Ion regulation-based tocn / hacc composite film and preparation method and application thereof

Abstract

The application discloses a kind of TOCN / HACC composite film based on ion regulation and its preparation method and application, belong to nanocellulose composite functional material technical field, including the following steps: ultrasonic dispersion is obtained to TOCN suspension in water with oxidized cellulose, KI solution is added to the TOCN suspension to adjust KI concentration in system, HACC solution is added and mixed stirring, then centrifugation, discard supernatant, the obtained precipitate is resuspended, filtered, dried, i.e. the TOCN / HACC composite film is obtained.The application successfully solves the technical problem that TOCN and HACC are directly mixed and prone to instantaneous agglomeration, and cannot be uniformly compounded, thereby realizing the uniform compounding and controllable assembly of the two at the microscale.The method provided by the application is simple in operation, mild in conditions and has significant regulation effect, and provides a new technical idea for the uniform compounding of nanocellulose and cationic polymer.

Description

Technical Field

[0001] This invention belongs to the technical field of nanocellulose composite functional materials, and particularly relates to a TOCN / HACC composite film based on ion regulation, its preparation method and application. Background Technology

[0002] Cellulose nanomaterials, as highly crystalline nanomaterials derived from natural fibers, possess high specific surface area, high Young's modulus, excellent mechanical properties, and good biocompatibility and biodegradability, showing broad application prospects in biomedicine, food packaging, and functional materials. Among these methods, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxygen radical) oxidation is currently one of the important routes for preparing cellulose nanomaterials. However, pure TOCN films have several inherent drawbacks: on the one hand, the abundant carboxylate groups on the TOCN surface endow the material with extremely strong hydrophilicity, leading to significant swelling or even dissolution of the film in aqueous or humid environments, resulting in a substantial decrease in structural stability; on the other hand, TOCN films themselves lack antibacterial properties, limiting their application in food packaging, biomedicine, and other fields where antibacterial properties are clearly required.

[0003] To improve the overall performance of TOCN films, combining TOCN with functional natural organic matter is a current research hotspot. Commonly used mixing methods include physical methods, grafting covalent methods, and chemical methods. For example, Li Meichan et al. (Li Meichan, Li Deqiang, Li Jun, et al. Preparation and properties of Janus oxidized cellulose-chitosan functional membranes [J]. Journal of Beijing Forestry, 2025, 47(08):173-181.) studied the different solubilities of cellulose and chitosan in the N,N-dimethylacetamide / lithium chloride solvent system. They prepared oxidized cellulose-chitosan functional membranes with Janus structure through Schiff base reaction, achieving differentiated hydrophilic and hydrophobic surfaces on the cellulose surface (contact angle <75°) and the chitosan surface (contact angle >99°), and obtained the highest DPPH radical scavenging rate of 83.28% and the elongation at break of 113.90%. Chen Xiaoxia et al. (Chen Xiaoxia, Qiu Yulong, Li Yiqian, et al. Preparation and characterization of chitosan-cellulose nanofiber composite membranes [J]. Food Research and Development, 2023, 44(22):1-6) studied the preparation of CS-GP-CNF composite membranes by crosslinking CNF with chitosan (CS) at concentrations of 0%, 1%, 2%, 3%, and 6% by mass. The resulting composite membranes had a relatively uniform, smooth surface without bubbles. With the increase of CNF addition, a small number of nodules appeared on the surface of the composite membrane. In addition, the CS-GP-CNF composite membrane has good water vapor barrier properties, and the CS-GP-CNF6 composite membrane can effectively slow down the increase rate of total bacterial count and volatile basic nitrogen content in chicken during storage at 4℃, effectively extending its shelf life. Chen Qijie et al. (Chen Qijie, Zhang Peng, You Na, et al. Preparation and properties of starch-based antibacterial membrane based on cellulose nanocrystal emulsified tangerine peel essential oil [J]. Food Science, 2024, 45(03):134-141.) studied the preparation of Pickering emulsion using corn starch as matrix and citric acid as crosslinking agent, and TEMPO oxidized cellulose nanocrystals (TOCN) emulsified tangerine peel essential oil (OPO) as antibacterial agent. A CS / TOCN-OPO antibacterial composite membrane was prepared by casting. The effects of TOCN and OPO dosage on the mechanical strength, water vapor transmission rate, water contact angle, and antibacterial properties of the composite membrane were investigated. The obtained composite membrane showed the best performance, high water vapor transmission rate, and good mechanical properties, with inhibition areas of 203.53 mm² against Escherichia coli and Staphylococcus aureus. 2 and 262.21 mm 2Yang Xuan (Yang Xuan, Tang Lirong, Lin Fengcai, et al. Preparation and performance study of nanocellulose / chitosan / gelatin composite membranes [J]. Biomass Chemical Engineering, 2018, 52(01):17-22.) et al. studied the preparation of nanocellulose / chitosan / gelatin composite membranes with different NCC and CS mass ratios using gelatin (Gel), chitosan (CS), and nanocellulose (NCC) as raw materials by solution blending. The obtained composite membranes formed a strongly interacting network structure among nanocellulose, chitosan, and gelatin, exhibiting good compatibility. The composite membranes achieved a maximum tensile strength of 33 MPa, an elongation at break of 14.9%, and a maximum water absorption rate of 341%. Tang Xingmei (Tang Xingmei, Ji Jiao, Jiang Hanbing, et al. Preparation of cellulose nanofibers / Camellia oleifera shell CQDs / PVA composite film and its application in fruit preservation [J]. China Pulp & Paper, 2025, 44(10):150-158.) et al. studied the preparation of TEMPO oxidized cellulose nanofibers (TOCNF) with carboxyl contents of 0.7, 1.2 and 1.6 mmol / g by adjusting the amount of oxidant using bleached eucalyptus pulp as raw material. TOCNF with different oxidation levels was then combined with carbon quantum dots (CQDs) which have excellent UV shielding properties, and an environmentally friendly composite preservation film was prepared using polyvinyl alcohol as a substrate via a casting method. The results showed that TOCNF and CQDs could synergistically improve the performance of the composite film, exhibiting good oxygen permeability and tensile strength, while also possessing good light transmittance. Blueberries treated with this film showed no obvious spoilage after 7 days of storage, and the weight loss rate was reduced by 37.8% compared to the control group. However, the existing technologies for improving TOCN thin films mainly focus on two methods: physical blending and chemical blending. Physical blending is simple to prepare and requires no additional processing, but the resulting membranes do not exhibit outstanding performance. Chemical blending produces composite membranes with better performance, but the preparation process is cumbersome and relies on pretreatment and crosslinking agents, which increases costs and is not conducive to large-scale industrial production.

[0004] Therefore, how to provide a simple and low-cost method for preparing TOCN thin films is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an ion-controlled TOCN / HACC composite thin film, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing an ion-controlled TOCN / HACC composite thin film includes the following steps: Oxidized cellulose was ultrasonically dispersed in water to obtain a TOCN suspension. KI solution was added to the TOCN suspension to adjust the KI concentration in the system. HACC solution was added and mixed and stirred. After centrifugation and discarding the supernatant, the resulting precipitate was resuspended, filtered, and dried to obtain the TOCN / HACC composite film.

[0007] Preparation Principle: The TOCN surface is rich in carboxylate anions with negative charges introduced by TEMPO oxidation, while the HACC molecular chain is rich in quaternary ammonium cations with positive charges, resulting in a strong electrostatic complexation driving force between the two. When directly mixed without external ion regulation, the electrostatic interaction energy is much higher than the thermal kinetic energy of the system, causing the two polyelectrolytes to undergo instantaneous non-equilibrium macroscopic flocculation, forming gel aggregates with extremely heterogeneous internal structures. This invention utilizes the high concentration of K+ to pre-add a KI solution to the mixed system. + The electrostatic shielding effect effectively compresses the Debye length between TOCN and HACC, significantly reducing their effective charge density and electrostatic bonding strength. Under this ion shielding effect, the polyelectrolyte complexation process changes from reaction-controlled to diffusion-controlled, allowing sufficient time for chain segments to undergo conformational rearrangement to form a thermodynamically stable, uniform three-dimensional network structure. This enables the uniform composite and controllable assembly of TOCN and HACC at the microscale. This uniform wet network undergoes isotropic capillary contraction during drying, maintaining its structural integrity and ultimately forming a dense composite film with excellent mechanical properties. Simultaneously, the carboxyl group of TOCN and the quaternary ammonium cation of HACC form an ionic cross-linked network through electrostatic complexation. This shields the hydrophilic groups, reducing water molecule binding sites and lowering the film's swelling rate; it also enhances the inter-chain bonding force, improving stress transfer efficiency and significantly improving the film's mechanical properties. Furthermore, the introduction of HACC endows the composite film with contact-type antibacterial functionality.

[0008] Preferably, the method for preparing the oxidized cellulose includes the following steps: Na₂CO₃, NaHCO₃, NaBr, TEMPO and cellulose were dissolved in water under heating conditions. After adjusting the pH, NaClO solution was added and the reaction was sealed. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. After filtration, washing and drying, the oxidized cellulose was obtained.

[0009] Beneficial effects: The method for preparing oxidized cellulose in this invention is the TEMPO oxidation method, which is a relatively mature and commonly used oxidation method. It has extremely high chemical selectivity, mild reaction conditions and recyclability.

[0010] Preferably, the ratio of the added Na2CO3, NaHCO3, NaBr, TEMPO, cellulose and water is 2.6g:0.88g:0.5g:0.05g:2.5g:350mL.

[0011] Preferably, the heating temperature is 35°C; The pH adjustment is performed by using a 1 mol / L NaOH solution to adjust the pH to 10.4-10.8.

[0012] Beneficial effects: The present invention selects relatively mild conditions, which can reduce energy consumption and eliminates the need to add additional reagents to adjust the pH value.

[0013] Preferably, the volume ratio of the TOCN suspension to the HACC solution is 25:(5-20).

[0014] Preferably, the mass concentration of the TOCN suspension is 0.5-2%; The HACC solution has a mass concentration of 0.1-0.5%.

[0015] Beneficial effects: Low-concentration samples are easier to mix evenly during addition and are less prone to instantaneous electrostatic complexation.

[0016] Preferably, the KI concentration in the system is 0.5-2 g / L.

[0017] Beneficial effects: High concentration of potassium + The electrostatic shielding effect effectively compresses the Debye length between TOCN and HACC, significantly reducing the effective charge density and electrostatic bonding strength of both, thus achieving uniform mixing.

[0018] Preferably, the resuspension solution used is water.

[0019] Preferably, the filtration is performed by vacuum filtration onto the PTFE filter membrane.

[0020] Beneficial effects: The properties of PTFE filter membrane itself determine that the composite membrane obtained after filtration to its surface and drying is easier to detach, and PTFE filter membrane is more durable and can be reused than ordinary filter membrane.

[0021] An ion-controlled TOCN / HACC composite film prepared by the method described above.

[0022] Application of an ion-controlled TOCN / HACC composite film in antibacterial packaging materials, biomedical materials, or functional coating materials.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes KI as an ion-regulating medium by adding KI to a TOCN suspension, which is simple, environmentally friendly, and also allows for the utilization of K. + The electrostatic shielding effect effectively regulates the electrostatic complexation rate of TOCN and HACC, transforming their instantaneous and violent flocculation into a slow and controllable assembly process. This successfully solves the technical challenge of instantaneous aggregation and inability to uniformly composite when TOCN and HACC are directly mixed, thus achieving uniform composite and controllable assembly at the microscale. Based on this, a TOCN-HACC composite film with a dense structure, excellent mechanical properties, low swelling ratio, and antibacterial properties was further prepared. This method is simple to operate, operates under mild conditions, and has significant controllability, providing a novel technical approach for the uniform composite of nanocellulose and cationic polymers.

[0024] The TOCN-HACC composite film provided by this invention constructs a stable physical cross-linked structure through electrostatic complexation between TOCN and HACC and intermolecular hydrogen bond network. The maximum tensile strength reaches 112.23 MPa, which is about 1.8 times higher than that of pure TOCN film (39.94 MPa). It has excellent mechanical properties, and the composite film still maintains structural integrity after long-term immersion and has good water stability. At the same time, it effectively inhibits Staphylococcus aureus and Escherichia coli, expanding the application field of the material. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The process flow diagrams are for Examples 1-4; Figure 2 Infrared spectra of the thin films obtained in Examples 1-4 and Comparative Example 1; Where b is a magnified view of part of the infrared spectrum in a; Figure 3 The figures show the mechanical properties of the films obtained in Examples 1-4 and Comparative Example 1, where a is a stress-strain curve, b is the average value of tensile strength and elongation at break, and c is a folded photograph of the actual product. Figure 4 The images show the antimicrobial zone effects of the films obtained in Examples 1-4 and Comparative Example 1, where a is the antimicrobial zone image for Escherichia coli and b is the antimicrobial zone image for Staphylococcus aureus.

[0026] Figure 5The electrostatic complexation and morphology images of the thin films prepared for Example 1 and Comparative Examples 1-2 are shown below. In the images, A is a TOCN solution; B is the complexation of TOCN and HACC in KI solution; C is the complexation of TOCN and HACC; 1 is a TOCN thin film; 2 is a TOCN-HACC1 composite thin film; 3 is a TOCN-HACC2 composite thin film; 4 is a TOCN-HACC3 composite thin film; 5 is a TOCN-HACC4 composite thin film; and 6 is a TOCN-HACC5 composite thin film. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels; Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0030] Example 1 A method for preparing TOCN / HACC composite thin films based on ion regulation, such as... Figure 1 As shown, it includes the following steps: (1) Take 2.5g of cellulose, 2.6g of Na2CO3, 0.88g of NaHCO3, 0.5g of NaBr, and 0.05g of TEMPO and add them to 350mL of deionized water. Adjust the pH to 10.4-10.8 with 1M NaOH solution at 35℃. Add 25mL of NaClO solution with a concentration of 30% available chlorine dropwise over 3h. After the reaction is complete, add 5mL of anhydrous ethanol to terminate the reaction. After filtration and washing until neutral, dry at 80℃ for 24h to obtain oxidized cellulose. Take 2.5g of oxidized cellulose and add it to 250mL of deionized water. Sonicate at 80% power for 1h to obtain a TOCN suspension with a concentration of 1wt%.

[0031] (2) Prepare a KI solution with a concentration of 1 g / L and a HACC solution with a concentration of 0.1 wt%. Take 25 mL of TOCN suspension, add the KI solution and stir to mix evenly so that the KI concentration in the suspension reaches 1 g / L. Then add 5 mL of HACC solution and continue stirring for 1 h to obtain a composite suspension. Centrifuge the composite suspension at 12000 rpm for 15 min, discard the supernatant, add deionized water to resuspend the precipitate, repeat the washing 3 times, and then vacuum filter it onto a PTFE filter membrane (50 mm in diameter). After drying at room temperature, the TOCN / HACC composite membrane is obtained and is denoted as TOCN-HACC1.

[0032] Example 2 A method for preparing TOCN / HACC composite thin films based on ion regulation, such as... Figure 1 As shown, it includes the following steps: (1) Take 2.5g of cellulose, 2.6g of Na2CO3, 0.88g of NaHCO3, 0.5g of NaBr, and 0.05g of TEMPO and add them to 350mL of deionized water. Adjust the pH to 10.4-10.8 with 1M NaOH solution at 35℃. Add 25mL of NaClO solution with a concentration of 30% available chlorine dropwise over 3h. After the reaction is complete, add 5mL of anhydrous ethanol to terminate the reaction. After filtration and washing until neutral, dry at 80℃ for 24h to obtain oxidized cellulose. Take 2.5g of oxidized cellulose and add it to 250mL of deionized water. Sonicate at 80% power for 1h to obtain a TOCN suspension with a concentration of 1wt%.

[0033] (2) Prepare a KI solution with a concentration of 1 g / L and a HACC solution with a concentration of 0.1 wt%. Take 25 mL of TOCN suspension, add the KI solution and stir to mix evenly so that the KI concentration in the suspension reaches 1 g / L. Then add 10 mL of HACC solution and continue stirring for 1 h to obtain a composite suspension. Centrifuge the composite suspension at 12000 rpm for 15 min, discard the supernatant, and resuspend the precipitate in deionized water with the supernatant. Repeat the washing 3 times, then vacuum filter it onto a PTFE filter membrane (50 mm in diameter). After drying at room temperature, the TOCN / HACC composite membrane is obtained and is denoted as TOCN-HACC2.

[0034] Example 3 A method for preparing TOCN / HACC composite thin films based on ion regulation, such as... Figure 1 As shown, it includes the following steps: (1) Take 2.5g of cellulose, 2.6g of Na2CO3, 0.88g of NaHCO3, 0.5g of NaBr, and 0.05g of TEMPO and add them to 350mL of deionized water. Adjust the pH to 10.4-10.8 with 1M NaOH solution at 35℃. Add 25mL of NaClO solution with a concentration of 30% available chlorine dropwise over 3h. After the reaction is complete, add 5mL of anhydrous ethanol to terminate the reaction. After filtration and washing until neutral, dry at 80℃ for 24h to obtain oxidized cellulose. Take 2.5g of oxidized cellulose and add it to 250mL of deionized water. Sonicate at 80% power for 1h to obtain a TOCN suspension with a concentration of 1wt%.

[0035] (2) Prepare a KI solution with a concentration of 1 g / L and a HACC solution with a concentration of 0.1 wt%. Take 25 mL of TOCN suspension, add the KI solution and stir to mix evenly so that the KI concentration in the suspension reaches 1 g / L. Then add 5 mL of HACC solution and continue stirring for 1 h to obtain a composite suspension. Centrifuge the composite suspension at 12000 rpm for 15 min, discard the supernatant, and add deionized water to resuspend the precipitate. Repeat the washing 3 times, then vacuum filter it onto a PTFE filter membrane (50 mm in diameter). After drying at room temperature, the TOCN / HACC composite membrane is obtained and is denoted as TOCN-HACC3.

[0036] Example 4 A method for preparing TOCN / HACC composite thin films based on ion regulation, such as... Figure 1 As shown, it includes the following steps: (1) Take 2.5g of cellulose, 2.6g of Na2CO3, 0.88g of NaHCO3, 0.5g of NaBr, and 0.05g of TEMPO and add them to 350mL of deionized water. Adjust the pH to 10.4-10.8 with 1M NaOH solution at 35℃. Add 25mL of NaClO solution with a concentration of 30% available chlorine dropwise over 3h. After the reaction is complete, add 5mL of anhydrous ethanol to terminate the reaction. After filtration and washing until neutral, dry at 80℃ for 24h to obtain oxidized cellulose. Take 2.5g of oxidized cellulose and add it to 250mL of deionized water. Sonicate at 80% power for 1h to obtain a TOCN suspension with a concentration of 1wt%.

[0037] (2) Prepare a KI solution with a concentration of 1 g / L and a HACC solution with a concentration of 0.1 wt%. Take 25 mL of TOCN suspension, add the KI solution and stir to mix evenly so that the KI concentration in the suspension reaches 1 g / L. Then add 5 mL of HACC solution and continue stirring for 1 h to obtain a composite suspension. Centrifuge the composite suspension at 12000 rpm for 15 min, discard the supernatant, and add deionized water to resuspend the precipitate. Repeat the washing 3 times, then vacuum filter it onto a PTFE filter membrane (50 mm in diameter). After drying at room temperature, the TOCN / HACC composite membrane is obtained and is designated as TOCN-HACC4.

[0038] Comparative Example 1 A method for preparing a TOCN thin film, differing from Example 1 only in that KI solution and HACC solution are not added in step (2), specifically including the following steps: 2.5 g of cellulose, 2.6 g of Na₂CO₃, 0.88 g of NaHCO₃, 0.5 g of NaBr, and 0.05 g of TEMPO were added to 350 mL of deionized water. The pH was adjusted to 10.4–10.8 using 1 M NaOH solution at 35 °C. 25 mL of NaClO solution with a 30% available chlorine concentration was added dropwise over 3 hours. After the reaction was complete, 5–10 mL of anhydrous ethanol was added to terminate the reaction. After filtration and washing until neutral, the solution was dried at 80 °C for 24 hours to obtain oxidized cellulose. 2.5 g of oxidized cellulose was added to 250 mL of deionized water and sonicated at 80% power for 1 hour to obtain a 1 wt% TOCN suspension. 25 mL of the TOCN suspension was vacuum filtered onto a PTFE membrane (50 mm in diameter) and dried at room temperature to obtain a TOCN membrane, denoted as TOCN.

[0039] Comparative Example 2 A method for preparing a TOCN / HACC composite film differs from Example 4 only in that KI solution is not added in step (2), and specifically includes the following steps: (1) Take 2.5g of cellulose, 2.6g of Na2CO3, 0.88g of NaHCO3, 0.5g of NaBr, and 0.05g of TEMPO and add them to 350mL of deionized water. Adjust the pH to 10.4-10.8 with 1M NaOH solution at 35℃. Add 25mL of NaClO solution with a concentration of 30% available chlorine dropwise over 3h. After the reaction is complete, add 5mL of anhydrous ethanol to terminate the reaction. After filtration and washing until neutral, dry at 80℃ for 24h to obtain oxidized cellulose. Take 2.5g of oxidized cellulose and add it to 250mL of deionized water. Sonicate at 80% power for 1h to obtain a TOCN suspension with a concentration of 1wt%.

[0040] (2) Prepare a 0.1 wt% HACC solution. Take 25 mL of TOCN suspension, add 20 mL of HACC solution, and continue stirring for 1 h to obtain a composite suspension. Centrifuge the composite suspension at 12000 rpm for 15 min, discard the supernatant, add an equal volume of deionized water to resuspend the precipitate, repeat the washing 3 times, and then vacuum filter it onto a PTFE filter membrane (50 mm in diameter). After drying at room temperature, the TOCN / HACC complex is obtained, denoted as TOCN-HACC5.

[0041] Under the experimental conditions described above, violent flocculation was observed immediately upon mixing the HACC solution and TOCN suspension, rapidly forming gel-like agglomerates, making it impossible to obtain a uniform suspension. Subsequent vacuum filtration failed to form a complete film; the resulting lumps were brittle, unable to unfold, and completely opaque.

[0042] Technical effects: 1. Infrared spectroscopy determination The thin films obtained in Examples 1-4 and Comparative Example 1 were subjected to Fourier Transform Infrared (FTIR) spectroscopy measurements, and the results are as follows: Figure 2 As shown.

[0043] The results showed that 1601cm -1 The peak at 1483 cm⁻¹ is caused by -COONa in TOCN, a characteristic peak specific to oxidation products. This indicates successful oxidation of the hydroxyl group at the C6 position of cellulose to a carboxyl group. Furthermore, the peak intensity weakens with increasing HACC concentration, suggesting that HACC consumption of the TOCN carboxyl group further confirms that the binding mechanism between TOCN and HACC is electrostatic complexation. With the addition of HACC, the peak intensity at 1483 cm⁻¹... -1 A new characteristic peak appeared at this location, which is a unique characteristic absorption peak of HACC quaternary ammonium cations. The peak intensity increases linearly with the increase of HACC addition. A peak at 1601 cm⁻¹ was also observed. -1 The peak intensity decreased synchronously because the characteristic peak of TOCN carboxylate was caused by strong electrostatic complexation with the quaternary ammonium group of HACC, indicating that the electrostatic complexation between HACC and TOCN was successfully achieved.

[0044] 2. Mechanical properties The tensile strength, elongation at break, and surface roughness of the films obtained in Examples 1-4 and Comparative Example 1 were tested according to GB / T 1040.3-2006, and the results are shown in Table 1 and 2006. Figure 3 As shown.

[0045] Table 1 It can be seen that the tensile strength of the TOCN film obtained in Comparative Example 1 is 39.94 MPa. With the increasing amount of HACC added in Examples 1-4, the tensile strength of the resulting composite film shows a continuous and significant increasing trend, with values ​​of 59.23 MPa, 68.94 MPa, 83.71 MPa, and 112.23 MPa, respectively. Compared to the TOCN film obtained in Comparative Example 1, the tensile strength of the TOCN-HACC4 composite film obtained in Example 4 increased by 1.8 times, and the composite film obtained in Example 4 can be bent at will. Figure 3 (Part C) has good flexibility.

[0046] 3. Optical properties and swelling properties The transmittance at 600 nm and the swelling rate at 24 h of the films obtained in Examples 1-4 and Comparative Examples 1-2 were measured by gravimetric method, and the results are shown in Table 2.

[0047] Table 2 It can be seen that as the amount of HACC added increases, the swelling rate of the film decreases.

[0048] 4. Antibacterial properties The antibacterial properties of the films obtained in Examples 1-4 and Comparative Examples 1-2 were tested using the antimicrobial zone method. The results are as follows: Figure 4 As shown in the figure, 1 is the TOCN film, and 2, 3, 4, and 5 are TOCN-HACC1, TOCN-HACC2, TOCN-HACC3, and TOCN-HACC4 films, respectively. It can be observed that after cultivation, bacterial flora still exists within the coverage area of ​​film 1, indicating that the pure TOCN film has no antibacterial properties. However, with the addition of HACC, films 2, 3, 4, and 5 all showed inhibitory effects against Staphylococcus aureus and Escherichia coli.

[0049] 5. Electrostatic Complexation Test Images of the mixed suspension samples prepared according to the three different methods in Example 1 and Comparative Examples 1-2 are shown below. Figure 5 As shown in the image, it is clear that the KI solution helps TOCN and HACC to recombine uniformly. Without the KI solution, TOCN and HACC would instantly agglomerate into gel-like clumps. Observing images of film samples with different labels also reveals that after adding HACC, the film surface becomes noticeably smoother and denser. Films formed by direct mixing agglomerate into clumps, cannot be unfolded, and are quite brittle.

[0050] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an ion-controlled TOCN / HACC composite thin film, characterized in that, Includes the following steps: Oxidized cellulose was ultrasonically dispersed in water to obtain a TOCN suspension. KI solution was added to the TOCN suspension to adjust the KI concentration in the system. HACC solution was added and mixed and stirred. After centrifugation and discarding the supernatant, the resulting precipitate was resuspended, filtered, and dried to obtain the TOCN / HACC composite film. The method for preparing the oxidized cellulose includes the following steps: Na2CO3, NaHCO3, NaBr, TEMPO and cellulose were dissolved in water under heating conditions. After adjusting the pH, NaClO solution was added and the reaction was sealed. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. After filtration, washing and drying, the oxidized cellulose was obtained. The heating condition is at a temperature of 35°C; The pH adjustment is performed by using a 1 mol / L NaOH solution to adjust the pH to 10.4-10.8; The KI concentration in the system is 0.5-2 g / L.

2. The method for preparing an ion-controlled TOCN / HACC composite thin film according to claim 1, characterized in that, The ratio of the added Na2CO3, NaHCO3, NaBr, TEMPO, cellulose and water is 2.6g:0.88g:0.5g:0.05g:2.5g:350mL.

3. The method for preparing an ion-controlled TOCN / HACC composite thin film according to claim 1, characterized in that, The volume ratio of the TOCN suspension to the HACC solution is 25:(5-20).

4. The method for preparing an ion-controlled TOCN / HACC composite thin film according to claim 1, characterized in that, The mass concentration of the TOCN suspension is 0.5-2%; The HACC solution has a mass concentration of 0.1-0.5%.

5. The method for preparing an ion-controlled TOCN / HACC composite thin film according to claim 1, characterized in that, The filtration is performed by vacuum filtration onto the PTFE membrane.

6. A TOCN / HACC composite film based on ion regulation prepared by the preparation method according to any one of claims 1-5.

7. The application of the ion-controlled TOCN / HACC composite film as described in claim 6 in antibacterial packaging materials, biomedical materials, or functional coating materials.

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