Water-retaining agent based on nonionic amide and preparation method thereof

Abstract

The invention discloses an intelligent water-retaining agent based on nonionic amide and a preparation method of the intelligent water-retaining agent, and belongs to the technical field of functional polymer materials. The water-retaining agent is prepared from the following raw materials in percentage by mass: 50 to 70 percent of PHEAA; 20 to 25 percent of PVP (Polyvinyl Pyrrolidone); 5 to 8% of HPG; 10 to 15% of PEGDA (polyethylene glycol diacrylate); 3-5% of a composite pore channel; 2 to 3% of up-conversion nano particles; 2-4% of an azobenzene derivative; 1 to 2 percent of PDA; 0.5 to 1.0 percent of CMC (Carboxymethyl Cellulose 0.3% to 0.5% of Fe3O4 nano particles; wherein the composite pore channel is a ferriprotein-Al < 3 + > composite pore channel, and the up-conversion nanoparticles are NaYF4: Yb < 3 + > / Tm < 3 + >. According to the material, the salt resistance and water retention are improved through cooperation of a nonionic network and bionic pore channels, dynamic controlled release of moisture is triggered by near-infrared light, the material has the magnetic recovery characteristic and cycling stability, the preparation process is environmentally friendly, and the material is suitable for intelligent agriculture and ecological restoration engineering in a complex environment.

Description

Technical Field

[0001] The present invention relates to the technical field of functional polymer materials, and in particular to a water-retaining agent based on nonionic amide and a preparation method thereof. Background Art

[0002] Traditional water-retaining agents are mainly polyacrylic acid (PAA) or acrylamide (AM) materials, but they generally have the following defects: 1. Poor environmental compatibility: Traditional ionic polymers are easily damaged by salt ions (such as Na + , Ca 2+ ) leads to the attenuation of water absorption performance, and the degradation products may pollute the soil; 2. Single function: Existing water-retaining agents mostly focus on static water retention, lack dynamic regulation capabilities such as light / magnetic response and intelligent controlled release, and are difficult to adapt to the alternating drought-humidity environment; 3. Insufficient structural stability: The gel network is prone to collapse after multiple water absorption / release cycles, and the capacity retention rate is less than 70%.

[0003] In recent years, researchers have tried to improve performance through composite modification technology. In addition, the preparation process of existing composite pore materials (such as zeolite, mesoporous silica) is complicated, and the interface compatibility with the polymer matrix is poor, resulting in uneven dispersion of functional particles. In response to the above bottlenecks, the present invention is based on the innovative design of non-ionic amide matrix (PHEAA / PVP / HPG), and achieves performance leap through the following technological breakthroughs: 1. Bionic composite pore construction: using recombinant ferritin solution and Al 3+ Directed assembly forms multi-level channels, and its surface hydroxyl groups hydrogen bond with the polymer chains, significantly improving the water adsorption kinetics; 2. Multifunctional synergistic response: the introduction of NaYF4:Yb 3+ / Tm 3+ Upconversion nanoparticles and Azo-C6 azobenzene derivatives realize near-infrared light-triggered aperture intelligent control, breaking through the limitation of traditional photoresponsive materials relying on ultraviolet light; 3. Interface enhancement process: through PDA coating and Ca 2+ Secondary crosslinking simultaneously optimizes the magnetically responsive dispersion of Fe₃O₄ and the stability of the gel network. This technology provides a new generation of environmentally adaptable material solutions for agricultural water conservation in arid regions, desertification control, and intelligent irrigation systems. Summary of the Invention

[0004] The object of the present invention is to provide a water-retaining agent based on nonionic amide and a preparation method thereof, which solves the problems of poor environmental compatibility, single function and insufficient structural stability of existing water-retaining agents.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A water-retaining agent based on nonionic amide, characterized in that, by mass percentage, its raw materials include:

[0007] PHEAA: 50-70%;

[0008] PVP: 20-25%;

[0009] HPG: 5-8%;

[0010] PEGDA: 10-15%;

[0011] Composite pores: 3-5%;

[0012] Upconversion nanoparticles: 2-3%;

[0013] Azobenzene derivatives: 2-4%;

[0014] PDA: 1-2%;

[0015] CMC: 0.5-1.0%;

[0016] Fe3O4 nanoparticles: 0.3-0.5%;

[0017] Wherein, the composite pore is ferritin-Al 3+ Composite channel, the upconversion nanoparticles are NaYF4:Yb 3+ / Tm 3+ .

[0018] In the present invention, PHEAA forms a strong hydrogen bond network through hydroxyl and amide groups, providing high water absorption and salt resistance; entanglement with PVP chain segments enhances mechanical strength; and synergistically with HPG to enhance the dynamic swelling ability of the gel.

[0019] According to a preferred embodiment of the present invention, the PHEAA is poly N-hydroxyethyl acrylamide, which is polymerized from N-hydroxyethyl acrylamide (HEMAA) monomers and has a chemical formula of (C5H9NO2) n .

[0020] According to a preferred embodiment of the present invention, the PHEAA is purchased from Xi'an Qiyue Biotechnology Co., Ltd. as PCL-b-PHEAA model.

[0021] The PVP described in the present invention is polyvinyl pyrrolidone, which acts as a flexible segment to reduce the brittleness of the gel and assists water diffusion through the hydrophilic pyrrolidone group. It complements the hydrogen bond network of PHEAA to prevent syneresis shrinkage of the gel.

[0022] According to a preferred embodiment of the present invention, the PVP is purchased from Hangzhou Juhe Chemical Co., Ltd.

[0023] The HPG in the present invention is hydroxypropyl guar gum, which provides a natural polysaccharide skeleton with excellent biodegradability, enhances network porosity through β-1,4 glycosidic bonds, forms an interpenetrating network with PHEAA / PVP, and improves the adhesion and sustained-release performance of the water-retaining agent in the soil.

[0024] According to a preferred embodiment of the present invention, the HPG is purchased from Longquan Chemical Plant in Yanggu County.

[0025] In the present invention, PEGDA is polyethylene glycol diacrylate, which acts as a crosslinking agent to form a three-dimensional network through double-bond free radical polymerization, regulate the pore size distribution and swelling rate of the gel, covalently bond with the carboxyl groups on the surface of Fe3O4 nanoparticles, and enhance the dispersibility of the magnetic particles.

[0026] According to a preferred embodiment of the present invention, the PEGDA was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0027] According to a preferred embodiment of the present invention, the ferritin-Al 3+ The preparation steps of the composite pores include: contacting a recombinant ferritin solution with a glycine-HCl buffer solution containing AlCl3 to obtain a mixed solution; and contacting the mixed solution with NaOH until the pH of the mixed solution reaches 7.0.

[0028] According to a preferred embodiment of the present invention, the volume ratio of the recombinant ferritin solution to the glycine-HCl buffer containing AlCl3 is 1:5, wherein the concentration of the recombinant ferritin solution is 10 mg / mL; and the amount of the AlCl3 substance is 0.1 mol.

[0029] According to a preferred embodiment of the present invention, the contact time of the recombinant ferritin solution and the glycine-HCl buffer containing AlCl3 is 24 hours, and the temperature of the mixed solution is 37°C.

[0030] According to a preferred embodiment of the present invention, the azobenzene derivative is Azo-C6.

[0031] According to a preferred embodiment of the present invention, the Azo-C6 is 1-methyl-3-(5-(4-(phenylazo)phenoxy)pentyl)-1H-imidazol-3-ium, which is purchased from Henan Alpha Chemical Co., Ltd.

[0032] According to a preferred embodiment of the present invention, the azobenzene derivative undergoes trans→cis isomerization under ultraviolet light, resulting in a change in molecular conformation and dynamic regulation of the gel pore size (photoresponsive controlled release). The cis structure restores to trans under near-infrared light (via upconversion), achieving a reversible response.

[0033] According to a preferred embodiment of the present invention, the recombinant ferritin solution was purchased from Shanghai Bolson Biotechnology Co., Ltd.

[0034] According to a preferred embodiment of the present invention, the glycine-HCl buffer was purchased from Shanghai Kanglang Biotechnology Co., Ltd.

[0035] According to a preferred embodiment of the present invention, the AlCl3 is purchased from Shandong Yihong Chemical Co., Ltd.

[0036] According to a preferred embodiment of the present invention, the NaOH is purchased from Guangdong Xiaoda Chemical Co., Ltd.

[0037] Ferritin-Al 3+ The ferritin cavity in the composite channel is exposed to Al 3+ After replacement, multi-level pores (pore diameter 2-5nm) are formed, which adsorb water molecules through surface hydroxyl groups to improve water retention dynamics. 3+ Chelating with the carboxyl group of CMC enhances the gel's ability to resist ion interference.

[0038] According to a preferred embodiment of the present invention, the upconversion nanoparticles are NaYF4:Yb 3+ / Tm 3+ , which was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0039] The upconversion nanoparticles in the present invention convert 980nm near-infrared light into ultraviolet light, triggering the photoisomerization of azobenzene derivatives to achieve intelligent aperture control; and linked with the ultraviolet light irradiation step (365nm×10min), forming a light-heat synergistic response mechanism.

[0040] According to a preferred embodiment of the present invention, the PDA is polydopamine, which is purchased from Shaanxi Xingbei Aike Biotechnology Co., Ltd.

[0041] The polydopamine coated upconversion nanoparticles of the present invention enhances interfacial compatibility, prevents particle agglomeration, and provides additional adsorption sites; the catechol groups of PDA bind to the Fe3O4 surface Fe 3+ Coordination to improve the stability of magnetic response.

[0042] According to a preferred embodiment of the present invention, the CMC is carboxymethyl cellulose, which is purchased from Sichuan Mai Tewei New Materials Co., Ltd.

[0043] In the present invention, carboxymethyl cellulose is used as a dispersant to stabilize the dispersion of nanoparticles (such as Fe3O4) in the premixed solution through electrostatic repulsion. 3+ Form ionic cross-linking points to assist in gel network stability.

[0044] According to a preferred embodiment of the present invention, the Fe3O4 nanoparticles are purchased from Zhejiang Yamei Nano Technology Co., Ltd.

[0045] The Fe3O4 nanoparticles in the present invention impart magnetic recovery function to the water-retaining agent, achieving rapid separation and reuse through an external magnetic field; the carboxyl groups modified with citric acid on the surface are cross-linked with PEGDA to enhance the particle-matrix interface bonding force.

[0046] The present invention also provides a method for preparing the water-retaining agent, which is characterized by comprising the following steps:

[0047] S1. Dissolve PHEAA, PVP, and HPG in deionized water and stir until completely dissolved; add CMC and adjust the pH of the solution to 6.8-7.2 to obtain a premixed solution;

[0048] S2. Add PEGDA and an azobenzene derivative to the premixed solution, introduce nitrogen, and then add ammonium persulfate to obtain a mixed solution;

[0049] S3, add ferritin-Al to the mixture 3+ Composite pores, upconversion nanoparticles and Fe3O4 nanoparticles, followed by UV irradiation to obtain a gel;

[0050] S4. Immerse the gel in an ethanol solution containing 0.5% CaCl2, freeze-dry, and then grind and sieve to obtain a water-retaining agent.

[0051] According to a preferred embodiment of the present invention, the ammonium persulfate is purchased from Shandong Yukang Chemical Co., Ltd.

[0052] According to a preferred embodiment of the present invention, the CaCl2 is purchased from Chujiang Haoyu Technology Co., Ltd.

[0053] According to a preferred embodiment of the present invention, the ethanol is purchased from Qingdao Xupu Supply Chain Co., Ltd.

[0054] According to a preferred embodiment of the present invention, in step S2, nitrogen is introduced for 20 minutes, and after adding ammonium persulfate, the reaction is carried out at a constant temperature of 40° C. for 3 hours.

[0055] According to a preferred embodiment of the present invention, in step S3, the wavelength of ultraviolet light irradiation is 365 nm, and the irradiation time is 10 min.

[0056] In the present invention, ultraviolet light irradiation (365nm×10min) is used to simultaneously complete azobenzene isomerization regulation and PEGDA secondary cross-linking to achieve dynamic pore response and network uniformity optimization; citric acid modification of the Fe3O4 nanoparticle surface combined with PEGDA cross-linking ensures uniform dispersion of magnetic particles and a magnetic field recovery rate of >95%.

[0057] According to a preferred embodiment of the present invention, in step S4, the volume ratio of the gel to the ethanol solution containing 0.5% CaCl2 is 1:5, and the contact time of the gel and the ethanol solution containing 0.5% CaCl2 is 12 hours.

[0058] According to a preferred embodiment of the present invention, in step S4, the freeze-drying temperature is -50°C, the time is 24 hours, and the particle size after pulverization and sieving is 80-100 mesh.

[0059] In step S4 of the present invention, freeze drying at -50°C utilizes the ice crystal template effect to form multi-level pores (micropore-mesopore synergy), and the specific surface area is increased to 200m 2 / g.

[0060] The present invention adopts ferritin-Al 3+ The biomimetic synthesis process of composite channels (directional assembly at 37°C×24h) avoids the high energy consumption and interface defects of the traditional template method and achieves high compatibility between the channel and the matrix.

[0061] In the present invention, Ca 2+ The secondary cross-linking is completed in an ethanol solution to avoid pore collapse caused by too rapid cross-linking in the aqueous phase and to improve the mechanical strength (compression modulus > 50 kPa).

[0062] The beneficial effects of the present invention are:

[0063] This nonionic amide-based water-retaining agent achieves comprehensive breakthroughs in efficient water retention, intelligent response, environmental adaptability, and recycling through the synergistic effects of multiple components and innovative process design. Its core mechanism revolves around the three dimensions of "main chain water absorption, pore water storage, and optical and magnetic regulation." The specific technical effects are as follows:

[0064] 1. High water retention and salt resistance: With non-ionic PHEAA as the main chain, combined with the flexible chain segments of PVP and the polysaccharide skeleton of HPG, a stable three-dimensional hydrogen bond network is constructed, which significantly improves the water absorption capacity of the material. By avoiding the charge competition between ionic groups and salt ions, and combining ferritin-Al 3+ The multi-stage adsorption of the composite pores and the chelation of CMC effectively inhibit the damage of salt ions to the gel network, achieving long-term water retention in a salinized environment.

[0065] 2. Light-responsive intelligent controlled release: Introducing upconversion nanoparticles, they convert highly penetrating near-infrared light into ultraviolet light, triggering the cis-trans isomerization of azobenzene derivatives and dynamically adjusting the gel pore size, thereby achieving on-demand water release. This design addresses the poor UV penetrability of traditional light-responsive materials and provides an intelligent solution for precision irrigation.

[0066] 3. Magnetic recovery and cycle stability: The uniformly dispersed magnetic Fe3O4 nanoparticles give the water retaining agent rapid magnetic separation capabilities, significantly improving the recovery efficiency. 2+ The dual reinforcement strategy of secondary cross-linking optimizes the mechanical strength and structural stability of the gel, ensuring stable performance after multiple water absorption / release cycles and extending the service life of the material.

[0067] 4. Bionic pores and efficient water storage: Ferritin-Al 3+ The composite pores are formed through biomimetic directed assembly technology to form multi-level nanopores. The surface hydroxyl groups strongly interact with water molecules, significantly improving the water storage rate and capacity. Compared with traditional template methods, this process avoids interfacial defects, enhances the compatibility between the pores and the substrate, and reduces the risk of structural collapse.

[0068] 5. Environmental Compatibility and Sustainability: Based on the biodegradable properties of the nonionic backbone and natural polysaccharide HPG, the material gradually degrades in the natural environment, reducing long-term soil pollution. Furthermore, the water-retaining agent is stable over a wide range of temperatures and pH values, making it suitable for complex environments such as arid, saline-alkali, and freeze-thaw cycles, demonstrating excellent universality.

[0069] 6. Green preparation process advantages: low-energy consumption and highly controllable preparation process are achieved by adopting low-temperature directional assembly, ultraviolet irradiation synchronous cross-linking and freeze-drying technology. 2+ The combination of cross-linking and ethanol solution impregnation strategy further optimizes the pore structure and mechanical properties, avoids the dependence on traditional high temperature or highly toxic reagents, and is in line with the concept of green chemistry.

[0070] In summary, the present invention overcomes the key bottlenecks of traditional water-retaining agents, such as single function, high salt sensitivity, and poor environmental adaptability, through component synergy and process innovation. It provides an efficient and sustainable material system for smart agricultural irrigation, desertification control, and ecological restoration, and has significant application potential and social value. DETAILED DESCRIPTION

[0071] The following specific implementation methods are only used to further illustrate the present application and should not be understood as limiting the scope of protection of the present application. Technicians in this field may make some non-essential improvements and adjustments to the present application based on the above application content.

[0072] 1. Implementation

[0073] Example 1

[0074] 1. Ferritin-Al 3+ Composite channel preparation

[0075] 1.1 Solution preparation

[0076] Place 10 mL of a 10 mg / mL recombinant ferritin solution (solvent: Tris-HCl buffer, pH 8.5) into a 50 mL centrifuge tube. Prepare AlCl₃-glycine buffer: Dissolve 0.1 mol AlCl₃ in 50 mL of glycine-HCl buffer (0.1 mol / L, pH 3.0) and ultrasonically disperse for 10 min.

[0077] 1.2 Directed Assembly

[0078] Ferritin solution and AlCl₃ buffer were mixed at a volume ratio of 1:5 (10 mL of ferritin solution, 50 mL of AlCl₃ buffer) and incubated on a shaker at 37°C, 120 rpm for 24 hours. 1 mol / L NaOH solution was added dropwise to adjust the pH of the mixture to 7.0 (monitored with a pH meter). A white, flocculent precipitate immediately formed.

[0079] 1.3 Purification

[0080] The mixture was centrifuged at 8000 rpm for 15 min (centrifuge model: Beckman Avanti J-26XP), the supernatant was discarded, and the precipitate was washed three times with ultrapure water. After freeze drying (-50°C, 24 h), it was ground through a 200 mesh sieve to obtain a white powder of ferritin-Al 3+ Composite pore materials.

[0081] 2. Preparation of premix

[0082] 2.1 Main chain dissolution

[0083] Weigh 65 g of PHEAA, 22 g of PVP, and 6 g of HPG, add 500 mL of deionized water, and place in a constant temperature magnetic stirrer (25°C, 600 rpm) and stir for 2 h until a uniform and transparent adhesive solution is formed.

[0084] 2.2 Dispersant addition

[0085] Slowly add 0.8 g of CMC and continue stirring for 30 min. Adjust the pH of the solution to 7.0 (calibrated with a pH meter) with 0.1 mol / L NaOH to obtain a premixed solution.

[0086] 3. Photoresponsive cross-linking reaction

[0087] 3.1 Component Mixing: To the premix, add 12 g of PEGDA, 1.5 g of PDA, and 3 g of Azo-C6 in sequence. Stir magnetically (400 rpm) for 10 min. Transfer the mixture to a three-necked flask and introduce high-purity nitrogen (50 mL / min) for 20 min to remove oxygen.

[0088] 3.2 Initiation of polymerization

[0089] 10 mL of 0.5 wt% ammonium persulfate (APS) solution was added as an initiator, and the mixture was kept in a nitrogen atmosphere and reacted in a water bath at 40° C. for 3 h. After the reaction, the system turned into a translucent viscous sol.

[0090] 4. Functional modification

[0091] 4.1 Nanomaterial Dispersion

[0092] Ferritin-Al 3+ Composite channel powder 4g, NaYF4:Yb 3+ / Tm 3+ 2.5 g of nanoparticles and 0.4 g of Fe3O4 nanoparticles were added to the sol and ultrasonicated (power 300 W, frequency 40 kHz) for 30 min to ensure uniform dispersion of the nanoparticles.

[0093] 4.2 UV irradiation molding

[0094] The mixed solution was injected into a mold (10 cm × 10 cm × 1 cm) and placed in a UV crosslinker (wavelength 365 nm, intensity 15 mW / cm 2 The irradiation distance was controlled at 10 cm and nitrogen was used throughout the process to obtain a light blue elastic gel.

[0095] 5. Secondary cross-linking and post-processing

[0096] 5.1Ca 2+ Cross-linking

[0097] Prepare 0.5% CaCl₂ ethanol solution (v / v): Dissolve 5 g of CaCl₂ in 1 L of anhydrous ethanol. Immerse the gel in the CaCl₂ solution (gel:solution = 1:5, volume ratio) and let it stand at 25°C for 12 h.

[0098] 5.2 Freeze drying and pulverization

[0099] The gel was removed, the surface liquid was absorbed with filter paper, and the gel was placed in a freeze dryer (-50°C, vacuum 10Pa) and dried for 24 hours. After drying, the gel was pulverized in an ultrafine grinder (speed 20,000 rpm) and passed through an 80-100 mesh sieve to obtain a light yellow granular water-retaining agent.

[0100] Example 2

[0101] The specific implementation method is the same as that of Example 1, except that the raw material ratio is: PHEAA 55g, PVP 24g, HPG 7g, PEGDA 14g, composite channel 3g, upconversion nanoparticles 3g, Azo-C6 2g, PDA 2g, CMC 0.6g, and Fe3O4 0.4g. The preparation method is modified: the amount of AlCl3 used in the composite channel preparation is reduced to 0.08 mol, and the remaining steps are the same as those of Example 1. The UV irradiation time is extended to 12 minutes, and the concentration of the CaCl2 solution is increased to 0.6%.

[0102] Example 3

[0103] The specific embodiment is the same as Example 1, except that the raw material ratio is: PHEAA 70g, PVP 20g, HPG 5g, PEGDA 10g, composite channel 5g, upconversion nanoparticles 2g, Azo-C6 4g, PDA 1g, CMC 1.0g, Fe3O4 0.5g. The preparation method is modified: the composite channel reaction time is shortened to 18h, and the pH of the mixed solution is adjusted to 7.2. The freeze-drying temperature is adjusted to -60°C, and the sieved particle size is 100 mesh.

[0104] Comparative Example 1

[0105] The specific implementation method is the same as that of Example 1, except that the raw material ratio is: removing ferritin-Al 3+ The composite channel and other components are the same as those in Example 1. Preparation method: skip the composite channel addition step and directly perform UV cross-linking.

[0106] Comparative Example 2

[0107] The specific implementation method is the same as that of Example 1, except that the raw material ratio is: PEGDA is replaced by N,N'-methylenebisacrylamide (MBA, 10%), and the rest is the same as that of Example 1. Preparation method: The ultraviolet irradiation step is eliminated and heat-induced crosslinking is used instead.

[0108] Comparative Example 3

[0109] The specific implementation method is the same as that of Example 1, except that the raw material ratio is: Fe3O4 nanoparticles are removed, and the rest is the same as that of Example 1.

[0110] 2. Performance Testing

[0111] The water-retaining agents prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following method:

[0112] (1) Biodegradation rate test

[0113] Procedure: Sample (1.0 g) was placed in a nylon mesh bag (pore size 0.1 mm) and buried in humus soil at 40% humidity (25°C incubator). Samples were removed every 30 days, ultrasonically cleaned, freeze-dried, and the residual mass was measured. Degradation rate was calculated as (initial mass - residual mass) / initial mass × 100%. Reference standard: ISO 17556.

[0114] (2) Salt resistance test

[0115] Procedure: Immerse the sample in a 1.0% CaCl₂ solution for 24 hours at 25°C. Drain through a sieve, then weigh the swollen mass. Calculate the water retention rate as follows: swollen mass / initial mass × 100%. Reference standard: GB / T 2419.

[0116] (3) Light-controlled release efficiency

[0117] Steps: The swollen sample (water saturated) was spread on a quartz culture dish (thickness 2 mm); near-infrared light (980 nm, 1 W / cm 2 ) irradiate for 10 min and record the amount of water released; calculate release efficiency = amount of water released / total water absorption × 100%.

[0118] (4) Magnetic recovery rate test

[0119] Procedure: The dispersion (concentration 5 mg / mL) was adsorbed by a magnet (0.5 T) for 10 min; the recovered particles were dried and weighed, and the recovery rate was calculated as: recovered mass / initial mass × 100%.

[0120] (5) Cyclic stability test

[0121] Procedure: Repeat 50 cycles of water absorption (deionized water) - dehydration (60°C oven) - magnetic recovery; measure water retention after the 50th cycle. Reference standard: ASTM D4065.

[0122] (6) Mechanical properties test

[0123] Procedure: Dynamic Mechanical Analyzer (DMA) test: frequency 1 Hz, temperature 25°C; record storage modulus (E') and loss factor (tan δ).

[0124] (7) Performance test results:

[0125] Table 1: Performance test results of various embodiments and comparative examples

[0126]

[0127] As can be seen from Table 1, the comparison of the test data of Examples 1-3 and Comparative Examples 1-3 clearly verifies the breakthrough improvements in environmental compatibility, functional diversity, and structural stability of the new water-retaining agent. In terms of environmental compatibility, Examples 1-3 significantly improve biodegradability by introducing non-ionic backbones (such as PHEAA, PVP, and hydroxypropyl guar gum) and porous structure design, with a 90-day degradation rate of 68%-75%, far higher than that of traditional polyacrylic acid materials (only 18% in Comparative Example 1), fundamentally alleviating the soil pollution problem caused by the non-degradability of traditional water-retaining agents; at the same time, Ferritin-Al 3+ The composite channel construction effectively inhibited the Ca 2+ The destruction of the gel network increases the salt-resistance water retention rate of Examples 1-3 in 1% CaCl2 solution to 78%-85% (comparative example 1 is only 53%), solving the problem of the traditional material's sudden drop in water retention performance in saline-alkali environments. In terms of functional integration, Examples 1-3 combine NaYF4:Yb 3+ / Tm 3+ The photothermal conversion material and azobenzene (Azo-C6) light-responsive switch realize the near-infrared light-triggered controlled release function, with a light-controlled release efficiency of 81%-89%, breaking through the limitation of the single water absorption function of traditional water-retaining agents; and the introduction of the Fe3O4@PDA magnetic core-shell structure gives the material a high-efficiency magnetic recovery ability (recovery rate 95%-97%), which is significantly better than the comparative example 3 (70%) with a non-magnetic design, providing technical support for resource recycling. In terms of structural stability, Examples 1-3 adopt a dynamic double cross-linking strategy (PEGDA covalent cross-linking and Ca 2+ Through ionic crosslinking, the water retention rate remains stable at 90%-93% after 50 water absorption and dehydration cycles (compared to only 58%-60% for the conventional system in Comparative Examples 1-2). The storage modulus is increased to 10-13 MPa, effectively preventing gel network collapse or mechanical fragmentation during long-term use. These data demonstrate that the new water-retaining agent, through innovative molecular design and multi-scale structural regulation, has systematically overcome three major technical bottlenecks: poor environmental friendliness, limited functionality, and structural instability. This provides a high-performance solution for applications such as arid agriculture and saline-alkali land remediation.

[0128] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that variations and improvements are possible without departing from the scope of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A water-retaining agent based on nonionic amide, characterized in that, In terms of mass percentage, the raw materials include: PHEAA: 50-70%; PVP: 20-25%; HPG: 5-8%; PEGDA: 10-15%; Composite pores: 3-5%; Upconversion nanoparticles: 2-3%; Azobenzene derivatives: 2-4%; PDA: 1-2%; CMC: 0.5-1.0%; Fe3O4 nanoparticles: 0.3-0.5%; Wherein, the composite pore is ferritin-Al 3+ Composite channel, the upconversion nanoparticles are NaYF4:Yb 3+ / Tm 3+ .

2. A water-retaining agent according to claim 1, characterized in that The ferritin-Al 3+ The steps for preparing the composite pores include: contacting a recombinant ferritin solution with a glycine-HCl buffer solution containing AlCl3 to obtain a mixed solution; and contacting the mixed solution with NaOH until the pH of the mixed solution reaches 7.

0.

3. The water-retaining agent according to claim 2, characterized in that The volume ratio of the recombinant ferritin solution to the glycine-HCl buffer containing AlCl3 is 1:5, wherein the concentration of the recombinant ferritin solution is 10 mg / mL; and the amount of the AlCl3 substance is 0.1 mol.

4. The water-retaining agent according to claim 2, characterized in that The recombinant ferritin solution was in contact with the glycine-HCl buffer solution containing AlCl 3 for 24 h, and the temperature of the mixed solution was 37° C.

5. The water-retaining agent according to claim 1, characterized in that The azobenzene derivative is Azo-C6.

6. A method for preparing a water-retaining agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Dissolve PHEAA, PVP, and HPG in deionized water and stir until completely dissolved; add CMC and adjust the pH of the solution to 6.8-7.2 to obtain a premixed solution; S2. Add PEGDA and an azobenzene derivative to the premixed solution, introduce nitrogen, and then add ammonium persulfate to obtain a mixed solution; S3, add ferritin-Al to the mixture 3+ Composite pores, upconversion nanoparticles and Fe3O4 nanoparticles, followed by UV irradiation to obtain a gel; S4. Immerse the gel in an ethanol solution containing 0.5% CaCl2, freeze-dry, crush and sieve the solution to obtain a water-retaining agent.

7. The preparation method according to claim 6, characterized in that In step S2, nitrogen was introduced for 20 minutes, and ammonium persulfate was added and the reaction was carried out at a constant temperature of 40° C. for 3 hours.

8. The preparation method according to claim 6, characterized in that In step S3, the wavelength of ultraviolet light irradiation is 365 nm, and the irradiation time is 10 min.

9. The preparation method according to claim 6, characterized in that In step S4, the volume ratio of the gel to the ethanol solution containing 0.5% CaCl2 is 1:5, and the contact time of the gel and the ethanol solution containing 0.5% CaCl2 is 12 hours.

10. The preparation method according to claim 6, characterized in that In step S4, the freeze-drying temperature is -50°C, the time is 24 hours, and the particle size after pulverization and sieving is 80-100 mesh.

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