Preparation method and application of a dual temperature-responsive cellulose-based hydrogel

Abstract

The application discloses a preparation method and application of a cellulose-based hydrogel with double temperature response. The cellulose-based hydrogel with double temperature response is prepared by a one-pot method, and the synthesis route is simple, and the reaction condition is mild. By adjusting the concentration of carboxymethyl cellulose (CMC) in the system, the hydrogel has adjustable maximum consolute temperature (5-20 DEG C) and minimum consolute temperature (30-50 DEG C), so that the mechanical property and the anti-freezing property of the gel are improved. The gel can also realize reversible switching of transparency with the change of the environmental temperature, and thus can be used for preparing a hydrogel intelligent window and an information encryption device.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing cellulose-based hydrogels with dual temperature response (hereinafter abbreviated as Gel-H / C gel), as well as their products and applications. Background Technology

[0002] Hydrogels, with their unique three-dimensional network structure and high water content, possess advantages such as stretchability, high light transmittance, and biocompatibility. Among them, phase change hydrogels are smart materials capable of responding to environmental changes. When subjected to external stimuli (such as heat, pH, electricity, salt, solvents, etc.), they can alter the aggregation state of macromolecules through dynamic hydrogen bonds, hydrophobic interactions, or ionic interactions, thereby changing their light transmittance and achieving a reversible change in transparency. Phase change hydrogels not only possess many advantages of traditional hydrogels but also offer advantages over traditional phase change materials, such as controllable phase change temperature, simple preparation processes, and low cost. Therefore, this unique response mechanism has led to widespread interest in applications such as smart windows, patterned information encryption, motion monitoring, and medical devices.

[0003] Cellulose is one of the most abundant natural polymers on Earth, possessing numerous advantages such as high mechanical strength, renewability, biocompatibility, and biodegradability. Its derivatives, such as methylcellulose (MC), hydroxypropylcellulose (HPC), and hydroxypropyl methylcellulose (HPMC), exhibit a minimum cosolubility temperature (LCST) due to hydrophobic aggregation in aqueous solutions at high temperatures. However, the generally high LCST of cellulose-based gel systems limits their widespread application.

[0004] Sodium carboxymethyl cellulose (CMC) is a macromolecular anionic sodium salt with excellent hydrophilicity. Furthermore, CMC possesses numerous hydroxyl and carboxyl groups, allowing it to entangle with polymer chains within the hydrogel, enhancing its light transmittance and mechanical properties. It also overcomes the problem of inorganic salt solutions leaching during long-term use of hydrogels. Introducing CMC into thermochromic hydrogel systems not only allows for hydrophilicity through the absorption of Na+, but also... + The strong hydration of ions affects the hydrogen bonds within the gel system, thereby controlling the phase transition temperature. Simultaneously, the cross-linking of CMC macromolecular chains with the hydrogel matrix through hydrogen bonds enhances the mechanical properties of the composite material and prevents volume shrinkage caused by the phase transition.

[0005] This patent describes a composite cellulose-based hydrogel (Gel-H / C gel) prepared using polyacrylamide (PAM), HPC, and CMC as raw materials via a one-pot process. By utilizing different concentrations of CMC solution, the maximum eutectic temperature (UCST) and LCST of the hydrogel can be flexibly adjusted, achieving two levels of transparency switching within the 1-50°C range. Furthermore, the thermochromic smart window fabricated by sandwiching the Gel-H / C gel between two glass plates exhibits excellent visible light transmittance and solar modulation capabilities. In outdoor testing, the hydrogel smart window demonstrated excellent thermal insulation performance, achieving a maximum cooling effect of approximately 3.4°C compared to ordinary windows, while simultaneously meeting the requirements of energy saving, lighting, and privacy protection. In addition, utilizing the temperature responsiveness differences of hydrogels with different CMC contents, an information encryption device was designed, enabling dual encryption of QR codes and pattern information, demonstrating its promising application prospects in the field of information encryption. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] As one aspect of the present invention, the present invention provides a method for preparing a cellulose-based hydrogel with dual temperature response, which comprises the following steps:

[0008] First, hydroxypropyl cellulose (HPC) and acrylamide (AM) are dissolved in deionized water. Then, appropriate amounts of sodium carboxymethyl cellulose (CMC), crosslinking agent N,N'-methylenebisacrylamide (MBA), and initiator ammonium persulfate (APS) are added, and the mixture is stirred until completely dissolved and then centrifuged to remove bubbles. Finally, the prepared precursor solution is injected into a mold, sealed, and reacted at high temperature to obtain the final dual-temperature responsive cellulose-based hydrogel, Gel-H / C. Hydrogels obtained by adding different concentrations of CMC are denoted as Gel-H / Cx, where x is the mass percentage concentration of CMC.

[0009] As a preferred embodiment of the dual temperature-responsive cellulose-based hydrogel preparation method of the present invention: when hydroxypropyl cellulose (HPC) and acrylamide (AM) are dissolved in deionized water, the concentration of hydroxypropyl cellulose (HPC) is 5 wt% and the concentration of acrylamide (AM) is 2 mol / L.

[0010] As a preferred embodiment of the method for preparing a dual-temperature-responsive cellulose-based hydrogel according to the present invention: after injecting the prepared precursor solution into a mold and sealing it, and reacting it at a high temperature to obtain the final dual-temperature-responsive cellulose-based hydrogel Gel-H / C, the reaction temperature is 60°C and the reaction time is 6 hours.

[0011] As another aspect of the present invention, the present invention also provides the application of the aforementioned dual temperature-responsive cellulose-based hydrogel in a thermochromic smart window.

[0012] As another aspect of the present invention, the present invention also provides the application of the aforementioned dual temperature-responsive cellulose-based hydrogel in anti-counterfeiting materials.

[0013] The beneficial effects of this invention are as follows: A cellulose-based hydrogel (Gel-H / C gel) with dual temperature response was prepared via a one-pot method. The dynamic hydrogen bond changes between PAM, HPC, and water molecules, as well as the hydrophobic aggregation properties of HPC, enable the Gel-H / C hydrogel to exhibit both UCST and LCST phase transition behaviors. Na in CMC... + Ions, through ionic dipole interactions and strong hydration, can alter the hydrogen bonding interactions between polymers and entangle with polymer chains, giving Gel-H / C gels adjustable UCST (5-20℃) and LCST (30-50℃) transition temperatures, thus improving mechanical properties and freeze-thaw resistance. Gel-H / C gel smart windows can reversibly switch transparency according to changes in ambient temperature, ensuring daytime illumination, nighttime privacy protection, and excellent thermal insulation. Furthermore, Gel-H / C gels can function as encryption / decryption / re-encryption devices, performing encryption or decryption at different temperatures, significantly enhancing information security and mobility. This work provides a new approach for preparing hydrogel smart windows and information encryption devices through phase separation mechanisms and has broad application prospects. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0015] Figure 1 The flowchart shows a cellulose-based hydrogel (Gel-H / C gel) with dual temperature response prepared in Example 1.

[0016] Figure 2(a) ATR-FTIR spectra of different Gel-H / C hydrogels. (b) Temperature-varying FTIR spectra of Gel-H / C5 hydrogel in the temperature range of 2℃-40℃. (c) Schematic diagram of the phase transition mechanism of Gel-H / C hydrogel.

[0017] Figure 3 (a) CLSM images of Gel-H / C5 hydrogel at different temperatures. (b) SEM images of Gel-H / C5 hydrogel at different temperatures. (c) SAXS scattering intensity diagrams of Gel-H / C5 hydrogel at 2℃, 25℃, and 40℃. (d) Comparison of maximum tensile strength and strain of Gel-H / C hydrogel. (e) DSC curve of Gel-H / C hydrogel.

[0018] Figure 4 Tensile strength curves of Gel-H / C gel with different CMC contents.

[0019] Figure 5 Images of the distortion and stretching of the Gel-H / C gel before and after freezing at -15°C.

[0020] Figure 6 The transmittance of the gel-H / C gel at different temperatures in the range of 250-2500 nm is given.

[0021] Figure 7 A comparison of a smart window made using Gel-H / C gel and a regular window made using glass in a simulated house model.

[0022] Figure 8 (a) Information encryption, thermal decryption, and self-encryption process using the Gel-H / C hydrogel QR code information encryption device; (b) Information thermal encryption and erasure process using the Gel-H / C hydrogel patterned information encryption device. Detailed Implementation

[0023] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1: A method for preparing a dual temperature-responsive cellulose-based hydrogel (Gel-H / C gel)

[0027] Example 2: Effect of different CMC contents on the structure of Gel-H / C hydrogel

[0028] Example 3: Changes in the microstructure of Gel-H / C5 hydrogel during phase transition

[0029] Example 4: Thermal insulation performance test of Gel-H / C gel at different temperatures

[0030] Example 5: Dual thermal response capability and controllable dynamic visual changes based on Gel-H / C gel

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] A method for preparing a dual temperature-responsive cellulose-based hydrogel (Gel-H / C gel)

[0034] First, hydroxypropyl cellulose (HPC) and acrylamide (AM) are dissolved in deionized water. Then, appropriate amounts of sodium carboxymethyl cellulose (CMC), crosslinking agent N,N'-methylenebisacrylamide (MBA), and initiator ammonium persulfate (APS) are added, stirred until completely dissolved, and then centrifuged to remove bubbles. Finally, the prepared precursor solution is injected into a mold, sealed, and reacted at high temperature to obtain the final dual-temperature responsive cellulose-based hydrogel, Gel-H / C. Hydrogels obtained by adding different concentrations of CMC are denoted as Gel-H / Cx, where x is the mass percentage concentration of CMC. See the appendix for the detailed preparation process. Figure 1 .

[0035] As a preferred embodiment of the dual temperature-responsive cellulose-based hydrogel preparation method of the present invention: when hydroxypropyl cellulose (HPC) and acrylamide (AM) are dissolved in deionized water, the concentration of hydroxypropyl cellulose (HPC) is 5 wt% and the concentration of acrylamide (AM) is 2 mol / L.

[0036] As a preferred embodiment of the method for preparing a dual-temperature-responsive cellulose-based hydrogel according to the present invention: after injecting the prepared precursor solution into a mold and sealing it, and reacting it at a high temperature to obtain the final dual-temperature-responsive cellulose-based hydrogel Gel-H / C, the reaction temperature is 60°C and the reaction time is 6 hours.

[0037] Example 2

[0038] Effect of different CMC contents on the structure of Gel-H / C hydrogel

[0039] To investigate the effects of different CMC contents on the structure of Gel-H / C hydrogels, attenuated total reflectance infrared spectroscopy (ATR-FTIR) and variable-temperature infrared spectroscopy were performed. (See attached...) Figure 2 As can be seen, when the CMC concentration increases from 0 to 5 wt%, the NH stretching vibration peak, C=O stretching vibration peak, and -NH2 bending peak of the amide in the hydrogel all exhibit a red shift, indicating that a stable and strong hydrogen bond interaction has formed between the CMC and the PAM molecular chains. Furthermore, the OH stretching vibration peak corresponding to the hydrogen bond shows a blue shift (from 3376 cm⁻¹). -1 up to 3405cm -1 This is because of the free Na in CMC. + It exhibits strong hydration, leading to a weakening of hydrogen bonds between cellulose molecules. Using Gel-H / C5 hydrogel as an example, variable-temperature infrared spectroscopy was conducted at 2-50℃ to examine structural changes during phase transitions, reflecting the internal hydrogen bond interactions of the gel before and after the UCST and LCST phase transitions. (See attached...) Figure 2 As can be seen from b, the OH stretching vibration peak shifts towards higher wavelengths with increasing temperature (from 3346 cm⁻¹). -1 Moved to 3367cm -1 Meanwhile, the CO stretching vibration peak from HPC was significantly enhanced and increased from 1060 cm⁻¹. -1 Move to 1076cm -1 This indicates that the hydrogen bonds on the HPC molecular chain have weakened. Therefore, it can be inferred that the Gel-H / C5 hydrogel underwent structural changes in three states with increasing temperature (see appendix). Figure 2 c). First, CMC's Na + The hydrogen bonds between the HPC and PAM molecular chains are weakened by the ionic dipole interaction of the hydroxyl groups on the HPC chain. Instead, hydrogen bonds gradually form between the HPC and water molecules. As the temperature continues to rise, because Na... +The strong hydration effect weakens the hydrogen bonds between HPC and water molecules, making it easier for HPC to undergo hydrophobic aggregation. In addition, as the temperature increases, the stretching vibration peaks of N-H, C=O and -NH₂ from PAM also shift to higher wavenumbers, which also indicates that as the temperature rises, the hydrogen bonds between the molecular chains of HPC and PAM are gradually dissociated. Therefore, these results show that the UCST and LCST phase transition processes of the hydrogel are mainly caused by temperature-induced changes in hydrogen bonds, and the addition of CMC simultaneously leads to a decrease in both the UCST and LCST phase transition temperatures of Gel-H / C5.

[0040] Example 3

[0041] Changes in the Microstructure of Gel-H / C5 Hydrogel During Phase Transition

[0042] Confocal laser scanning microscopy (CLSM) was used to further investigate the changes in the microstructure of Gel-H / C5 hydrogel during phase transition. In the Figure 3 a CLSM image, the blue fluorescence represents the polymer-rich phase, which refracts and scatters light. Therefore, the denser the blue region is, the more opaque the hydrogel appears optically. At 25°C (UCST < T < LCST), only a few bright spots were observed in the CLSM image of the Gel-H / C5 hydrogel, indicating that there was no obvious light-scattering domain at this time, so the hydrogel was in a transparent state. However, when the hydrogel was exposed to low temperature (2°C, T < UCST) and high temperature (50°C, T > LCST), the polymer-rich phase presented aggregated and dense bright spots in the CLSM image due to the reduced compatibility of polymer chains in aqueous solution. It is worth noting that the size of the polymer phase is significantly smaller and denser at high temperature, proving that the two phase transitions originate from different mechanisms.

[0043] Scanning electron microscopy (SEM) was used to investigate the cross-sectional morphology and structure of Gel-H / C5 hydrogel at different temperatures. From the Figure 3 b, it can be seen that the Gel-H / C5 hydrogel presents a porous network structure. Due to the entanglement formed between CMC and polymer molecular chains, the cross-section of Gel-H / C5 is rougher. When the hydrogel is exposed to low temperature (2°C, T < UCST), it can be observed that the pore wall of the hydrogel becomes thicker, which is attributed to the hydrogen bonding interaction between PAM and HPC molecular chains. When the hydrogel is exposed to high temperature (50°C, T > LCST), it shows a loose macroporous honeycomb structure. Moreover, the pore wall of Gel-H / C5 is thicker than that of Gel-H / C0, because the addition of CMC reduces the LCST phase transition temperature of Gel-H / C5, making the hydrophobic aggregation of HPC more obvious.

[0044] In-situ small-angle X-ray scattering (SAXS) was used to further analyze the microstructure of Gel-H / C5 hydrogel at different temperatures. As shown in the Figure 3 As shown in Figure c, the scattering intensity (I(q)) decreases with increasing q, with almost no obvious characteristic peaks, indicating a homogeneous internal structure of the hydrogel. Notably, the scattering intensity of Gel-H / C5 is weakest at 25℃, indicating that phase separation has not occurred at this point. However, when cooled to 2℃, the scattering intensity increases, due to phase separation caused by polymer chain aggregation. When heated to 40℃, the scattering intensity further increases, indicating that the hydrophobic aggregation of HPC molecular chains exhibits stronger light scattering. Furthermore, the radius of gyration (Rg) of Gel-H / C5 hydrogel at 25℃ is 32.4 nm, which is higher than that at 2℃ (30.6 nm) and 40℃ (27.7 nm), indicating that phase separation makes the molecular chains more compact.

[0045] CMC significantly enhances the mechanical properties of hydrogels by forming entanglements with polymer molecular chains. As the CMC content increases from 0 wt% to 5 wt%, the hydrogels exhibit a significant increasing trend in both tensile stress and tensile strain (see appendix). Figure 3 d). When the CMC content reaches 5wt%, the tensile strength of the Gel-H / C5 hydrogel is 54kPa, which is more than twice that of Gel-H / C0; at the same time, its elongation at break is 204%, almost three times that of Gel-H / C0 (see appendix). Figure 4 This phenomenon confirms that the topological entanglement formed by CMC with PAM and HPC molecular chains effectively improves the mechanical properties of the hydrogel. Furthermore, as a sodium salt, CMC can improve the hydrogel's antifreeze ability, ensuring its stability and reliability in low-temperature applications. (Appendix) Figure 5 This demonstrates that the Gel-H / C5 hydrogel can still be freely twisted and stretched without any damage after being refrigerated at -15℃ for 12 hours. The differential scanning calorimetry (DSC) curve of the Gel-H / C hydrogel is shown to be... Figure 3 e) It can be seen that the crystallization peak of Gel-H / C5 hydrogel is at -18℃, which is 6℃ lower than the crystallization temperature of Gel-H / C0 (-12℃), indicating that Na + Ions prevent water molecules from accumulating and ice crystals from forming.

[0046] Example 4

[0047] Thermal insulation performance test of Gel-H / C gel at different temperatures

[0048] It is well known that thermal radiation in the near-infrared (IR, 780-2500 nm) region contributes 53% of the total solar energy (UV contributes 3%; visible contributes 44%). Considering that the Gel-H / C5 hydrogel maintains high transparency within a temperature range suitable for the human body, which would well meet the application requirements of smart windows, the transmittance of the Gel-H / C5 hydrogel at different temperatures within the 250-2500 nm range was tested. (See attached image) Figure 6 As shown, the transmittance of Gel-H / C5 hydrogel in the visible light range is less than 25% at 2℃, exceeds 90% at 25℃, and is close to 0% in the 250-2500nm range at 40℃. Notably, the transmittance of the hydrogel drops sharply in the IR region, indicating that Gel-H / C5 hydrogel has excellent IR blocking capabilities, which is crucial for the heat insulation and energy-saving performance of smart windows. The transmittance modulation efficiency of Gel-H / C5 hydrogel was calculated as follows (Ttum = 90.24%, ΔTsolar,25-2℃ = 66.88%, ΔTsolar,25-40℃ = 80.81%). The high Ttum of Gel-H / C5 ensures high visibility indoors during the day without the need for additional lighting; while in cool nights and hot summers, the low transmittance blocks indoor lights and infrared radiation, providing privacy and heat insulation. To evaluate the reliability and durability of the Gel-H / C5 hydrogel, 25 cycles of heating-cooling were performed within the range of 2–40 °C, and its transmittance change at 550 nm was measured. During the 25 cycles, the transmittance of the Gel-H / C5 hydrogel showed almost no change at 2 °C, 25 °C, and 40 °C, exhibiting a reversible and stable phase transition, ensuring good service life in applications.

[0049] To demonstrate the application potential of Gel-H / C5 hydrogel as a smart window in terms of thermal insulation performance, a 1mm thick hydrogel sample was sealed and assembled into a simulated house model using silicone and glass sheets (see attached). Figure 7 Meanwhile, a model house with ordinary glass windows was assembled for comparison. Initially, the temperature inside both model houses was approximately 28.4℃. At this time, the smart window was transparent, allowing a clear view of the outside scenery (see attached image). Figure 7 a) After 4 hours of sunlight exposure, as the ambient temperature began to rise, the smart windows became opaque. Indoor temperature monitoring results for the model room showed that the temperature inside the model room with ordinary glass windows reached 52.4℃, while the temperature inside the model room with smart windows was only 49.0℃, approximately 3.4℃ lower than the temperature inside the model room with ordinary glass windows (see attached image). Figure 7b). These experimental results confirm that, compared to traditional glass windows, the Gel-H / C5 smart window can not only effectively regulate light transmittance and reduce direct sunlight, but also regulate indoor temperature, demonstrating excellent heat insulation and energy-saving effects.

[0050] Example 5

[0051] Dual thermal response capabilities and controllable dynamic visual changes based on Gel-H / C gel

[0052] Based on the dual thermal response capabilities and controllable dynamic visual changes of Gel-H / C gel, its application potential in QR code information encryption and decryption was designed and demonstrated. (See attached image) Figure 8 As shown, first, the strips of Gel-H / C0, Gel-H / C2, and Gel-H / C5 gel are placed in sequence and then encapsulated in a glass interlayer with silicone. Then, the device is placed above the QR code paper, against a black cardboard background, to form a QR code information encryption device. (See attached...) Figure 8 As can be seen, since all three gels are opaque at 1°C, the QR code information is invisible and in an encrypted state. When the temperature rises to 15°C, the QR code information hidden by Gel-H / C5 becomes visible, but the complete information is still not available. When the temperature reaches 25°C, all gels become transparent, and the QR code information is completely decrypted. Scanning the QR code reveals the hidden information (a landscape photo). When the device is heated again to 35°C, the Gel-H / C5 and Gel-H / C2 gels undergo an LCST phase transition and become opaque, hiding the QR code information again. When the temperature rises to 50°C, the QR code information is completely encrypted.

[0053] In addition, a pattern information encryption device was designed. (See attached image) Figure 8 As shown in Figure b, a heart-shaped Gel-H / C5 gel is embedded within a Gel-H / C0 (1mm thick) and encapsulated in silicone within a glass interlayer. Photographed against a black cardboard background, the device becomes opaque at 1°C, completely concealing the pattern. As the temperature rises to 15°C, the heart pattern is fully decrypted; at 25°C, the Gel-H / C0 becomes transparent, the heart pattern disappears, and the pattern remains encrypted. As the temperature further rises to 35°C, the pattern is decrypted again while remaining opaque; at 50°C, the device becomes opaque once more, and the pattern is fully encrypted again. This process can be repeated multiple times without any change in appearance.

Claims

1. A method for preparing a cellulose-based hydrogel with dual temperature response, characterized in that: It consists of the following steps, First, hydroxypropyl cellulose (HPC) and acrylamide (AM) are dissolved in deionized water, with the hydroxypropyl cellulose (HPC) concentration being 5 wt% and the acrylamide (AM) concentration being 2 mol / L. Then, appropriate amounts of sodium carboxymethyl cellulose (CMC), crosslinking agent N,N'-methylenebisacrylamide (MBA), and initiator ammonium persulfate (APS) are added, stirred until completely dissolved, and then centrifuged to remove bubbles. Finally, the prepared precursor solution is injected into a mold, sealed, and reacted at high temperature to obtain a cellulose-based hydrogel with dual temperature response, Gel-H / C.

2. The method for preparing a cellulose-based hydrogel with dual temperature response according to claim 1, characterized in that: When adding appropriate amounts of sodium carboxymethyl cellulose (CMC), crosslinking agent N,N'-methylenebisacrylamide (MBA), and initiator ammonium persulfate (APS), and stirring until completely dissolved before centrifugation to remove bubbles, the mass percentage concentration of sodium carboxymethyl cellulose (CMC) is 0 wt% < CMC wt% ≤ 5 wt%.

3. The method for preparing cellulose-based hydrogels with dual temperature response according to claim 1, characterized in that: After the prepared precursor solution is injected into the mold and sealed, it is reacted at high temperature to obtain a cellulose-based hydrogel with dual temperature response, Gel-H / C. The reaction temperature is 60℃ and the reaction time is 6 hours.

4. A cellulose-based hydrogel with dual temperature response prepared by the method according to claim 1, characterized in that: The hydrogel can reversibly switch its transparency within a range of 1°C to 50°C depending on changes in ambient temperature.

5. The application of a dual-temperature-responsive cellulose-based hydrogel prepared according to the preparation method of claim 1 in anti-counterfeiting materials.

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