Preparation method of cellulose-based water-induced deformation and color-changing film

Abstract

The invention provides a preparation method of a cellulose-based water-induced deformation and color-changing film. Water-induced deformation and color-changing response are realized synergistically. The film is mainly prepared from the following components in parts by weight: 16.67 to 25 parts of hydrophilic micelle, 33.33 to 50 parts of absolute ethyl alcohol, 10 to 16 parts of modified cellulose, 12.5 to 20 parts of cross-linking agent and 2.5 to 4 parts of red dye. The cellulose-based water-induced deformation and color-changing film can realize deformation and color-changing response at the same time, the water absorption rate and the water absorption capacity of the two surfaces of the film are regulated and controlled by utilizing the content difference of hydrophilic micelles in the upper surface and the lower surface of the film, and the water-induced deformation response of the film is realized. Meanwhile, after the thin film absorbs water and swells, the microstructure arrangement in the thin film is changed due to the increase of the volume, so that incident light generates a stronger scattering effect in the material, and the hydrochromic behavior of the thin film is realized. The cellulose-based water-induced deformation and color-changing film has synergistic deformation and color-changing response to water stimulation, and has great application potential in the fields of actuators, wearable electronic equipment, intelligent robots and the like.

Description

Technical Field

[0001] This invention belongs to the field of cellulose-based film technology and relates to a method for preparing cellulose-based water-induced deformation and color-changing films. Background Technology

[0002] In recent years, with the increasing global awareness of environmental protection, the use of traditional petroleum-based non-degradable materials has been strictly limited, leading to widespread attention on degradable, renewable, and environmentally friendly cellulose-based functional materials. Cellulose, as one of the most abundant natural polymers, possesses advantages such as renewability, multiple hydroxyl active sites, and high biocompatibility, making it an ideal alternative to petroleum-based materials. Simultaneously, with the rapid development of emerging industries such as wearable devices, flexible electronics, and intelligent robots, the market demand for environmentally responsive cellulose-based smart materials is growing. These materials need to accurately sense external stimuli such as humidity, temperature, and pH, and exhibit controllable deformation or optical responses to achieve adaptive regulation, information feedback, or mechanical action.

[0003] Water, as a green, safe, and readily available stimulus, offers advantages over stimuli such as low energy consumption, easy control, and good biocompatibility, making it particularly suitable for actuators and wearable electronic devices. Therefore, water-responsive cellulose-based deformable and color-changing films have become a research hotspot. However, the fabrication process and response performance of cellulose-based water-induced deformable and color-changing films still face multiple challenges. Regarding performance optimization, there is a significant contradiction in the synergistic control between rapid deformation and color-changing response. In terms of fabrication processes, achieving multifunctional integration requires complex design and precise assembly steps, significantly increasing the fabrication difficulty and hindering large-scale material production. These constraints severely limit the practical application of cellulose-based water-induced deformable and color-changing films. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing cellulose-based hydrodeformable and color-changing films. By utilizing the difference in water absorption properties on both sides of the cellulose-based hydrodeformable and color-changing film, reversible deformation of the film under water stimulation is achieved. Based on the change in refractive index after water absorption and swelling, the cellulose-based hydrodeformable and color-changing film is endowed with a visible color response to water stimulation.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] Technical Solution 1. A cellulose-based water-induced deformable and color-changing film, characterized in that it mainly comprises 16.67-25 parts of hydrophilic micelles, 33.33-50 parts of anhydrous ethanol, 10-16 parts of modified cellulose, 12.5-20 parts of crosslinking agent and 2.5-4 parts of red dye.

[0007] The aforementioned hydrophilic micelles are any one of polyethylene glycol-polylactic acid, polyethylene glycol-polycaprolactone, polyoxyethylene-polyoxypropylene-polyoxyethylene, and polyethylene glycol-polypropylene glycol-polyethylene glycol.

[0008] The modified cellulose mentioned above is any one of microcrystalline cellulose, hydroxypropyl methylcellulose, and ethyl cellulose.

[0009] The crosslinking agent mentioned above is any one of toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0010] The red dye mentioned above is any one of anthraquinone, toluidine red, or rhodamine B.

[0011] A cellulose-based water-induced deformable and discolorable film, comprising the following steps:

[0012] a1. Modified cellulose and crosslinking agent are added to an Erlenmeyer flask and reacted at a certain temperature to obtain an EP solution;

[0013] a2. Mix hydrophilic micelles with anhydrous ethanol and stir at 60°C for 10 min to obtain a micelle solution;

[0014] a3. Add the red dye and micelle solution to the EP solution and stir at a certain speed. After the dye is completely dispersed, a mixed solution is obtained.

[0015] a4. Pour the mixed solution into a silicone mold and dry it in a vacuum drying oven to obtain a cellulose-based hydromorphic and color-changing film.

[0016] The reaction temperature described in step a1 above is 70–90°C, and the reaction time is 1–3 hours.

[0017] The stirring speed mentioned in step a3 above is 300-500 r, and the stirring time is 10-30 min.

[0018] The drying temperature described in step a4 above is 60-80℃, and the drying time is 12-16h.

[0019] The present invention has the following main advantages:

[0020] 1. This invention utilizes gravity sedimentation to deposit micelles on the bottom of a film. By controlling the difference in micelle content on both sides of the cellulose-based water-induced deformable and color-changing film, the water absorption rate on both sides of the film is controlled, thereby achieving the bending response of the film to water stimulation.

[0021] 2. This invention utilizes water stimulation to regulate the bending deformation behavior of cellulose-based water-induced deformable and color-changing films. After water immersion, the film rapidly absorbs moisture, utilizing the difference in water absorption rates on both sides to drive bending deformation; after water evaporation, the film returns to its initial flat shape. This process not only exhibits good reversibility but also remains stable through multiple water immersion-evaporation cycles, providing reliable performance assurance for practical applications.

[0022] 3. The cellulose-based water-induced deformation and color-changing film of the present invention not only possesses water-actuated properties, but also undergoes a reversible color change with prolonged immersion time. After the film absorbs water and swells, the surface color changes from red to light red due to light scattering. This unique optical response characteristic endows the film with great application potential in humidity sensing, actuators, and smart building fields. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation process of cellulose-based water-induced deformable and color-changing films. Figure 2 It is the bending process of cellulose-based water-induced deformable and discolorable films in water. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1:

[0026] A method for preparing a cellulose-based water-induced deformable and color-changing film comprises the following components and mass percentages: 25 parts polyethylene glycol-polylactic acid, 50 parts anhydrous ethanol, 10 parts hydroxypropyl methylcellulose, 12.5 parts hexamethylene diisocyanate, and 2.5 parts rhodamine B.

[0027] The method for preparing a cellulose-based water-induced deformable and color-changing film according to this embodiment includes the following steps:

[0028] (1) Add 10 parts of hydroxypropyl methylcellulose and 12.5 parts of hexamethylene diisocyanate to an Erlenmeyer flask and react at 80°C for 1.5 h to obtain EP solution;

[0029] (2) Mix 25 parts of polyethylene glycol-polylactic acid with 50 parts of anhydrous ethanol and stir at 60°C for 10 min to obtain a polyethylene glycol-polylactic acid solution.

[0030] (3) Add 2.5 parts of Rhodamine B and polyethylene glycol-polylactic acid solution to EP solution, stir at 300r, and after the dye is completely dispersed, a mixed solution is obtained;

[0031] (4) Pour the mixed solution into a silicone mold and dry it in a vacuum drying oven at 60°C for 12 hours to obtain a cellulose-based hydromorphic and color-changing film.

[0032] The deformation response rate of cellulose-based hydromorphic and color-changing films was tested by immersing them in water. Figure 2 As shown, when the immersion time is 15 s, the bending angle of the film is 90°. With the extension of the immersion time, the bending angle of the film increases from 90° to 180°. Furthermore, after the water evaporates, the film returns to its initial flat state, indicating that the cellulose-based water-induced deformation and discoloration film has good reversibility. The results show that the cellulose-based water-induced deformation and discoloration film has a rapid deformation response and good reversibility.

[0033] Example 2

[0034] A method for preparing a cellulose-based water-induced deformable and color-changing film comprises the following components and mass percentages: 20 parts polyethylene glycol-polypropylene glycol-polyethylene glycol, 40 parts anhydrous ethanol, 16 parts ethyl cellulose, 20 parts diphenylmethane diisocyanate, and 4 parts toluidine red.

[0035] The method for preparing a cellulose-based water-induced deformable and color-changing film according to this embodiment includes the following steps:

[0036] (1) Add 16 parts of ethyl cellulose and 20 parts of diphenylmethane diisocyanate to an Erlenmeyer flask and react at 80°C for 1.5 h to obtain EP solution;

[0037] (2) Mix 20 parts of polyethylene glycol-polypropylene glycol-polyethylene glycol with 40 parts of anhydrous ethanol and stir at 60°C for 10 min to obtain a polyethylene glycol-polypropylene glycol-polyethylene glycol solution.

[0038] (3) Add 4 parts of toluidine red and polyethylene glycol-polypropylene glycol-polyethylene glycol solution to EP solution, stir at 300r, and after the dye is completely dispersed, a mixed solution is obtained;

[0039] (4) Pour the mixed solution into a silicone mold and dry it in a vacuum drying oven at 60°C for 12 hours to obtain a cellulose-based hydromorphic and color-changing film.

[0040] By immersing cellulose-based hydromorphic and color-changing films in water, the deformation response speed of the films was tested. It was found that the response time for the film to bend to 90° was 20 s. In the initial bending stage (0–20 s), the film first transitioned from a bent state to a grasping state; in the grasping state transition stage (20–40 s), the film recovered from the grasping state to a bent state; in the drying recovery stage, the film returned to its initial flat state. The results indicate that the cellulose-based hydromorphic and color-changing films exhibit dynamically reversible deformation behavior, and their motion pattern changes regularly with immersion time.

[0041] Example 3

[0042] A method for preparing a cellulose-based water-induced deformable and color-changing film comprises the following components and mass percentages: 16.67 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene, 33.33 parts of anhydrous ethanol, 13.33 parts of hydroxypropyl methylcellulose, 16.67 parts of toluene diisocyanate, and 3.33 parts of anthraquinone.

[0043] The method for preparing a cellulose-based water-induced deformable and color-changing film according to this embodiment includes the following steps:

[0044] (1) Add 13.33 parts of hydroxypropyl methylcellulose and 16.67 parts of toluene diisocyanate to an Erlenmeyer flask and react at 80°C for 1.5 h to obtain an EP solution;

[0045] (2) Mix 16.67 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene with 33.33 parts of anhydrous ethanol and stir at 60°C for 10 min to obtain a polyoxyethylene-polyoxypropylene-polyoxyethylene solution.

[0046] (3) Add 3.33 parts of anthraquinone and polyoxyethylene-polyoxypropylene-polyoxyethylene solution to EP solution, stir at 300r, and after the dye is completely dispersed, a mixed solution is obtained;

[0047] (4) Pour the mixed solution into a silicone mold and dry it in a vacuum drying oven at 60°C for 12 hours to obtain a cellulose-based hydromorphic and color-changing film.

[0048] By immersing a cellulose-based hydromorphic and color-changing film in water, the deformation response speed of the film was tested. It was found that the response time for the film to bend to 90° was 12 seconds. Furthermore, with increasing immersion time, the film's color changed from red to light red, which is related to the film's water absorption and swelling behavior. After the film absorbs water and swells, its internal microstructure changes, leading to light scattering and causing the film to appear white. The cellulose-based hydromorphic and color-changing film not only exhibits a deformation response to water stimulation but also a color change, demonstrating its dual-stimulus response characteristics. This unique property makes it show broad application prospects in fields such as intelligent sensing, bionic robots, anti-counterfeiting labels, and environmental monitoring.

[0049] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A cellulose-based water-induced deformable and color-changing film, characterized in that: The film mainly comprises 16.67–25 parts of hydrophilic micelles, 33.33–50 parts of anhydrous ethanol, 10–16 parts of modified cellulose, 12.5–20 parts of crosslinking agent, and 2.5–4 parts of red dye.

2. A cellulose-based water-induced deformable and color-changing film as described in claim 1, characterized in that: The hydrophilic micelles are any one of polyethylene glycol-polylactic acid, polyethylene glycol-polycaprolactone, polyoxyethylene-polyoxypropylene-polyoxyethylene, and polyethylene glycol-polypropylene glycol-polyethylene glycol.

3. A cellulose-based water-induced deformable and color-changing film as described in claim 1, characterized in that, The microcrystalline cellulose, hydroxypropyl methylcellulose, and ethyl cellulose mentioned herein.

4. The cellulose-based water-induced deformable and color-changing film according to claim 1, characterized in that, The crosslinking agent is any one of toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

5. The cellulose-based water-induced deformable and color-changing film according to claim 1, characterized in that, The red dye is any one of anthraquinone, toluidine red, and rhodamine B.

6. The cellulose-based water-induced deformable and color-changing film according to claim 1, characterized in that, This thin film exhibits a synergistic response of deformation and discoloration to water stimulation. By utilizing the difference in micelle content on both sides of the film, the water absorption rate on both sides is controlled, giving it a bending response to water stimulation. Simultaneously, after the film absorbs water and swells, the changes in its internal microstructure lead to light scattering, achieving a synergistic discoloration response.

7. The cellulose-based water-induced deformable and color-changing film according to claim 1, wherein the preparation method comprises the following steps: a1. Modified cellulose and crosslinking agent are added to an Erlenmeyer flask and reacted at a certain temperature to obtain an EP solution; a2. Mix hydrophilic micelles with anhydrous ethanol and stir at 60°C for 10 min to obtain a micelle solution; a3. Add the red dye and micelle solution to the EP solution and stir at a certain speed. After the dye is completely dispersed, a mixed solution is obtained. a4. Pour the mixed solution into a silicone mold and dry it in a vacuum drying oven to obtain a cellulose-based hydromorphic and color-changing film.

8. The cellulose-based water-induced deformable and color-changing film according to claim 7, characterized in that, The reaction temperature described in step a1 is 70–90°C, and the reaction time is 1–3 h.

9. The cellulose-based water-induced deformable and color-changing film according to claim 7, characterized in that, The stirring speed in step a3 is 300-500 r, and the stirring time is 10-30 min.

10. A cellulose-based water-induced deformable and color-changing film according to claim 7, characterized in that, The drying temperature described in step a4 is 60-80℃, and the drying time is 12-16h.

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