Antibacterial protective diaphragm based on electrostatic spinning coating method and preparation method thereof

Abstract

The application discloses a sterilization protective diaphragm based on an electrostatic spinning coating method, which comprises a polytetrafluoroethylene base film and a sterilization electrostatic spinning layer, wherein the sterilization electrostatic spinning layer is composed of polybenzimidazole, polyacrylic acid and a metal salt, is obtained through an electrostatic spinning and crosslinking agent treatment method, the molar ratio of the polybenzimidazole to the polyacrylic acid is 1:1, and the pore size gradually increases from one side of the sterilization electrostatic spinning layer, which is attached to the polytetrafluoroethylene base film, to the other side of the sterilization electrostatic spinning layer. The application further discloses a preparation method of the sterilization protective diaphragm based on the electrostatic spinning coating method. The polyion liquid is combined with the electrostatic spinning method to prepare electrostatic spinning fibers for use as an inner layer of a protective garment. The electrostatic spinning fibers can resist bacteria, inhibit bacteria, isolate foreign matters in the outside world from invading the human body, have a good killing and inhibiting effect on bacteria and bacteria, and have a porous structure and a pore size gradient, and have good air permeability.

Description

Technical Field

[0001] This invention belongs to the field of textile functional fiber technology, and particularly relates to a method for preparing a bactericidal protective membrane based on electrospinning coating. Background Technology

[0002] With the increasing awareness of health and safety among the public, medical multifunctional protective clothing made with polytetrafluoroethylene composite film as the isolation layer is being used more and more widely. It has durable physical and mechanical properties such as waterproof, water-repellent, antibacterial, antistatic, flame retardant and breathable, and has excellent barrier properties against blood and viruses under natural and pressure conditions.

[0003] In fields such as protective equipment, high requirements are placed on the antibacterial and anti-corrosion properties of the outer layer fibers, with less emphasis on modifications that combine antibacterial and adhesive properties in the inner layer. While polytetrafluoroethylene (PTFE) films offer good barrier properties, they suffer from poor breathability and moisture absorption. Prolonged wear can lead to the accumulation of moisture and excessive body heat, as well as sweat buildup between the skin and fabric. The organic matter in sweat can induce microbial growth, causing inflammation and bacterial infections, thus harming human health. To address these issues, there is an urgent need to develop a film that comes into contact with the human body and possesses excellent bactericidal properties. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art and provide a bactericidal protective membrane based on electrospinning coating and its preparation method, which can effectively kill bacteria trapped on the membrane surface, thereby solving the problem of bacterial infection inside clothing and the risk of bacterial transfer.

[0005] To achieve the above objectives, the technical solution of the present invention is to provide a bactericidal protective membrane based on electrospinning coating, comprising a polytetrafluoroethylene membrane and a bactericidal electrospinned layer, wherein the bactericidal electrospinned layer is composed of polybenzimidazole, polyacrylic acid and metal salt, and is obtained by electrospinning and crosslinking agent treatment; the molar ratio of polybenzimidazole and polyacrylic acid is 1:1; from the side of the bactericidal electrospinned layer that is bonded to the polytetrafluoroethylene membrane to the other side of the bactericidal electrospinned layer, the pore size gradually increases.

[0006] The asymmetry of membrane pore size determines the direction of sweat and bacterial transport in the human body. After bacteria enter the diaphragm layer through the large pores, the bacterial cell membrane, composed of acidic phospholipids with a negatively charged surface, allows ionic liquid monomers to aggregate and form polymerized ionic liquids. These polymerized ionic liquids possess numerous cationic sites on their polymer chains. When the polymerized ionic liquid interacts electrostatically with the bacterial cell membrane, it can undergo rearrangement and diffusion across the membrane, thus more effectively disrupting the bacterial structure.

[0007] A further technical solution is that the sterilization electrospun layer includes a first porous membrane layer and a second porous membrane layer, the first porous membrane layer and the second porous membrane layer are disposed on the same side of the polytetrafluoroethylene membrane layer, the first porous membrane layer is bonded to the polytetrafluoroethylene membrane layer, the weight average molecular weight of polyacrylic acid contained in the first porous membrane is less than 2000 g / mol, the weight average molecular weight of polyacrylic acid contained in the second porous membrane is greater than 3000 g / mol, and the crosslinking agent is an electrophilic crosslinking agent.

[0008] When the molar ratio of polybenzimidazole to polyacrylic acid is 1:1, i.e., at an equistoichiometric molar ratio of cationic and anionic units, the ionic crosslinking density reaches its maximum. A highly crosslinked network will limit pore size expansion caused by high surface energy; that is, when the crosslinking density is high, the average pore size is small.

[0009] A further technical solution is that the electrophilic crosslinking agent includes α,α'-dibromo-p-xylene, α,α'-dichloro-p-xylene, or triformyl chloride.

[0010] α,a'-dibromo-p-xylene, α,a'-dichloro-p-xylene, or triformyl chloride belong to the same aromatic acid halides. Using them as crosslinking agents can tighten PBI films and improve their chemical resistance.

[0011] A further technical solution is that when the antibacterial electrospun layer is prepared from polyacrylic acid with the same weight-average molecular weight, the crosslinking agent is an aqueous solution of hydrazine.

[0012] Hydrazine not only acts as a crosslinking agent to trigger electrostatic crosslinking between polybenzimidazole and organic acids to form a porous polyelectrolyte membrane, but also reduces the embedded metal salt in situ into the metal nanoparticles within the porous membrane. The porous membrane structure can provide a supporting environment to immobilize the metal nanoparticles.

[0013] A further technical solution is that the metal salt includes one or more of copper acetate, palladium acetate, or silver nitrate.

[0014] Inorganic antibacterial substances, including silver ions, copper ions, and zinc oxide, have many advantages in preparing various antibacterial materials, such as broad-spectrum antibacterial activity, high heat resistance, high chemical stability, safety, long-lasting antibacterial effect, and low likelihood of developing drug resistance.

[0015] This invention also provides a method for preparing a bactericidal protective membrane based on electrospinning coating, comprising the following steps:

[0016] S1: Polybenzimidazole and polyacrylic acid are dissolved to form a polybenzimidazole-polyacrylic acid blend, which is then mixed with a metal salt to obtain a polyionic liquid;

[0017] S2: The polyionic liquid is completely dissolved in a solvent to obtain an electrospinning solution of the polymer;

[0018] S3: A bactericidal electrospun layer based on a polyionic liquid is prepared by electrospinning the electrospinning solution on one side of a polytetrafluoroethylene vinyl film using an electrospinning machine.

[0019] S4: After drying to form a mixed film of polytetrafluoroethylene film / sterilizing electrospun layer, it is immersed in a crosslinking agent.

[0020] Porous structures can provide a supportive environment to immobilize metal nanoparticles or metal salts, preventing them from leaching out.

[0021] A further technical solution is that the molar ratio of the metal salt to the polybenzimidazole-polyacrylic acid blend is (0.01~0.9):1.

[0022] The pore size of the membrane increases with increasing metal salt content. The addition of metal salt affects the pore formation process. After the metal salt is immersed in the crosslinking agent solution, the metal cations can dissolve, increasing the local ionic strength and forming an ionic environment that hinders the ionic crosslinking between polybenzimidazole and organic acids, thereby increasing the pore size.

[0023] A further technical solution is that when the bactericidal electrospun layer is prepared by a double-layer electrospun method, the crosslinking agent is α,α'-dibromo-p-xylene, α,α'-dichloro-p-xylene, or triformyl chloride.

[0024] A further technical solution is that when the bactericidal electrospun layer is prepared by a single-layer electrospun method, the crosslinking agent is an aqueous solution of hydrazine.

[0025] When water and hydrazine molecules diffuse into the hybrid membrane, the phase separation process of the hydrophobic polyionic liquid and the ionic crosslinking reaction occurring through inter-electrolyte complexation occur simultaneously, forming porous polyelectrolyte membranes (PPMs). Simultaneously, due to the reducing properties of hydrazine, the metal salts within the polymer blend are reduced in situ to metal nanoparticles, anchored on the porous polyelectrolyte membranes (PPMs). The aqueous hydrazine solution acts as a crosslinking agent, ensuring sufficient contact between the top layer of the membrane and the N2H4 aqueous solution, allowing water and hydrazine molecules to rapidly and fully diffuse into the polyionic liquid / PAA hybrid membrane. After the crosslinking of the top porous membrane is complete, forming a porous structure, the diffusion rate of water and hydrazine molecules to the bottom of the polymer blend is buffered and slowed to a constant level, resulting in a stable degree of ionic crosslinking. The phase separation process in the bottom region becomes relatively mild, leading to smaller, more uniform pores. This initial diffusion process creates a pore size gradient in the antibacterial electrospun layer, with the surface pore size larger than the interior pore size.

[0026] The beneficial effects of this invention are as follows:

[0027] When the polybenzimidazole-polyacrylic acid composite mold is immersed in a crosslinking agent solution, the polybenzimidazole diffuses in the solution, and the polybenzimidazole and polyacrylic acid simultaneously undergo ionic crosslinking reactions to form a three-dimensional porous network, generating a density gradient of ionic crosslinking along the membrane cross-section. The gradually narrowing pores provide strong capillary forces, promoting the rapid extraction of water from the skin to the outer layer of the textile for evaporation.

[0028] 2. The porous structure of porous polyelectrolyte membranes can provide a possible supporting environment for immobilizing nano-metal particles. Polyionic liquids are materials that combine the properties of ionic liquids and polymers by introducing ionic liquid units into polymer structures. Their antibacterial mechanism mainly involves cations binding to the electronegative cell membrane of bacteria through electrostatic interactions, causing cell membrane rupture and ultimately leading to bacterial death. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention. Example

[0030] The bactericidal protective membrane of this embodiment includes a polytetrafluoroethylene layer, a first porous membrane layer and a second porous membrane layer arranged sequentially. The pore diameter of the first porous membrane layer is 342±83nm, and the pore diameter of the second porous membrane layer is 2.4±1µm. The pores of the second porous membrane layer are larger than those of the first porous membrane layer, and the outer side of the second porous membrane layer is in contact with the human body.

[0031] This embodiment also provides a method for preparing a bactericidal protective membrane based on electrospinning coating, including the following steps:

[0032] 0.500 g of polybenzimidazole with a Mw of 1900 and 0.036 g of PAA2000 were uniformly dissolved in 2 mL of DMSO to achieve an imidazole / carboxylate molar ratio of approximately 1:1. Copper acetate was added to make the weight percentage 0.1%, and the mixture was stirred to obtain the first electrospinning solution.

[0033] 0.500 g of polybenzimidazole with a Mw of 1900 and 0.036 g of PAA4000 were uniformly dissolved in 2 mL of DMSO. Copper acetate was added to make the weight percentage 0.1%, and the mixture was stirred to obtain the second electrospinning solution.

[0034] The first electrospinning solution is used to perform a porous membrane electrospinning operation on one side of a polytetrafluoroethylene (PFTE) membrane to obtain the first porous membrane.

[0035] The second electrospinning solution is used to perform electrospinning on the surface of the first porous membrane to obtain the second porous membrane.

[0036] The pore size of the second porous membrane is larger than that of the first porous membrane.

[0037] A polyionic liquid / PAA hybrid film was formed by immersing the hybrid film in an acetonitrile solution of α,α'-dibromo-p-xylene (DBX). The top layer of the film was then brought into full contact with a 3 wt% acetonitrile solution of α,α'-dibromo-p-xylene (DBX). Crosslinking was carried out at 80°C for 24 hours, allowing water molecules and α,α'-dibromo-p-xylene (DBX) molecules to rapidly and fully diffuse into the polyionic liquid / PAA hybrid film. The composite film was then subjected to crosslinking at 80°C. o After drying at C, the cross-linked PBI membrane is very stable in various organic solvents. Example

[0038] The bactericidal protective membrane of this embodiment includes a polytetrafluoroethylene layer, a first porous membrane layer and a second porous membrane layer arranged sequentially. The pore diameter of the first porous membrane layer is 342±83nm, and the pore diameter of the second porous membrane layer is 2.4±1µm. The pores of the second porous membrane layer are larger than those of the first porous membrane layer, and the outer side of the second porous membrane layer is in contact with the human body.

[0039] In 22 o Add 2 wt% α,a'-dichloro-p-xylene (DCX) to ethanol at concentration C. Immerse the polyionic liquid / PAA hybrid film in the ethanol solution of α,a'-dichloro-p-xylene (DCX), ensuring the top layer of the film is in full contact with the 2 wt% α,a'-dichloro-p-xylene (DCX) ethanol solution. After crosslinking for 12 hours, ethanol molecules and α,a'-dichloro-p-xylene (DCX) molecules rapidly and fully diffuse into the polyionic liquid / PAA hybrid film. The composite film is then subjected to crosslinking at 80°C. o Drying at C.

[0040] The remaining steps are the same as in Example 1. Example

[0041] The bactericidal protective membrane of this embodiment includes a polytetrafluoroethylene layer, a first porous membrane layer and a second porous membrane layer arranged sequentially. The pore diameter of the first porous membrane layer is 342±83nm, and the pore diameter of the second porous membrane layer is 2.4±1µm. The pores of the second porous membrane layer are larger than those of the first porous membrane layer, and the outer side of the second porous membrane layer is in contact with the human body.

[0042] Add 2 wt% tricarboxylic acid chloride (TMC) to 2-methyltetrahydrofuran, immerse the polyionic liquid / PAA hybrid film in the 2-methyltetrahydrofuran solution of tricarboxylic acid chloride (TMC), ensuring full contact between the top layer of the film and the solution, and crosslink for 12 hours. Example

[0043] The bactericidal protective membrane of this embodiment includes a polytetrafluoroethylene layer and a porous membrane layer arranged sequentially. The side of the porous membrane layer closest to the polytetrafluoroethylene layer is the inner side, and the pore diameter of the inner side is 342±83nm. The side of the porous membrane layer away from the polytetrafluoroethylene layer is the outer side, and the pore diameter of the outer side is 2.4±1µm. The pores on the outer side are larger than those on the inner side. The outer side of the porous membrane layer is in contact with the human body.

[0044] This embodiment also provides a method for preparing a bactericidal protective membrane based on electrospinning coating, including the following steps:

[0045] Step 1: Prepare the polyionic liquid electrospinning solution

[0046] 0.500 g of polybenzimidazole with a Mw of 1900 and 0.036 g of PAA2000 were uniformly dissolved in 2 mL of DMSO to achieve an imidazole / carboxylate molar ratio of approximately 1:1. Copper acetate was added to make the weight percentage 0.1%, and the mixture was stirred to obtain the electrospinning solution.

[0047] Step 2: Electrospinning

[0048] A porous membrane was obtained by electrospinning a polytetrafluoroethylene (PFTE) membrane onto one side of the membrane using an electrospinning solution. The extrusion rate of the electrospinning solution during the porous membrane electrospinning operation was 0.03 mL / min to 0.5 mL / min. In this embodiment, an electrospinning machine with an extrusion rate of 0.03 mL / min to 0.5 mL / min was used, and the voltage was set to 5 kV to 20 kV. The distance between the electrospinning solution nozzle and the receiving substrate during the porous membrane electrospinning operation was 8 cm to 35 cm. The porous membrane obtained through directional electrospinning exhibits a regular stacked arrangement, which is beneficial for forming a relatively dense fiber membrane layer. This results in a high-strength mechanical structure for the first porous membrane layer, ensuring both porosity and specific surface area.

[0049] Step 3: Film Formation

[0050] Composite membrane at 80 o Drying at C forms a polytetrafluoroethylene / polybenzimidazole / polyacrylic acid mixed film. The mixed film is then immersed in a hydrazine aqueous solution, with N2H4 aqueous solution used as an activating agent. The top layer of the film is in full contact with the N2H4 aqueous solution, and water molecules and N2H4 molecules rapidly and fully diffuse into the polyionic liquid / PAA mixed film.

[0051] After the cross-linking of the top porous membrane is complete, forming a porous structure, the diffusion rate of water and hydrazine molecules to the bottom of the polymer-mixed membrane is buffered and slowed to a constant level, resulting in a stable degree of ionic cross-linking. The phase separation process in the bottom region becomes less intense and relatively mild, thus forming smaller, more uniform pores.

[0052] This initial diffusion process creates a concentration gradient of N2H4 entering the mixed membrane, causing the pore size to gradually increase from one side of the bactericidal electrospun layer to the other side of the polytetrafluoroethylene membrane.

[0053] Simultaneously, due to the reducing properties of hydrazine, the metal salts within the blended membrane are reduced in situ by hydrazine to metal nanoparticles anchored on the PPM. In an aquatic environment, these heavy metal nanoparticles can partially decompose into heavy metal ions, resulting in ion-induced toxicity. Furthermore, nanoscale particles exhibit more severe toxic effects than micron-scale particles. The toxicity induced by heavy metal nanoparticles in water includes the toxicity induced by heavy metal ions, but is greater than that induced by simple ions. Example

[0054] In this embodiment, the weight fraction of copper acetate in the electrospinning solution is 0.3%, and the rest is the same as in Example 4. Example

[0055] In this embodiment, the weight fraction of copper acetate in the electrospinning solution is 1%, and the rest is the same as in Example 4. Example

[0056] In this embodiment, the weight fraction of copper acetate in the electrospinning solution is 3%, and the rest is the same as in Example 4. Example

[0057] In this embodiment, the weight fraction of copper acetate in the electrospinning solution is 9%, and the rest is the same as in Example 4.

[0058] After crosslinking modification, the average pore size and molecular weight cutoff of the film both decreased. Bromine is more reactive than chlorine, which makes α,α'-dibromo-p-xylene (DBX) a stronger crosslinking agent.

[0059] The pore size of the membrane increases with the increase of metal salt content in the blend. The addition of metal salt affects the pore formation process. After the metal salt is immersed in the crosslinking agent solution, the metal cations can dissolve, increasing the local ionic strength, forming an ionic environment, which hinders the ionic crosslinking between polybenzimidazole and organic acid, thereby increasing the pore size.

[0060] Because Cu 2+ The cation can complex with polyacrylic acid and polyionic liquids, and this competition can reduce the degree of direct ionic complexation between polyacrylic acid and polybenzimidazole. Taking Example 8 as an example, with a higher copper salt loading of 9 wt%, the membrane pore size reaches 2.8 ± 1.0 µm.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bactericidal protective membrane based on electrospinning coating, characterized in that, Includes a polytetrafluoroethylene film and a bactericidal electrospun layer; The bactericidal electrospun layer is composed of polybenzimidazole, polyacrylic acid and metal salt, and is obtained by electrospinning and crosslinking agent treatment; the molar ratio of polybenzimidazole and polyacrylic acid is 1:1; the pore size gradually increases from the side of the bactericidal electrospun layer that is bonded to the polytetrafluoroethylene film to the other side of the bactericidal electrospun layer. The antibacterial electrospun layer is prepared from polyacrylic acid of the same weight-average molecular weight, and the crosslinking agent is an aqueous solution of hydrazine.

2. The bactericidal protective membrane based on electrospinning coating according to claim 1, characterized in that, The metal salt includes one or more of copper acetate, palladium acetate, or silver nitrate.

3. A method for preparing a bactericidal protective membrane based on electrospinning coating as described in claim 1, characterized in that, Includes the following steps: S1: Polybenzimidazole and polyacrylic acid are dissolved to form a polybenzimidazole-polyacrylic acid blend, which is then mixed with a metal salt to obtain a polyionic liquid; S2: The polyionic liquid is completely dissolved in a solvent to obtain an electrospinning solution of the polymer; S3: A bactericidal electrospun layer based on polyionic liquid is prepared by electrospinning the electrospinning solution on one side of a polytetrafluoroethylene vinyl film using an electrospinning machine. S4: After drying to form a mixed film of polytetrafluoroethylene film / sterilizing electrospun layer, it is immersed in a crosslinking agent.

4. The bactericidal protective membrane based on electrospinning coating according to claim 3, characterized in that, The molar ratio of the metal salt to the polybenzimidazole-polyacrylic acid blend is (0.01~0.9):1.