hours, then remove and add 1 volume of deionized water, centrifuge to collect the supernatant, and freeze-dry to obtain antibacterial cellulose-PMMA;

[0045] S3.3: Mix 90 parts by mass of methyl methacrylate and 0.3 parts by mass of dibenzoyl peroxide, stir at 50°C at a stirring speed of 150 rpm for 10 minutes, then add 8 parts by mass of antibacterial cellulose-PMMA, 15 parts by mass of a comonomer, the comonomer consists of methacrylamide and allyl methacrylate in a molar ratio of 1:1, 2 parts by mass of butanediol dipropylene glycol, 1 part by mass of zinc stearate and 1 part by mass of dioctyl phosphate, heat to 80°C, continue stirring at a stirring speed of 120 rpm for 1 hour, cool down and perform vacuum degassing, then inject into a tempered glass mold for hot pressing molding, the hot pressing temperature is 120°C, the hot pressing pressure is 40 KPa, and the heat and pressure are maintained for 2 hours to obtain a high-strength antibacterial acrylic material. Example 2

[0046] A method for preparing a high-strength antibacterial acrylic material, such as Figure 1 As shown, the following steps are included:

[0047] S1: Preparation of antibacterial nanocellulose

[0048] S1.1: 6 parts by mass of copper hydroxide are placed in a container, 100 parts by mass of 20% aqueous ammonia is added, and the mixture is magnetically stirred at 200 rpm for 10 minutes to obtain a copper ammonia solution. 3 parts by mass of thiourea and 8 parts by mass of cellulose pulp are then added, wherein the cellulose pulp has a degree of polymerization of 1000 and an α-cellulose content of 90%. The mixture is magnetically stirred at 300 rpm for 20 minutes to obtain a copper ammonia cellulose solution.

[0049] S1.2: 3 parts by mass of polyethylene oxide and 100 parts by mass of deionized water are mixed in a container and stirred until the polyethylene oxide is completely dissolved to obtain a polyethylene oxide aqueous solution. The cuprammonium cellulose solution prepared in step S1.1 and the polyethylene oxide aqueous solution are mixed in a mass ratio of 1:2, and then placed in an ultrasonic disperser at an ultrasonic frequency of 25 kHz. Ultrasonic treatment is performed for 8 minutes to obtain an antibacterial cellulose spinning solution.

[0050] S1.3: Place the antibacterial cellulose spinning solution in the syringe of the electrospinning machine, adjust the distance between the syringe needle and the receiving plate to 1.5 cm, and the relative humidity of the environment to 40%. Then start the electrospinning machine and perform electrospinning at a voltage of 15 kV and a syringe pushing speed of 15 μL / min. Then, scrape and collect the cellulose film layer formed on the receiving plate, and place it in an oven at 60°C to dry for 2 hours to obtain antibacterial nanocellulose.

[0051] S2: Glycyrrhizic acid-modified antibacterial nanocellulose

[0052] S2.1: Strong acidic cation exchange resin Amberlyst 15 and 1.2 mol / L tetrabutylammonium hydroxide were placed in a container at a solid-liquid ratio of 1:2, stirred for 3 hours, and then filtered. The filtered solid was rinsed three times with deionized water to obtain a tetrabutylammonium-modified resin. 1.5 parts by mass of disodium glycyrrhizate was placed in a container, 100 parts by mass of deionized water was added, and the mixture was stirred until the disodium glycyrrhizate was completely dissolved. Then, 40 parts by mass of the tetrabutylammonium-modified resin was added, and the mixture was stirred for 10 hours, and then filtered to obtain a filtrate. The filtrate was placed in a freeze dryer and freeze-dried to obtain tetrabutylammonium-modified glycyrrhizic acid.

[0053] S2.2: 0.6 parts by mass of antibacterial nanocellulose and 20 parts by mass of N, N-dimethylformamide were mixed in a container and magnetically stirred at a stirring speed of 450 rpm for 10 minutes to obtain an antibacterial nanocellulose solution. Under a nitrogen atmosphere, 0.3 parts by mass of tetrabutylammonium-modified glycyrrhizic acid and 15 parts by mass of N, N-dimethylformamide were mixed in a container and stirred until the tetrabutylammonium-modified glycyrrhizic acid was completely dissolved. Then, 0.5 parts by mass of 1-ethyl-(3-dimethylformamide) was added. The mixture was stirred for 30 minutes, and then the antibacterial nanocellulose solution was added. The mixture was sealed and shaken up and down for 6 minutes, and then heated to 40°C and kept warm for 20 hours to obtain a reaction solution. The reaction solution was placed in a dialysis bag with a cutoff of 1 kDa and dialyzed against deionized water for 45 hours. The solution was then placed in a centrifuge and centrifuged at 4000 rpm for 3 minutes. The supernatant was separated and collected, and freeze-dried to obtain glycyrrhizic acid-modified nanocellulose.

[0054] S3: Preparation of antibacterial cellulose-PMMA and polymethyl methacrylate composites

[0055] S3.1: 0.6 parts by mass of glycyrrhizic acid-modified nanocellulose and 25 parts by mass of N,N-dimethylformamide were mixed and magnetically stirred for 15 minutes, followed by the addition of 0.1 parts by mass of α-dibromopropionyl bromide. The mixture was stirred for 20 hours and then washed with 120 parts by mass of deionized water. The supernatant was collected by centrifugation and lyophilized to obtain brominated nanocellulose.

[0056] S3.2: Add 0.8 parts by mass of brominated nanocellulose, 2.5 parts by mass of methyl methacrylate, and 0.5 parts by mass of pentamethyldipropylenetriamine to a container, then add 60 parts by mass of N,N-dimethylformamide under a nitrogen atmosphere and stir until the solid is completely dissolved, then add 0.45 parts by mass of CuBr and seal the container, heat to 60°C and evacuate to a vacuum, maintain the vacuum for 25 minutes, then introduce nitrogen to restore the pressure in the container to 1 atmosphere, keep warm for 22 hours, then remove and add 1 volume of deionized water, centrifuge to collect the supernatant, and freeze-dry to obtain antibacterial cellulose-PMMA;

[0057] S3.3: Mix 100 parts by mass of methyl methacrylate and 0.5 parts by mass of dibenzoyl peroxide, stir at 50°C at a stirring speed of 150 rpm for 10 minutes, then add 10 parts by mass of antibacterial cellulose-PMMA, 20 parts by mass of a comonomer, the comonomer consists of methacrylamide and allyl methacrylate with a molar ratio of 1:2, 4 parts by mass of butanediol dipropylene glycol, 3 parts by mass of zinc stearate and 1.5 parts by mass of dioctyl phosphate, raise the temperature to 80°C, continue stirring at a stirring speed of 120 rpm for 1 hour, cool down and perform vacuum degassing, then inject into a tempered glass mold for hot pressing molding, the hot pressing temperature is 120°C, the hot pressing pressure is 40 KPa, and the heat and pressure are maintained for 2 hours to obtain a high-strength antibacterial acrylic material. Example 3

[0058] A method for preparing a high-strength antibacterial acrylic material, such as Figure 1 As shown, the following steps are included:

[0059] S1: Preparation of antibacterial nanocellulose

[0060] S1.1: 4 parts by mass of copper hydroxide are placed in a container, 80 parts by mass of 25% aqueous ammonia are added, and the mixture is magnetically stirred at 250 rpm for 15 minutes to obtain a copper ammonia solution. 2 parts by mass of thiourea and 6 parts by mass of cellulose pulp having a degree of polymerization of 1100 and an α-cellulose content of 95% are then added, and magnetic stirring is continued at 400 rpm for 25 minutes to obtain a copper ammonia cellulose solution.

[0061] S1.2: Mix 2 parts by mass of polyethylene oxide and 95 parts by mass of deionized water in a container and stir until the polyethylene oxide is completely dissolved to obtain a polyethylene oxide aqueous solution. The cuprammonium cellulose solution prepared in step S1.1 and the polyethylene oxide aqueous solution are mixed in a mass ratio of 1:1. The mixture is then placed in an ultrasonic disperser and ultrasonicated at a frequency of 30 kHz for 10 minutes to obtain an antibacterial cellulose spinning solution.

[0062] S1.3: Place the antibacterial cellulose spinning solution in the syringe of the electrospinning machine, adjust the distance between the syringe needle and the receiving plate to 2 cm, and the relative humidity of the environment to 60%. Then start the electrospinning machine and perform electrospinning at a voltage of 20 kV and a syringe pushing speed of 20 μL / min. Then, scrape and collect the cellulose film layer formed on the receiving plate, and place it in an oven at 65°C to dry for 2.5 hours to obtain antibacterial nanocellulose.

[0063] S2: Glycyrrhizic acid modified antibacterial nanocellulose

[0064] S2.1: Strong acidic cation exchange resin Amberlyst 15 and 1.5 mol / L tetrabutylammonium hydroxide were placed in a container at a solid-liquid ratio of 1:1.8, stirred for 3.5 hours, and then filtered. The filtered solid was rinsed four times with deionized water to obtain a tetrabutylammonium-modified resin. 1 part by mass of disodium glycyrrhizate was placed in a container, 80 parts by mass of deionized water was added, and the mixture was stirred until the disodium glycyrrhizate was completely dissolved. Then, 35 parts by mass of the tetrabutylammonium-modified resin was added, and the mixture was stirred for 12 hours and then filtered to obtain a filtrate. The filtrate was placed in a freeze dryer and freeze-dried to obtain tetrabutylammonium-modified glycyrrhizic acid.

[0065] S2.2: 0.4 parts by mass of antibacterial nanocellulose and 15 parts by mass of N, N-dimethylformamide were mixed in a container and magnetically stirred at a stirring speed of 500 rpm for 20 minutes to obtain an antibacterial nanocellulose solution. Under a nitrogen atmosphere, 0.2 parts by mass of tetrabutylammonium-modified glycyrrhizic acid and 12 parts by mass of N, N-dimethylformamide were mixed in a container and stirred until the tetrabutylammonium-modified glycyrrhizic acid was completely dissolved. Then, 0.4 parts by mass of 1-ethyl-(3-dimethylformamide) was added. The mixture was stirred for 35 minutes, and then the antibacterial nanocellulose solution was added. The mixture was sealed and shaken up and down for 8 minutes, and then heated to 45°C and kept warm for 24 hours to obtain a reaction solution. The reaction solution was placed in a dialysis bag with a cutoff of 1.2 kDa and dialyzed against deionized water for 50 hours. The solution was then placed in a centrifuge and centrifuged at 4500 rpm for 4 minutes. The supernatant was separated and collected, and freeze-dried to obtain glycyrrhizic acid-modified nanocellulose.

[0066] S3: Preparation of antibacterial cellulose-PMMA and polymethyl methacrylate composites

[0067] S3.1: 0.6 parts by mass of glycyrrhizic acid-modified nanocellulose and 25 parts by mass of N,N-dimethylformamide were mixed and magnetically stirred for 20 minutes, followed by the addition of 0.1 parts by mass of α-dibromopropionyl bromide. The mixture was stirred for 24 hours and then washed with 120 parts by mass of deionized water. The supernatant was collected by centrifugation and lyophilized to obtain brominated nanocellulose.

[0068] S3.2: Add 0.6 parts by mass of brominated nanocellulose, 2 parts by mass of methyl methacrylate, and 0.4 parts by mass of pentamethyldipropylenetriamine to a container, then add 50 parts by mass of N,N-dimethylformamide under a nitrogen atmosphere and stir until the solid is completely dissolved, then add 0.4 parts by mass of CuBr and seal the container, heat to 65°C and evacuate to a vacuum, maintain the vacuum for 30 minutes, then introduce nitrogen to restore the pressure in the container to 1 atmosphere, keep warm for 24 hours, then remove and add 2 times the volume of deionized water, centrifuge to collect the supernatant, and freeze-dry to obtain antibacterial cellulose-PMMA;

[0069] S3.3: Mix 90 parts by mass of methyl methacrylate and 0.3 parts by mass of dibenzoyl peroxide, stir at 60°C at a stirring speed of 200 rpm for 15 minutes, then add 8 parts by mass of antibacterial cellulose-PMMA, 15 parts by mass of a comonomer, the comonomer consists of methacrylamide and allyl methacrylate in a molar ratio of 1:1, 2 parts by mass of butanediol dipropylene glycol, 1 part by mass of zinc stearate and 1 part by mass of dioctyl phosphate, heat to 85°C, continue stirring at a stirring speed of 150 rpm for 1.5 hours, cool down and perform vacuum degassing, then inject into a tempered glass mold for hot pressing molding, the hot pressing temperature is 150°C, the hot pressing pressure is 60 KPa, and the heat and pressure are maintained for 3 hours to obtain a high-strength antibacterial acrylic material.

[0070] Comparative Example 1

[0071] Compared with Example 1, the difference of Comparative Example 1 is that Comparative Example 1 removes step S3.1 and step S3.2, replaces the antibacterial cellulose-PMMA in step S3.3 with glycyrrhizic acid-modified nanocellulose of equal mass, and the remaining steps are the same as in Example 1. The obtained high-strength antibacterial acrylic material is recorded as Comparative Example 1.

[0072] Comparative Example 2

[0073] Compared with Example 1, the difference of Comparative Example 2 is that step S2 is removed in Comparative Example 2, and the glycyrrhizic acid-modified nanocellulose in step S3.1 is replaced with antibacterial nanocellulose of equal mass. The remaining steps are the same as those in Example 1. The obtained high-strength antibacterial acrylic material is recorded as Comparative Example 2.

[0074] Comparative Example 3

[0075] Compared with Example 1, the difference of Comparative Example 3 is that the thiourea in step S.1 is replaced by an equal mass of sodium sulfite in Comparative Example 3, and the remaining steps are the same as those in Example 1. The obtained high-strength antibacterial acrylic material is recorded as Comparative Example 3.

[0076] Experiment 1: The high-strength antibacterial acrylic materials prepared in Examples 1-3 and Comparative Examples 1-2 were taken as samples, and their tensile strength was tested on a universal testing machine according to GB / T1040-92 standard, and their impact strength was tested on a pendulum impact tester according to GB / T1843-1996 standard. 8 samples were taken for each example and comparative example, and the average value of the test was taken as the test result, as shown in Table 1.

[0077] Table 1: Mechanical properties of high-strength antibacterial acrylic materials

[0078]

[0079] As can be seen from the data of Examples 1-3 and Comparative Examples 1-2 in Table 1, the tensile strength and impact strength of the examples are higher than those of Comparative Examples 1-2. This proves that using antibacterial nanocellulose as a matrix, reacting with α-dibromopropionyl bromide through hydroxyl groups, and then initiating polymerization of methyl methacrylate by atom transfer radical polymerization, and accessing PMMA on the glycyrrhizic acid-modified nanocellulose can improve the compatibility of glycyrrhizic acid-modified nanocellulose with acrylic materials, making it evenly distributed in the acrylic matrix, thereby improving the mechanical properties of the acrylic material;

[0080] It can also be proved that the modification of antibacterial nanocellulose with glycyrrhizic acid can provide antioxidant capacity for antibacterial nanocellulose, reduce the oxidation of free radicals in the system during subsequent polymerization with MMA, improve the stability of polymerization, and improve the mechanical properties of acrylic materials.

[0081] Experiment 2: Take the high-strength antibacterial acrylic materials prepared in Examples 1-3 and Comparative Examples 1-3 as samples, sterilize their surfaces with ultraviolet light for 30 minutes, and then prepare 100 μL of Escherichia coli suspension (10 8 CFU / mL) and 100 μL of Staphylococcus aureus suspension (1×10 8CFU / mL), the plate count method was used to determine the number of viable bacteria in 100 μL of Escherichia coli suspension and 100 μL of Staphylococcus aureus suspension, recorded as N0, and then the solution was aspirated and smeared on the sample surface with an area of ​​1 cm × 1 cm. The solution was incubated for 1 hour under the conditions of relative humidity not less than 90% and 37°C light. The bacterial solution on the sample surface was then resuspended with sterile physiological saline, and the number of viable bacteria was determined by the plate count method, recorded as N1. The inhibition rate was calculated as n% = (N0-N1) / N0×100%. The higher the inhibition rate, the better the antibacterial performance. Three parallel experiments were performed for each sample, and the average inhibition rate was taken, as shown in Table 2.

[0082] Table 2: Antibacterial rate of high-strength antibacterial acrylic materials

[0083]

[0084] It can be seen from the data of Example 1 and Comparative Example 1 in Table 2 that the antibacterial property of the acrylic material is reduced when the glycyrrhizic acid-modified nanocellulose is not brominated and then the brominated nanocellulose grafted PMMA is obtained to prepare the antibacterial cellulose-PMMA. This proves that the preparation of antibacterial cellulose-PMMA helps to disperse cellulose in the acrylic matrix and improve its antibacterial property.

[0085] It can be seen from the data of Example 2 and Comparative Example 2 that the antibacterial performance of the acrylic material is significantly reduced when glycyrrhizic acid is not used to modify the antibacterial nanocellulose. This proves that the antibacterial performance of the acrylic material can be improved by modifying the antibacterial nanocellulose with glycyrrhizic acid through the inhibitory ability of glycyrrhizic acid on bacterial metabolism.

[0086] From the data of Example 2 and Comparative Example 3, it can be seen that after thiourea is replaced with sodium sulfite in the process of dissolving cellulose in the copper ammonia solution, the antibacterial property of the acrylic material decreases. It can be proved that the addition of thiourea can improve the antibacterial activity of copper ions and further enhance the antibacterial property of the acrylic material.

[0087] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a high-strength antibacterial acrylic material, characterized in that: The following steps are involved: S1: Preparation of antibacterial nanocellulose Copper hydroxide and ammonia water are mixed, thiourea and cellulose pulp are added, and the mixture is stirred to obtain a copper ammonia cellulose solution. A polyethylene oxide aqueous solution is prepared and mixed with the copper ammonia cellulose solution, subjected to ultrasonic treatment, and then subjected to electrospinning. The resulting cellulose film layer is scraped off, collected, and dried to obtain antibacterial nanocellulose. S2: Glycyrrhizic acid modified antibacterial nanocellulose The ion exchange resin and tetrabutylammonium hydroxide are mixed and stirred, and then filtered and washed to obtain tetrabutylammonium modified resin; disodium glycyrrhizate is dissolved in deionized water, the tetrabutylammonium modified resin is added, stirred, and then filtered and freeze-dried to obtain tetrabutylammonium modified glycyrrhizic acid; the tetrabutylammonium modified glycyrrhizic acid is dissolved in N,N-dimethylformamide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added and stirred, and then an antibacterial nanocellulose solution prepared by mixing antibacterial nanocellulose and N,N-dimethylformamide is added, the mixture is sealed and shaken, and after the temperature reaction, the reaction solution is dialyzed against deionized water, centrifuged, and freeze-dried to obtain glycyrrhizic acid modified nanocellulose; S3: Preparation of antibacterial cellulose-PMMA and polymethyl methacrylate composites The glycyrrhizic acid-modified nanocellulose is dissolved in N,N-dimethylformamide, and α-dibromopropionyl bromide is added. The mixture is stirred, washed, and then centrifuged to obtain brominated nanocellulose. Under a nitrogen atmosphere, the brominated nanocellulose, methyl methacrylate, and pentamethyldipropylenetriamine are dissolved in N,N-dimethylformamide, and CuBr is added to seal the reaction. The mixture is then taken out and deionized water is added for centrifugal separation. The supernatant is collected and freeze-dried to obtain antibacterial cellulose-PMMA. 90-100 parts by mass of methyl methacrylate and 0.3-0.5 parts by mass of dibenzoyl peroxide are heated and stirred for prepolymerization. Then, 8-10 parts by mass of antibacterial cellulose-PMMA, 15-20 parts by mass of a comonomer, 2-4 parts by mass of a cross-linking agent, 1-3 parts by mass of zinc stearate, and 1-1.5 parts by mass of dioctyl phosphate are added. The mixture is heated and stirred for polymerization, and then degassing and hot pressing are performed to obtain a high-strength antibacterial acrylic material.

2. The method for preparing a high-strength antibacterial acrylic material according to claim 1, characterized in that: Step S1: Preparation of antibacterial nanocellulose, comprising the following steps: S1.1: 4-6 parts by mass of copper hydroxide are placed in a container, 80-100 parts by mass of aqueous ammonia are added, and magnetic stirring is performed at a stirring speed of 200-250 rpm for 10-15 minutes to obtain a copper ammonia solution. 2-3 parts by mass of thiourea and 6-8 parts by mass of cellulose pulp are then added, and magnetic stirring is continued at a stirring speed of 300-400 rpm for 20-25 minutes to obtain a copper ammonia cellulose solution; S1.2: Mix 2-3 parts by mass of polyethylene oxide and 95-100 parts by mass of deionized water in a container and stir until the polyethylene oxide is completely dissolved to obtain a polyethylene oxide aqueous solution. The cuprammonium cellulose solution prepared in step S1.1 and the polyethylene oxide aqueous solution are mixed in a mass ratio of 1:(1-2), and then placed in an ultrasonic disperser. The ultrasonic frequency is adjusted to 25-30 kHz and ultrasonic treatment is performed for 8-10 minutes to obtain an antibacterial cellulose spinning solution. S1.3: Place the antibacterial cellulose spinning solution in the syringe of the electrospinning machine, adjust the distance between the syringe needle and the receiving plate to 1.5-2 cm, and the relative humidity of the environment to 40-60%. Then start the electrospinning machine, and perform electrospinning at a voltage of 15-20 kV and a syringe pushing speed of 15-20 μL / min. Then scrape and collect the cellulose film layer formed on the receiving plate, and place it in an oven at 60-65°C to dry for 2-2.5 hours to obtain antibacterial nanocellulose.

3. The method for preparing a high-strength antibacterial acrylic material according to claim 2, characterized in that: Step S2, wherein glycyrrhizic acid is used to modify the antibacterial nanocellulose, comprises the following steps: S2.1: Place an ion exchange resin and 1.2-1.5 mol / L tetrabutylammonium hydroxide in a container at a solid-to-liquid ratio of 1:(1.8-2), stir for 3-3.5 hours, and then filter. Rinse the filtered solid 3-4 times with deionized water to obtain a tetrabutylammonium-modified resin. Place 1-1.5 parts by mass of disodium glycyrrhizate in a container, add 80-100 parts by mass of deionized water, and stir until the disodium glycyrrhizate is completely dissolved. Then, add 35-40 parts by mass of tetrabutylammonium-modified resin, stir for 10-12 hours, and then filter to obtain a filtrate. Place the filtrate in a freeze dryer for freeze-drying to obtain tetrabutylammonium-modified glycyrrhizic acid. S2.2: 0.4-0.6 parts by mass of antibacterial nanocellulose and 15-20 parts by mass of N, N-dimethylformamide are mixed in a container and magnetically stirred at a stirring speed of 450-500 rpm for 10-20 minutes to obtain an antibacterial nanocellulose solution. Under a nitrogen atmosphere, 0.2-0.3 parts by mass of tetrabutylammonium-modified glycyrrhizic acid and 12-15 parts by mass of N, N-dimethylformamide are mixed in a container and stirred until the tetrabutylammonium-modified glycyrrhizic acid is completely dissolved. Then, 0.4-0.5 parts by mass of 1-ethyl- (3-dimethylaminopropyl) carbodiimide and 0.3-0.32 parts by mass of N-hydroxysuccinimide were stirred for 30-35 minutes, and then the antibacterial nanocellulose solution was added. After sealing, the mixture was shaken up and down for 6-8 minutes, and then heated to 40-45°C and kept warm for 20-24 hours to obtain a reaction solution. The reaction solution was placed in a dialysis bag and dialyzed against deionized water for 45-50 hours. The solution was then placed in a centrifuge and centrifuged at 4000-4500 rpm for 3-4 minutes. The supernatant was separated and collected for freeze-drying to obtain glycyrrhizic acid-modified nanocellulose.

4. The method for preparing a high-strength antibacterial acrylic material according to claim 3, characterized in that: Step S3 is to prepare a composite of antibacterial cellulose-PMMA and polymethyl methacrylate, comprising the following steps: S3.1: 0.6-0.8 parts by weight of glycyrrhizic acid-modified nanocellulose and 25-30 parts by weight of N,N-dimethylformamide are mixed and magnetically stirred for 15-20 minutes, followed by the addition of 0.1-0.2 parts by weight of α-dibromopropionyl bromide. The mixture is stirred for 20-24 hours, and then washed with 120-150 parts by weight of deionized water. The supernatant is collected by centrifugation and lyophilized to obtain brominated nanocellulose; S3.2: Add 0.6-0.8 parts by mass of brominated nanocellulose, 2-2.5 parts by mass of methyl methacrylate, and 0.4-0.5 parts by mass of pentamethyldipropylenetriamine to a container, then add 50-60 parts by mass of N,N-dimethylformamide under a nitrogen atmosphere and stir until the solid is completely dissolved, then add 0.4-0.45 parts by mass of CuBr and seal the container, heat to 60-65°C and evacuate to a vacuum, maintain the vacuum for 25-30 minutes, then introduce nitrogen to restore the pressure in the container to one atmosphere, keep warm for 22-24 hours, then remove and add 1-2 times the volume of deionized water, centrifuge to collect the supernatant, and freeze-dry to obtain antibacterial cellulose-PMMA; S3.3: Mix 90-100 parts by mass of methyl methacrylate and 0.3-0.5 parts by mass of dibenzoyl peroxide, stir at 50-60°C at a stirring speed of 150-200 rpm for 10-15 minutes, then add 8-10 parts by mass of antibacterial cellulose-PMMA, 15-20 parts by mass of comonomer, 2-4 parts by mass of cross-linking agent, 1-3 parts by mass of zinc stearate and 1-1.5 parts by mass of dioctyl phosphate, heat to 80-85°C, continue stirring at a stirring speed of 120-150 rpm for 1-1.5 hours, cool down and perform vacuum degassing, then inject into a tempered glass mold for hot pressing molding, the hot pressing temperature is 120-150°C, the hot pressing pressure is 40-60KPa, and the heat and pressure are maintained for 2-3 hours to obtain a high-strength antibacterial acrylic material.

5. The method for preparing a high-strength antibacterial acrylic material according to claim 2, characterized in that: The mass fraction of the ammonia water in step S1.1 is 20-25%.

6. The method for preparing a high-strength antibacterial acrylic material according to claim 2, characterized in that: The degree of polymerization of the cellulose pulp in step S1.1 is 1000-1100, and the α-cellulose content of the cellulose pulp is 90-95%.

7. The method for preparing a high-strength antibacterial acrylic material according to claim 3, characterized in that: The ion exchange resin in step S2.1 is the strongly acidic cation exchange resin Amberlyst 15.

8. The method for preparing a high-strength antibacterial acrylic material according to claim 3, characterized in that: The cutoff of the dialysis bag in step S2.2 is 1-1.2 kDa.

9. The method for preparing a high-strength antibacterial acrylic material according to claim 4, characterized in that: The comonomers in step S3.3 consist of methacrylamide and allyl methacrylate in a molar ratio of 1:(1-2).

10. The method for preparing a high-strength antibacterial acrylic material according to claim 4, characterized in that: The cross-linking agent in step S3.3 is butanediol dipropylene glycol.

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