Sulfobetaine modified carboxymethyl chitosan, and preparation method and application thereof

Abstract

The application provides sulfobetaine modified carboxymethyl chitosan and a preparation method and application thereof. The preparation method comprises the following steps: under the protection of nitrogen, 1,3-propanesultone is subjected to nucleophilic addition reaction with N,N-dimethylallylamine to prepare vinyl sulfobetaine; then, the monomer and carboxymethyl chitosan are subjected to reaction in an aqueous medium through a free radical polymerization grafting technology; after the reaction is completed, the sulfobetaine modified carboxymethyl chitosan is obtained through filtration, dialysis and freeze-drying. The sulfobetaine modified carboxymethyl chitosan of the application can inhibit the biofilm formation of pathogenic bacteria such as escherichia coli and staphylococcus aureus through a dynamic hydration effect to inhibit bacterial adhesion; and the preparation method has the advantages of mild reaction condition, good process repeatability and controllable production cost, and has application value in the fields of medical textiles and functional protective clothing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of printing and dyeing auxiliaries, and particularly relates to sulfobetaine modified carboxymethyl chitosan as well as a preparation method and application thereof. BACKGROUND

[0002] With the continuous improvement of public health awareness, the safety and protection performance of textiles has become an important consideration for consumers. Modern research shows that due to the differences in material properties and microstructure, various types of fabrics have the potential risk of microbial attachment and reproduction. Whether it is natural fiber or chemical fiber, it provides an ideal attachment carrier for bacteria, fungi and other microorganisms. Especially in a suitable environment of temperature and humidity, the grooves and textures on the surface of the fabric can form a microbial growth matrix, and the number of bacteria can grow exponentially in a short time. This biological contamination not only causes odor and color spots on the fabric, but also reduces the mechanical properties. In addition, bacterial adhesion can cause the spread of infectious diseases and implant rejection, thus posing a significant health risk. In the field of textiles, bacterial adhesion can cause odor, reduce the quality of textiles and consumer comfort. Therefore, improving the antibacterial properties of fabrics is an important way to improve the comfort of natural fiber fabrics.

[0003] The development of antibacterial materials is shifting from the traditional sterilization paradigm to a biological safety-oriented transition, and the anti-bacterial adhesion technology has become the focus of innovation. This technology builds a physical barrier to block the initial adhesion of microorganisms first, and uses biomimetic surface topological structure regulation, interface charge repulsion and other non-killing mechanisms to form a protective layer at the contact interface, effectively avoiding the risk of drug resistance and ecological load caused by sterilizing agents. Compared with the traditional antibacterial mode, the anti-adhesion design has three advantages: by blocking the colonization of bacteria at the source, it can suppress the microenvironment required for biofilm formation and avoid the subsequent massive use of sterilizing agents; relying on the interface modification effect of the anti-adhesion unit, it can achieve biological inert protection in medical devices, food packaging and other scenarios, eliminating the interference of chemical residues on the human microecology; based on the long-term stability of physical anti-adhesion, it breaks through the technical bottleneck of the action time and concentration decay of chemical sterilizing agents, and provides an environmentally friendly solution for sustainable development.

[0004] In order to more effectively prevent the adhesion of bacteria on the surface of the material, many researchers have used different methods to prevent the adhesion of bacteria on textiles. Hydrophilic materials with strong hydration surface properties can effectively prevent the adhesion of bacteria. In order to form a hydration layer on the surface of the material to resist bacterial adhesion, researchers have developed two strategies: 1) by introducing hydrophilic substances on the surface of the material, these substances can form a hydration layer on the surface of the material, thereby forming a protective barrier to effectively prevent bacterial adhesion; 2) due to the presence of highly hydrophilic anionic and cationic groups in the zwitterionic polymer, it has stronger hydration capacity in aqueous solution.

[0005] Carboxymethyl chitosan (CMC) is a derivative of chitosan, which solves the problem of poor water solubility of chitosan through carboxymethylation modification, while retaining its broad-spectrum antibacterial properties and biocompatibility. However, its single cationic property is easily interfered by anionic substances in the environment (such as Cl- in sweat), leading to a decrease in antibacterial efficiency. In addition, carboxymethyl chitosan as an antibacterial agent also has some shortcomings, such as weak antibacterial activity, limited stability, significant influence by environmental factors, and a large number of live and dead bacteria adhering to the surface of the substrate after a period of use, thereby leading to the formation of biofilms and ultimately reducing the antibacterial performance.

[0006] Sulfobetaine can effectively prevent bacterial adhesion and has a special ability to hinder the formation of microbial biofilms. This material has great application potential in the field of functional materials, and has been widely used in the fields of cosmetics, medicine, agriculture, textiles and the like. However, sulfobetaine has poor antibacterial effect, which is not conducive to finishing fabrics as an antibacterial agent.

[0007] In order to integrate the antibacterial activity of natural carboxymethyl chitosan and the hydration of sulfobetaine, sulfobetaine modified carboxymethyl chitosan with anti-bacterial adhesion is prepared by free radical block polymerization, chemical modification and structure regulation. At present, there is no report on the research of sulfobetaine modified carboxymethyl chitosan for textile finishing processing. SUMMARY

[0008] The present application innovatively develops a sulfobetaine modified carboxymethyl chitosan anti-bacterial adhesion agent, which realizes the enhancement of anti-adhesion performance through precise design of molecular structure. The material uses naturally derived carboxymethyl chitosan as the matrix, and uses free radical polymerization grafting technology to modify the sulfobetaine zwitterionic group on the molecular chain to form a biomimetic interface with dynamic hydration effect. The modified composite has good anti-bacterial adhesion performance when contacting bacteria, and the grafted sulfobetaine segment forms a physical barrier on the fiber surface through strong hydration, which significantly weakens the initial adhesion of bacteria.

[0009] Compared with traditional antibacterial agents, the present application adopts another strategy to prevent bacterial adhesion on the material surface, which overcomes the problems of dead bacteria residues and biofilm regeneration caused by the sterilization mechanism. The zwitterionic property also avoids the potential risk of inducing bacterial mutation of cationic antibacterial agents. The preparation process uses an aqueous reaction system, which can realize selective grafting under mild conditions. The obtained product is highly compatible with the textile processing flow, and the fabric after padding finishing exhibits certain antibacterial performance and anti-adhesion performance, which is especially suitable for medical protection fields with high requirements for biological safety and functional durability, and provides a solution for developing environmentally friendly antibacterial and anti-bacterial adhesion textiles.

[0010] A sulfobetaine modified carboxymethyl chitosan, the structure of which is as follows:

[0011]

[0012] Preferably, the grafting rate of the sulfobetaine modified carboxymethyl chitosan is 6.06-15.77%.

[0013] The sulfobetaine modified carboxymethyl chitosan is used in a bacterial adhesion preventing agent.

[0014] A preparation method of the sulfobetaine modified carboxymethyl chitosan, comprising:

[0015] 1) Under nitrogen protection, a solution of N,N-dimethylallylamine is added dropwise into a solution of 1,3-propanesultone by using a micro-injection pump to perform a nucleophilic addition reaction, and after the reaction is completed, a vinyl sulfobetaine is obtained by rotary evaporation;

[0016] 2) Carboxymethyl chitosan is dissolved in water to obtain a carboxymethyl chitosan solution;

[0017] 3) An ammonium persulfate solution is added dropwise into the carboxymethyl chitosan solution, and after stirring, a vinyl sulfobetaine solution is added dropwise, and a free radical polymerization grafting is performed under nitrogen protection;

[0018] 4) After the reaction is completed, the sulfobetaine modified carboxymethyl chitosan is obtained by filtration, dialysis and freeze-drying.

[0019] Preferably, in step 1) of the preparation method, the molar ratio of 1,3-propanesultone to N,N-dimethylallylamine is 0.7-0.9:1; the concentration of the 1,3-propanesultone solution is 0.75-1.25 mol / L; and the concentration of the N,N-dimethylallylamine solution is 0.75-1.25 mol / L.

[0020] Preferably, in step 1) of the preparation method, the reaction temperature of the nucleophilic addition reaction is 50-70°C, and the reaction time is 5-7 hours; the rotary evaporation temperature is 40-60°C, and the reaction time is 1-2 hours.

[0021] Preferably, in step 2) of the preparation method, the concentration of the chitosan solution is 0.01-0.03 mol / L, calculated based on the molar amount of the carboxymethyl chitosan.

[0022] As preferred, in step 3) of the above preparation method, the amount of ammonium persulfate is 0.75-1.25 wt% of the amount of carboxymethyl chitosan.

[0023] As preferred, in step 3) of the above preparation method, the molar ratio of the vinyl sulfobetaine to the carboxymethyl chitosan, calculated based on the molar amount of the carboxymethyl chitosan unit, is 0.8-1.0:1.

[0024] As preferred, in step 3) of the above preparation method, the polymerization temperature is 60-80℃, and the polymerization time is 3-5 hours.

[0025] As preferred, in step 4) of the above preparation method, the dialysis is performed using a dialysis bag with a molecular weight cutoff of 2000-5000 da, and the dialysis time is 36-60 hours; the freeze-drying temperature is -50℃ to -60℃, and the freeze-drying time is 66-80 hours.

[0026] A finishing method for natural fiber textiles, wherein the natural fiber textiles are impregnated with a sulfobetaine-modified carboxymethyl chitosan solution, dried, and baked to obtain bacteria-adhesion-resistant natural fiber textiles, and the sulfobetaine-modified carboxymethyl chitosan has the following structure:

[0027]

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) Sulfobetaine (SPB) is an amphoteric surfactant, which forms a strong hydration layer by neutralizing the positive and negative charges in the molecule. The hydration layer acts as a physical barrier, preventing bacteria from directly contacting the material surface. The hydration layer can reduce the adsorption energy of bacteria on the material surface, making it difficult for bacteria to overcome the resistance of the hydration layer and adhere to the material surface. In addition, the hydration layer also has a certain flowability, which can flush away the bacteria when they try to approach the material surface, thereby reducing bacterial adhesion. The bacterial adhesion resistance of carboxymethyl chitosan finished samples to E. coli and S. aureus is only 11.2% and 23.4%, respectively, while the SPCM finished cotton fabric exhibits excellent bacterial adhesion resistance, with a bacterial adhesion resistance of 89.5% and 94.2% to E. coli and S. aureus, respectively, which is 7 times and 3 times higher than that of carboxymethyl chitosan, respectively.

[0030] (2) The preparation method of the present application is simple and convenient, and the reaction conditions are mild.

[0031] In summary, the present application utilizes the excellent properties of sulfobetaine and carboxymethyl chitosan respectively, grafts sulfobetaine onto carboxymethyl chitosan, effectively improves the bacterial adhesion prevention performance of carboxymethyl chitosan, so that it can be applied to fabric antibacterial application. The sulfobetaine modified carboxymethyl chitosan antibacterial and bacterial adhesion prevention agent obtained by the preparation method of the present application can be used for antibacterial finishing of fabric, and excellent antibacterial property and good antibacterial adhesion prevention performance are imparted to the fabric. Moreover, the preparation process is simple, the reaction conditions are mild, and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The infrared spectra of vinyl sulfobetaine (SPB), carboxymethyl chitosan (CMC), and sulfobetaine modified carboxymethyl chitosan (SPCM) are shown.

[0033] Figure 2 The sulfobetaine content on the adhesion of Staphylococcus aureus and Escherichia coli on different treated cotton fabrics. DETAILED DESCRIPTION

[0034] The present application will be further described below in conjunction with specific examples. These examples are only used to illustrate the present application and are not used to limit the scope of the present application. After reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0035] Examples 1-5: Change the molar ratio of vinyl sulfobetaine to carboxymethyl chitosan.

[0036] Preparation of sulfobetaine modified carboxymethyl chitosan:

[0037] 1) First, 0.05 mol of 1,3-propanesultone is dissolved in 50 mL of tetrahydrofuran solution, and under nitrogen protection, 60 mL of 1 mol / L N,N-dimethylallylamine solution is added dropwise into the mixture at 50°C, and stirred for 6h. The obtained product vinyl sulfobetaine is collected by rotary evaporation at 50°C for 1.5h.

[0038] 2) Then, 1 mmol of carboxymethyl chitosan is dissolved in 50 mL of aqueous solution to obtain a 0.02 mol / L carboxymethyl chitosan solution.

[0039] 3) To the above system, 1 wt% ammonium persulfate (percentage of total mass of carboxymethyl chitosan) is added dropwise under nitrogen protection, followed by the addition of vinyl sulfobetaine and carboxymethyl chitosan with a molar ratio of 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, respectively, and reacted at 70°C for 4h.

[0040] 4) After the reaction solution is cooled, 5 parts of the reaction solution are dialyzed for 48 h using a 3500 da dialysis bag, and then the solvent is removed by a freeze dryer at -55°C for 72 h to obtain five different sulfobetaine modified carboxymethyl chitosans.

[0041] The reaction process of the above preparation method is as follows:

[0042]

[0043] Preparation of Comparative Example:

[0044] Comparative Example 1: Carboxymethyl chitosan with a unit molar mass of 1 mmol is dissolved in 50 mL of an aqueous solution to obtain a 0.02 mol / L carboxymethyl chitosan solution, and 1 wt% ammonium persulfate (percentage of the total mass of carboxymethyl chitosan) is added dropwise.

[0045] Comparative Example 2: 1) 0.05 mol of 1,3-propanesultone is dissolved in 50 mL of a tetrahydrofuran solution, and 60 mL of a 1 mol / L N,N-dimethylallylamine solution is added dropwise to the mixture under nitrogen protection at 50°C using a micro-injection pump, and the reaction is stirred for 6 h. The resulting product, vinyl sulfobetaine, is collected by rotary evaporation at 50°C for 1.5 h.

[0046] 2) 1 mmol of vinyl sulfobetaine is dissolved in 50 mL of an aqueous solution to obtain a 0.02 mol / L vinyl sulfobetaine solution, and an equal amount of ammonium persulfate is added dropwise.

[0047] Finally, 40 g / L of the finishing liquid of the seven different sulfobetaine modified carboxymethyl chitosans prepared is used as an antibacterial adhesion agent, and seven different antibacterial adhesion cotton fabrics I are obtained by antibacterial adhesion finishing of seven pretreated cotton fabrics.

[0048] Among them, the antibacterial adhesion finishing process is:

[0049] Double-dip double-rolling (bath ratio 1:20, dipping time 1 min, rolling rate 80%) → drying (70°C, 4 min) → baking (130°C, 3 min) → antibacterial adhesion cotton fabric.

[0050] According to GB / T20944.3-2008, under the above conditions, the change of the molar ratio of vinyl sulfobetaine and carboxymethyl chitosan, the anti-bacterial adhesion rate of the finished cotton fabric was explored (reference: Wu J D, Zhang C, Xu S T, et al. Preparation of zwitterionic polymer-functionalized cotton fabrics and the performance of anti-biofouling and long-term biofilm resistance [J]. Colloid and Interface Science Communications, 2018, 24: 98-104.) The experimental results are shown in Table 1.

[0051] Table 1: Effect of molar ratio of vinyl sulfobetaine and carboxymethyl chitosan on the anti-bacterial adhesion rate of the prepared cotton fabric and its grafting rate.

[0052]

[0053] From Table 1, it can be seen that the increase of the molar ratio of vinyl sulfobetaine and carboxymethyl chitosan shows a trend of first increasing and then decreasing. When the molar ratio of carboxymethyl chitosan and sulfobetaine is 0.9:1 (grafting rate = 15.77%), the anti-adhesion rate of sulfobetaine modified carboxymethyl chitosan to Escherichia coli and Staphylococcus aureus is 89.5% and 94.2% respectively, which is 7 times and 3 times higher than that of carboxymethyl chitosan finishing. The experimental results of Examples 1-5 are shown in Figure 2 .

[0054] Figure 1 The infrared spectra of vinyl sulfobetaine (SPB), carboxymethyl chitosan (CMC), and sulfobetaine modified carboxymethyl chitosan (SPCM) are shown in the figure. Compared with the original CMC, SPCM shows obvious SO3 asymmetric stretching vibration peak and bending vibration characteristic peak at 1120 cm -1 and 620 cm -1 , respectively, while the above characteristic peaks do not appear in the original CMC spectrum, which confirms that SO3 - groups have been successfully introduced into the CMC molecular chain. It is worth noting that the characteristic spectrum of SPB corresponds to the symmetric and asymmetric stretching vibration peaks of sulfonic acid group at 1040 cm -1 and 1120 cm -1 , respectively, while 602 cm 1 and 620 cm -1The absorption peaks of SPB are attributed to the bending vibration of SO3-. - The relevant characteristic peaks show high consistency, and the original CMC does not show any corresponding signal, which can be determined that SPB has been successfully grafted to the CMC skeleton.

[0055] Examples 6-10: Change the amount of ammonium persulfate.

[0056] 1) First, 0.05 mol of 1,3-propanesultone is dissolved in 50 mL of tetrahydrofuran solution, and 60 mL of 1 mol / L N,N-dimethylallylamine solution is added dropwise into the mixture under nitrogen protection at 60°C, and the reaction is stirred for 6 h. The resulting product, vinyl sulfobetaine (SPB), is collected by rotary evaporation at 50°C for 1.5 h.

[0057] 2) Then, 1 mmol of carboxymethyl chitosan is dissolved in 50 mL of aqueous solution to obtain a 0.02 mol / L carboxymethyl chitosan solution.

[0058] 3) Then, under nitrogen protection, add ammonium persulfate solution to the above system, control the amount of ammonium persulfate to be 0.1wt%, 0.5wt%, 0.75wt%, 1.0wt%, 1.5wt% of carboxymethyl chitosan, then add vinyl sulfobetaine, and the molar ratio of vinyl sulfobetaine to carboxymethyl chitosan is 0.9:1, and react at 60°C for 3 h.

[0059] 4) After the reaction solution is cooled, it is dialyzed for 36 h using a 5000 da dialysis bag, and then the solvent is removed by freeze-drying machine at -50°C for 80 h to obtain five different sulfobetaine modified carboxymethyl chitosan (SPCM).

[0060] The reaction process of the above preparation method is as follows:

[0061]

[0062] Finally, five different sulfobetaine modified carboxymethyl chitosan finishing liquids are prepared by using 40 g / L of the prepared sulfobetaine modified carboxymethyl chitosan, and the finishing liquid is a bacterial adhesion prevention agent. Five different bacterial adhesion prevention cotton fabrics I are obtained by bacterial adhesion prevention finishing of five pretreated cotton fabrics.

[0063] The bacterial adhesion prevention finishing process is as follows:

[0064] Double dip and double roll (bath ratio 1:40, dipping time 1 min, roll yield 90%) → drying (70°C, 3 min) → curing (140°C, 1 min) → bacterial adhesion prevention cotton fabric.

[0065] According to GB / T20944.3-2008, under the above conditions, the change of the molar ratio of sulfobetaine and carboxymethyl chitosan, the anti-bacterial adhesion rate of the finished cotton fabric was explored, and the results are shown in Table 2. Table 2: Effect of ammonium persulfate dosage on anti-bacterial adhesion of cotton fabric prepared by sulfobetaine modified carboxymethyl chitosan.

[0066]

[0067] As shown in Table 2, the amount of ammonium persulfate has a significant effect on the anti-bacterial adhesion performance of SPCM. With the gradual increase of ammonium persulfate dosage, the anti-bacterial adhesion rate of SPCM shows a trend of first increasing and then decreasing. The reason for this phenomenon may be that the increase of initiator dosage leads to the increase of free radical number in the reaction process. The increase of free radical number promotes the diffusion of SPB to CMC, and then promotes the smooth progress of the reaction, significantly improves the anti-bacterial adhesion effect. However, with the increase of ammonium persulfate concentration, the molecular volume increases and the interaction between molecules increases, and the free radical concentration in the reaction medium is too high, which leads to the recombination reaction or termination reaction of polymer chain, the volume of reaction product increases and the solubility decreases, thereby self-polymerization of by-products, resulting in the decrease of anti-bacterial adhesion performance of SPCM. When the dosage of ammonium persulfate is 1.0wt%, the anti-bacterial adhesion rates of SPCM to E. coli and S. aureus are 89.5% and 94.2% respectively, indicating that the anti-adhesion performance of SPCM under this condition is at the best level.

[0068] Examples 11-15: Change the finishing concentration of sulfobetaine modified carboxymethyl chitosan.

[0069] 1) First, 0.05 mol of 1,3-propanesultone was dissolved in 50 mL of tetrahydrofuran solution, and 60 mL of 1 mol / L N,N-dimethylallylamine solution was added dropwise into the mixture under nitrogen protection at 70°C, and stirred for 6h. The product vinyl sulfobetaine (SPB) was collected by rotary evaporation at 50°C for 1.5h.

[0070] 2) Then, 1 mmol of carboxymethyl chitosan was dissolved in 50 mL of aqueous solution to obtain a 0.02 mol / L carboxymethyl chitosan solution.

[0071] 3) Then, ammonium persulfate solution was added dropwise to the above system under nitrogen protection, and the amount of ammonium persulfate was controlled to be 1.0wt% of carboxymethyl chitosan, then vinyl sulfobetaine was added, and the molar ratio of vinyl sulfobetaine and carboxymethyl chitosan was 0.9:1, and the reaction was carried out at 80°C for 5h.

[0072] 4) After the reaction solution is cooled, it is dialyzed for 60 h using a 2000 da dialysis bag, and then the solvent is removed by a freeze dryer at -60 °C for 66 h to obtain sulfobetaine modified carboxymethyl chitosan (SPCM).

[0073] The reaction process of the above preparation method is as follows:

[0074]

[0075] Finally, five different sulfobetaine modified carboxymethyl chitosan finishing liquids are prepared using 10 g / L, 20 g / L, 30 g / L, 40 g / L, and 50 g / L, respectively, and the finishing liquids are bacterial adhesion prevention agents. Five different bacterial adhesion prevention cotton fabrics I are obtained by performing bacterial adhesion prevention finishing on five pretreated cotton fabrics.

[0076] The bacterial adhesion prevention finishing process is as follows:

[0077] Two dips and two rolls (bath ratio is 1:30, dipping time is 1 min, and rolling rate is 90%) → drying (90 °C, 4 min) → baking (140 °C, 3 min) → bacterial adhesion prevention cotton fabric.

[0078] According to GB / T20944.3-2008, under the above conditions, the finishing concentration of sulfobetaine modified carboxymethyl chitosan is explored to explore the bacterial adhesion prevention rate of the finished cotton fabric, and the results are shown in Table 3.

[0079] Table 3 Influence of bacterial adhesion resistance of cotton fabric prepared by different concentrations of sulfobetaine modified carboxymethyl chitosan

[0080]

[0081] The concentration of the SPCM finishing liquid has a significant concentration response relationship with the bacterial adhesion prevention performance of the cotton fabric. When the concentration gradient of the finishing liquid increases to 40 g / L, the bacterial adhesion inhibition rate of the fabric surface treated by SPCM shows a continuous upward trend, and reaches a maximum value at 40 g / L, with an adhesion prevention rate of 89.5% for E. coli and 94.2% for S. aureus. The reason for this phenomenon is that as the concentration of the finishing liquid increases, the chemical grafting density of the SPCM functional groups on the fiber surface significantly increases, thereby achieving better bacterial adhesion prevention performance by enhancing hydration. However, when the concentration exceeds 40 g / L, increasing the concentration of the finishing liquid does not show a significant increase in the bacterial adhesion prevention rate, but high concentration finishing can affect the whiteness and hand feel of the fabric. Based on the concept of green economy, 40 g / L is finally determined as the optimal finishing liquid concentration of the SPCM finishing system.

Claims

1. A method for preparing sulfobetaine-modified carboxymethyl chitosan, characterized in that, include: 1) Using tetrahydrofuran as solvent, under nitrogen protection, N,N-dimethylallylamine solution was added dropwise to 1,3-propanesulfonate lactone solution via a micro-injection pump for a nucleophilic addition reaction. After the reaction, the solution was obtained by rotary evaporation, yielding vinyl sulfobetaine. The molar ratio of 1,3-propanesulfonate lactone to N,N-dimethylallylamine was 0.7~0.9:1, the concentration of 1,3-propanesulfonate lactone solution was 0.75~1.25 mol / L, and the concentration of N,N-dimethylallylamine solution was 0.75~1.25 mol / L. 2) Dissolve carboxymethyl chitosan in water to obtain a carboxymethyl chitosan solution. The concentration of the carboxymethyl chitosan solution is 0.01~0.03 mol / L, calculated based on the molar amount of carboxymethyl chitosan unit. 3) Add ammonium persulfate solution dropwise to the above carboxymethyl chitosan solution, stir evenly, and then add vinyl sulfobetaine solution dropwise. Perform free radical polymerization grafting under nitrogen protection. The molar ratio of vinyl sulfobetaine to carboxymethyl chitosan is 0.8~1.0:1, calculated based on the molar amount of carboxymethyl chitosan unit. 4) After the reaction is complete, the sulfobetaine-modified carboxymethyl chitosan is obtained by filtration, dialysis and freeze drying.

2. The sulfobetaine-modified carboxymethyl chitosan prepared according to the method of claim 1, is characterized in that, The grafting rate of the sulfobetaine-modified carboxymethyl chitosan was 6.92-15.77%.

3. The application of sulfobetaine-modified carboxymethyl chitosan as described in claim 2 in the preparation of an antibacterial adhesive.

4. The method for preparing sulfobetaine-modified carboxymethyl chitosan according to claim 1, characterized in that, In step 1), the nucleophilic addition reaction temperature is 50~70℃ and the reaction time is 5~7 hours; the rotary evaporation temperature is 40~60℃ and the reaction time is 1~2 hours.

5. The method for preparing sulfobetaine-modified carboxymethyl chitosan according to claim 1, characterized in that, In step 3), the amount of ammonium persulfate is 0.75~1.25 wt% of the amount of carboxymethyl chitosan.

6. The method for preparing sulfobetaine-modified carboxymethyl chitosan according to claim 1, characterized in that, In step 3), the polymerization temperature is 60~80 ℃ and the polymerization time is 3~5 hours.

7. The method for preparing sulfobetaine-modified carboxymethyl chitosan according to claim 1, characterized in that, In step 4), dialysis bags with a capacity of 2000~5000 da are used, and the dialysis time is 36~60h; the freeze-drying temperature is -50℃~-60℃, and the freeze-drying time is 66~80h.

8. A finishing method for natural fiber textiles, characterized in that: Natural fiber textiles are impregnated with a sulfobetaine-modified carboxymethyl chitosan solution, dried, and baked to obtain natural fiber textiles that prevent bacterial adhesion. The sulfobetaine-modified carboxymethyl chitosan is prepared by a method for preparing sulfobetaine-modified carboxymethyl chitosan as described in claim 1.

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