An upper critical solution temperature type intelligent organic gel and a preparation method and application thereof

Abstract

This invention discloses an upper critical solution temperature-type intelligent organic gel, its preparation method, and its applications, belonging to the field of functional polymer materials technology. The organic gel is prepared by ultraviolet-initiated polymerization of methacryloylethyl sulfobetaine and acrylic acid as comonomers, with metal ions as crosslinking agents, in a mixed medium of water and glycerol. This invention introduces methacryloylethyl sulfobetaine as a key functional monomer, successfully inducing the organic gel to exhibit a unique upper critical solution temperature-type temperature response behavior, achieving reversible adjustment of transmittance with temperature; simultaneously, it endows the organic gel with excellent self-healing and adhesion properties, making it applicable to temperature sensors, strain sensors, and human-computer interaction devices. Methacrylethyl sulfobetaine is an essential component for the organic gel of this invention to achieve multiple intelligent functions. The preparation process of this invention is simple, the raw materials are readily available, and the performance is stable, overcoming the technical shortcomings of traditional organic gels that are single-function and lack upper critical solution temperature response.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials technology, and in particular to an upper critical solution temperature type smart organic gel, its preparation method and application. Background Technology

[0002] In recent years, the rapid development of flexible electronics and artificial intelligence has driven a surge in research on flexible smart materials. As a class of soft materials with dynamic response characteristics, smart gels can reversibly sense and respond to external physical or chemical stimuli (such as temperature, pH, light, ionic strength, electric field, magnetic field, specific molecules, etc.), thereby altering their structure or properties, such as swelling / shrinkage, phase transitions, changes in optical or mechanical properties, and adhesion / deadhesion. Benefiting from their softness similar to biological tissues, good environmental compatibility, and tunable physicochemical properties, smart gels have broad application prospects in sensors, actuators, bionic skin, and human-computer interaction.

[0003] Temperature-responsive organic gels are a hot topic in the field of smart gels, achieving reversible performance regulation through temperature stimulation. These gels typically combine thermoresponsive polymers with low critical solution temperatures (LCST, such as poly(N-isopropylacrylamide)) or high critical solution temperatures (UCST, such as poly(3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate) and poly(N-acryloylglycine amide)) with hydrogels, allowing visualization of the temperature response solely through changes in transparency. Compared to LCST gels, which are prone to instability at high temperatures, UCST gels exhibit more stable cross-linked networks at room temperature, and their homogeneous state at high temperatures is more conducive to functional retention, making them more suitable for long-term operation in smart devices. Furthermore, their response temperature can be flexibly adjusted through pH and zwitterionic ratios, and the introduction of hydrophilic / hydrophobic structures can further modulate thermal sensitivity.

[0004] Furthermore, most organogels, lacking specific functional monomers, often fail to achieve the synergistic effect of adjustable temperature response and transmittance. They also exhibit poor self-healing and adhesion properties, making them unsuitable for the multifunctional requirements of temperature sensors, strain sensors, and human-computer interaction devices. Research has revealed that methacryloylethyl sulfobetaine, as an amphoteric monomer, possesses functional groups such as sulfonate and quaternary ammonium ions in its molecular structure that can form dynamic intermolecular hydrogen bonds. However, there are currently no reports on the preparation of organogels with upper critical solution temperature response, adjustable transmittance, self-healing, adhesion, and multi-sensing functions using methacryloylethyl sulfobetaine as a key monomer. Therefore, achieving both upper critical solution temperature response and adjustable transmittance while maintaining self-healing and adhesion properties is a pressing technical challenge in the field of smart gels. Summary of the Invention

[0005] Based on the above, the present invention provides a smart organic gel with adjustable transmittance and upper critical solution temperature-responsiveness induced by methacryloylethyl sulfobetaine, which is suitable for the fields of flexible sensing and human-computer interaction.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is a method for preparing an upper critical solution temperature type smart organic gel, comprising the following steps: Methacrylethyl sulfobetaine and acrylic acid were dissolved in a solvent and mixed well. Then aluminum salt, crosslinking agent and photoinitiator were added and mixed well to obtain a mixed solution. The mixed solution was irradiated with ultraviolet light to obtain the upper critical solution temperature type smart organic gel; The solvent is a mixture of water and glycerin.

[0007] The second technical solution of the present invention is an upper critical solution temperature type smart organic gel prepared by the above preparation method.

[0008] The third technical solution of the present invention is the application of the above-mentioned upper critical solution temperature type smart organic gel in the preparation of temperature sensors, strain sensors or flexible sensing layers for human-computer interaction devices.

[0009] The fourth technical solution of the present invention is a temperature sensor, comprising the above-mentioned upper critical solution temperature type smart organic gel.

[0010] The fifth technical solution of the present invention is a strain sensor, comprising the above-mentioned upper critical solution temperature type smart organic gel.

[0011] The sixth technical solution of the present invention is a human-computer interaction device, wherein the flexible sensing layer comprises the above-mentioned upper critical solution temperature type intelligent organic gel.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the present invention is simple, the gelation time is short, the production cost is low, and the reaction process is easy to control.

[0013] (2) The upper critical solution temperature type intelligent organic gel prepared by this invention forms hydrogen bonds, electrostatic interactions between anions and cations, and coordination of metal ions between molecules, forming a multi-layer physical cross-linking network, thereby endowing the gel with excellent self-healing and adhesion properties. At the same time, the zwitterionic methacryloylethyl sulfobetaine segments in the gel and their reversible phase separation that occurs with temperature give it typical UCST behavior, temperature responsiveness, adjustable transparency and excellent mechanical properties, and it can achieve rapid and reversible changes in transmittance with a fast response.

[0014] (3) The wearable strain sensor prepared by the upper critical solution temperature type intelligent organic gel assembly obtained by the present invention has excellent strain sensitivity and fast response, and can monitor various joint movements of the human body.

[0015] (4) The intelligent organic gel assembly strain sensor of the upper critical solution temperature type prepared by the present invention is integrated with a microcontroller to remotely control the manipulator, and successfully realizes human-machine interaction. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0017] Figure 1 This is a schematic diagram of the preparation process of the upper critical solution temperature type smart organic gel of the present invention.

[0018] Figure 2 A schematic diagram of the test temperature response structure provided by the present invention.

[0019] Figure 3 This is a schematic diagram of the wearable strain sensor structure provided by the present invention.

[0020] Figure 4 This is a schematic diagram of the human-computer interaction structure provided by the present invention.

[0021] Figure 5 The tensile stress-strain curves are for the organic gels prepared in Examples 1-4 of this invention.

[0022] Figure 6 The tensile stress-strain curve is shown for the organic gel prepared in Comparative Example 1 of this invention.

[0023] Figure 7 The transmittance experiments of the organic gels prepared in Examples 1-4 of this invention are shown in: (a) is an optical photograph; (b) is a transmittance curve.

[0024] Figure 8 The transparency changes of the organic gels prepared in Example 2 and Comparative Example 1 of the present invention at different temperatures: (a) Example 2; (b) Comparative Example 1.

[0025] Figure 9 The self-healing experiment of the organic gel prepared in Example 4 of the present invention: (a) inflation experiment of the self-healing organic gel balloon; (b) tensile stress-strain curves before and after self-healing.

[0026] Figure 10The adhesion strength curves of the organic gel prepared in Example 4 of this invention on different substrates are shown.

[0027] Figure 11 The sensitivity factor curve is a fitting of the temperature response of the organic gel prepared in Example 4 of this invention.

[0028] Figure 12 The sensitivity factor curve is the curve fitted to the strain sensor prepared by the organic gel in Example 4 of this invention.

[0029] Figure 13 The resistance change curves of the strain sensor prepared using the organic gel in Example 4 of this invention during 30% strain tensile cycles are shown: (a) is the original gel; (b) is the gel after self-healing.

[0030] Figure 14 The resistance change curve of the strain sensor prepared using the organic gel in Example 4 of this invention is obtained by attaching it to the elbow and cyclically bending and recovering.

[0031] Figure 15 The resistance change curve of a strain sensor prepared using the organic gel of Example 4 of the present invention is obtained by attaching it to the knee and cyclically bending and recovering.

[0032] Figure 16 The resistance change curve of the strain sensor prepared using the organic gel of Example 4 of the present invention is obtained by attaching it to a finger and cyclically bending and recovering.

[0033] Figure 17 The strain sensor assembly prepared in this invention is applied to human-computer interaction: (a) is a photograph of the sensor controlling the operation of the robotic arm; (b) is the data output by the five sensors (thumb, index finger, middle finger, ring finger and little finger) as the fingers move in sequence.

[0034] Figure 18 The percentage of mass change of the organic gels prepared in Comparative Examples 3 and 4 of this invention during 7 days of storage.

[0035] Figure 19 Photographs showing the mechanical properties of the organic gel prepared in Comparative Example 4 of this invention.

[0036] Figure 20 The stress-strain curves are for the organic gels prepared in Comparative Example 5 and Example 4 of this invention. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] This invention addresses the technical problems of traditional organic gels, such as lack of upper critical solution temperature response and limited functionality, by introducing methacryloylethyl sulfobetaine as a key functional monomer. It integrates multiple intelligent properties of the organic gel, including temperature response, adjustable transmittance, self-healing, and adhesion. The organic gel of this invention can be assembled into a wearable temperature sensor and a wearable strain sensor, enabling high-precision temperature sensing and detection of human physiological signals; the strain sensor exhibits high sensitivity and rapid response. Furthermore, this invention has developed a prototype wearable device integrating the organic gel sensor and a microcontroller for remotely controlling a robotic arm, successfully achieving human-machine interaction.

[0043] The first aspect of this invention provides a method for preparing an upper critical solution temperature type smart organic gel, comprising the following steps: Methacrylethyl sulfobetaine and acrylic acid were dissolved in a solvent and mixed well. Then aluminum salt, crosslinking agent and photoinitiator were added and mixed well to obtain a mixed solution. The mixed solution was irradiated with ultraviolet light to obtain the upper critical solution temperature type smart organic gel; The solvent is a mixture of water and glycerin.

[0044] In a preferred embodiment of the present invention, the ratio of the amount of methacryloylethyl sulfobetaine to the amount of acrylic acid, solvent, aluminum salt, crosslinking agent and photoinitiator is (0.001~0.004) mol∶(2~5) g∶5 mL∶(0.8~1.1) g∶(0.09~0.15) g∶(20~30) µL.

[0045] In a preferred embodiment of the present invention, the solvent is a mixture of water and glycerol in a volume ratio of (4~2):(1~3). More preferably, the volume ratio of water to glycerol in the solvent is 2:3, 3:2, or any value between the two aforementioned ratios.

[0046] In a preferred embodiment of the present invention, the aluminum salt is aluminum trichloride; the crosslinking agent is zinc methacrylate; and the photoinitiator is one of 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methylpropyl phenylacetone, 1-hydroxycyclohexylphenyl ketone, and lithium phenyl-2,4,6-trimethylbenzoylphosphonate.

[0047] In a preferred embodiment of the present invention, the wavelength of the ultraviolet light irradiation is 365 nm or 405 nm, and the irradiation time is 1 to 3 min.

[0048] This invention uses simple free radical polymerization to copolymerize acrylic acid and methacryloyl ethyl sulfobetaine to obtain an organic gel. The organic gel forms a three-dimensional network through physical cross-linking, including hydrogen bonding, metal ion coordination, and electrostatic interaction.

[0049] Electrostatic interactions between methacryloylethyl sulfobetaine molecules and hydrogen bonding between acrylic acid molecules form an interpenetrating network, while the polyacrylic acid chains form a coordination crosslinking network with zinc and aluminum ions. This synergistic effect increases the crosslinking density, resulting in excellent mechanical properties and fatigue resistance in the gel. Furthermore, the incorporation of zwitterionic methacryloylethyl sulfobetaine induces an upper critical solution temperature-responsive behavior in the organic gel, giving it temperature-driven reversible transmittance adjustment. Without methacryloylethyl sulfobetaine, the prepared organic gel exhibits no upper critical solution temperature behavior, unadjustable transmittance, and no self-healing properties.

[0050] The sulfonate groups in methacryloylethyl sulfobetaine molecules are strongly hydrophilic. When the content of methacryloylethyl sulfobetaine molecules increases, the polymer chains transform from a tightly coiled state to a stretched state—the chain segments are fully solvated (hydrated), forming a larger "hydrated shell." This "chain stretching + hydrated shell thickening" makes the organic gel network structure more uniform and regular, reducing light scattering centers and thus improving transparency. Furthermore, the strong interaction between methacryloylethyl sulfobetaine molecules and water makes the refractive indices of the aqueous and polymer phases within the system closer, significantly reducing light scattering and contributing to improved transparency. Increased water content disrupts the interactions between polymer chains; some stretched polymer chains lose their cross-linking constraints, forming larger aggregates. The significant increase in the refractive index difference between the aggregates and the surrounding aqueous phase leads to enhanced light scattering, ultimately resulting in decreased transparency. This invention allows for precise control of light transmittance by adjusting the amount of added methacryloylethyl sulfobetaine molecules and water to regulate micelle size.

[0051] Methacryloxyethyl sulfobetaine is a typical betaine-type zwitterionic monomer, carrying both positive and negative charges within its molecule. It exhibits both strong hydrophilicity and temperature responsiveness, resulting in an organic gel that displays a UCST-type phase transition. Due to the different hydration states of the polymer chains at different temperatures, specifically, the aggregation state of the polymer chains causes strong light scattering, i.e., phase separation (opaqueness); increasing the temperature disrupts the dynamic cross-linked network, leading to reduced light scattering, significantly increased transmittance, and a transparent state.

[0052] The polymer chain aggregation-dispersion process is highly repeatable, and the transmittance response remains stable after multiple temperature cycles. The organic gel achieves reversible control of transmittance through the dynamic changes in the cross-linked network structure induced by temperature, exhibiting good cycling stability.

[0053] A second aspect of the present invention provides an upper critical solution temperature type smart organic gel prepared by the above-described preparation method.

[0054] This upper critical solution temperature type smart organic gel is a three-dimensional porous organic gel formed by polymethacryloyl ethyl sulfobetaine, polyacrylic acid, aluminum trichloride, zinc methacrylate, water and glycerol.

[0055] In this invention, methacrylyl ethyl sulfobetaine is a key monomer for inducing the upper critical solution temperature-responsive behavior of organic gels. By adding methacrylyl ethyl sulfobetaine, the prepared organic gel has temperature-driven reversible transmittance adjustment characteristics. When methacrylyl ethyl sulfobetaine is not added, the prepared organic gel has no upper critical solution temperature behavior, its transmittance is not adjustable, and it has no self-healing properties.

[0056] The upper critical solution temperature is 25~50℃. When the temperature is higher than the upper critical solution temperature, the transmittance is ≥85%; when the temperature is lower than the upper critical solution temperature, the transmittance is ≤15%. Moreover, the temperature response of the transmittance is reversible, and the transmittance adjustment range does not significantly decrease after more than 10 cycles of use.

[0057] The self-healing efficiency of the organic gel of this invention is ≥80% (it can complete self-healing after being placed at room temperature for 12 hours after cutting), and the adhesion strength to glass, metal and skin is ≥15kPa.

[0058] The third aspect of the present invention provides the application of the above-mentioned upper critical solution temperature type smart organic gel in the preparation of temperature sensors, strain sensors or flexible sensing layers for human-computer interaction devices.

[0059] The temperature sensor utilizes the upper critical solution temperature-type temperature response characteristics of the organic gel to convert temperature changes into transmittance signals or resistance signals for detection; the strain sensor utilizes the mechanical response characteristics of the organic gel to convert strain changes into resistance signals for detection.

[0060] In the human-computer interaction device, the organic gel adheres to human skin or a flexible substrate through adhesiveness, enabling human motion recognition, temperature sensing, and transmission of human-computer interaction signals.

[0061] A fourth aspect of the present invention provides a temperature sensor comprising the above-described upper critical solution temperature type smart organic gel.

[0062] A fifth aspect of the present invention provides a strain sensor comprising the above-described upper critical solution temperature type smart organic gel.

[0063] The sixth aspect of the present invention provides a human-computer interaction device, wherein the flexible sensing layer comprises the above-mentioned upper critical solution temperature type smart organic gel.

[0064] The application of this invention is based on the characteristics of the prepared upper critical solution temperature type smart organic gel, which is then applied to wearable strain sensors and human-computer interaction, achieving a deep integration of "UCST behavior - multifunctional integration - adaptation to emerging scenarios".

[0065] Furthermore, the wearable strain sensor includes two copper wires, two sections of conductive adhesive, and an organic gel disposed between the two copper wires.

[0066] Furthermore, the human-computer interaction includes an organic gel strain sensor, a microcontroller, Bluetooth, and a manipulator.

[0067] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0068] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0069] This invention provides a method for preparing an upper critical solution temperature type smart organogel (e.g., Figure 1 (As shown), the steps are as follows: Step 1: Dissolve methacryloylethyl sulfobetaine and acrylic acid in water and glycerol binary solvent and stir until homogeneous to obtain the first mixed solution; Step 2: Add aluminum trichloride, crosslinking agent (zinc methacrylate), and photoinitiator sequentially to the first mixed solution to obtain the second mixed solution; Step 3: Inject the second mixed solution into a polytetrafluoroethylene mold and polymerize it under ultraviolet light to obtain an organic gel.

[0070] The above-mentioned method is used to prepare three applications of the upper critical solution temperature smart organogel, specifically including: Application 1, such as Figure 2 As shown, the upper critical solution temperature type smart organic gel is applied to temperature response testing. The device includes two conductive adhesive segments 1, one organic gel 2, and two copper wires 3. The two copper wires 3 are connected to both ends of the organic gel 2, and then the two conductive adhesive segments 1 are used to bond them together, and the temperature sensor is attached to the surface of an object or the forehead of a human body to monitor human movement.

[0071] Application 2, such as Figure 3 As shown, the upper critical solution temperature type smart organic gel is applied to a wearable strain sensor. The strain sensor includes two conductive adhesive segments 1, an organic gel 2, and two copper wires 3. The two copper wires 3 are connected to both ends of the organic gel 2, and then the two conductive adhesive segments 1 are used to bond the strain sensor to the surface of a human joint or skin to monitor human movement.

[0072] Application 3, such as Figure 4 As shown, the upper critical solution temperature type smart organic gel is used as a strain sensor in human-computer interaction. This human-computer interaction includes an organic gel strain sensor, a microcontroller unit, Bluetooth, and a manipulator. Specifically, the organic gel strain sensor is connected to the microcontroller unit to synchronously capture finger movement signals, and then transmits the data remotely via Bluetooth to control the manipulator's robotic arm.

[0073] Examples 1-4 Methacrylethyl sulfobetaine (0.001 ~ 0.004 mol) and 4.0 g of acrylic acid were dissolved in a mixture of 3 mL of water and 2 mL of glycerol and stirred for 0.5 hours. Then, 1.07 g of aluminum trichloride (3% aluminum ions relative to the mass of acrylic acid monomer), 0.12 g of zinc methacrylate, and 25 µL of 2-hydroxy-2-methylpropyl phenyl ketone were added to the resulting mixture and magnetically stirred until a homogeneous solution was formed. The solution was then poured into a polytetrafluoroethylene mold and irradiated under 365 nm UV light for 3 minutes to obtain an organogel.

[0074] Comparative Example 1 The only difference from Example 1 is that the addition of methacryloylethyl sulfobetaine is omitted.

[0075] Table 1. Proportions of raw materials in Examples 1-4 and Comparative Example 1

[0076] A strip-shaped sample with a length of 40 mm, a width of 10 mm, and a thickness of 2.0 mm was taken from the upper critical solution temperature type smart organic gel prepared according to the above method and subjected to a tensile test at a speed of 50 mm / min in an electronic universal testing machine to obtain its stress-strain curve. Figure 5 Tensile stress-strain curves of the organic gels prepared in Examples 1-4 of this invention. Figure 6 This is the tensile stress-strain curve of the organic gel prepared in Comparative Example 1 of this invention. From... Figure 5 It can be observed that Example 4 exhibits the best mechanical properties, with a maximum elongation at break of 536% and a maximum breaking stress of 354 kPa. Other organic gels show poorer mechanical properties; for example, the hydrogel of Example 1 has the weakest stress. This is because its low crosslinking density, high degree of freedom in the polymer chains, and weakened interactions between the polymer chains result in the worst mechanical properties. Comparative Example 1 has a maximum elongation at break of 134% and a maximum breaking stress of 227 kPa.

[0077] The properties of the organic gels obtained in the examples were further tested: (1) Transparency change test The transmittance of the organic gels prepared in Examples 1-4 is as follows: Figure 7 As shown in (a), the transparency of the organic gel increases with the increase of the amount of methacryloyl ethyl sulfobetaine added.

[0078] The organic gels prepared in Examples 1-4 were sampled as long strips with a length of 30 mm, a width of 8 mm, and a thickness of 2.0 mm. The transmittance of these strips was measured using a UV spectrophotometer, and the results are shown below. Figure 7 As shown in (b), Example 4 has the highest light transmittance, while Example 1 has the lowest light transmittance.

[0079] The transparency changes of the organic gels prepared in Example 2 and Comparative Example 1 were tested. In Example 2, the transparency of the hydrogel showed a significant difference at high and low temperatures; it was opaque at 25°C and became completely transparent at 50°C. Representative images are shown below. Figure 8 As shown in (a) in the figure; while the transparency of the hydrogel in Comparative Example 1 showed no significant change, as shown in the representative image. Figure 8 As shown in (b) of the diagram.

[0080] (2) Self-healing performance test The self-healing ability of the organic gel prepared in Example 4 was determined using an electronic universal testing machine. The organic gel sample was cut in half with scissors, and one half of the organic gel was kept in contact with the other half. It was then placed at ambient temperature (20°C) to promote damage repair, and the loading speed was always maintained at 50 mm / min.

[0081] like Figure 9 As shown in (a), to visually demonstrate the self-healing behavior of the organic gel, four pieces of organic gel of different colors were brought into contact with each other. Without any external stimulation, the organic gel self-healed into a complete film after 12 hours, and the self-healed organic gel film could be blown into a large balloon without leaking air. Figure 9 As shown in (b), the repaired organic gel was subjected to tensile testing under the same test conditions as the original organic gel. The repaired organic gel exhibited a maximum tensile strength (286 kPa) and elongation at break (445%) comparable to the original organic gel, with a self-healing efficiency as high as 89%. The excellent self-healing properties of the organic gel can effectively extend the service life of the material, making the equipment suitable for various complex environments.

[0082] (3) Adhesion performance test Adhesive strength was obtained through an overlap shear test. During the test, the organic gel sample prepared in Example 4 (25 mm × 20 mm × 2 mm) was gently placed between two substrates (copper, paper, steel, glass, polyimide, polytetrafluoroethylene, nitrile rubber, and pigskin), ensuring proper clamping. The two identical substrates were then pulled at a constant speed of 50 mm / min using an electronic universal testing machine, and the adhesive strength was calculated by dividing the maximum tensile force (Newtons) by the initial contact area (square meters). The results are as follows: Figure 10 As shown, the maximum adhesion strength of stainless steel is 34 kPa, glass is 40 kPa, copper is 19 kPa, paper is 1.4 kPa, nitrile rubber is 38 kPa, polyimide is 16 kPa, polytetrafluoroethylene is 1.4 kPa, and pigskin is 8.80 kPa.

[0083] (4) Temperature response test The organic gel (30 mm × 10 mm × 2 mm) prepared in Example 4 was connected to two copper conductors, and then the two sections of conductive adhesive were used to bond them together, and the temperature sensor was attached to the surface of the object for monitoring. Its structure is as follows. Figure 2 As shown. Figure 11 The temperature response of this organogel temperature sensor was demonstrated. As the temperature increased from -10 °C to 50 °C, the relative resistivity of the gel decreased linearly with increasing temperature, demonstrating the material's excellent thermosensitive properties. To determine the sensitivity of the temperature sensor, the temperature coefficient of resistance (TCR)—i.e., the slope of the fitted curve—was calculated. The TCR value was -2.24% / °C over the temperature range of -10 °C to 50 °C.

[0084] (5) Application in wearable strain sensors (test sample is the organic gel prepared in Example 4) The organic gel (30 mm × 10 mm × 2 mm) prepared in Example 4 was connected to two copper conductors and assembled into a wearable strain sensor by binding it tightly with conductive adhesive. Its structure is as follows: Figure 3 As shown.

[0085] To further investigate the sensitivity of the fabricated flexible strain sensor, the relative resistance change under different strains was monitored, and the fitted sensitivity factor (GF) was calculated as follows: Figure 12 As shown, the results indicate that the sensitivity factor of the flexible strain sensor is 2.1 in the strain range of 0 to 100, which shows that the wearable strain sensor assembled from temperature-responsive organic gel with adjustable transmittance has excellent sensitivity in a small strain range.

[0086] Figure 13 (a) shows the relative rate of change of resistance monitored over 200 consecutive tensile cycles at a strain of 30%. Figure 13 Figure (b) shows the relative change rate of resistance of the self-healing organic gel after 200 consecutive tensile cycles at a strain of 30%. Figure 13 The results show that the wearable strain sensor assembled from a temperature-responsive organic gel with adjustable transmittance has excellent cycle stability and durability.

[0087] The assembled flexible strain sensor was attached to the elbow joint, and the joint strain was accurately monitored by the real-time resistance changes at different elbow flexion angles. The results are as follows: Figure 14 As shown; Figure 15 The real-time resistance change at the leg joint during bending and stretching is shown, indicating that the strain sensor can also detect human movement with large strain.

[0088] The assembled wearable strain sensor is attached to the finger joint, and the writing process of different letters is monitored by the changes in resistance during the cyclic bending and recovery of the finger joint. For example... Figure 16 As shown, the electrical signals exhibit unique responsiveness when writing different letters ("A", "K" and "M"), while the same letter produces a repeatable signal curve, demonstrating the application of the assembled strain sensor in practical writing detection.

[0089] (6) Application in human-computer interaction (the test sample is the organic gel prepared in Example 4) The organic gel prepared in Example 4 was assembled into a wearable strain sensor and connected to the microcontroller unit to synchronously capture finger movement signals. Data was then remotely transmitted via Bluetooth to control the manipulator hand. Its structure is as follows: Figure 4 As shown.

[0090] like Figure 17 As shown in (a), when the sensor is mounted on the finger, the robotic hand can accurately follow the bending motion of the finger to mimic human hand movements and has a synchronous response effect. Figure 17 As shown in (b), when the sensor is mounted on multiple fingers, there is no signal interference or significant signal delay between the signals connected to them. This organogel sensor shows great promise for applications in flexible electronics, human-computer interfaces, and smart devices.

[0091] Comparative Example 2 The only difference from Example 4 is that the mixture of 3 mL water and 2 mL glycerol is replaced with a mixture of 1 mL water and 4 mL glycerol; all other steps and parameters are the same as in Example 4.

[0092] The organic gel prepared in this comparative example was subjected to the same effect verification as in Example 4. The results showed that the monomer methacryloyl ethyl sulfobetaine added under this solvent ratio was difficult to dissolve and could not be prepared into an organic gel with UCST behavior.

[0093] Comparative Example 3 The only difference from Example 4 is that 2 mL of glycerol is replaced with 2 mL of water; all other steps and parameters are the same as in Example 4.

[0094] The gel prepared in this comparative example was subjected to the same effect verification as in Example 4, such as... Figure 18 As shown, Comparative Example 3 without glycerin lost water quickly, and the mass retention rate of the gel on day 7 was only 40% of the initial mass, while Example 4 with glycerin did not lose water easily and had good water retention.

[0095] Comparative Example 4 The only difference from Example 4 is that aluminum trichloride is replaced with an equal amount of sodium chloride.

[0096] The organogel prepared in this comparative example was subjected to the same effect verification as in Example 4, and the results are as follows: Figure 19 As shown, Comparative Example 4, prepared with added sodium chloride, exhibited almost no mechanical properties. The results indicate that sodium ions only neutralize the charge and do not contribute to cross-linking, while aluminum ions can coordinate with the carboxyl groups of polyacrylic acid to form an ionic cross-linking network.

[0097] Comparative Example 5 The only difference from Example 4 is that aluminum trichloride is replaced with an equal amount of calcium chloride.

[0098] The organogel prepared in this comparative example was subjected to the same effect verification as in Example 4, such as... Figure 20 As shown, Comparative Example 5, with added calcium chloride, exhibits certain mechanical properties, but its mechanical strength is significantly lower than that of Example 4, which contains aluminum trichloride. The results indicate that the strength and density of the coordination crosslinking between calcium ions and carboxylate ions are lower than those of the three-coordinated aluminum ions.

[0099] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing an upper critical solution temperature type smart organic gel, characterized in that, Includes the following steps: Methacrylethyl sulfobetaine and acrylic acid were dissolved in a solvent and mixed well. Then aluminum salt, crosslinking agent and photoinitiator were added and mixed well to obtain a mixed solution. The mixed solution was irradiated with ultraviolet light to obtain the upper critical solution temperature type smart organic gel; The solvent is a mixture of water and glycerin.

2. The preparation method according to claim 1, characterized in that, The ratio of the amount of the methacryloylethyl sulfobetaine to the amount of the acrylic acid, solvent, aluminum salt, crosslinking agent and photoinitiator is (0.001~0.004) mol∶(2~5) g∶5 mL∶(0.8~1.1) g∶(0.09~0.15) g∶(20~30) µL.

3. The preparation method according to claim 1, characterized in that, The solvent is a mixture of water and glycerol in a volume ratio of (4~2):(1~3).

4. The preparation method according to claim 1, characterized in that, The aluminum salt is aluminum trichloride; the crosslinking agent is zinc methacrylate; and the photoinitiator is one of 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methylpropylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and lithium phenyl-2,4,6-trimethylbenzoylphosphonate.

5. The preparation method according to claim 1, characterized in that, The wavelength of the ultraviolet light irradiation is 365 nm or 405 nm, and the irradiation time is 1 to 3 minutes.

6. An upper critical solution temperature type smart organic gel prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the upper critical solution temperature type smart organic gel as described in claim 6 in the preparation of temperature sensors, strain sensors, or flexible sensing layers for human-computer interaction devices.

8. A temperature sensor, characterized in that, Including the upper critical solution temperature type smart organic gel as described in claim 6.

9. A strain sensor, characterized in that, Including the upper critical solution temperature type smart organic gel as described in claim 6.

10. A human-computer interaction device, characterized in that, The flexible sensing layer includes the upper critical solution temperature type smart organic gel as described in claim 6.

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