Preparation method and application of high-sensitivity temperature-responsive cellulose-based structural color material

Abstract

The invention discloses a preparation method and application of a high-sensitivity temperature-responsive cellulose-based structural color material, and belongs to the field of functional polymer materials. The preparation method comprises the following steps: adding an isopropanol solvent into a certain volume of aqueous solution to obtain an isopropanol dilute solution; hydroxypropyl cellulose is dissolved in an isopropanol dilute solution, a cholesteric liquid crystal structure is formed through self-assembly, a bright structural color is presented, and the hydroxy propyl cellulose structural color material is prepared. A hydroxy propyl cellulose structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes, then the transparent polydimethylsiloxane film is used for sealing the hydroxy propyl cellulose structural color material, the temperature sensor with the visual structural color is prepared, and the temperature sensor with the visual structural color is attached to the skin of the human body and can display different colors along with temperature changes. The prepared structural color material is sensitive in response to temperature stimulation, rapid in color change and suitable for human body visual real-time temperature monitoring in the field of intelligent sensing.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials and relates to a method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material. Background Technology

[0002] Temperature sensing technology has wide applications in fields such as healthcare, environmental monitoring, and industrial control, and its performance improvement is crucial for achieving real-time monitoring. However, traditional temperature sensors suffer from limitations such as limited sensitivity, slow response time, and difficulty in visual readings. Furthermore, the use of synthetic dyes, heavy metals, or recalcitrant polymers in the manufacturing process of some sensors poses risks of environmental pollution and biocompatibility. Therefore, there is a need to develop novel temperature sensing materials that combine high sensitivity, rapid response, and environmental friendliness.

[0003] Structural color materials, whose colors originate from periodically arranged nanostructures, possess unique photonic band gaps that allow light to be reflected, refracted, interfered with, or scattered, thus producing a variety of colors. These materials offer advantages such as high color saturation, strong resistance to fading, and environmental friendliness, making them potential for constructing visual sensors. Among structural color materials, photonic crystals based on cellulose derivatives show significant potential. Hydroxypropyl cellulose, in particular, is a widely available and biodegradable polymer that can self-assemble into cholesteric liquid crystal structures in suitable solvents, exhibiting vivid structural colors. This structure is extremely sensitive to temperature changes, enabling rapid and reversible modulation of optical signals by controlling the lattice spacing, thus laying the foundation for developing highly sensitive structural color materials.

[0004] To address the shortcomings of existing sensors in terms of sensitivity, response speed, visualization capabilities, and material environmental compatibility, we propose a method for preparing and applying highly sensitive temperature-responsive cellulose-based structural color materials. The prepared cellulose-based structural color materials exhibit significant and rapid color changes upon temperature stimulation, possessing advantages such as fast response speed, high sensitivity, good stability, and excellent reversibility. Furthermore, the preparation process utilizes biocompatible and biodegradable green raw materials, effectively avoiding the environmental pollution problems that may arise from traditional processes. Compared to existing methods for preparing structural color materials, the method proposed in this invention is characterized by its simplicity and significant performance improvement, demonstrating broad application prospects in flexible electronics, smart packaging, and biosensing. Summary of the Invention

[0005] To overcome the shortcomings of existing materials, the purpose of this invention is to propose a method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material. The highly sensitive temperature-responsive cellulose-based structural color material prepared by this method exhibits significant and rapid color changes under temperature stimulation, possessing characteristics such as high sensitivity, rapid response, and environmental friendliness. This invention utilizes the self-assembly of hydroxypropyl cellulose in aqueous solution to form a cholesteric liquid crystal structure, which displays different structural colors under different temperature conditions, and the color changes rapidly, enabling visualized real-time temperature monitoring in the field of intelligent sensing. The technical solution provided by this invention to solve the above-mentioned technical problems is: a method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material, comprising the following steps: S1. Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution. The mass fraction of isopropanol solvent in water is 5 wt% ~ 20 wt%. Then add the light absorber to the dilute isopropanol solution and stir rapidly to obtain a homogeneous solution. The mass fraction of the light absorber in water is 0.1 wt% ~ 0.5 wt%. S2. Add hydroxypropyl cellulose powder to the mixed solution, with a mass fraction of hydroxypropyl cellulose of 60wt% to 80wt%, and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 to 30°C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material. S3. The prepared high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. Then, transparent polydimethylsiloxane is used as an encapsulation layer to seal the high-sensitivity temperature-responsive cellulose-based structural color material. After standing at room temperature for 2 to 5 minutes, the material is assembled until the color is uniform, and a visual structural color temperature sensor is obtained.

[0006] A further technical solution is that the isopropanol solvent in step S1 has a water mass fraction of 5 wt% to 20 wt%.

[0007] Furthermore, the light-absorbing agent is cuttlefish ink.

[0008] Furthermore, the light-absorbing agent has a water mass fraction of 0.1 wt% to 0.5 wt%.

[0009] A further technical solution is that, in step S2, the viscosity of the added hydroxypropyl cellulose is one or more of the following: 2.0 ~ 2.9 mPa•s, 3.0 ~ 6 mPa•s, 6.0 ~ 10.0 mPa•s, and 150 ~ 400 mPa•s; the centrifuge speed is 3000 ~ 5000 rpm; and the time is 3 ~ 5 min.

[0010] Furthermore, the mass fraction of added hydroxypropyl cellulose is 60 wt% to 80 wt%.

[0011] Furthermore, the self-assembly time of the highly sensitive temperature-responsive cellulose-based structural color material is 2 to 4 weeks.

[0012] Furthermore, the highly sensitive temperature-responsive cellulose-based structural color materials with different concentrations exhibit different structural colors.

[0013] A further technical solution is that the coating method in step S3 includes either blade coating or spin coating.

[0014] Furthermore, the thickness of the polydimethylsiloxane film includes one or more of the following: 25 μm, 50 μm, and 100 μm.

[0015] Furthermore, the sensor exhibits different structural colors at different temperatures.

[0016] A highly sensitive temperature-responsive cellulose-based structural color material is applied to real-time temperature monitoring of the human body in the field of intelligent sensing.

[0017] The advantages and beneficial effects of this invention are as follows: (1) Based on the self-assembly behavior of hydroxypropyl cellulose in aqueous solution, this invention achieves reversible changes in structural color by controlling temperature, thereby constructing a structural color material with temperature response characteristics. Compared with traditional temperature sensors, this material can rapidly exhibit significant color changes at different temperatures, with fast response speed and high sensitivity, while also possessing advantages such as good stability and reversibility, thus overcoming the problems of slow response and insufficient sensitivity of traditional temperature sensors.

[0018] (2) Throughout the entire preparation and application process, this invention uses only water, isopropanol, and cellulose as raw materials, ensuring the green and environmentally friendly characteristics of the materials from the source. The preparation method is simple, the conditions are mild, and no harmful substances are generated throughout the process, meeting the requirements of environmentally friendly production. The prepared sensor is made of non-toxic, harmless, and biodegradable materials, demonstrating significant environmental advantages and application potential in the field of wearable health monitoring. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 This is a digital photograph of the cellulose-based structural color material obtained by the present invention; Figure 3 (a) Scanning electron microscope image and (b) polarizing microscope image of the cellulose-based structural color material prepared in this invention; Figure 4 The temperature response reflectance spectrum of the cellulose-based structural color material prepared in this invention is shown. Figure 5 This is a graph showing the temperature response sensitivity variation of the cellulose-based structural color material prepared in this invention. Figure 6 This is a digital photograph of the cellulose-based structural color material prepared according to the present invention used in human body temperature monitoring. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1

[0022] like Figure 1 As shown, the preparation method and application of a highly sensitive temperature-responsive cellulose-based structural color material prepared in this invention are achieved through the following steps: Step 1: Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution; then add the light absorber to the dilute isopropanol solution and stir quickly to obtain a homogeneous solution. The isopropanol has a mass fraction of 5 wt% in water, and the light absorber is cuttlefish ink, which has a mass fraction of 0.1 wt% in water.

[0023] Step 2: Add hydroxypropyl cellulose powder to the mixed solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 ~ 30 °C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material; The hydroxypropyl cellulose had a viscosity of 2.9 mPa·s and a mass fraction of 75 wt%; the centrifuge speed was 4500 rpm and the time was 5 min; the assembly time was 4 weeks.

[0024] Step 3: The assembled high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. The structural color sensing material is then sealed with transparent polydimethylsiloxane and left to stand at room temperature for 2 to 5 minutes. Assembly is then carried out until the color is uniform and a bright structural color is presented. The coating method is blade coating; the thickness of the polydimethylsiloxane film is 25 μm.

[0025] Example 2

[0026] A method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material, which is prepared through the following steps: Step 1: Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution; then add the light absorber to the dilute isopropanol solution and stir quickly to obtain a homogeneous solution. The isopropanol has a water mass fraction of 10 wt%, and the light absorber is cuttlefish ink, which has a water mass fraction of 0.5 wt%.

[0027] Step 2: Add hydroxypropyl cellulose powder to the mixed solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 ~ 30°C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material; The hydroxypropyl cellulose had a viscosity of 2.9 mPa•s and a mass fraction of 75 wt%; the centrifuge speed was 4500 rpm and the time was 5 min; the assembly time was 4 weeks.

[0028] Step 3: The assembled high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. The structural color sensing material is then sealed with transparent polydimethylsiloxane and left to stand at room temperature for 2 to 5 minutes. Assembly is then carried out until the color is uniform and a bright structural color is presented. The coating method is blade coating; the thickness of the polydimethylsiloxane film is 50 μm.

[0029] Example 3

[0030] A method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material, which is prepared through the following steps: Step 1: Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution; then add the light absorber to the dilute isopropanol solution and stir quickly to obtain a homogeneous solution. The isopropanol has a water mass fraction of 15 wt%, and the light absorber is cuttlefish ink, which has a water mass fraction of 0.3 wt%.

[0031] Step 2: Add hydroxypropyl cellulose powder to the mixed solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 ~ 30°C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material; The hydroxypropyl cellulose had a viscosity of 2.9 mPa•s and a mass fraction of 75 wt%; the centrifuge speed was 4500 rpm and the time was 5 min; the assembly time was 4 weeks.

[0032] Step 3: The assembled high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. The structural color sensing material is then sealed with transparent polydimethylsiloxane and left to stand at room temperature for 2 to 5 minutes. Assembly is then carried out until the color is uniform and a bright structural color is presented. The coating method is blade coating; the thickness of the polydimethylsiloxane film is 100 μm.

[0033] A schematic diagram of the specific preparation process is shown below. Figure 1 As shown.

[0034] The colors of the cellulose-based structural color materials prepared in steps 1, 2, and 3 of Example 3 were observed, and the results are as follows: Figure 2 As shown.

[0035] Figure 2 The color of the cellulose-based structural color material was revealed; Example 3 exhibited a cyan structural color.

[0036] The cellulose-based structural color material prepared in Example 3 was subjected to scanning electron microscopy and polarizing microscopy tests, and the results are as follows: Figure 3 As shown in (a) and 3(b).

[0037] Figure 3 (a) reveals that the prepared cellulose-based structural color material exhibits a periodic layered structure of cholesteric liquid crystal. Figure 3 (b) shows a clear birefringence phenomenon.

[0038] The optical properties of the cellulose-based structural color material prepared in Example 3 were tested, and the results are as follows: Figure 4 As shown.

[0039] Figure 4The study revealed that reflectance spectroscopy tests on cellulose-based structural color materials showed that, in Examples 1, 2, 3, and 4, the maximum reflection wavelength increased with increasing temperature between 30°C and 42°C, and the structural color exhibited a red shift. Furthermore, at the same temperature, the maximum reflection wavelength also increased with increasing isopropanol concentration. In Example 3, the maximum reflection wavelength was 542 nm at 30°C, and the reflection peak was relatively narrow, indicating high structural color saturation and a regular periodic structure of the photonic crystal.

[0040] The response sensitivity changes of the cellulose-based structural color material prepared in Example 3 at different temperatures were studied, and the results are as follows: Figure 5 As shown.

[0041] Figure 5 It was revealed that in Examples 1, 2, 3, and 4, the response sensitivity increased with the increase of isopropanol concentration in the cellulose-based structural color material; among them, the temperature response sensitivity of Example 3 was 14.24 nm / °C, indicating a fast response speed.

[0042] The cellulose-based structural color material prepared in Example 3 was used for real-time temperature monitoring of the human body, and the results are as follows: Figure 6 As shown.

[0043] Figure 6 It was revealed that the cellulose-based structural color material prepared in Example 3 has a reflection wavelength of approximately 520 nm at 30°C; a reflection wavelength that is red-shifted to approximately 580 nm at 33.5°C; and a reflection wavelength that is red-shifted to approximately 620 nm at 36°C.

[0044] These results demonstrate the preparation method and application of a highly sensitive temperature-responsive cellulose-based structural color material prepared in Example 3.

[0045] Example 4

[0046] A method for preparing and applying a highly sensitive temperature-responsive cellulose-based structural color material, which is prepared through the following steps: Step 1: Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution; then add the light absorber to the dilute isopropanol solution and stir quickly to obtain a homogeneous solution. The isopropanol has a water mass fraction of 20 wt%, and the light absorber is cuttlefish ink, which has a water mass fraction of 0.1 wt%.

[0047] Step 2: Add hydroxypropyl cellulose powder to the mixed solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 ~ 30°C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material; The hydroxypropyl cellulose had a viscosity of 2.9 mPa•s and a mass fraction of 75 wt%; the centrifuge speed was 4500 rpm and the time was 5 min; the assembly time was 4 weeks.

[0048] Step 3: The assembled high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. The structural color sensing material is then sealed with transparent polydimethylsiloxane and left to stand at room temperature for 2 to 5 minutes. Assembly is then carried out until the color is uniform and a bright structural color is presented. The coating method is blade coating; the thickness of the polydimethylsiloxane film is 25 μm.

[0049] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a highly sensitive temperature-responsive cellulose-based structural color material, characterized in that, Includes the following steps: S1. Mix isopropanol solvent with water and stir to obtain a homogeneous dilute isopropanol solution. The mass fraction of isopropanol solvent in water is 5 wt% ~ 20 wt%. Then add the light absorber to the dilute isopropanol solution and stir rapidly to obtain a homogeneous solution. The mass fraction of the light absorber in water is 0.1 wt% ~ 0.5 wt%. S2. Add hydroxypropyl cellulose powder to the mixed solution, with a mass fraction of hydroxypropyl cellulose of 60 wt% to 80 wt%, and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20 to 30 °C until a uniform structural color appears, thus obtaining a highly sensitive temperature-responsive cellulose-based structural color material. S3. The prepared high-sensitivity temperature-responsive cellulose-based structural color material is uniformly coated on the surface of a polydimethylsiloxane film containing carbon nanotubes. Then, transparent polydimethylsiloxane is used as an encapsulation layer to seal the high-sensitivity temperature-responsive cellulose-based structural color material. After standing at room temperature for 2 to 5 minutes, the material is assembled until the color is uniform, and a visual structural color temperature sensor is obtained.

2. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The light-absorbing agent in step S1 is cuttlefish ink.

3. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The hydroxypropyl cellulose in step S2 includes one or more of the following: viscosity of 2.0 ~ 2.9 mPa•s, 3.0 ~ 6 mPa•s, 6.0 ~ 10.0 mPa•s, and 150 ~ 400 mPa•s.

4. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, In step S2, the centrifuge speed is 3000-5000 rpm and the time is 3-5 minutes.

5. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The self-assembly time in step S2 is 2 to 4 weeks.

6. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The coating method in step S3 includes either blade coating or spin coating.

7. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The thickness of the polydimethylsiloxane film includes one or more of the following: 25 μm, 50 μm, and 100 μm.

8. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, The self-assembled, highly sensitive temperature-responsive cellulose-based structural color material exhibits a bright structural color.

9. The method for preparing a highly sensitive temperature-responsive cellulose-based structural color material according to claim 1, characterized in that, Carbon nanotubes were introduced into the bottom polydimethylsiloxane layer to increase the thermal conductivity and color saturation of the sensor. To avoid the influence of solvent evaporation on the structural color, transparent polydimethylsiloxane was used to seal the highly sensitive temperature-responsive cellulose-based structural color material, resulting in a temperature sensor with visualized structural color.

10. Application of a highly sensitive temperature-responsive cellulose-based structural color material, wherein the highly sensitive temperature-responsive cellulose-based structural color material is prepared based on the preparation method described in any one of claims 1 to 9, characterized in that, The highly sensitive temperature-responsive cellulose-based structural color material is applied to real-time temperature monitoring of the human body in the field of intelligent sensing.

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