Preparation method and application of azobenzene-based pH / UV intelligent response information reversible loading hydrogel robot

Abstract

The application relates to a preparation method and application of an azobenzene-based pH / UV intelligent response information reversible load hydrogel robot, and belongs to the technical field of hydrogels. The application aims to solve the problem that a light response information load material cannot be rewritable, high-strength, fast in response speed and multifunctional. The azobenzene-based pH / UV intelligent response information reversible load hydrogel robot is prepared by the following steps: synthesizing 4-hydroxy azobenzene by a diazo method; taking 4-hydroxy azobenzene, potassium carbonate, 6-bromohexyl acetate and acrylamide as raw materials; adopting Williamson ether reaction, nucleophilic substitution reaction, ester hydrolysis and amide reaction to prepare azobenzene-based gel monomers; taking acrylamide and the azobenzene-based gel monomers as a gel matrix; taking N,N'-methylene bisacrylamide as a crosslinking agent; and adopting free radical polymerization, hydrogen bond crosslinking and hydrophobic crystallization crosslinking strategies to prepare the azobenzene-based pH / UV intelligent response information reversible load hydrogel robot, which is applied to intelligent information load and rewritable code transmission.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrogels, specifically relating to a method for preparing and applying a reversibly loaded hydrogel robot based on azobenzene's pH / UV intelligent response information. Background Technology

[0002] In today's information age, paper, as the most widely used information storage medium, suffers from drawbacks such as poor recyclability and high cost. While the advancement and development of internet technology has alleviated the limitations of physical information media like paper and cables through multimedia transmission, it has also created new challenges in areas such as information security. Cases of information leaks and illegal transactions are increasing, posing significant security risks and economic losses to society and the nation as a whole. Therefore, internet technology cannot replace physical information media, necessitating the development of erasable physical information storage materials. Intelligent responsive polymer hydrogel materials exhibit reversible changes in their physical / chemical properties under external stimuli (such as light, electricity, magnetism, heat, and ions), making them suitable for recording, erasing, encrypting, and decrypting information. They hold broad application prospects in information storage and security anti-counterfeiting.

[0003] Gels can be stimulated by a variety of stimuli, with heat and ions providing a contact-based response, limiting their practical applications. While electromagnetic and optical signals offer the advantage of remote controllability, electromagnetic signals are difficult to detect and control, and the entire gel must participate in the response. In contrast, optical signals, as a localized, instantaneous, externally tunable stimulus, have a simpler reaction process and produce fewer byproducts. Designing high-performance intelligent photoresponsive gels is crucial for developing green, reproducible, and highly secure information storage technologies. However, most current photoresponsive information-loading hydrogels are based on fluorescent ink materials or photochemical reaction mechanisms such as photopolymerization and photodegradation. Fluorescent inks are indelible and have limited functionality, while gels based on photopolymerization and photodegradation suffer from poor mechanical properties, extremely slow response speeds, and irreversibility. Gels based on photoisomerization mechanisms (such as azobenzene) offer advantages such as high reaction efficiency and reversibility, and the π-π conjugation effect of the azobenzene structure can enhance the gel's crosslinking strength. However, its poor water solubility creates a barrier to introducing photoisomeric particles into the gel. In summary, existing photoresponsive information-carrying hydrogels cannot simultaneously achieve the characteristics of rewritability, high strength, fast response speed, and multifunctional integration. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that photoresponsive information loading materials cannot simultaneously achieve rewritability, high strength, fast response speed, and multifunctional integration, and to provide a method for preparing and applying a pH / UV smart reversible information loading hydrogel robot based on azobenzene.

[0005] This invention discloses a reversibly loaded hydrogel robot based on azobenzene's intelligent pH / UV response information. The process involves synthesizing 4-hydroxyazobenzene (Azo-OH) via a diazo method. Using Azo-OH, potassium carbonate, methyl 6-bromohexanoate, and acrylamide (AM) as raw materials, an azophenyl gel monomer (AzoAM) is prepared through Williamson ether reaction, nucleophilic substitution reaction, ester hydrolysis, and amide reaction. Using acrylamide (AM) and AzoAM as the gel matrix, deionized water as the solvent, and N,N'-methylenebisacrylamide as the crosslinking agent, a pH / UV dual reversibly responsive hydrogel is prepared through crosslinking strategies including free radical polymerization, hydrogen bonding crosslinking, and hydrophobic crystallization. The specific preparation method is carried out according to the following steps:

[0006] I. Preparation of 4-hydroxyazobenzene:

[0007] ① Mix aniline with hydrochloric acid, stir magnetically for a period of time under ice bath conditions, and then add sodium nitrite aqueous solution dropwise to obtain mixed solution I;

[0008] ② Add sodium phenolate solution to mixed solution I obtained in step ①, and stir magnetically at low temperature for a period of time to obtain 4-hydroxyazobenzene;

[0009] II. Preparation of azophenyl gel monomer:

[0010] ① Dissolve 4-hydroxyazobenzene, potassium carbonate, methyl 6-bromohexanoate and potassium iodide in dimethylformamide to obtain mixed solution II; heat mixed solution II under reflux in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain an orange intermediate azobenzene derivative.

[0011] ② Dissolve the orange intermediate azophenyl ester derivative in anhydrous ethanol, add potassium hydroxide to obtain mixed solution III; reflux mixed solution III in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain the yellow azophenyl carboxylic acid derivative.

[0012] ③ Dissolve the yellow azophenylcarboxylic acid derivative, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide in dimethylformamide to obtain mixed solution IV; heat and stir mixed solution IV in a water bath under magnetic stirring for a period of time to activate the carboxyl group, add acrylamide monomer and then heat and stir in a water bath under magnetic stirring for a period of time. Thin-layer chromatography indicates the reaction endpoint to obtain orange azophenyl gel monomer;

[0013] III. Preparation of polymeric azophenyl hydrogel:

[0014] ① Dissolve the orange azophenyl gel monomer in deionized water and stir for a period of time to obtain an orange azophenyl gel monomer solution;

[0015] ② Add acrylamide, ammonium persulfate and methylenebisacrylamide sequentially to the orange azophenyl gel monomer solution, and stir at room temperature until the solution is evenly dispersed to obtain mixed solution V; add tetramethylethylenediamine dropwise to mixed solution V, stir vigorously and then transfer to a mold to obtain the gel;

[0016] ③ The gel is soaked in deionized water to remove unreacted monomers. After washing, a reversible hydrogel robot based on azobenzene's pH / UV intelligent response information is obtained.

[0017] A hydrogel robot based on azobenzene with reversible pH / UV intelligent response information loading is applied in intelligent information loading and rewritable password transmission.

[0018] Advantages of this invention:

[0019] I. The present invention provides a reversible hydrogel robot based on azobenzene with pH / UV intelligent response information, which selects polyacrylamide as the gel matrix and has both biocompatibility and pH response characteristics.

[0020] II. The present invention prepares a reversible hydrogel robot based on azobenzene with pH / UV intelligent response information, which introduces π-π conjugation, hydrogen bonding and free radical polymerization of azobenzene groups as a gel crosslinking strategy, and exhibits good mechanical properties.

[0021] III. The pH / UV intelligent response information reversible loaded hydrogel robot prepared by the present invention can generate corresponding response results to both pH and UV signals, and is a multifunctional integrated material.

[0022] IV. The pH / UV intelligent response information reversible loaded hydrogel robot prepared by the present invention exhibits changes in transmittance under different pH stimuli and can be used as a carrier material for copying second-level response information.

[0023] V. The present invention provides a reversible hydrogel robot based on azobenzene with intelligent pH / UV response information. Under UV light irradiation, the robot exhibits rapid water loss by utilizing the photoisomerization and photothermal effect of the azobenzene group. The process is green and efficient with no by-products generated.

[0024] VI. The present invention provides a reversible hydrogel robot based on azobenzene with pH / UV intelligent response information. Under UV light irradiation, the robot utilizes a template to restrict light transmission and the convection movement of water molecules between air and gel, enabling the storage of patterned reversible light response information. Attached Figure Description

[0025] Figure 1 This is a reaction mechanism diagram of step one in Example 1;

[0026] Figure 2 This is a reaction mechanism diagram for step two of Example 1;

[0027] Figure 3 This is a reaction mechanism diagram for step three of Example 1;

[0028] Figure 4 These are infrared spectra. In the figure, a represents the infrared spectrum of phenol, the raw material in step one of Example 1, and b represents the infrared spectrum of Azo-OH obtained in step one of Example 1.

[0029] Figure 5 This is the 1H NMR spectrum of Azo-OH obtained in step one of Example 1;

[0030] Figure 6 The images are UV absorption graphs of Azo-OH heated for different times, obtained in step one of Example 1; a, b, c, and d represent the UV absorption graphs of Azo-OH heated for 0, 0.5, 1, and 2 hours, respectively.

[0031] Figure 7 These are infrared spectra. In the figure, a represents the infrared spectrum of Azo-OH, b represents the infrared spectrum of AzoES obtained in step two ① of Example 1, and c represents the infrared spectrum of the organic carboxylate AzoCANa obtained by reacting AzoCA obtained in step two ② with sodium hydroxide.

[0032] Figure 8 This is the 1H NMR spectrum of the AzoES synthesized in step two of Example 1;

[0033] Figure 9 This is the 1H NMR spectrum of AzoAM synthesized in step two of Example 1;

[0034] Figure 10 This is the particle size distribution diagram of Azo-OH obtained in step one of Example 1;

[0035] Figure 11 This is the particle size distribution diagram of AzoAM obtained in step two of Example 1;

[0036] Figure 12 This is a photograph of the orange azophenyl gel monomer solution obtained in step 3① of Example 1 before gelation;

[0037] Figure 13 This is a photograph of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1.

[0038] Figure 14The figures show infrared spectra. Figure a represents the infrared spectrum of Azo-OH, and figure b represents the infrared spectrum of the reversibly loaded hydrogel robot based on pH / UV smart response information obtained in step 3③ of Example 1.

[0039] Figure 15 The figures are X-ray diffraction patterns. In the figure, a represents the X-ray diffraction pattern of polyacrylamide gel (PAM), and b represents a reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3 ② of Example 1.

[0040] Figure 16 This is the thermogravimetric analysis diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0041] Figure 17 This is the differential scanning calorimetry spectrum of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0042] Figure 18 A scanning electron microscope image magnified 30x for the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0043] Figure 19 This is a 100x magnified scanning electron microscope image of the reversibly loaded hydrogel robot based on azobenzene's pH / UV smart response information obtained in step 3③.

[0044] Figure 20 This is a 400x magnified scanning electron microscope image of the reversible hydrogel robot based on azobenzene's intelligent pH / UV response information obtained in step 3③ of Example 1.

[0045] Figure 21 This is a graph showing the swelling rate of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information as a function of time, obtained in step 3③ of Example 1.

[0046] Figure 22 This is a graph showing the weight change over time of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1 during the degradation test;

[0047] Figure 23 It is a tensile stress-strain curve diagram. In the figure, a represents the tensile stress-strain curve diagram of PAM, and b represents the tensile stress-strain curve diagram of the reversible loaded hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1.

[0048] Figure 24It is a compressive stress-strain curve diagram. In the figure, a represents the tensile stress-strain curve diagram of PAM, and b represents the compressive stress-strain curve diagram of the reversible hydrogel robot based on pH / UV smart response information obtained in step 3③ of Example 1.

[0049] Figure 25 The graph shows the change rate of gel mass as a function of pH. In the graph, a represents the change rate of PAM gel mass as a function of pH, and b represents the change rate of the reversible loaded hydrogel robot based on pH / UV smart response information obtained in step 3. ③ as a function of pH.

[0050] Figure 26 This is a diagram showing the result of immersing a hydrogel robot, which is reversibly loaded with pH / UV intelligent response information based on azobenzene, in a solution with pH=1 after step 3③ of Example 1.

[0051] Figure 27 This is a diagram showing the result of immersing a hydrogel robot, which is reversibly loaded with pH / UV intelligent response information based on azobenzene, in a solution of pH=14 after step 3③ of Example 1.

[0052] Figure 28 This is a graph showing the change in the light transmittance / opaqueness switching time of the reversible loaded hydrogel robot based on azobenzene pH / UV intelligent response information as a function of the number of cycles, obtained in step 3③ of Example 1.

[0053] Figure 29 This is a graph showing the results of a reversible hydrogel robot with transparent / opaque switching cycle test based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1.

[0054] Figure 30 This is a schematic diagram of the fully transparent state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0055] Figure 31 This is a schematic diagram of the semi-transparent state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0056] Figure 32 This is a schematic diagram of the opaque state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0057] Figure 33 This is a schematic diagram of the gel morphology of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information before UV response, obtained in step 3③ of Example 1.

[0058] Figure 34This is a gel thermal imaging image of a hydrogel robot reversibly loaded with azobenzene-based pH / UV smart response information before UV response, obtained in step 3③ of Example 1.

[0059] Figure 35 This is a schematic diagram of the gel morphology after UV response of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1.

[0060] Figure 36 This is a gel thermal imaging image of a reversibly loaded hydrogel robot under UV response, obtained from step 3.③ of Example 1;

[0061] Figure 37 This is a graph showing the gel mass loss and the change of gel upper / lower diameter over time during the UV response process of the reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1. In the graph, a represents the result of the mass loss rate changing over time, and b represents the result of the change of gel upper / lower diameter over time during the UV response process of the reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1.

[0062] Figure 38 This is a graph showing the change of gel surface temperature over time during the UV response process of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3.③ of Example 1. In the graph, a represents the curve of PAM gel surface temperature changing over time, and b represents the curve of surface temperature changing over time during the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3.③ of Example 1.

[0063] Figure 39 This is a schematic diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information, obtained in step 3③ of Example 1, in front of the pH response loading information;

[0064] Figure 40 This is a photo of the reversibly loaded hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1, after being covered by a heart-shaped template soaked in alkali solution for 12 seconds.

[0065] Figure 41 This is a photograph of the novel pattern reversibly loaded onto a hydrogel robot based on azobenzene pH / UV intelligent response information after being re-immersed in acid for 2 minutes, obtained in step 3③ of Example 1.

[0066] Figure 42 This is a schematic diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information, obtained in step 3③ of Example 1, in front of the photoresponsive loading information;

[0067] Figure 43 This is a schematic diagram of the arrow template covering the reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3③ of Example 1;

[0068] Figure 44 This is a schematic diagram of the arrow information loading of the azobenzene-based pH / UV smart response information reversibly loaded hydrogel robot under UV light, obtained in step 3③ of Example 1. Detailed Implementation

[0069] Specific Implementation Method 1: This implementation method is a method for preparing a reversibly loaded hydrogel robot based on azobenzene's pH / UV intelligent response information, specifically completed according to the following steps:

[0070] I. Preparation of 4-hydroxyazobenzene:

[0071] ① Mix aniline with hydrochloric acid, stir magnetically for a period of time under ice bath conditions, and then add sodium nitrite aqueous solution dropwise to obtain mixed solution I;

[0072] ② Add sodium phenolate solution to mixed solution I obtained in step ①, and stir magnetically at low temperature for a period of time to obtain 4-hydroxyazobenzene;

[0073] II. Preparation of azophenyl gel monomer:

[0074] ① Dissolve 4-hydroxyazobenzene, potassium carbonate, methyl 6-bromohexanoate and potassium iodide in dimethylformamide to obtain mixed solution II; heat mixed solution II under reflux in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain an orange intermediate azobenzene derivative.

[0075] ② Dissolve the orange intermediate azophenyl ester derivative in anhydrous ethanol, add potassium hydroxide to obtain mixed solution III; reflux mixed solution III in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain the yellow azophenyl carboxylic acid derivative.

[0076] ③ Dissolve the yellow azophenylcarboxylic acid derivative, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide in dimethylformamide to obtain mixed solution IV; heat and stir mixed solution IV in a water bath under magnetic stirring for a period of time to activate the carboxyl group, add acrylamide monomer and then heat and stir in a water bath under magnetic stirring for a period of time. Thin-layer chromatography indicates the reaction endpoint to obtain orange azophenyl gel monomer;

[0077] III. Preparation of polymeric azophenyl hydrogel:

[0078] ① Dissolve the orange azophenyl gel monomer in deionized water and stir for a period of time to obtain an orange azophenyl gel monomer solution;

[0079] ② Add acrylamide, ammonium persulfate and methylenebisacrylamide sequentially to the orange azophenyl gel monomer solution, and stir at room temperature until the solution is evenly dispersed to obtain mixed solution V; add tetramethylethylenediamine dropwise to mixed solution V, stir vigorously and then transfer to a mold to obtain the gel;

[0080] ③ The gel is soaked in deionized water to remove unreacted monomers. After washing, a reversible hydrogel robot based on azobenzene's pH / UV intelligent response information is obtained.

[0081] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the molar ratio of aniline to hydrochloric acid in step one ① is 1:(2-5); the molar ratio of aniline to sodium nitrite in step one ① is 1:(1.5-2.0); the temperature of the ice bath in step one ① is 0℃; the magnetic stirring speed in step one ① is 800r / min-1200r / min, and the magnetic stirring time is 40min-60min. Other steps are the same as in Specific Implementation Method One.

[0082] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in the following ways: the concentration of the sodium phenolate solution in step one ② is 1.0 mol / L to 1.5 mol / L; the molar ratio of sodium phenolate in the sodium phenolate solution in step one ② to aniline in step one ① is 1:(1 to 1.5); the temperature of the low-temperature magnetic stirring reaction in step one ② is 0℃ to 5℃, and the time is 8h to 12h; the magnetic stirring speed in step one ② is 800r / min to 1200r / min. Other steps are the same as in Specific Implementation Method One or Two.

[0083] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the molar ratio of 4-hydroxyazobenzene, potassium carbonate, methyl 6-bromohexanoate, and potassium iodide in step two① is 1:(0.7-1.0):(0.7-1.0):(3.5-5); the concentration of 4-hydroxyazobenzene in mixed solution II in step two① is 50 mmol / L to 80 mmol / L; the reflux time in the water bath in step two① is 12 h, and the reflux temperature is 95 °C; the magnetic stirring speed in step two① is 800 r / min to 1200 r / min. Other steps are the same as in Specific Implementation Methods One to Three.

[0084] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in the following ways: the molar ratio of the orange intermediate azophenyl ester derivative to potassium hydroxide in step two ② is 1:(2.5-3); the concentration of the orange intermediate azophenyl ester derivative in mixed solution III in step two ② is 20 mmol / L to 50 mmol / L; the reflux time in the water bath in step two ② is 6 hours, and the reflux temperature is 65°C; the magnetic stirring speed in step two ② is 800 r / min to 1200 r / min. Other steps are the same as in Specific Implementation Methods One to Four.

[0085] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in the following ways: In step two to three, the water bath heating and stirring time is 1 hour, and the water bath heating and stirring temperature is 55°C to 65°C; the molar ratio of the yellow azobenzene carboxylic acid derivative, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and acrylamide in step two to three is 1:(1.0 to 1.2):(2 to 3):(3.5 to 5); the concentration of the yellow azobenzene carboxylic acid derivative in the mixed solution IV in step two to three is 40 mmol / L to 80 mmol / L; the water bath heating and stirring time after adding the acrylamide monomer in step two to three is 4 hours, and the water bath heating and stirring temperature is 55°C; the magnetic stirring speed in step two to three is 800 r / min to 1200 r / min. Other steps are the same as in Specific Implementation Methods One to Five.

[0086] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the concentration of the orange azophenyl gel monomer solution mentioned in step three ① is 60 mmol / L; the stirring speed mentioned in step three ① is 800 r / min to 1200 r / min, and the stirring time is 5 min to 15 min. Other steps are the same as in Specific Implementation Methods One to Six.

[0087] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: In step three ②, the mass ratio of acrylamide, ammonium persulfate, and methylenebisacrylamide is 1g:(0.04g~0.08g):0.04g; the concentration of acrylamide in mixed solution V in step three ② is 0.28mol / L; the volume ratio of tetramethylethylenediamine to mixed solution V in step three ② is 1:1000; the speed of vigorous stirring in step three ② is 800r / min~1200r / min, and the duration of vigorous stirring is 5min~10min, carried out at room temperature. Other steps are the same as in Specific Implementation Methods One to Seven.

[0088] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step three ③, the gel is soaked in deionized water for cleaning, with the water changed every 12 hours. The soaking and cleaning time is 48 hours to 96 hours, and the mass ratio of the gel to the volume of deionized water during a single soak is 1 g: 80 mL. Other steps are the same as in Specific Implementation Methods One to Eight.

[0089] Specific Implementation Method 10: This implementation method is an application of a hydrogel robot based on azobenzene with reversible pH / UV intelligent response information in intelligent information load and rewritable password transmission.

[0090] The beneficial effects of the present invention are verified using the following embodiments:

[0091] Example 1: A method for preparing a reversibly loaded hydrogel robot based on azobenzene's pH / UV intelligent response information, specifically completed according to the following steps:

[0092] I. Preparation of 4-hydroxyazobenzene (Azo-OH):

[0093] ① Mix 25 mmol aniline with 40 mL of 3 mol / L hydrochloric acid, stir magnetically for 40 min under 0℃ ice bath conditions, and then add 25 mL of 2 mol / L sodium nitrite aqueous solution to obtain mixed solution I;

[0094] In step 1①, the magnetic stirring speed is 1000 r / min;

[0095] ② Add 30 mL of 1.0 mol / L sodium phenolate solution to the mixed solution I obtained in step ①, and stir magnetically for 10 h at a reaction temperature not exceeding 5℃ to obtain 4-hydroxyazobenzene (Azo-OH);

[0096] In step 1②, the magnetic stirring speed is 800 r / min;

[0097] II. Preparation of azophenyl gel monomer (AzoAM):

[0098] ① Dissolve 7.6 mmol of 4-hydroxyazobenzene (Azo-OH), 23.9 mmol of potassium carbonate, 11.4 mmol of methyl 6-bromohexanoate and 3.9 mmol of potassium iodide in 100 mL of dimethylformamide (DMF) to obtain mixed solution II; add mixed solution II to a 250 mL three-necked flask and heat under reflux for 12 h with magnetic stirring and in a water bath at 95 °C. Thin-layer chromatography indicates the reaction endpoint to obtain an orange intermediate azobenzene derivative (AzoES);

[0099] The magnetic stirring speed mentioned in step 2① is 1000 r / min;

[0100] ② Dissolve 4 mmol of the orange intermediate azophenyl ester derivative (AzoES) in 100 mL of anhydrous ethanol, add 12 mmol of potassium hydroxide (KOH) to obtain mixed solution III; reflux mixed solution III under magnetic stirring and 65 °C water bath for 6 h, and indicate the reaction endpoint by thin-layer chromatography to obtain the yellow azophenyl carboxylic acid derivative (AzoCA);

[0101] The magnetic stirring speed mentioned in step 2② is 1000 r / min;

[0102] ③ Dissolve 3 mmol of yellow azophenylcarboxylic acid derivative (AzoCA), 2.5 mmol of N-hydroxysuccinimide and 2.5 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide in 50 mL of dimethylformamide to obtain mixed solution IV; heat and stir mixed solution IV under magnetic stirring and 55 °C water bath for 1 h to activate the carboxyl group, add 15 mmol of acrylamide monomer and then heat and stir under magnetic stirring and 55 °C water bath for 4 h. Thin-layer chromatography indicates the reaction endpoint to obtain orange azophenyl gel monomer (AzoAM);

[0103] The magnetic stirring speed mentioned in step 2③ is 1000 r / min;

[0104] III. Preparation of polymeric azophenyl hydrogel:

[0105] ① Dissolve 0.6 mmol of orange azophenyl gel monomer in 10 mL of deionized water and stir for 10 min to obtain an orange azophenyl gel monomer solution;

[0106] The stirring speed mentioned in step 3① is 1000 r / min;

[0107] ② Add 1g of acrylamide, 0.04g of ammonium persulfate and 0.04g of methylenebisacrylamide sequentially to the orange azophenyl gel monomer solution obtained in step ③ ①. Stir at room temperature until the solution is evenly dispersed to obtain mixed solution V. Add 10μL of tetramethylethylenediamine dropwise to mixed solution V. Stir at 1000r / min for 10min and then transfer to a mold to obtain the gel.

[0108] The speed of vigorous stirring mentioned in step 3② is 1000 r / min;

[0109] ③ The gel was soaked in deionized water to remove unreacted monomers. After washing, a reversible hydrogel robot based on azobenzene pH / UV intelligent response information was obtained.

[0110] In step 3, the gel is soaked in deionized water for cleaning, and the water is changed every 12 hours. The soaking and cleaning time is 72 hours. The mass ratio of gel to deionized water is 1g:80mL for each soak.

[0111] Figure 1 This is a reaction mechanism diagram of step one in Example 1;

[0112] pass Figure 1 It is known that Azo-OH is synthesized via the diazo method using 4-aminobenzene, hydrochloric acid, sodium nitrite, and sodium phenolate as raw materials.

[0113] Figure 2 This is a reaction mechanism diagram for step two of Example 1;

[0114] pass Figure 2 It is known that AzoAM monomers containing flexible carbon segments can be prepared by using Azo-OH, potassium carbonate, methyl 6-bromohexanoate, and potassium hydroxide as raw materials, through a reaction mechanism involving Williamson ether reaction, ester hydrolysis, and amidation reaction.

[0115] Figure 3 This is a reaction mechanism diagram for step three of Example 1;

[0116] pass Figure 3 It is known that a pH / UV dual reversible hydrogel was prepared by using AM and AzoAM as gel monomers, ammonium persulfate as initiator, and N,N'-methylenebisacrylamide as crosslinking agent, through crosslinking strategies such as free radical polymerization, hydrogen bonding crosslinking, and hydrophobic crystallization.

[0117] Figure 4 These are infrared spectra. In the figure, a represents the infrared spectrum of phenol, the raw material in step one of Example 1, and b represents the infrared spectrum of Azo-OH obtained in step one of Example 1.

[0118] Depend on Figure 4 It can be seen that in the infrared spectrum of phenol, 3218 cm⁻¹ -1 An absorption peak for the stretching vibration of OH appears at 1592 cm⁻¹. -1 and 1473cm -1 A stretching vibration peak of the benzene ring skeleton appears at 1210 cm⁻¹. -1 The peak at 748 cm⁻¹ represents the CO stretching vibration peak of phenol. -1 and 689cm -1 The peak at 836 cm⁻¹ corresponds to the Ph-H bending vibration absorption peak, which is a characteristic absorption peak of benzene ring monosubstituted products. Azo-OH retains the original benzene ring skeleton of phenol, the CO stretching vibration absorption peak, and the phenol-H bending vibration absorption peak. However, the OH stretching vibration absorption peak tends to shift to a lower wavenumber due to the conjugation effect, with a new peak at 836 cm⁻¹. -1The Ph-H bending vibration absorption peak corresponds to the para-substitution of the benzene ring, indicating that Azo-OH was successfully prepared.

[0119] Figure 5 This is the 1H NMR spectrum of Azo-OH obtained in step one of Example 1;

[0120] Depend on Figure 5 It can be seen that the proton chemical shifts on the benzene ring in 4-hydroxyazobenzene are located between 6.5 and 8.5 ppm, influenced by π-π conjugation, p-π conjugation, and the lone pair electrons of the O atom. The protons at positions b and c are located at the ortho- and meta positions of the azo group, influenced by π-π conjugation. Their proton NMR peaks are located at a low field, resulting in the largest chemical shifts. Based on the integrated area, the H atom at 7.88 ppm corresponds to the H atom at position b of the benzene ring, and at 7.50 ppm to the H atom at position c. Position d is located at the ortho position of the hydroxyl group, where the lone pair electron-donating effect is greater than the electron-withdrawing effect of p-π conjugation. Therefore, the proton at position d has the smallest chemical shift at a high field, corresponding to the NMR peak at 6.95 ppm, and the integrated area matches the number of H atoms. The proton NMR peak at position a is located between positions c and d, corresponding to an NMR peak at 7.44 ppm with an integrated area of ​​1. The active H on the Azo-OH hydroxyl group corresponds to a lone peak with a chemical shift of 5.19 ppm. The hydroxyl H readily undergoes deuterium-hydrogen substitution with water molecules, resulting in an integrated area less than 1.

[0121] Figure 6 The images are UV absorption graphs of Azo-OH heated for different times, obtained in step one of Example 1; a, b, c, and d represent the UV absorption graphs of Azo-OH heated for 0, 0.5, 1, and 2 hours, respectively.

[0122] Depend on Figure 6 It can be seen that the 340 nm absorption peak is the characteristic absorption of trans azobenzene, and the 440 nm absorption peak is the characteristic absorption of cis azobenzene. With the heating process, the absorption peak of Azo-OH at 340 nm decreases significantly, while the absorption peak at 440 nm increases significantly, proving that the heating excites the azo bond to change from cis to trans, and the cis to trans conversion process is slower.

[0123] Figure 7 These are infrared spectra. In the figure, a represents the infrared spectrum of Azo-OH, b represents the infrared spectrum of AzoES obtained in step two ① of Example 1, and c represents the infrared spectrum of the organic carboxylate AzoCANa obtained by reacting AzoCA obtained in step two ② with sodium hydroxide.

[0124] Depend on Figure 7 It can be seen that AzoES preserved 1592cm. -1 and 1473cm -1 The absorption peak of the stretching vibration of the benzene ring skeleton is at 2950 cm⁻¹. -1 The newly added stretching vibration absorption peak is for the saturated CH structure and at 1720 cm⁻¹.-1 The C=O stretching vibration peak of -COOCH3 is present; AzoCANa retains the absorption peak of the stretching vibration of the benzene ring skeleton, as well as the characteristic absorption peaks of mono- and para-substituted benzene rings, originally at 1720 cm⁻¹. -1 The AzoES ester group C=O stretching vibration absorption peak disappears, and a peak appears at 1600 cm⁻¹. -1 The characteristic absorption peak of organic carboxylic acid salts at that location.

[0125] Figure 8 This is the 1H NMR spectrum of the AzoES synthesized in step two of Example 1;

[0126] Depend on Figure 8 It can be seen that the NMR peaks at 7.89 ppm, 7.5 ppm, 7.44 ppm, and 6.99 ppm correspond to protons at positions b, c, a, and d in the molecule, respectively. Due to the strong electron-withdrawing effect of the O atom, the H on the C bonded to O is located at a low field due to induction. Therefore, the proton at 4.05 ppm is the e-proton, which is split into a t-peak by coupling with the ortho-CH2 group, while the solitary peak at 3.68 ppm is the j-proton. The H on the C bonded to the carbonyl group at 2.37 ppm is the i-proton. The H on the C bonded to the alkyl group at 1.84 ppm, 1.73 ppm, and 1.54 ppm are all H on the C bonded to the alkyl group, which correspond to the f, h, and g-protons, respectively, according to the induction force.

[0127] Figure 9 This is the 1H NMR spectrum of AzoAM synthesized in step two of Example 1;

[0128] Depend on Figure 9 It can be seen that the NMR peaks at 7.92 ppm, 7.44 ppm, 7.02 ppm, and 6.82 ppm correspond to protons at positions b, c, a, and d in the molecule; the NMR peak patterns at chemical shifts of 4.08 ppm, 2.43 ppm, 1.88 ppm, 1.80 ppm, and 1.53 ppm are the same as those in AzoES, and therefore correspond to protons at positions e, i, f, g, and h, respectively; the introduction of double bond groups into the molecule causes the H on the C of the double bond to couple and split with the other H, and the double bond... The coupling constant of the cis H coupling is smaller than that of the anti H. Therefore, 6.82 ppm, 6.38 ppm, and 5.87 ppm correspond to protons l, k, and l', respectively. Among them, l is split into a d peak by coupling with proton k, k is split into a dd peak by coupling with protons l and l', and l' is split into a d peak by coupling with proton k. The active H of the amine group is connected to the carbonyl group, and the inductive effect places it in a low field. Moreover, this proton is also prone to deuterium substitution. Therefore, the proton peak with an integral area of ​​less than 1 corresponds to 2.86 ppm.

[0129] Figure 10 This is the particle size distribution diagram of Azo-OH obtained in step one of Example 1;

[0130] Depend on Figure 10It can be seen that the particle size of Azo-OH is 14.8 nm and the sample size is uniform. It is speculated that the conjugated stacking of Azo makes its particle size significantly larger than the average particle size of small molecule compounds.

[0131] Figure 11 This is the particle size distribution diagram of AzoAM obtained in step two of Example 1;

[0132] Depend on Figure 11 It can be seen that the particle size of AzoAM monomer is 245.2 nm, which is significantly larger than that of Azo-OH. The possible reason is that Azo monomer material has amphiphilic properties: one end is a hydrophobic azophenyl group, and the other end is a hydrophilic gel matrix, which has the structural basis of surfactant. Aggregation may occur in solution, thus significantly increasing the particle size.

[0133] Figure 12 This is a photograph of the orange azophenyl gel monomer solution obtained in step 3① of Example 1 before gelation;

[0134] Figure 13 This is a photograph of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1.

[0135] pass Figure 13 and Figure 12 As can be seen from the comparison, the reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in this invention is an orange-yellow gel.

[0136] Figure 14 The figures show infrared spectra. Figure a represents the infrared spectrum of Azo-OH, and figure b represents the infrared spectrum of the reversibly loaded hydrogel robot based on pH / UV smart response information obtained in step 3③ of Example 1.

[0137] Depend on Figure 14 It can be seen that the Azo-based gel retains 1592 cm⁻¹. -1 A strong absorption peak for the stretching vibration of the benzene ring skeleton appears at 1660 cm⁻¹. -1 The -C=O stretching vibration peak of PAM is located at 3350 cm⁻¹. -1 and 3190cm -1 Peaks of symmetric and asymmetric stretching vibrations of the NH bond at the location.

[0138] Figure 15 The figures are X-ray diffraction patterns. In the figure, a represents the X-ray diffraction pattern of polyacrylamide gel (PAM), and b represents a reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3 ② of Example 1.

[0139] Compared with PAM hydrogels, both showed two broad diffraction peaks with the amorphous structure characteristics of composite PAM hydrogels, but the intensity of the crystallization peaks was significantly weakened, indicating that the non-covalent stacking of Azo groups enhanced the amorphous degree of the gel and no new crystalline regions were formed.

[0140] Figure 16 This is the thermogravimetric analysis diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0141] Depend on Figure 16 It can be seen that the gel thermal decomposition process is divided into three stages, with temperature ranges of room temperature - 250℃, 250-400℃, and 400-800℃, respectively. The process from room temperature to 250℃ is mainly the stage of thermal volatilization of water molecules. When the temperature rises to 250-400℃, different degrees of mass loss occur again, which is the thermal decomposition process of hydrogel cross-links and side chains. When the temperature rises to 400-800℃, there is no significant mass loss, which is presumably the process of hydrogel carbon skeleton breaking.

[0142] Figure 17 This is the differential scanning calorimetry spectrum of the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0143] Depend on Figure 17 It can be seen that the temperature ranges of the hydrogel endothermic process are room temperature to 350℃, 350-650℃, and 650-800℃, respectively. Compared with the TG curve, it can be seen that the mass loss is significant from room temperature to 350℃, but the corresponding endothermic process is not obvious. This corresponds to the evaporation of water, dehydration and condensation of gel side chains, and depolymerization or sublimation of Azo crystal regions. The mass loss is not significant above 400℃. The endothermic process corresponds to the main chain breaking and decomposition, but the network has not yet degraded. The endothermic peaks of 528℃ and 702℃ in the Azo-based gel correspond to the depolymerization and decomposition of the carbon skeleton, respectively.

[0144] Figure 18 A scanning electron microscope image magnified 30x for the reversible hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3③ of Example 1;

[0145] Figure 19 This is a 100x magnified scanning electron microscope image of the reversibly loaded hydrogel robot based on azobenzene's pH / UV smart response information obtained in step 3③.

[0146] Figure 20 This is a 400x magnified scanning electron microscope image of the reversible hydrogel robot based on azobenzene's intelligent pH / UV response information obtained in step 3③ of Example 1.

[0147] Depend on Figures 18-20It can be seen that Azo-based gels exhibit a typical hydrogel microstructure, with continuous and densely connected pores of varying sizes.

[0148] Figure 21 The hydrogel robot, based on the pH / UV intelligent response information of azobenzene, was reversibly loaded in step 3② of Example 1 and immersed in deionized water at room temperature. The gel was removed at different time points, and after the surface moisture was absorbed with filter paper, it was weighed until the gel weight no longer changed. The results are shown in […]. Figure 21 , Figure 21 This is a graph showing the change in swelling rate of Azo-based gel over time. Figure 21 It can be seen that the hydrogel robot based on azobenzene pH / UV intelligent response information reversibly loaded with hydrogel obtained in this invention, after being soaked in deionized water for 112 hours, showed that its swelling rate increased to 549% and then tended to stabilize, demonstrating good swelling performance.

[0149] Figure 22 This is a graph showing the weight change over time of the reversibly loaded hydrogel robot based on azobenzene's pH / UV smart response information obtained in step 3② of Example 1, during a degradation test. Figure 22 It can be seen that the Azo-based gel did not degrade in phosphate buffer solution, indicating that the hydrogel has good stability and is suitable for long-term use in in vitro environments;

[0150] Figure 23 This is the tensile stress-strain curve of the reversible hydrogel robot and PAM based on azobenzene pH / UV smart response information obtained in step 3 ② of Example 1. Figure 24 This is a compressive stress-strain curve of the reversibly loaded hydrogel robot based on azobenzene's intelligent pH / UV response information and PAM obtained in step 3.2 of Example 1. Figure a represents the stress-strain curve of PAM, and figure b represents the stress-strain curve of the reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information obtained in step 3.2 of Example 1. Figure 23 and 24 It can be seen that the improved mechanical properties and toughness of the gel result in a significantly increased stress required for the same tensile / compressive deformation.

[0151] Figure 25 This is a graph showing the change in gel mass rate as a function of pH. In the graph, 'a' represents the change in PAM gel mass rate as a function of pH, and 'b' represents the change in the mass rate of the reversible loaded hydrogel based on azobenzene's pH / UV smart response information obtained in step 3.2 of Example 1 as a function of pH. Figure 25It is evident that pH significantly affects the mass change of Azo-based gels compared to PAM gels. The mass loss under acidic conditions and the mass gain under alkaline conditions are both greater than those under PAM gels. These mass changes lead to significant volume changes in the gel. This phenomenon may be attributed to the regulatory effect of the -NH- segment in AzoAM. Under acidic conditions, -NH2 and -NH in the gel matrix tend to form interchain hydrogen bonds. As the acidity of the solution increases, the proportion of protonated groups decreases, the hydrogen bonding becomes stronger, the gel network space shrinks, and the hydrophilicity and water-holding capacity decrease, resulting in gel shrinkage. Under alkaline conditions, -NH2 and -NH in the gel matrix are protonated, and the interchain hydrogen bonds break due to ionic repulsion. As the alkalinity of the solution increases, the proportion of protonated groups increases, the interchain hydrogen bonding becomes stronger, the gel network space expands, and the gel becomes more hydrophilic, exhibiting swelling.

[0152] Figure 26 This is a diagram showing the result of immersing a hydrogel robot, which is reversibly loaded with pH / UV intelligent response information based on azobenzene, in a solution with pH=1 after step 3② of Example 1. Figure 27 This is a graph showing the result of immersing the pH / UV dual-responsive azophenyl hydrogel obtained in step 3② of Example 1 in a solution at pH=14. Figure 26 and 27 It is known that changes in the mass of Azo-based gels cause significant volume changes and alterations in transmittance. When immersed in acidic solutions, the gel is completely opaque; when immersed in alkaline solutions, a transparent region appears from the outer diameter to the center. The speculated reason is that under acidic conditions, the interchain hydrogen bonds in the Azo-based gel are strong, resulting in a denser polymer network that facilitates the conjugated stacking of Azo groups, forming hydrophobic crystalline regions and reducing gel transmittance. Under alkaline conditions, the interchain hydrogen bonds are weak, the loose polymer network makes it difficult for Azo groups to contact each other, the hydrophobic crystalline regions disappear, and gel transmittance increases.

[0153] Figure 28 This is a graph showing the change in the light transmittance / opaqueness switching time of the reversible hydrogel robot based on azobenzene's pH / UV intelligent response information as a function of the number of cycles, obtained from step 3② of Example 1. Figure 28 It can be seen that the Azo-based gel maintains stable performance after switching between transparent and opaque states 25 times in alkali / acid environments, meeting the lifespan requirements for its information transmission applications.

[0154] Figure 29 This is a graph showing the results of a reversible hydrogel robot with transparent / opaque switching cycle test based on azobenzene pH / UV intelligent response information, obtained in step 3② of Example 1. Figure 29It is observed that the switching time of the Azo-based gel increases with the number of times the transparent / opaque state is switched. This is because the three-dimensional network structure of the gel stores part of the solution during this process, affecting the proton exchange in the next stage; and NaCl molecules are generated during acid-base neutralization, which are dispersed in the gel network in an ionic state, thus hindering H to some extent. + and OH - Effective collision;

[0155] Figure 30 This is a schematic diagram of the fully transparent state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3② of Example 1; Figure 31 This is a schematic diagram of the semi-transparent state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3② of Example 1; Figure 32 This is a schematic diagram of the opaque state of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3② of Example 1; according to Figures 30-32 It can be seen that the letters covered by the Azo-based gel are clearly visible and information is transmitted during the light-transmitting stage; in contrast, the letters covered by the opaque gel are completely hidden and information cannot be transmitted.

[0156] Figure 33 This is a schematic diagram of the gel morphology of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information before UV response, obtained in step 3② of Example 1. Figure 34 This is a gel thermal imaging image of a reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3② of Example 1 before UV response. Figure 35 This is a schematic diagram of the gel morphology after UV response of the reversibly loaded hydrogel robot based on azobenzene pH / UV smart response information obtained in step 3② of Example 1. Figure 36 This is a gel thermal imaging image of a reversibly loaded hydrogel robot after UV response, obtained from step 3.② of Example 1, based on azobenzene-based pH / UV smart response information; (The image is derived from...) Figures 33-36 It is known that the photothermal effect generated by the Azo cis-trans isomerization process induced by ultraviolet light irradiation participates in this process. At the same time, Azo isomerization causes the conjugated arrangement to depolymerize, the crosslink density on the irradiated surface is small, the gel network is looser, and the water encapsulated in the three-dimensional space is more easily volatilized by heat, which reduces the swelling rate of the gel on the light side, resulting in a decrease in the volume of the gel on the light side.

[0157] Figure 37This is a graph showing the gel mass loss and the change of gel upper / lower diameter over time during the UV response process of the reversible loaded hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3 ② of Example 1. In the graph, a represents the result of the mass loss rate changing over time, and b represents the result of the change of gel upper / lower diameter over time during the UV response process of the reversible loaded hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3 ② of Example 1. Figure 38 This is a graph showing the change in gel surface temperature over time during the UV response process of the reversibly loaded hydrogel robot based on azobenzene's pH / UV intelligent response information, obtained in step 3② of Example 1. In the graph, a represents the curve of PAM gel surface temperature changing over time, and b represents the curve of surface temperature changing over time during the reversible loading hydrogel robot based on azobenzene's pH / UV intelligent response information, obtained in step 3② of Example 1. Figure 37 and 38 Further evidence suggests that pH / UV dual-responsive azophenyl hydrogels will experience significant mass loss under UV irradiation. Even with a low temperature increase, the decrease in gel coach density caused by the cis-trans isomerization of the Azo group will accelerate water loss, resulting in the experimental phenomenon of a continuously increasing difference between the upper and lower radii of the gel.

[0158] Figure 39 This is a schematic diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information, obtained in step 3② of Example 1, in front of the pH response loading information; Figure 40 This is a photo of the reversibly loaded hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3② of Example 1, after being covered by a heart-shaped template wetted with alkali solution for 12 seconds. Figure 41 This is a photograph taken after re-immersion in acid for 2 minutes following step 3.② of Example 1, which uses a novel pattern based on azobenzene-based pH / UV intelligent response information and reversibly loaded with a hydrogel robot. Figures 39-41 It can be seen that the prepared azobenzene-based pH / UV intelligent response information reversible loaded hydrogel robot, when placed in an acidic solution at pH=1 to maintain its opacity, and with filter paper cut into a suitable shape dipped in 1M NaOH solution and placed on the gel for 12 seconds as a template, the information loading was observed. Clear shape boundaries were observed on the gel without smudging. When the gel was re-immersed in the acidic solution, it returned to its opacity. This experiment demonstrates that the azobenzene-based pH / UV intelligent response information reversible loaded hydrogel robot possesses both information loading and rewritable functional characteristics.

[0159] Figure 42 This is a schematic diagram of the reversible hydrogel robot based on azobenzene pH / UV smart response information, obtained in step 3② of Example 1, in front of the photoresponsive loading information; Figure 43This is a schematic diagram of the arrow template covering the reversible hydrogel robot based on azobenzene pH / UV intelligent response information obtained in step 3② of Example 1; Figure 44 This is a schematic diagram of the arrow information loading of the azobenzene-based pH / UV smart response information reversibly loaded hydrogel robot under UV light, obtained in step 3② of Example 1. Figures 42-44 It is evident that, based on the reversible pH / UV intelligent response information loading hydrogel robot based on azobenzene exhibits water loss in response to UV light, after covering the gel surface with a pattern and then irradiating it with UV light, the pattern template hinders light transmission and the convection movement of water molecules between the air and the gel, while other areas of the surface rapidly lose water, causing the covered area to bulge above the gel surface. This process can complete the loading of photoresponsive information, and the loading process involves only water loss without any byproducts, making it environmentally friendly. This experiment further demonstrates that the pH / UV intelligent response information reversible loading hydrogel robot based on azobenzene possesses multi-pathway information loading and rewritable functional characteristics.

Claims

1. A method for preparing a reversibly loaded hydrogel based on azobenzene's pH / UV smart response information, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of 4-hydroxyazobenzene, with the following structural formula: ； II. Preparation of azophenyl gel monomer, with the following structural formula: ； III. Preparation of polymeric azophenyl hydrogel: ① Dissolve the azophenyl gel monomer in deionized water and stir for a period of time to obtain an orange azophenyl gel monomer solution; ② Add acrylamide, ammonium persulfate and methylenebisacrylamide sequentially to the orange azophenyl gel monomer solution, and stir at room temperature until the solution is evenly dispersed to obtain mixed solution V; add tetramethylethylenediamine dropwise to mixed solution V, stir vigorously and then transfer to a mold to obtain the gel; ③ The gel is soaked in deionized water to remove unreacted monomers. After washing, a reversible hydrogel with pH / UV smart response information based on azobenzene is obtained.

2. The method for preparing a reversibly loaded hydrogel based on azobenzene's pH / UV intelligent response information according to claim 1, characterized in that... The method for preparing 4-hydroxyazobenzene in step one is as follows: ① Mix aniline with hydrochloric acid, stir magnetically for a period of time under ice bath conditions, and then add sodium nitrite aqueous solution dropwise to obtain mixed solution I; ② Add sodium phenolate solution to mixed solution I obtained in step one ①, and stir magnetically at low temperature for a period of time to obtain 4-hydroxyazobenzene.

3. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 2, characterized in that... The molar ratio of aniline to hydrochloric acid in step ① is 1:(2~5); the molar ratio of aniline to sodium nitrite in step ① is 1:(1.5~2.0); the temperature of the ice bath in step ① is 0℃; the magnetic stirring speed in step ① is 800r / min~1200r / min, and the magnetic stirring time is 40min~60min.

4. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 2, characterized in that... The concentration of the sodium phenolate solution in step ② is 1.0 mol / L to 1.5 mol / L; the molar ratio of sodium phenolate in the sodium phenolate solution in step ② to aniline in step ① is 1:(1~1.5); the temperature of the low-temperature magnetic stirring reaction in step ② is 0℃ to 5℃, and the time is 8h to 12h; the speed of magnetic stirring in step ② is 800r / min to 1200r / min.

5. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 1, characterized in that... The method for preparing the azophenyl gel monomer in step two is as follows: ① Dissolve 4-hydroxyazobenzene, potassium carbonate, methyl 6-bromohexanoate and potassium iodide in dimethylformamide to obtain mixed solution II; heat mixed solution II under reflux in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain an orange intermediate azobenzene derivative. ② Dissolve the orange intermediate azophenyl ester derivative in anhydrous ethanol, add potassium hydroxide to obtain mixed solution III; reflux mixed solution III in a water bath for a period of time under magnetic stirring, and indicate the reaction endpoint by thin-layer chromatography to obtain the yellow azophenyl carboxylic acid derivative. ③ Dissolve the yellow azophenylcarboxylic acid derivative, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide in dimethylformamide to obtain mixed solution IV; heat and stir mixed solution IV in a water bath under magnetic stirring for a period of time to activate the carboxyl group, add acrylamide monomer and then heat and stir in a water bath under magnetic stirring for a period of time. Thin-layer chromatography indicates the reaction endpoint to obtain azophenyl gel monomer.

6. The method for preparing a reversibly loaded hydrogel based on azobenzene's pH / UV smart response information according to claim 5, characterized in that... The molar ratio of 4-hydroxyazobenzene, potassium carbonate, methyl 6-bromohexanoate, and potassium iodide in step ① is 1:(0.7~1.0):(0.7~1.0):(3.5~5); the concentration of 4-hydroxyazobenzene in mixed solution II in step ① is 50 mmol / L~80 mmol / L; the reflux time in the water bath in step ① is 12 h, and the reflux temperature in the water bath is 95 °C; the magnetic stirring speed in step ① is 800 r / min~1200 r / min.

7. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 5, characterized in that... The molar ratio of the orange intermediate azophenyl ester derivative to potassium hydroxide in step ② is 1:(2.5~3); the concentration of the orange intermediate azophenyl ester derivative in mixed solution III in step ② is 20mmol / L~50mmol / L; the reflux time in the water bath in step ② is 6h, and the reflux temperature in the water bath is 65℃; the magnetic stirring speed in step ② is 800r / min~1200r / min.

8. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 5, characterized in that... The water bath heating and stirring time in step ③ is 1 hour, and the water bath heating and stirring temperature is 55℃~65℃; the molar ratio of the yellow azobenzene carboxylic acid derivative, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and acrylamide in step ③ is 1:(1.0~1.2):(2~3):(3.5~5); the concentration of the yellow azobenzene carboxylic acid derivative in the mixed solution IV in step ③ is 40mmol / L~80mmol / L; the water bath heating and stirring time after adding the acrylamide monomer in step ③ is 4 hours, and the water bath heating and stirring temperature is 55℃; the magnetic stirring speed in step ③ is 800r / min~1200r / min.

9. The method for preparing a reversibly loaded hydrogel based on azobenzene's intelligent pH / UV response information according to claim 1, characterized in that... The concentration of the orange azophenyl gel monomer solution mentioned in step 3① is 60 mmol / L; the stirring speed mentioned in step 3① is 800 r / min to 1200 r / min, and the stirring time is 5 min to 15 min.

10. The method for preparing a reversibly loaded hydrogel based on azobenzene's pH / UV smart response information according to claim 1, characterized in that... In step 3②, the mass ratio of acrylamide, ammonium persulfate, and methylenebisacrylamide is 1g:(0.04g~0.08g):0.04g; the concentration of acrylamide in mixed solution V in step 3② is 0.28mol / L; the volume ratio of tetramethylethylenediamine to mixed solution V in step 3② is 1:1000; the speed of vigorous stirring in step 3② is 800r / min~1200r / min, the time of vigorous stirring is 5min~10min, and the process is carried out at room temperature.

11. The method for preparing a reversibly loaded hydrogel based on azobenzene's pH / UV intelligent response information according to claim 1, characterized in that... In step 3, the gel is soaked in deionized water for cleaning, and the water is changed every 12 hours. The soaking and cleaning time is 48 hours to 96 hours. The mass ratio of gel to deionized water is 1 g: 80 mL for each soak.

12. The application of a reversible pH / UV smart response hydrogel based on azobenzene prepared by the preparation method described in claim 1, characterized in that... Applications in intelligent information payloads and rewritable cryptographic transmission.

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