Ammonia-responsive multifunctional cellulose nanocrystals, preparation and application thereof

Abstract

The application belongs to the technical field of nanomaterials, and particularly relates to an ammonia gas responsive multifunctional cellulose nanocrystal as well as preparation and application thereof. The application provides a preparation method of the multifunctional cellulose nanocrystal, the prepared multifunctional cellulose nanocrystal has excellent thermal stability, ultraviolet absorption performance, ammonia gas responsive color changing function and antibacterial function, the preparation process is simple, environment-friendly and low in cost, is suitable for scale-up production, and has wide application prospects in the fields of visual detection of ammonia gas, ultraviolet blocking materials and antibacterial materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and in particular relates to an ammonia-responsive multifunctional cellulose nanocrystal and its preparation and application. Background Art

[0002] Cellulose nanocrystals (CNCs) are nanoscale cellulose extracted from natural fibers. They possess not only the characteristics of nanoparticles but also unique strength and optical properties, offering broad application prospects. Furthermore, CNCs offer advantages such as lightweight, high strength, environmental friendliness, and biodegradability, holding them in great demand for applications in food, medicine, aesthetics, construction, and the environment. Composite materials containing CNCs are currently being widely used in a variety of fields, including packaging, engineering plastics, biomedical engineering, and 3D printing. However, CNCs suffer from poor thermal stability, which hinders their melt blending with polymer matrices and the performance of the resulting composite products. Notably, CNCs contain numerous hydroxyl groups on their surfaces, making them amenable to modification. This has the potential to enhance their thermal stability and impart specific functionalities, such as ammonia response, antibacterial properties, and UV absorption. Developing simple and economical methods to prepare hybrid cellulose nanocrystals with high thermal stability, excellent ammonia response, and multiple functionalities, such as antibacterial properties, holds great promise for future applications. Summary of the Invention

[0003] Against this backdrop, the present invention provides ammonia-responsive multifunctional cellulose nanocrystals, their preparation, and applications. The ammonia-responsive multifunctional cellulose nanocrystals prepared by the present invention exhibit excellent thermal stability, ammonia response, UV absorption, and antibacterial properties. The preparation process is simple, environmentally friendly, low-cost, and suitable for scale-up production.

[0004] Technical solution of the present invention:

[0005] A method for preparing ammonia-responsive multifunctional cellulose nanocrystals comprises the following steps:

[0006] (1) Disperse 41 parts of cellulose nanocrystals in a mixed solvent of 1000 parts of deionized water and 3000 parts of methanol, and stir at room temperature for 30 minutes to obtain a uniform cellulose nanocrystal dispersion for later use;

[0007] (2) Weigh 16.5 parts of copper chloride dihydrate and dissolve it in 2000 parts of methanol to obtain a uniform copper chloride solution for later use;

[0008] (3) Add the copper chloride solution obtained in step (2) to the cellulose nanocrystal dispersion obtained in step (1), and stir at room temperature for 3 hours to obtain a uniform blend solution for later use;

[0009] (4) Weigh 16.6 parts of 1H-indazole-6-carboxylic acid and 5.6 parts of KOH and add them to 3000 parts of methanol. Stir at room temperature for 3 hours to obtain a uniform mixed solution for later use.

[0010] (5) The blended solution obtained in step (4) is added dropwise to the blended solution in step (3), and the mixture is stirred at room temperature for 12 h. The mixture is then centrifuged, washed with methanol, and dried to obtain ammonia-responsive multifunctional cellulose nanocrystals.

[0011] The present invention has the beneficial effects:

[0012] The ammonia-responsive multifunctional cellulose nanocrystals prepared by the present invention have excellent thermal stability, ammonia response performance, ultraviolet absorption performance and antibacterial properties. The preparation process is simple, environmentally friendly, low-cost, and suitable for large-scale production. It has broad application prospects in the fields of visual detection of ammonia, ultraviolet blocking materials and antibacterial materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The infrared spectra of cellulose nanocrystals and the multifunctional cellulose nanocrystals prepared by the present invention are shown;

[0014] Figure 2 This is a photo of the antibacterial activity experiment of the multifunctional cellulose nanocrystals prepared in the present invention against Escherichia coli;

[0015] Figure 3 This is a photo of the antibacterial activity experiment of the multifunctional cellulose nanocrystals prepared in the present invention against Staphylococcus aureus;

[0016] Figure 4 The UV-visible absorption curves are those of the cellulose nanocrystals and the multifunctional cellulose nanocrystal aqueous dispersion prepared by the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below through examples. It is necessary to point out that the examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Those skilled in the art may make some non-essential improvements and adjustments based on the above-mentioned contents of the present invention. Unless otherwise specified, the parts of the raw materials are all parts by mass.

[0018] In the following specific embodiments and comparative example formulations and preparation methods, the cellulose nanocrystals (i.e., unmodified cellulose nanocrystals) used are products provided by Guilin Qihong Technology Co., Ltd., with a diameter of 4 to 10 nm and a length of 100 to 500 nm; 1H-indazole-6-carboxylic acid is an analytically pure reagent provided by Shanghai Bid Pharmaceutical Technology Co., Ltd.; and copper chloride dihydrate, methanol, and potassium hydroxide are analytically pure reagents provided by Xilong Science Co., Ltd.

[0019] Example:

[0020] A method for preparing ammonia-responsive multifunctional cellulose nanocrystals comprises the following steps:

[0021] (1) Disperse 41 parts of cellulose nanocrystals in a mixed solvent of 1000 parts of deionized water and 3000 parts of methanol, and stir at room temperature for 30 minutes to obtain a uniform cellulose nanocrystal dispersion for later use;

[0022] (2) Weigh 16.5 parts of copper chloride dihydrate and dissolve it in 2000 parts of methanol to obtain a uniform copper chloride solution for later use;

[0023] (3) Add the copper chloride solution obtained in step (2) to the cellulose nanocrystal dispersion obtained in step (1), and stir at room temperature for 3 hours to obtain a uniform blend solution for later use;

[0024] (4) Weigh 16.6 parts of 1H-indazole-6-carboxylic acid and 5.6 parts of KOH and add them to 3000 parts of methanol. Stir at room temperature for 3 hours to obtain a uniform mixed solution for later use.

[0025] (5) The blended solution obtained in step (4) is added dropwise to the blended solution in step (3), and the mixture is stirred at room temperature for 12 h. The mixture is then centrifuged, washed with methanol, and dried to obtain ammonia-responsive multifunctional cellulose nanocrystals.

[0026] The cellulose nanocrystal material involved in the present invention (i.e., unmodified cellulose nanocrystals) is white in color and does not change color after exposure to an ammonia environment; while the multifunctional cellulose nanocrystal material product prepared by the present invention is dark green in color and quickly changes color (within 1 minute) to dark blue after exposure to an ammonia environment, indicating that the multifunctional cellulose nanocrystals have excellent ammonia-responsive color-changing properties.

[0027] The antibacterial activity test method of inhibition zone was used to evaluate the antibacterial performance of the product. The cellulose nanocrystal material involved in the present invention (i.e., unmodified cellulose nanocrystals) had an inhibition zone of 0 mm against Escherichia coli and Staphylococcus aureus, while the multifunctional cellulose nanocrystal material product synthesized by the method of the embodiment of the present invention had a significant inhibition zone against Escherichia coli and Staphylococcus aureus, indicating that the multifunctional cellulose nanocrystal material has an excellent antibacterial effect.

[0028] The thermal stability of the product was evaluated using a thermogravimetric analyzer (SDT-Q600, TA Company, USA); the cellulose nanocrystals involved in the present invention (i.e., unmodified cellulose nanocrystals) had an initial thermal degradation temperature of 235°C; while the multifunctional cellulose nanocrystal material product synthesized by the method of the embodiment of the present invention had an initial thermal degradation temperature of 255°C, indicating that the multifunctional cellulose nanocrystal material product has significantly improved thermal stability.

[0029] In summary, the multifunctional cellulose nanocrystal material product prepared by the present invention has excellent antibacterial properties, thermal stability, ammonia response color change properties and ultraviolet absorption properties, and the preparation process is simple, environmentally friendly, low-cost, and suitable for magnification. It has broad application prospects in the fields of visual detection of ammonia, ultraviolet blocking materials and antibacterial materials.

[0030] The content of the present invention is not limited to the embodiments listed. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the description of the present invention is covered by the claims of the present invention.

Claims

1. A method for preparing ammonia-responsive multifunctional cellulose nanocrystals, characterized in that The steps include: (1) Disperse 41 parts of cellulose nanocrystals in a mixed solvent of 1000 parts of deionized water and 3000 parts of methanol, and stir at room temperature for 30 minutes to obtain a uniform cellulose nanocrystal dispersion for later use; (2) Weigh 16.5 parts of copper chloride dihydrate and dissolve it in 2000 parts of methanol to obtain a uniform copper chloride solution for later use; (3) Add the copper chloride solution obtained in step (2) to the cellulose nanocrystal dispersion obtained in step (1), and stir at room temperature for 3 hours to obtain a uniform blend solution for later use; (4) Weigh 16.6 parts of 1H-indazole-6-carboxylic acid and 5.6 parts of KOH and add them to 3000 parts of methanol. Stir at room temperature for 3 hours to obtain a uniform mixed solution for later use. (5) The blended solution obtained in step (4) is added dropwise to the blended solution in step (3), and the mixture is stirred at room temperature for 12 h. The mixture is then centrifuged, washed with methanol, and dried to obtain ammonia-responsive multifunctional cellulose nanocrystals.

2. Ammonia-responsive multifunctional cellulose nanocrystals obtained according to the preparation method of claim 1.

3. The use of ammonia-responsive multifunctional cellulose nanocrystals obtained by the preparation method according to claim 1, characterized in that: Used in the fields of visual detection of ammonia, UV blocking materials and antibacterial materials.

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