Preparation method of pH developing antibacterial nanofiber wrap yarn

Abstract

The invention discloses a preparation method of pH developing antibacterial nanofiber wrap yarn. The preparation method comprises the following steps: step 1, preparing a core-layer spinning solution and a shell-layer spinning solution; 2, a coaxial conjugate electrostatic spinning device is built; 3, the pH developing antibacterial nanofiber wrap yarn with the core yarn as a core layer and the outer wrapping layer of the pH developing antibacterial nanofiber of the core-shell structure as a skin layer is formed. Coaxial electrostatic spinning and conjugate electrostatic spinning are combined, spun nanofibers of a core-shell structure with a natural antibacterial agent as a core layer are rotationally wrapped on core yarn, meanwhile, pH response materials are loaded on the pH developing antibacterial nanofibers of the core-shell structure, and the pH developing antibacterial nanofiber wrap yarn is formed.

Description

Technical Field

[0001] The present invention relates to the field of intelligent antibacterial textiles, and specifically to a preparation method of a pH-color-changing antibacterial nanofiber-coated yarn. Background Art

[0002] Nowadays, bacteria have a profound impact on human health, and numerous problems caused by bacteria in recent years are also challenges faced by humans today. With the increasing awareness of personal protection, antibacterial textiles have received more and more attention from scholars in various fields. Various sudden injuries often occur in life, and medical gauze is currently a commonly used surgical dressing for treating skin wounds. However, improper use of gauze can cause the wound to deteriorate during regeneration. If the gauze cannot be replaced in time, due to its porous and loose structure, the gauze adsorbs the wound exudate, providing appropriate conditions for the growth and reproduction of bacteria, thus causing secondary infection of the wound. With the development of intelligent textiles, medical textile materials with functions such as information transmission and health detection have become a research hotspot in the textile field. Timely monitoring of the wound status can detect problems earlier and appropriately treat the wound according to the situation, which is more conducive to wound healing. Therefore, it is very necessary to develop and design a responsive and antibacterial textile with the ability to monitor environmental changes.

[0003] pH-responsive color change converts the change in pH value into a color change, and uses the different visual changes in color to reflect the pH value of the surrounding environment, so as to achieve information such as prompting, warning, and alerting. When inflammation occurs in a wound, the pH value of the exudate will change. Acid-base indicators can change color under different pH conditions to help monitor the wound status. Anthocyanins and litmus are a type of water-soluble pigments that exhibit different colors through structural changes in different pH environments and have pH responsiveness. Their excellent pH sensitivity can actively respond to the pH changes in wounds and have great potential in the monitoring and response of antibacterial textiles. The common antibacterial gauzes on the market are mainly anionic antibacterial gauzes, but they have problems such as high cost, easy oxidation, and poor antifungal and anti-mold effects. Natural tea tree essential oil is one of the most active natural antibacterial agents discovered so far, with characteristics such as natural, safe, broad-spectrum antibacterial, promoting wound healing, and low cost. However, its application is limited due to the problem of easy volatilization. Especially when combined with textiles to prepare antibacterial yarns, there is often a high burst release, and encapsulation is required to alleviate this problem. Currently, the encapsulation technologies mainly include adsorption method, microencapsulation method, and electrospinning method. The adsorption method and microencapsulation method generally have problems such as poor stability and complex synthesis steps. At the same time, the adsorption method makes the antibacterial yarn have poor washability and a high burst release effect. On this basis, combined with the pH-responsive color display function, there will inevitably be problems such as a long and complex preparation process. Coaxial electrospinning in electrospinning has good encapsulation stability, can load various drugs into core-shell fibers, and at the same time, under the protection of the shell layer, the burst release of the inner layer drug can be effectively alleviated. The different degradation rates of the core and shell polymers can also achieve sequential and controlled release of the drug.

[0004] In the literature "Preparation and Wound Healing Promotion Performance of pH-Responsive Antibacterial Hydrogel Wound Dressings", a hydrogel is used as a carrier, and it is given both pH-responsive function and antibacterial function at the same time. However, the wound dressing in the form of hydrogel has poor air permeability and is not conducive to the recovery of the wound. The weavability of this composite hydrogel form of wound dressing is poor, and the application range is somewhat limited. Therefore, here, materials with pH-responsive and antibacterial functions are mainly loaded in the form of covered yarns. The wound dressings or antibacterial textiles woven therefrom have certain air permeability while ensuring antibacterial performance and pH-responsive characteristics. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a preparation method of a pH-color-displaying antibacterial nanofiber covered yarn.

[0006] The technical solution of the present invention to solve the above technical problem is to provide a preparation method of a pH-color-displaying antibacterial nanofiber covered yarn, which is characterized in that the method includes the following steps:

[0007] Step 1, prepare a core layer spinning solution and a shell layer spinning solution;

[0008] Dissolve the polymer and the natural pH-responsive agent in an organic solvent to obtain the shell spinning solution; use the natural antibacterial agent as the core spinning solution;

[0009] Step 2: Set up a coaxial conjugate electrospinning device;

[0010] The device includes a shell spinning solution propeller, a core spinning solution propeller, a coaxial needle, a positive electrode, a negative electrode, a unwinding roller, a metal rotating funnel, and a collecting device;

[0011] The coaxial needle is a coaxial structure with a core channel and a shell channel, and the shell channel is nested outside the core channel; both the shell spinning solution propeller and the core spinning solution propeller are installed on the coaxial needle; the shell spinning solution propeller is connected to the shell channel and pushes the shell spinning solution into the shell channel during spinning; the core spinning solution propeller is connected to the core channel and pushes the core spinning solution into the core channel during spinning;

[0012] An unwinding roller, a metal rotating funnel, and a collecting device are arranged in sequence along the advancing direction of the core yarn; the core yarn is wound on the unwinding roller and the core yarn is released during spinning; the collecting device is used to collect the pH color-changing antibacterial nanofiber-coated yarn and control the moving speed of the core yarn;

[0013] The two coaxial needles are on the same horizontal plane; the metal rotating funnel is at the same distance from the two coaxial needles, is located on the mid-perpendicular plane of the two, and is within the electrostatic field range generated by the coaxial needles when high voltage is applied; one of the two coaxial needles is connected to the positive electrode of the power supply, and the other is connected to the negative electrode of the power supply to generate an electrostatic field; the metal rotating funnel can rotate along its own central axis;

[0014] Step 3: Prepare the pH color-changing antibacterial nanofiber-coated yarn;

[0015] Set the spinning parameters; place the shell spinning solution in the shell spinning solution propeller and the core spinning solution in the core spinning solution propeller; one end of the core yarn is wound on the unwinding roller, passes through the metal rotating funnel, and the other end is wound on the collecting device, and the core yarn is pulled and moved by the collecting device;

[0016] Start coaxial conjugate electrospinning to uniformly coat the core-shell structured pH color-changing antibacterial nanofibers with the core layer being the natural antibacterial agent and the shell layer being the polymer and the natural pH-responsive agent on the outside of the core yarn, forming a primary coated yarn with the core yarn as the core layer and the core-shell structured pH color-changing antibacterial nanofibers as the skin layer; then dry the primary coated yarn until all the solvent volatilizes to obtain the pH color-changing antibacterial nanofiber-coated yarn.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The present invention combines coaxial electrospinning with conjugate electrospinning, wraps the nanofibers with a core-shell structure having a natural antibacterial agent as the core layer around the core yarn in a rotational manner, and simultaneously loads a pH-responsive material on the pH-color-changing antibacterial nanofibers with a core-shell structure to form a pH-color-changing antibacterial nanofiber-coated yarn.

[0019] (2) The pH-color-changing antibacterial nanofiber-coated yarn provided by the present invention encapsulates a natural antibacterial agent in a polymer in a core-shell structure using coaxial electrospinning technology, which greatly alleviates the burst release problem of the antibacterial agent in antibacterial fabrics and can achieve a long-term stable, continuous, and slow-release antibacterial effect. By adding a natural pH-responsive agent, the healing or deterioration of the wound can be monitored at any time and adjusted in a timely manner. At the same time, the natural pH-responsive agent has a low cost and high safety, which is beneficial to wound recovery and production applications.

[0020] (3) The present invention further wraps and twists the prepared pH-color-changing antibacterial nanofibers on the yarn under the technology of conjugate electrospinning to obtain a pH-color-changing antibacterial nanofiber-coated yarn. In the form of a coated yarn, while retaining its excellent antibacterial performance and pH-responsive effect, the overall mechanical properties are improved, making its application field in antibacterial textiles more extensive. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the preparation process of the nanofiber-coated yarn of the present invention; <{

[0022] Figure 2 is a schematic diagram of the structure of the coaxial needle of the present invention;

[0023] Figure 3 is a surface SEM image of the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 of the present invention magnified 1000 times;

[0024] Figure 4 is a surface SEM image of the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 of the present invention magnified 500 times;

[0025] Figure 5 is a diameter distribution histogram of the core-shell structure pH-color-changing antibacterial nanofibers in the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 of the present invention;

[0026] Figure 6 is a physical image of the antibacterial test of the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 of the present invention against Escherichia coli; where (a) is the blank sample of Escherichia coli diluted three times; (b) is without anthocyanin; (c) is with added anthocyanin; (d) is the blank sample of Escherichia coli diluted five times; (e) is without anthocyanin; (f) is with added anthocyanin;

[0027] Figure 7This is the physical map of the antibacterial test of the pH-colorimetric antibacterial nanofiber-coated yarn prepared in Example 2 of the present invention; among them, (a) is the blank sample of Staphylococcus aureus diluted three times; (b) without anthocyanin; (c) with added anthocyanin; (d) is the blank sample of Staphylococcus aureus diluted five times; (e) without anthocyanin; (f) with added anthocyanin.

[0028] Figure 8 This is the color response state diagram of the pH-colorimetric antibacterial nanofiber-coated yarns of Examples 1 to 4 of the present invention at different pH values.

[0029] In the figure, the shell layer spinning solution propeller 1, the core layer spinning solution propeller 2, the coaxial needle 3, the positive electrode 4, the negative electrode 5, the core-shell structure pH-colorimetric antibacterial nanofiber 6, the core yarn 7, the unwinding roller 8, the metal rotary funnel 9, the fiber web 10, the pH-colorimetric antibacterial nanofiber-coated yarn 11, the collection device 12; the shell layer channel 301, the core layer channel 302. Detailed implementation manners

[0030] The following are specific embodiments of the present invention. The specific embodiments are only used to further illustrate the present invention in detail and do not limit the protection scope of the present invention.

[0031] The present invention provides a preparation method of a pH-colorimetric antibacterial nanofiber-coated yarn (abbreviated as the method), which is characterized in that the method includes the following steps:

[0032] Step 1, prepare the core layer spinning solution and the shell layer spinning solution;

[0033] Dissolve the polymer and the natural pH-responsive agent in an organic solvent to obtain the shell layer spinning solution; use the natural antibacterial agent as the core layer spinning solution;

[0034] Preferably, in Step 1, the polymer is PAN or PVDF; the natural pH-responsive agent is natural anthocyanin or litmus; the organic solvent is DMF (N,N-dimethylformamide) or DMAC (N,N-dimethylacetamide).

[0035] Preferably, in Step 1, the mass fraction of the polymer is 12-15%, and the mass fraction of the natural pH-responsive agent is 0.5-3%.

[0036] Preferably, in Step 1, the preparation process of the shell layer spinning solution is: stir at a temperature of 60-70°C and a speed of 400-600 rpm for 6-10 h.

[0037] Preferably, in Step 1, the natural antibacterial agent is tea tree essential oil.

[0038] Step 2, build a coaxial conjugate electrospinning device;

[0039] The device includes a shell layer spinning solution propeller 1, a core layer spinning solution propeller 2, a coaxial needle 3, a positive electrode 4, a negative electrode 5, a unwinding roller 8, a metal rotary funnel 9, and a collection device 12;

[0040] The coaxial needle 3 has a coaxial structure with a core layer channel 302 and a shell layer channel 301. The shell layer channel 301 is nested outside the core layer channel 302; both the shell layer spinning solution propeller 1 and the core layer spinning solution propeller 2 are installed on the coaxial needle 3; the shell layer spinning solution propeller 1 is communicated with the shell layer channel 301, and when spinning, it pushes the shell layer spinning solution into the shell layer channel 301; the core layer spinning solution propeller 2 is communicated with the core layer channel 302, and when spinning, it pushes the core layer spinning solution into the core layer channel 302;

[0041] An unwinding roller 8, a metal rotary funnel 9, and a collection device 12 are arranged in sequence along the advancing direction of the core yarn 7; the core yarn 7 is wound on the unwinding roller 8, and the core yarn 7 is released during spinning; the collection device 12 is used to collect the final product, namely the pH color-changing antibacterial nanofiber-coated yarn 11 (abbreviated as coated yarn 11), and control the moving speed of the core yarn 7;

[0042] The two coaxial needles 3 are on the same horizontal plane; the metal rotary funnel 9 is at the same distance from the two coaxial needles 3, is on the mid-perpendicular plane of the two, and is within the electrostatic field range generated by the coaxial needles 3 when high voltage is applied; one of the two coaxial needles 3 is connected to the positive electrode 4 of the power supply, and the other is connected to the negative electrode 5 of the power supply for generating an electrostatic field; the metal rotary funnel 9 can rotate along its own central axis;

[0043] Preferably, in step 2, the core yarn 7 is a yarn, preferably one of cotton yarn, polyester yarn, nylon yarn, or polyester-cotton yarn.

[0044] Preferably, in step 2, the metal rotary funnel 9 is of a flared type.

[0045] Preferably, in step 2, to avoid interference, the outer side wall of the coaxial needle 3 is provided with an opening, the shell layer spinning solution propeller 1 is fixed at the opening of the outer side wall of the coaxial needle 3, and is communicated with the side wall of the shell layer channel 301; more preferably, the shell layer spinning solution propeller 1 and the core layer spinning solution propeller 2 are perpendicular to each other.

[0046] Step 3, prepare the pH color-changing antibacterial nanofiber-coated yarn 11;

[0047] Set the spinning parameters; place the shell layer spinning solution in the shell layer spinning solution propeller 1, and place the core layer spinning solution in the core layer spinning solution propeller 2; one end of the core yarn 7 is wound on the unwinding roller 8, passes through the metal rotary funnel 9, and the other end is wound on the collection device 12, and the core yarn 7 is pulled and moved by the collection device 12;

[0048] Start coaxial conjugate electrospinning to achieve uniform coating of core-shell structured pH color-changing antibacterial nanofibers 6 with a natural antibacterial agent in the core layer, a polymer, and a natural pH-responsive agent in the shell layer on the outer side of the core yarn 7, forming a primary coated yarn with the core yarn 7 as the core layer and the core-shell structured pH color-changing antibacterial nanofibers 6 as the cortex layer; then dry the primary coated yarn until all the solvent evaporates to obtain the pH color-changing antibacterial nanofiber coated yarn 11.

[0049] Preferably, in step 3, the specific process of coaxial conjugate electrospinning is as follows: Turn on the DC power supply and start electrospinning. During the electrospinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured pH color-changing antibacterial nanofibers 6; the opposite charges of positive and negative make the core-shell structured pH color-changing antibacterial nanofibers 6 spun from the two coaxial needles 3 entangle with each other. At the same time, electrostatic induction will occur between the two coaxial needles 3 and the metal rotary funnel 9, and the core-shell structured pH color-changing antibacterial nanofibers 6 will be collected on the metal rotary funnel 9; through the traction effect of the core yarn 7 on the electrospun fibers, a triangular fiber web 10 formed by fiber bundles of multiple core-shell structured pH color-changing antibacterial nanofibers 6 is formed at the opening of the metal rotary funnel 9; through the stretching and traction of the core yarn 7 by the collection device 12, the fiber bundles in the fiber web 10 have orientation; at the same time, the rotation of the metal rotary funnel 9 makes the fiber bundles uniformly entangle and coat on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the cortex layer is formed on the collection device 12.

[0050] Preferably, in step 3, the electrospinning parameters are as follows: the distance between the two coaxial needles 3 is 15 - 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 - 14 cm; the electrospinning angle of the two coaxial needles 3 is 30 - 70°; the voltage of the positive electrode 4 is 5 - 8 kV, and the voltage of the negative electrode 5 is -8 - -5 kV; the propulsion speed of the shell layer spinning solution is 0.2 - 0.4 mL / h, and the propulsion speed of the core layer spinning solution is 0.05 - 0.15 mL / h; by adjusting the rotation speed of the collection device 12 to adjust the moving speed (i.e., the collection speed) of the core yarn 7, so that the collection speed matches the electrospinning speed, and the moving speed of the core yarn 7 is 0.1 - 0.3 mm / s; the rotation speed of the metal rotary funnel 9 is 250 - 350 rpm; the electrospinning environment temperature is 27 ± 3 °C, and the humidity is 35 ± 5%.

[0051] Preferably, in step 3, the mass ratio of the core-shell structured pH color-changing antibacterial nanofibers 6 to the core yarn 7 is 0.3 - 0.5:1.

[0052] Preferably, in step 3, the average diameter of the pH color-changing antibacterial nanofiber coated yarn 11 is 0.2 - 0.7 mm.

[0053] Preferably, in step 3, the drying process is as follows: drying for at least 4 h in an indoor environment (i.e., at a temperature of 25 ± 5 °C and a humidity of 25 - 40%).

[0054] In the examples, the performance tests are pH response test and antibacterial test;

[0055] pH response test: According to the experimental protocol, buffer solutions with pH values of 3, 5, and 7 are prepared using 0.2 mol / L disodium hydrogen phosphate and 0.1 mol / L citric acid, and a buffer solution with a pH value of 10 is prepared using 0.2 mol / L glycine and 0.2 mol / L sodium hydroxide. Cut 20 cm of the yarn spun in step (2) and immerse it in the pH buffer solutions (pH values are 3, 5, 7, and 10) for 2 minutes to measure the sensitivity of the covered yarn to acid and alkali solutions. After removing the solution on the surface of the yarn, place it on a white plate and record its color. Start timing when the sample is completely immersed in the solution, and stop timing when the sample is completely discolored, and record the time required for discoloration.

[0056] Antibacterial test: The antibacterial test is carried out using the detection method in GB / T 20944.3 - 2008 "Evaluation of antibacterial properties of textiles - Part 3: Oscillation method".

[0057] Example 1:

[0058] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0059] Weigh an appropriate amount of PVDF solid powder and anthocyanin solid powder and dissolve them in DMF. Heat in a water bath at 65 °C and stir with a magnetic stirrer at 500 rpm for 8 h to obtain a completely dissolved PVDF - anthocyanin solution with a purplish - red color. The PVDF - anthocyanin solution is the shell layer spinning solution, where the mass fraction of PVDF is 13.5% and the mass fraction of anthocyanin is 0.5%;

[0060] Prepare tea tree essential oil as the core layer spinning solution.

[0061] (2) Set up a coaxial conjugate electrospinning device: Wind the cotton yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area.

[0062] (3) Prepare the pH - color - showing antibacterial nanofiber covered yarn 11;

[0063] The propulsion rate of the core layer spinning solution is 0.1 mL / h, and the propulsion rate of the shell layer spinning solution is 0.3 mL / h; the voltage of the positive electrode 4 is 6.5 KV, and the voltage of the negative electrode 5 is -6.5 KV; the distance between the two sets of coaxial needles 3 is 16 cm, and the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the rotation speed of the metal rotary funnel 9 is 300 rpm, and the moving speed of the core yarn 7 is 0.3 mm / s; the spinning environment temperature is 27 °C ± 3 °C, and the relative humidity is 30% - 40%;

[0064] The shell layer spinning solution and the core layer spinning solution are respectively transported to the shell layer channel 301 and the core layer channel 302 of the coaxial needle 3; the DC power supply is turned on to start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured pH color-changing antibacterial nanofibers 6; the core-shell structured pH color-changing antibacterial nanofibers 6 are collected on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured pH color-changing antibacterial nanofibers 6 is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 4 h until the solvent completely volatilizes, and a pH color-changing antibacterial nanofiber coated yarn 11 with an average diameter of 0.2 - 0.7 mm is obtained, where the mass ratio of the core-shell structured pH color-changing antibacterial nanofibers 6 to the core yarn 7 is 0.3 - 0.5:1.

[0065] Example 2:

[0066] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0067] Weigh an appropriate amount of PAN solid powder and anthocyanin solid powder and dissolve them in DMF. Heat them in a water bath at 65 °C and stir them with a magnetic stirrer at 500 rpm for 8 h to obtain a completely dissolved PAN-anthocyanin solution with a purple-red color. The PAN-anthocyanin solution is the shell layer spinning solution, where the mass fraction of PAN is 13.5% and the mass fraction of anthocyanin is 0.75%;

[0068] Prepare tea tree essential oil as the core layer spinning solution.

[0069] (2) Set up the coaxial conjugate electrospinning device: Wind the polyester yarn as the core yarn 7 on the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area.

[0070] (3) Prepare the pH color-changing antibacterial nanofiber coated yarn 11:

[0071] The advancing rate of the core layer spinning solution is 0.1 mL / h, and the advancing rate of the shell layer spinning solution is 0.3 mL / h; the voltage of the positive electrode 4 is 6.5 KV, and the voltage of the negative electrode 5 is -6.5 KV; the distance between the two coaxial needles 3 is 16 cm, and the distance between the coaxial needle 3 and the metal rotating funnel 9 is 13 cm; the rotation speed of the metal rotating funnel 9 is 300 rpm, and the moving speed of the core yarn 7 is 0.3 mm / s; the spinning environment temperature is 27°C ± 3°C, and the relative humidity is 30% - 40%;

[0072] The shell layer spinning solution and the core layer spinning solution are respectively transported to the shell layer channel 301 and the core layer channel 302 of the coaxial needle 3; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured pH-responsive antibacterial nanofibers 6; the core-shell structured pH-responsive antibacterial nanofibers 6 are collected on the metal rotating funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured pH-responsive antibacterial nanofibers 6 is formed at the opening of the metal rotating funnel 9; the rotation of the metal rotating funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 5 h until the solvent completely evaporates, and a pH-responsive antibacterial nanofiber coated yarn 11 with an average diameter of 0.2 - 0.7 mm is obtained, where the mass ratio of the core-shell structured pH-responsive antibacterial nanofibers 6 to the core yarn 7 is 0.3 - 0.5:1.

[0073] From Figure 3 , Figure 4 It can be seen that the appearance morphology structure of the pH-responsive antibacterial nanofiber coated yarn is good.

[0074] From Figure 5 It can be seen that the diameter distribution of the core-shell structured pH-responsive antibacterial nanofibers in the pH-responsive antibacterial nanofiber coated yarn is relatively uniform and the morphology is good.

[0075] Table 1

[0076]

[0077] Table 1 shows the experimental data of the antibacterial experiment of the pH-responsive antibacterial nanofiber coated yarn prepared in Example 2; it can be seen from Table 1 that the pH-responsive antibacterial nanofiber coated yarn has a significant inhibitory effect on Escherichia coli and Staphylococcus aureus, and the antibacterial rate reaches more than 85%, with excellent antibacterial performance, and is suitable for use in the medical and sanitary fields.

[0078] From Figure 6It can be seen that the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 has a good inhibitory effect on Escherichia coli.

[0079] From Figure 7 It can be seen that the pH-color-changing antibacterial nanofiber-coated yarn prepared in Example 2 has a good inhibitory effect on Staphylococcus aureus.

[0080] Example 3:

[0081] (1) Prepare the core-layer spinning solution and the shell-layer spinning solution;

[0082] Weigh an appropriate amount of PVDF solid powder and litmus solid powder and dissolve them in DMAC. Heat in a water bath at 65 °C and stir with a magnetic stirrer at 500 rpm for 8 h to obtain a completely dissolved PVDF-litmus solution with a purple color. The PVDF-litmus solution is the shell-layer spinning solution, where the mass fraction of PVDF is 13.5% and the mass fraction of litmus is 1%;

[0083] Prepare tea tree essential oil as the core-layer spinning solution.

[0084] (2) Set up a coaxial conjugate electrospinning device: Wind the polyamide yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area.

[0085] (3) Prepare the pH-color-changing antibacterial nanofiber-coated yarn 11:

[0086] The feeding rate of the core-layer spinning solution is 0.1 mL / h, and the feeding rate of the shell-layer spinning solution is 0.3 mL / h; the voltage of the positive electrode 4 is 6.5 KV, and the voltage of the negative electrode 5 is -6.5 KV; the distance between the two groups of coaxial needles 3 is 16 cm, and the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the rotation speed of the metal rotary funnel 9 is 300 rpm, and the moving speed of the core yarn 7 is 0.3 mm / s; the spinning environment temperature is 27 °C ± 3 °C, and the relative humidity is 30% - 40%;

[0087] The shell spinning solution and the core spinning solution are respectively conveyed to the shell channel 301 and the core channel 302 of the coaxial needle 3; the DC power supply is turned on and spinning starts. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured pH-responsive antibacterial nanofibers 6; the core-shell structured pH-responsive antibacterial nanofibers 6 are collected on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured pH-responsive antibacterial nanofibers 6 is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 4 h until the solvent completely volatilizes, and a pH-responsive antibacterial nanofiber coated yarn 11 with an average diameter of 0.2 - 0.7 mm is obtained, wherein the mass ratio of the core-shell structured pH-responsive antibacterial nanofibers 6 to the core yarn 7 is 0.3 - 0.5:1.

[0088] Example 4:

[0089] (1) Prepare the core spinning solution and the shell spinning solution;

[0090] Weigh an appropriate amount of PAN solid powder and litmus solid powder and dissolve them in DMAC. Heat them in a water bath at 65 °C and stir them with a magnetic stirrer at 500 rpm for 8 h to obtain a completely dissolved PAN-litmus solution with a purple color. The PAN-litmus solution is the shell spinning solution, wherein the mass fraction of PAN is 13.5%, and the mass fraction of litmus is 1.25%;

[0091] Prepare tea tree essential oil as the core spinning solution.

[0092] (2) Set up the coaxial conjugate electrospinning device: Wind the polyester-cotton yarn as the core yarn 7 on the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area.

[0093] (3) Prepare the pH-responsive antibacterial nanofiber coated yarn 11:

[0094] The advancing rate of the core spinning solution is 0.1 mL / h, and the advancing rate of the shell spinning solution is 0.3 mL / h; the voltage of the positive electrode 4 is 6.5 KV, and the voltage of the negative electrode 5 is -6.5 KV; the distance between the two groups of coaxial needles 3 is 16 cm, and the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the rotation speed of the metal rotary funnel 9 is 300 rpm, and the moving speed of the core yarn 7 is 0.3 mm / s; the spinning environment temperature is 27 °C ± 3 °C, and the relative humidity is 30% - 40%;

[0095] The shell spinning solution and the core spinning solution are respectively delivered to the shell channel 301 and the core channel 302 of the coaxial needle 3; the DC power supply is turned on to start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured pH-responsive antibacterial nanofibers 6; the core-shell structured pH-responsive antibacterial nanofibers 6 are collected on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured pH-responsive antibacterial nanofibers 6 is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 5 h until all the solvent volatilizes, and a pH-responsive antibacterial nanofiber coated yarn 11 with an average diameter of 0.2 - 0.7 mm is obtained, wherein the mass ratio of the core-shell structured pH-responsive antibacterial nanofibers 6 to the core yarn 7 is 0.3 - 0.5:1.

[0096] Table 2

[0097]

[0098] Table 2 shows the time of color change of the pH-responsive antibacterial nanofiber coated yarns prepared in Examples 1 - 4 in different pH buffer solutions; it can be seen from Table 2 that the nanofiber coated yarns added with the pH-responsive agent anthocyanin have good pH sensitivity and can respond quickly within 3 s.

[0099] It can be seen from Figure 8 that the color change of the nanofiber coated yarns added with the pH-responsive agent anthocyanin is obvious.

[0100] Table 3

[0101]

[0102]

[0103] Table 3 shows the strength test data of the pH-responsive antibacterial nanofiber coated yarns prepared in Examples 1 - 4; it can be seen from Table 3 that compared with the core yarn, the change in the tensile fracture strength of the pH-responsive antibacterial nanofiber coated yarn does not significantly decrease in mechanical properties, and it has good mechanical properties. It can withstand a certain tensile force during practical applications, is not easy to break, and has good durability.

[0104] Those not described in the present invention are applicable to the prior art.

Claims

1. A preparation method of a pH-color-changing antibacterial nanofiber-coated yarn, characterized in that, The method comprises the following steps: Step 1, preparing a core layer spinning solution and a shell layer spinning solution; Dissolving a polymer and a natural pH-responsive agent in an organic solvent to obtain a shell layer spinning solution; using a natural antibacterial agent as the core layer spinning solution; Step 2, setting up a coaxial conjugate electrospinning device; The device includes a shell layer spinning solution propeller (1), a core layer spinning solution propeller (2), a coaxial needle (3), a positive electrode (4), a negative electrode (5), a unwinding roller (8), a metal rotary funnel (9) and a collecting device (12); The coaxial needle (3) is a coaxial structure with a core layer channel (302) and a shell layer channel (301), and the shell layer channel (301) is nested outside the core layer channel (302); both the shell layer spinning solution propeller (1) and the core layer spinning solution propeller (2) are installed on the coaxial needle (3); the shell layer spinning solution propeller (1) is communicated with the shell layer channel (301), and during spinning, the shell layer spinning solution is pushed into the shell layer channel (301); the core layer spinning solution propeller (2) is communicated with the core layer channel (302), and during spinning, the core layer spinning solution is pushed into the core layer channel (302); An unwinding roller (8), a metal rotary funnel (9) and a collecting device (12) are sequentially arranged along the advancing direction of the core yarn (7); the core yarn (7) is wound on the unwinding roller (8) and releases the core yarn (7) during spinning; the collecting device (12) is used for collecting the pH color-changing antibacterial nanofiber-coated yarn (11) and controlling the moving speed of the core yarn (7); Two coaxial needles (3) are on the same horizontal plane; the metal rotary funnel (9) is at the same distance from the two coaxial needles (3), is located on the mid-perpendicular plane of the two, and is within the electrostatic field range generated by the coaxial needles (3) when high voltage is applied; one of the two coaxial needles (3) is connected to the positive electrode (4) of the power supply, and the other is connected to the negative electrode (5) of the power supply to generate an electrostatic field; the metal rotary funnel (9) can rotate along its own central axis; Step 3, preparing the pH color-changing antibacterial nanofiber-coated yarn (11); Setting spinning parameters; placing the shell layer spinning solution in the shell layer spinning solution propeller (1), and placing the core layer spinning solution in the core layer spinning solution propeller (2); one end of the core yarn (7) is wound on the unwinding roller (8), passes through the metal rotary funnel (9), and the other end is wound on the collecting device (12), and the core yarn (7) is pulled and moved by the collecting device (12); Starting coaxial conjugate electrospinning, realizing that the core-shell structured pH color-changing antibacterial nanofibers (6) with the core layer being a natural antibacterial agent and the shell layer being a polymer and a natural pH-responsive agent are uniformly coated on the outside of the core yarn (7), forming a primary coated yarn with the core yarn (7) as the core layer and the core-shell structured pH color-changing antibacterial nanofibers (6) as the cortical layer; then drying the primary coated yarn until all the solvent volatilizes to obtain the pH color-changing antibacterial nanofiber-coated yarn (11).

2. The preparation method of the pH color-changing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 1, the polymer is PAN or PVDF; the natural pH-responsive agent is natural anthocyanin or litmus; the organic solvent is DMF or DMAC; In Step 1, the mass fraction of the polymer is 12-15%, and the mass fraction of the natural pH-responsive agent is 0.5-3%.

3. The preparation method of the pH color-developing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 1, the preparation process of the shell spinning solution is as follows: stirring at a temperature of 60 - 70°C and a rotation speed of 400 - 600 rpm for 6 - 10 h.

4. The preparation method of the pH-color-changing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 1, the natural antibacterial agent is tea tree essential oil.

5. The preparation method of the pH color-developing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 2, the outer sidewall of the coaxial needle (3) is perforated, and the shell spinning solution propeller (1) is fixed at the perforated position of the outer sidewall of the coaxial needle (3) and communicates with the sidewall of the shell channel (301).

6. The preparation method of the pH color-changing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 2, the core yarn (7) is a yarn; the metal rotary funnel (9) is of a flared type.

7. The preparation method of the pH color-changing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 3, the specific process of coaxial conjugate electrospinning is as follows: Turn on the power supply and start spinning. During the spinning process, the core yarn (7) is in a straight state; under the action of a high - voltage electric field, the spinning solutions in the two coaxial needles (3) are stretched into fibrous shapes in the electric field, respectively forming core - shell structured pH - color - developing antibacterial nanofibers (6); the difference in positive and negative charges causes the core - shell structured pH - color - developing antibacterial nanofibers (6) spun from the two coaxial needles (3) to be entangled with each other. At the same time, an electrostatic induction will occur between the two coaxial needles (3) and the metal rotary funnel (9), and the core - shell structured pH - color - developing antibacterial nanofibers (6) are collected on the metal rotary funnel (9); through the traction effect of the core yarn (7) on the electrospun fibers, a triangular - cone - shaped fiber web (10) formed by fiber bundles of multiple core - shell structured pH - color - developing antibacterial nanofibers (6) is formed at the opening of the metal rotary funnel (9); through the stretching and traction of the core yarn (7) by the collection device (12), the fiber bundles in the fiber web (10) have orientation; at the same time, the rotation of the metal rotary funnel (9) causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn (7) to form an outer coating layer, and finally a primary coated yarn with the core yarn (7) as the core layer and the outer coating layer as the skin layer is formed on the collection device (12).

8. The preparation method of the pH color-changing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 3, the spinning parameters are as follows: the distance between the two coaxial needles (3) is 15 - 18 cm; the distance between the coaxial needle (3) and the metal rotary funnel (9) is 13 - 14 cm; the spinning angle of the two coaxial needles (3) is 30 - 70°; the voltage of the positive electrode (4) is 5 - 8 kV, and the voltage of the negative electrode (5) is - 8 - - 5 kV; the propulsion rate of the shell spinning solution is 0.2 - 0.4 mL / h, and the propulsion rate of the core layer spinning solution is 0.05 - 0.15 mL / h; by adjusting the rotation speed of the collection device (12) to adjust the moving speed of the core yarn (7), so that the collection speed matches the spinning speed, the moving speed of the core yarn (7) is 0.1 - 0.3 mm / s; the rotation speed of the metal rotary funnel (9) is 250 - 350 rpm; the spinning environment temperature is 27 ± 3°C, and the humidity is 35 ± 5%.

9. The preparation method of the pH color-developing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 3, the mass ratio of the core - shell structured pH - color - developing antibacterial nanofibers (6) to the core yarn (7) is 0.3 - 0.5:1; In Step 3, the average diameter of the pH - color - developing antibacterial nanofiber coated yarn (11) is 0.2 - 0.7 mm.

10. The preparation method of the pH color-developing antibacterial nanofiber-coated yarn according to claim 1, characterized in that, In Step 3, the drying process is: drying in an indoor environment for at least 4 h.

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