A self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel, a preparation method and application thereof

Abstract

The application discloses a self-shrinking, self-healing and multi-stimulus responding rosin-based copper salt supramolecular hydrogel as well as a preparation method and application thereof, and belongs to the technical field of hydrogels. The rosin-based copper salt supramolecular hydrogel is synthesized by means of coordination between copper nitrate and obtained disodium sulfonated dehydroabietic acid after sulfonation reaction and neutralization reaction of dehydroabietic acid as raw material, and has self-shrinking, self-healing and multi-stimulus responding performances. The preparation method of the hydrogel comprises the following steps: (1) preparation of sulfonated dehydroabietic acid; (2) preparation of disodium sulfonated dehydroabietic acid; and (3) preparation of the rosin-based copper salt supramolecular hydrogel. The rosin-based copper salt supramolecular hydrogel can realize self-shrinking of copper ions and maintain three-dimensional shape memory, and simultaneously has comprehensive performances of self-healing, multi-stimulus responding such as pH and oxidation and reduction, visual chiral identification, high conductivity and high swelling rate, and has inhibiting effects on pseudomonas aeruginosa and bacillus subtilis.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel technology, specifically relating to a self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel, its preparation method, and its application. Background Technology

[0002] Low molecular weight mass gels (LMMGs) are a class of soft materials that spontaneously assemble into three-dimensional network structures through non-covalent interactions such as hydrogen bonding, electrostatic interactions, π-π stacking, and van der Waals forces. Due to their flexible molecular structure design, tunable microstructure, and multi-stimulus responsiveness, LMMGs have attracted widespread attention in the field of smart materials. Among various gel material systems, multi-stimulus responsive hydrogels can exhibit macroscopic responses to various external stimuli such as temperature, pH, ion concentration, light, electric field, and redox, realizing functions such as sol-gel transition, swelling-self-shrinkage behavior, and shape memory, thus becoming one of the important research directions in stimulus-responsive materials. Currently, polymer gels with self-shrinkage behavior have many applications in smart materials, drug delivery, sensors, catalysis, and dye adsorption; however, research on the self-shrinkage properties of low molecular weight supramolecular gels remains relatively insufficient.

[0003] In recent years, researchers have introduced the coordination interaction between metal ions and ligands into gel systems, preparing metal gels using small molecule ligands with multiple coordination sites. The introduction of metal ions effectively modulates gel properties, expanding the research scope of supramolecular gel chemistry. For example, the literature "Cu..." 2+ The article "Triggered Shrinkage of a Natural Betulin-Derived Supramalcular Gel to Fabricate Moldable Self-Supporting Gel" reports on an organic gel based on betulin derivatives, Cu... 2+ The introduction of [a specific ingredient] triggered the self-shrinkage of the organic gel. The solvent used in the synthesis of this gel was methanol / water, which is volatile, toxic, and not environmentally friendly.

[0004] Rosin is an abundant and inexpensive natural renewable resource. Its derivative, dehydroabsic acid, possesses a semi-rigid molecular framework and multiple chiral carbons, making it suitable for constructing gel systems. Previous studies have utilized dehydroabsic acid derivatives to prepare organic gels. The paper "Supramolecular Hydrogels with Chiral Nanofibril Structures Formed from β-Cyclodextrin and a Rosin-Based Amino Acid Surfactant" synthesized an amino acid surfactant based on dehydroabsic acid, constructing a hydrogel through host-guest interactions. This research, starting from dehydroabsic acid, involved a complex synthetic route involving esterification, aminolysis, re-esterification, and saponification. It also used expensive condensation reagents such as HATU, resulting in high costs.

[0005] Patent publication number CN 112920426 A describes a rosin-based calcium salt supramolecular hydrogel, its preparation method, and its application. This method utilizes dehydroabsic acid to synthesize sodium dehydroabsicate, and then, in the presence of calcium ions, forms a calcium dehydroabsicate supramolecular hydrogel through coordination interactions of metal ions. However, the rosin-based calcium salt supramolecular hydrogel in this method is only used as a template for the synthesis of nano-metal sulfides, and its function is relatively limited. Summary of the Invention

[0006] To address the above problems, this invention provides a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing, and multi-stimulus responsive properties. The rosin-based copper salt supramolecular hydrogel was successfully synthesized by reacting disodium sulfonated dehydroabirate with copper ions. This hydrogel exhibits self-shrinking only in response to divalent copper ions while maintaining three-dimensional shape memory. It also possesses comprehensive properties including self-healing, multi-stimulus responsiveness, chiral recognition, high conductivity, and high swelling ratio. Furthermore, this hydrogel also exhibits inhibitory properties against Pseudomonas aeruginosa and Bacillus subtilis.

[0007] This invention is achieved through the following technical solution:

[0008] A self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel was developed using dehydroabietic acid as a raw material. The hydrogel underwent sulfonation and neutralization reactions, followed by the reaction of the resulting disodium sulfonated dehydroabietic acid with Cu. 2+ By combining through coordination, a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing, and multi-stimulus response was obtained.

[0009] The self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel contains sulfonated dehydroabietic acid disodium salt and Cu 2+ A double-tooth bridge connection coordination mode is adopted.

[0010] Furthermore, the structure of the self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel is a three-dimensional network composed of intertwined nanofibers with a diameter of 10–20 nm.

[0011] A method for preparing a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing, and multi-stimulus responsive properties as described above includes the following steps:

[0012] (1) Preparation of sulfonated dehydroabietic acid: Dehydroabietic acid is sulfonated with concentrated sulfuric acid in an ice-salt bath. After the reaction is completed, the dehydroabietic acid is precipitated by ice water, separated and washed and recrystallized to obtain sulfonated dehydroabietic acid.

[0013] (2) Preparation of disodium sulfonated dehydroabirate: The sulfonated dehydroabirate obtained in step (1) is prepared into a solution. The sulfonated dehydroabirate solution is mixed with sodium hydroxide solution and neutralized at room temperature. After the reaction is completed, the solution is filtered and the filtrate is allowed to stand at room temperature to crystallize and then recrystallized to obtain disodium sulfonated dehydroabirate.

[0014] (3) Preparation of rosin-based copper salt supramolecular hydrogel: The sodium sulfonated dehydroabirate obtained in step (2) is prepared into a solution. The sodium sulfonated dehydroabirate solution is mixed with copper nitrate solution and allowed to stand. A gel is formed immediately at room temperature to obtain a self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel.

[0015] Further, in step (3), the volume ratio of the disodium sulfonated dehydroabirate solution to the copper nitrate solution is 1:(1-2), the concentration of the disodium sulfonated dehydroabirate solution is 20-100 mmol / L, and the concentration of the copper nitrate solution is 20-80 mmol / L.

[0016] Further, in step (2), the volume ratio of the sulfonated dehydroabietic acid solution to the sodium hydroxide solution is 1:(1-2), the concentration of the sulfonated dehydroabietic acid solution is 0.4-0.5 mol / L, and the concentration of the sodium hydroxide solution is 0.8-1 mol / L.

[0017] Furthermore, in step (2), the reaction time of the neutralization reaction is 0.8 to 1 hour.

[0018] Further, in step (1), the mass-to-volume ratio of the dehydroabsic acid to concentrated sulfuric acid is 10 g: (30-40) mL.

[0019] Furthermore, in step (1), the sulfonation reaction temperature is -10 to -5°C, and the reaction time is 25 to 30 minutes.

[0020] Application of a self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel as described above in inhibiting or killing bacteria.

[0021] The preparation principle of the self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel of the present invention:

[0022] Natural dehydroabietic acid was functionalized by sulfonation to introduce key coordination and hydrophilic groups. Its solubility was then optimized through neutralization to obtain disodium sulfonated dehydroabietic acid. A rosin-based copper salt supramolecular hydrogel was obtained by simply mixing copper ions with disodium sulfonated dehydroabietic acid. Utilizing the dynamic coordination between copper ions and carboxylate groups as the main driving force, and in conjunction with the hydrophobic interactions of the rosin skeleton, a three-dimensional supramolecular network was rapidly constructed at room temperature. This endowed the rosin-based copper salt supramolecular hydrogel with properties of multi-stimulus response, self-shrinkage, self-healing, high conductivity, and high swelling ratio.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0024] 1. This invention uses dehydroabietic acid, a natural and renewable resource, as a raw material. Combining this with the tricyclic diterpenoid structure of rosin, sulfonated disodium dehydroabietic acid is prepared through sulfonation and neutralization reactions. This disodium dehydroabietic acid is then reacted with copper ions to successfully synthesize a rosin-based copper salt supramolecular hydrogel. The raw materials are inexpensive, and the synthetic route is simple and feasible.

[0025] 2. The rosin-based copper salt supramolecular hydrogel of the present invention exhibits unique and excellent multifunctional integrated properties: it can spontaneously shrink at room temperature and maintain the three-dimensional shape memory of the container in the process; it has self-healing ability without external stimulation; at the same time, the hydrogel has sensitive and reversible response to pH and redox stimuli, and can achieve visual identification of chiral mandelic acid enantiomers; the presence of conductive copper ions in the hydrogel gives it high ionic conductivity.

[0026] 3. The rosin-based copper salt supramolecular hydrogel of this invention has an equilibrium swelling ratio as high as 9220%, exhibiting excellent water absorption and retention capabilities. The hydrogel's self-healing ability allows it to spontaneously repair itself after damage, thus improving its application durability.

[0027] 4. The rosin-based copper salt supramolecular hydrogel of the present invention has the ability to inhibit Pseudomonas aeruginosa and Bacillus subtilis. Copper ions themselves have antibacterial activity, and their coordination with the rosin skeleton produces a synergistic effect. Attached Figure Description

[0028] Figure 1These are macroscopic morphology comparison photographs of the hydrogels prepared in Example 1 and Comparative Example 1; wherein Cu is labeled as the rosin-based copper salt supramolecular hydrogel prepared in Example 1, and Ag, Pb, Zn, and Cd are labeled as the hydrogels prepared with other metal ions in Comparative Example 1.

[0029] Figure 2 The image shows the 1H NMR spectrum of the sulfonated dehydroabietic acid disodium salt and rosin-based copper salt supramolecular hydrogel prepared in Example 1.

[0030] Figure 3 The image shows the electrospray ionization / time-of-flight mass spectra of the sulfonated dehydroabietic acid disodium salt and rosin-based copper salt supramolecular hydrogels prepared in Example 1.

[0031] Figure 4 Fourier transform infrared spectrum of the sulfonated dehydroabietic acid disodium salt and rosin-based copper salt supramolecular hydrogel prepared in Example 1.

[0032] Figure 5 The image shows the ultraviolet spectrum of the sulfonated disodium dehydroabirate and rosin-based copper salt supramolecular hydrogel prepared in Example 1.

[0033] Figure 6 The images show transmission electron microscopy (TEM) images of the rosin-based copper salt supramolecular hydrogel prepared in Example 1 before and after self-shrinkage; where A is the TEM image of the rosin-based copper salt supramolecular hydrogel before self-shrinkage, and B is the TEM image of the rosin-based copper salt supramolecular hydrogel after self-shrinkage.

[0034] Figure 7 The images show scanning electron microscope (SEM) images of the rosin-based copper salt supramolecular hydrogel prepared in Example 1 before and after self-shrinkage; where A is the SEM image of the rosin-based copper salt supramolecular hydrogel before self-shrinkage, and B is the SEM image of the rosin-based copper salt supramolecular hydrogel after self-shrinkage.

[0035] Figure 8 These are three-dimensional shape memory photographs of the rosin-based copper salt supramolecular hydrogel prepared in Example 1 after automatic shrinkage at different times; wherein, A is the shrinkage process of the rosin-based copper salt supramolecular hydrogel stained with Rhodamine B in a covered cuvette, and B is the process of the unstained rosin-based copper salt supramolecular hydrogel shrinking and maintaining a columnar shape in a round-bottomed glass bottle.

[0036] Figure 9 The rheological analysis diagrams of the storage modulus G' and loss modulus G'' of the rosin-based copper salt supramolecular hydrogel prepared in Example 1 under different conditions are shown. Among them, A is the frequency scan curve under the condition of 25°C and fixed strain of 1%, and B is the strain scan curve under the condition of 25°C and fixed frequency of 1Hz.

[0037] Figure 10The diagram shows the self-healing performance test of the rosin-based copper salt supramolecular hydrogel prepared in Example 1; where A is a recovery test diagram of the rosin-based copper salt supramolecular hydrogel by applying alternating strain amplitudes of 25% and 0.5%, and B is a self-healing photograph of the rosin-based copper salt supramolecular hydrogel.

[0038] Figure 11 The images show the multi-stimulus response performance analysis of the rosin-based copper salt supramolecular hydrogel prepared in Example 1. A represents the gel-sol transition triggered by hydrochloric acid and sodium hydroxide solution; B represents the gel-sol transition triggered by ascorbic acid and oxygen; C represents the gel-sol transition triggered by shaking and standing; D represents the gel-sol transition triggered by sodium citrate and copper nitrate solution; E represents the gel-sol transition triggered by disodium ethylenediaminetetraacetate and copper nitrate solution; and F represents the visual chiral recognition of 0.1 equivalents of S-mandelic acid / R-mandelic acid by the rosin-based copper salt supramolecular hydrogel.

[0039] Figure 12 The image shows the fitted curve of the electrochemical impedance spectroscopy of the rosin-based copper salt supramolecular hydrogel prepared in Example 1.

[0040] Figure 13 The images show the rosin-based copper salt supramolecular hydrogel before and after swelling, as well as the swelling rate diagram, of the rosin-based copper salt supramolecular hydrogel prepared in Example 1. In the images, A is the freeze-dried hydrogel, B is the hydrogel after swelling, and C is the swelling rate diagram of the rosin-based copper salt supramolecular hydrogel.

[0041] Figure 14 The images show the antibacterial effects of ciprofloxacin and the rosin-based copper salt supramolecular hydrogel prepared in Example 1 on Bacillus subtilis and Pseudomonas aeruginosa; where A is a photograph of the inhibition zone against Bacillus subtilis and B is a photograph of the inhibition zone against Pseudomonas aeruginosa. Detailed Implementation

[0042] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0043] Example 1

[0044] Preparation of self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogels:

[0045] (1) Take 10g of dehydroabietic acid and add it to a three-necked flask. Place it in an ice-salt bath and keep the reaction temperature at -5℃. Slowly add 40mL of concentrated sulfuric acid. After the addition is complete, continue the reaction for 30min. After the reaction is complete, slowly add 100mL of ice water to precipitate the product. Then, after vacuum filtration, washing, and recrystallization, sulfonated dehydroabietic acid is obtained.

[0046] (2) Add deionized water to sulfonated dehydroabietic acid to prepare a solution. Mix 0.5 mol / L sulfonated dehydroabietic acid solution with 1 mol / L sodium hydroxide solution at a volume ratio of 1:1 and react at room temperature for 1 h. After the reaction is completed, filter to separate insoluble impurities. Let the filtrate stand at room temperature for 24 h to allow crystals to precipitate. Recrystallize and purify the precipitated crystals to obtain disodium sulfonated dehydroabietic acid.

[0047] (3) Add deionized water to disodium sulfonate to prepare a solution. Mix 0.5 mL of 20 mmol / L disodium sulfonate aqueous solution with 0.5 mL of 20 mmol / L Cu(NO3)2 aqueous solution evenly and let stand at room temperature to obtain a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing and multiple stimulus response.

[0048] Example 2

[0049] Preparation of self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogels:

[0050] (1) Take 10g of dehydroabietic acid and add it to a three-necked flask. Place it in an ice-salt bath and keep the reaction temperature at -10℃. Slowly add 30mL of concentrated sulfuric acid. After the addition is complete, continue the reaction for 25min. After the reaction is complete, slowly add 100mL of ice water to precipitate the product. Then, after vacuum filtration, washing and recrystallization, sulfonated dehydroabietic acid is obtained.

[0051] (2) Add deionized water to sulfonated dehydroabietic acid to prepare a solution. Mix 0.4 mol / L sulfonated dehydroabietic acid solution with 0.8 mol / L sodium hydroxide solution at a volume ratio of 1:2 and react at room temperature for 0.8 h. After the reaction is completed, filter to separate insoluble impurities. Let the filtrate stand at room temperature for 24 h to allow crystals to precipitate. Recrystallize and purify the precipitated crystals to obtain disodium sulfonated dehydroabietic acid.

[0052] (3) Add deionized water to disodium sulfonate to prepare a solution. Mix 0.5 mL of 100 mmol / L disodium sulfonate aqueous solution with 0.5 mL of 60 mmol / L Cu(NO3)2 aqueous solution evenly and let stand at room temperature to obtain a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing and multiple stimulus response.

[0053] Example 3

[0054] Preparation of self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogels:

[0055] (1) Take 10g of dehydroabietic acid and add it to a three-necked flask. Place it in an ice-salt bath and keep the reaction temperature at -8℃. Slowly add 75mL of concentrated sulfuric acid. After the addition is complete, continue the reaction for 30min. After the reaction is complete, slowly add 100mL of ice water to precipitate the product. Then, after vacuum filtration, washing, and recrystallization, sulfonated dehydroabietic acid is obtained.

[0056] (2) Add deionized water to sulfonated dehydroabietic acid to prepare a solution. Mix 0.5 mol / L sulfonated dehydroabietic acid solution with 1 mol / L sodium hydroxide solution at a volume ratio of 1:1 and react at room temperature for 0.8 h. After the reaction is completed, filter to separate insoluble impurities. Let the filtrate stand at room temperature for 24 h to allow crystals to precipitate. Recrystallize and purify the precipitated crystals to obtain disodium sulfonated dehydroabietic acid.

[0057] (3) Add deionized water to disodium sulfonate to prepare a solution. Mix 0.5 mL of 80 mmol / L disodium sulfonate aqueous solution with 1 mL of 80 mmol / L Cu(NO3)2 aqueous solution and let stand at room temperature to obtain a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing and multiple stimulus response.

[0058] Comparative Example 1

[0059] 0.5 mL of 20 mmol / L aqueous solutions of AgNO3, Pb(NO3)2, Zn(NO3)2, and Cd(NO3)2 were respectively mixed with 0.5 mL of 20 mmol / L aqueous solution of disodium sulfonate dehydroabietic acid. The mixtures were thoroughly mixed and allowed to stand at room temperature (cadmium nitrate requires a 60°C water bath for 2 hours) to form hydrogels. The presence of self-shrinkage behavior was then observed. Comparative photographs of the macroscopic morphology of the hydrogels from Comparative Example 1 and Example 1 are shown below. Figure 1 As shown. By Figure 1 It is evident that only the rosin-based copper salt supramolecular hydrogel in Example 1 exhibits self-shrinking behavior.

[0060] Material structure characterization analysis

[0061] (I) Analysis of proton nuclear magnetic resonance (NMR) spectrum

[0062] The proton NMR spectrum of the supramolecular hydrogels of disodium sulfonate dehydroabirate and rosin-based copper salt in Example 1 was analyzed, and the results are as follows: Figure 2 As shown. Figure 2 The 1H NMR spectrum showed that the peaks of the rosin-based copper salt supramolecular hydrogel were broadened relative to those of disodium sulfonate dehydroabirate, which is due to the paramagnetic Cu... 2+ Its chemical environment was altered after coordination with disodium sulfonated dehydroabirate.

[0063] (II) Electrospray ionization / time-of-flight mass spectrometry analysis

[0064] Electrospray ionization / time-of-flight mass spectrometry analysis was performed on the supramolecular hydrogels of disodium sulfonate dehydroabirate and rosin-based copper salt in Example 1. The results are as follows: Figure 3 As shown. Figure 3 The positive ion mode electrospray ionization / time-of-flight mass spectrometry results show that the main peak corresponds to [CuL(NO3)]. x ·y(H2O)] + The remaining peaks correspond to m / z = 483.1 ([2Cu(NO3)2·3H2O]). + ), m / z= 524.1([2Cu(NO3)2·4H2O_Na] + ), m / z = 488.2([CuL] + ), m / z =520.2([Cu(NO3)2·5H2O_H] + ), m / z=568.0([CuL(NO3)·H2O] + ), m / z=671.2([CuL(NO 3)2 ·2H2O_Na] + ), m / z=795.1([CuL(NO3)4·2H2O_Na] + ), m / z = 900.3([Cu3L(NO3)4·2H2O_H] + ), and m / z = 963.2([Cu4L(NO3)4·2H2O_H] + ).

[0065] (III) Fourier transform infrared spectroscopy analysis

[0066] Fourier transform infrared (FTIR) spectroscopy analysis was performed on the supramolecular hydrogels of disodium sulfonate dehydroabirate and rosin-based copper salt in Example 1. The results are as follows: Figure 4 As shown. Figure 4 The infrared spectrum of the supramolecular hydrogels of disodium sulfonate dehydroabirate and rosin-based copper salts shows that the sulfonate is located at 1563 cm⁻¹. -1 and 1396cm -1 Both asymmetric and symmetric stretching vibrations are attributed to the carboxyl group (COO-). The frequency difference σ between the asymmetric and symmetric stretching vibrations is calculated. n = n as (COO-)-n s (COO-) indicates that it is close to the free state of sulfonated dehydroabietic disodium salt; therefore, Cu 2+ It may adopt a bidentate bridging coordination mode with disodium sulfonate dehydroabirate.

[0067] (iv) Ultraviolet spectroscopy analysis

[0068] The supramolecular hydrogels of disodium sulfonate dehydroabirate and rosin-based copper salt in Example 1 were analyzed by ultraviolet spectroscopy, and the results are as follows: Figure 5 As shown. Figure 5 The UV spectra of disodium sulfonated dehydroabirate and rosin-based copper salt supramolecular hydrogels showed that, compared with disodium sulfonated dehydroabirate, the rosin-based copper salt supramolecular hydrogel exhibited a new shoulder peak at 268 nm, indicating that Cu... 2+ It successfully coordinated with disodium sulfonated dehydroabirate.

[0069] (v) Transmission electron microscopy analysis

[0070] Transmission electron microscopy analysis was performed on the rosin-based copper salt supramolecular hydrogel in Example 1, and the results are as follows: Figure 6 As shown. Figure 6 Scanning electron microscopy images from AB show that the rosin-based copper salt supramolecular hydrogel has increased fiber diameter after self-shrinkage, forming a three-dimensional network of intertwined nanofibers with a high aspect ratio. The fiber diameter is 10-20 nm and the length is several micrometers.

[0071] (vi) Scanning electron microscopy analysis

[0072] SEM analysis was performed on the rosin-based copper salt supramolecular hydrogel in Example 1, and the results are as follows: Figure 7 As shown. Figure 7 Comparison of scanning electron microscopy images from AB showed that the original gel fiber diameter was 16.99 nm, and after self-shrinkage, the gel formed a dense interwoven fiber network with a fiber diameter of 31.6 nm, indicating an increase in fiber diameter.

[0073] Based on the above analysis, coordination should be the main driving force for gel self-assembly. The possible gel formation mechanism is: firstly, disodium sulfonate dehydroabietic acid reacts with Cu... 2+ The two dental bridges coordinate to form one-dimensional chains, and then these one-dimensional chains intertwine and cross-link to form a three-dimensional network structure, which surrounds water to form a gel.

[0074] Material performance testing and analysis

[0075] (a) Self-shrinking properties

[0076] The self-shrinkage behavior of the rosin-based copper salt supramolecular hydrogel in Example 1 was tested at room temperature. The mass of the gel was measured at regular intervals, and the self-shrinkage rate was calculated using the following formula. It was observed that the self-shrinkage rate remained almost constant. Self-shrinkage rate = (m o -m s ) / m o × 100%, where m0 is the mass of the gel before self-shrinkage, m s The mass of the gel after self-shrinkage.

[0077] The rosin-based copper salt supramolecular hydrogel in Example 1 began to self-shrink after standing for 20 minutes, maintaining the three-dimensional shape of the container during the self-shrinkage. After 10 days, the gel reached a stable state through self-shrinkage. Shaking the newly formed gel will cause it to transform into a solution state; after standing for a period of time, it will return to a gel state, but will no longer possess the self-shrinkage property. 2+ This triggered the self-shrinkage of the rosin-based copper salt supramolecular hydrogel while maintaining the three-dimensional shape of the container, demonstrating three-dimensional shape memory. A covered cuvette and a small round-bottomed glass bottle were used for the gel self-shrinkage experiment. To better observe the gel self-shrinkage phenomenon, the gel in the covered cuvette was stained with Rhodamine B, as shown below. Figure 8 As shown in AB, over time, the gel contained in the small round-bottomed glass bottle gradually shrinks into a cylindrical shape, thus exhibiting three-dimensional shape memory properties. Figure 8 As shown in Figure A, the rhodamine B-stained rosin-based copper salt supramolecular hydrogel self-shrinks in a covered cuvette. Figure 8 As shown in Figure B, the rosin-based copper salt supramolecular hydrogel self-shrinks and maintains its cylindrical shape in a small round-bottomed glass bottle.

[0078] (ii) Rheological properties

[0079] The rheological characterization of the rosin-based copper salt supramolecular hydrogel in Example 1 was performed, and the measurement results are as follows: Figure 9 As shown. Figure 9 Frequency scan measurements of A showed that the value of G' was consistently higher than that of G'', indicating that the gel exhibited a significant elastic response rather than acting as a viscous soft substance. Furthermore, Figure 9 The stress scanning measurements of B show that the storage modulus G' is typically an order of magnitude larger than the loss modulus G''. Within the linear viscoelastic region, the storage modulus G' is 22000 Pa. When the strain exceeds 3.55%, the value of G' decreases rapidly and is subsequently surpassed by the loss modulus (G''), indicating that the hydrogel exhibits shear-thinning properties.

[0080] (iii) Self-healing properties

[0081] The rosin-based copper salt supramolecular hydrogel from Example 1 was cut into two rectangular blocks of the same size, one of which was stained with Rhodamine B. Under conditions without external stimuli, the two gels remained in direct contact at the interface, and the hydrogel maintained its structural integrity under gravitational load. The test results are as follows: Figure 10 As shown.

[0082] Figure 10B indicates that the rosin-based copper salt supramolecular hydrogel exhibits self-healing properties at room temperature without any external stimulation. When four gels are brought into contact, the stained and unstained gels can alternately adhere together after half an hour, and the four gels can be lifted vertically with a small wooden stick. Dynamic oscillatory rheological testing further quantitatively characterizes the self-healing properties of the gel, such as... Figure 10 As shown in Figure A, when the stress is relatively high (γ=25%), the G' value of the hydrogel decreases from 1900 Pa to 300 Pa, indicating that the network inside the gel is disrupted. When the stress is reduced to a smaller value (γ=0.5%), the G' value returns to its original value. This is due to the dynamic nature of the cross-linked structure of the coordination bonds between disodium sulfonate dehydroabietic acid and copper ions.

[0083] (III) Multiple stimulus response performance

[0084] For the pH stimulus response test, 100 μL of 1 mol / L hydrochloric acid solution was added to the rosin-based copper salt supramolecular hydrogel of Example 1. After sonication for two minutes, the gel turned into a blue transparent solution. Subsequently, 1 mol / L sodium hydroxide solution was added, and the system returned to the gel state. Figure 11 A).

[0085] Regarding the redox response, after adding ascorbic acid solution to the gel and sonicating for two minutes, the gel collapsed into a pale yellow solution. Subsequently, the solution was passed through a 10... 6 After 30 minutes of oxygen exposure, the gel returns to its original state. This process can be repeated up to 3 times. Figure 11 B).

[0086] The hydrogel was shaken to test its shear stress response. The experimental results showed that applying shear stress can induce a reversible sol-gel phase transition. This process can be repeated several times. Figure 11 C).

[0087] Upon addition of 1.5 equivalents of sodium citrate or disodium EDTA (100 μL), the gel immediately turned into a blue solution. Subsequently, the addition of 2 equivalents of copper nitrate (100 μL) restored the system to its gel state. Figure 11 DE).

[0088] When equal equivalents of R-mandelic acid and S-mandelic acid solutions are added to the same rosin-based copper salt supramolecular hydrogel, the S-mandelic acid solution causes the gel to collapse, while the addition of R-mandelic acid solution does not affect the stability of the gel. After standing for a period of time, the S-mandelic acid solution further causes the gel to collapse, while the R-mandelic acid solution maintains its original state. Clearly, the chiral collapse of the rosin-based copper salt supramolecular hydrogel can be used to distinguish between R-mandelic acid and S-mandelic acid, with a sensitivity reaching 0.1 equivalents of added mandelic acid in the rosin-based copper salt supramolecular hydrogel. Figure 11 F).

[0089] (iv) Electrical conductivity properties

[0090] The conductivity of the rosin-based copper salt supramolecular hydrogel in Example 1 was tested using a Huachen electrochemical workstation. The conductivity σ was calculated using the following formula: σ = l / SR, where l, S, and R are the length, cross-sectional area, and resistance of the conductor, respectively. During the test, the rosin-based copper salt supramolecular hydrogel had a length of 1.1 cm and a cross-sectional area of ​​2.5625 cm². 2 R = 38Ω, and the measured conductivity is 11.29 mS·cm. -1 ( Figure 12 ).

[0091] (v) Swelling rate performance

[0092] The freeze-dried rosin-based copper salt supramolecular hydrogel sample (0.0688 g) was accurately weighed and immersed in deionized water at 25°C. The sample was removed at predetermined time intervals, excess surface moisture was wiped off, and then it was weighed again. Measurements were continued until the mass of the hydrated hydrogel reached a constant (6.4125 g). The water absorption rate was calculated using the following formula:

[0093] Swelling rate = (W s -W d ) / W d × 100%

[0094] Among them, W s W represents the mass of the hydrogel after swelling. d This indicates the mass of the freeze-dried hydrogel. The mass W of the rosin-based copper salt supramolecular hydrogel powder during the testing experiment. d =0.0688g ( Figure 13 A), the mass W of the hydrogel after swelling s =6.4125g ( Figure 13 B), the measured swelling rate was 9220% ( Figure 13 C).

[0095] Materials Application Analysis

[0096] The rosin-based copper salt supramolecular hydrogel prepared in Example 1 was applied to inhibit or kill bacteria to study its inhibitory effect on different bacterial strains. Specifically, 40 mg / mL of deionized water was used to prepare the hydrogel. -1 A supramolecular hydrogel suspension of rosin-based copper salt was used. Its antibacterial efficacy against Gram-negative bacteria *Pseudomonas aeruginosa* and Gram-positive bacteria *Bacillus subtilis* was evaluated. The broad-spectrum antibiotic ciprofloxacin (100 μg / mL) was used in the experiment. -1) was used as a positive control. LB agar was used as the growth medium. 100 μL of bacterial cultures in each logarithmic growth phase were evenly spread onto the surface of the agar medium using a sterile cotton swab. Ciprofloxacin (10 μL) and 40 mg / mL were respectively... -1 A 10 μL suspension of rosin-based copper salt supramolecular hydrogel was dropped onto an agar plate to detect its antibacterial activity against two bacterial strains. The plates were incubated at 37°C for 24 hours. Figure 14 As shown in A and Table 1, the concentration is 40 mg·mL. -1 The rosin-based copper salt supramolecular hydrogel suspension produced an inhibition zone diameter of 34.5 mm against Bacillus subtilis, an antibacterial effect that even surpassed that of the antibiotic ciprofloxacin (27.5 mm). And as... Figure 14 As shown in B and Table 1, 40 mg·mL -1 The inhibition zone diameter of the rosin-based copper salt supramolecular hydrogel suspension against Pseudomonas aeruginosa reached 10.5 mm, which is smaller than that of the antibiotic ciprofloxacin (18.5 mm). This result indicates that the rosin-based copper salt supramolecular hydrogel has an inhibitory effect on both Bacillus subtilis and Pseudomonas aeruginosa, and its inhibitory effect on Bacillus subtilis is more significant.

[0097] Table 1. Diameter of the inhibition zone of rosin-based copper salt supramolecular hydrogel against Bacillus subtilis and Pseudomonas aeruginosa

[0098]

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel, characterized in that, Using dehydroabietic acid as a raw material, after sequential sulfonation and neutralization reactions, the resulting disodium sulfonated dehydroabietic acid is reacted with Cu. 2+ By combining through coordination, a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing, and multi-stimulus response was obtained. In the self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel, disodium sulfonate dehydroabirate and Cu 2+ A double-tooth bridge connection coordination mode is adopted.

2. The self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 1, characterized in that, The self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel has a structure consisting of a three-dimensional network of intertwined nanofibers with a diameter of 10–20 nm.

3. A method for preparing a rosin-based copper salt supramolecular hydrogel with self-shrinking, self-healing, and multi-stimulus responsive properties as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Preparation of sulfonated dehydroabietic acid: Dehydroabietic acid is sulfonated with concentrated sulfuric acid in an ice-salt bath. After the reaction is completed, the dehydroabietic acid is precipitated by ice water, separated and washed and recrystallized to obtain sulfonated dehydroabietic acid. (2) Preparation of disodium sulfonated dehydroabirate: The sulfonated dehydroabirate obtained in step (1) is prepared into a solution. The sulfonated dehydroabirate solution is mixed with sodium hydroxide solution and neutralized at room temperature. After the reaction is completed, the solution is filtered and the filtrate is allowed to stand at room temperature to crystallize and then recrystallized to obtain disodium sulfonated dehydroabirate. (3) Preparation of rosin-based copper salt supramolecular hydrogel: The sodium sulfonated dehydroabirate obtained in step (2) is prepared into a solution. The sodium sulfonated dehydroabirate solution is mixed with copper nitrate solution and allowed to stand. A gel is formed immediately at room temperature to obtain a self-shrinking, self-healing, and multi-stimulus responsive rosin-based copper salt supramolecular hydrogel.

4. The method for preparing the self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 3, characterized in that, In step (3), the volume ratio of the disodium sulfonate dehydroabirate solution to the copper nitrate solution is 1:(1-2), the concentration of the disodium sulfonate dehydroabirate solution is 20-100 mmol / L, and the concentration of the copper nitrate solution is 20-80 mmol / L.

5. The method for preparing the self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 3, characterized in that, In step (2), the volume ratio of the sulfonated dehydroabietic acid solution to the sodium hydroxide solution is 1:(1-2), the concentration of the sulfonated dehydroabietic acid solution is 0.4-0.5 mol / L, and the concentration of the sodium hydroxide solution is 0.8-1 mol / L.

6. The method for preparing the self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 3, characterized in that, In step (2), the neutralization reaction takes 0.8 to 1 hour.

7. The method for preparing the self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 3, characterized in that, In step (1), the mass-to-volume ratio of dehydroabsic acid to concentrated sulfuric acid is 10 g: (30-40) mL.

8. The method for preparing the self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel according to claim 3, characterized in that, In step (1), the sulfonation reaction temperature is -10 to -5°C and the reaction time is 25 to 30 minutes.

9. The use of a self-shrinking, self-healing, multi-stimulus responsive rosin-based copper salt supramolecular hydrogel as described in any one of claims 1-2 in the preparation of products that inhibit or kill bacteria.

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