Temperature-sensitive regulation molybdenum disulfide composite nano material and application thereof in crop cold damage control

Abstract

The invention discloses a temperature-sensitive regulation molybdenum disulfide composite nano material and application thereof in crop cold damage control, and belongs to the technical field of anti-cold agents. The preparation method comprises the following steps: mixing monomers (N-isopropylacrylamide and N-tert-butyl acrylamide), a cross-linking agent, a surfactant and a MoS2 dispersion liquid, and heating to react for a period of time; then adding an initiator, and continuously reacting for a period of time; and after the reaction is finished, cooling and dialyzing to obtain the temperature-sensitive regulation and control molybdenum disulfide composite nano material. The composite nano material is dispersed in water to prepare a suspension, and the suspension is applied to crops such as corn and soybean plants in a foliage spraying manner, so that the cold resistance of the crops is enhanced, and the biomass of the crops such as the corn and the soybean which are damaged by cold is improved. The method is simple and efficient, and has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel crop antifreeze agents, and particularly relates to a temperature-sensitive regulated molybdenum disulfide composite nanomaterial and its application in crop cold damage control. Background Art

[0002] The continuous growth of the global population has led to a significant increase in food demand. However, frequent low-temperature freezing disasters pose a serious threat to global food security, and their occurrence frequency and impact range are expanding year by year. In current agricultural practices, chemical antifreeze agents, as a conventional means to enhance crop cold tolerance, may induce phytotoxic reactions due to excessive application or improper operation, thereby hindering their normal physiological processes and even leading to risks of ecological environmental pollution. Specifically: Reported cold-resistant reagents include abscisic acid (ABA), salicylic acid (SA), betaine, polyamines, calcium ions, ethephon, proline, chitosan, spermidine, sodium nitroprusside (nitric oxide donor), etc. These substances have all been applied in plant stress resistance, especially in cold resistance. However, high concentrations of abscisic acid may inhibit plant growth, and it has a high cost and is easily affected by environmental degradation; excessive use of salicylic acid may cause oxidative damage, and its effect depends on the application concentration and environmental conditions; betaine has limited effects on some crops and requires multiple applications to increase costs; polyamines (such as putrescine) are easily decomposed at high or low temperatures, and excessive amounts lead to cytotoxicity; calcium ions (Ca 2+ ) need to have an antagonistic effect with other elements, and the concentration needs to be precisely regulated; ethephon (ETH) may accelerate senescence; there is a risk of phytotoxicity to sensitive crops (such as tomatoes); the exogenous application efficiency of proline is low, and it needs to be used in coordination with other stress-resistant substances; the molecular weight of chitosan affects the effect and may change the soil microbial community; spermidine has a high cost and poor stability and requires special storage conditions; sodium nitroprusside produces toxicity in excess and is easily decomposed under light, and it needs to be stored away from light.

[0003] Therefore, the development of a new type of plant cold-resistant preparation with both biological safety and high functional efficiency has become an urgent need in modern agriculture. Summary of the Invention

[0004] [Technical Problem]

[0005] Provide a temperature-sensitive regulated molybdenum disulfide composite nanomaterial and apply it in crop cold damage regulation.

[0006] [Technical Solution]

[0007] The present invention provides a temperature-sensitive regulated molybdenum disulfide composite nanomaterial for crop cold damage regulation, and the preparation method of the temperature-sensitive regulated molybdenum disulfide composite nanomaterial comprises the following steps:

[0008] Mix the monomer, crosslinker, surfactant with the MoS2 dispersion, and heat the mixture for a period of time; then add the initiator and continue the reaction for a period of time; after the reaction is completed, cool and dialyze to obtain a thermosensitive regulated molybdenum disulfide composite nanomaterial, denoted as P(NIPAm-TBA)-MoS2 NMs (abbreviated as PNT-MoS2 NMs).

[0009] Among them, the monomer is N-isopropylacrylamide (NIPAm) and N-tert-butylacrylamide (TBA).

[0010] In one embodiment of the present invention, the mass ratio of N-isopropylacrylamide to N-tert-butylacrylamide in the monomer is (2-4):1. Specifically, 3:1 can be selected.

[0011] In one embodiment of the present invention, the crosslinker is N,N'-methylenebisacrylamide (BIS).

[0012] In one embodiment of the present invention, the mass fraction of the crosslinker relative to the monomer is 2%-5%. Further, 2%-3% can be selected.

[0013] In one embodiment of the present invention, the surfactant is sodium dodecyl sulfate (SDS).

[0014] In one embodiment of the present invention, the mass fraction of the surfactant relative to the monomer is 2%-5%. Further, 3%-5% can be selected.

[0015] In one embodiment of the present invention, the concentration of the MoS2 dispersion is 0.1-1.0 mg / mL. Specifically, 0.5 mg / mL can be selected.

[0016] In one embodiment of the present invention, the mass fraction of MoS2 relative to the monomer is 2%-5%. Further, 3%-5% can be selected.

[0017] In one embodiment of the present invention, the temperature of the heating reaction is 60-90 °C, and specifically, 70 °C can be selected.

[0018] In one embodiment of the present invention, the heating reaction time is 20-60 min. Specifically, 30 min can be selected.

[0019] In one embodiment of the present invention, the initiator is selected from any one or more of the following: ammonium persulfate (APS), azobisisobutyronitrile (AIBN), potassium persulfate (KPS).

[0020] In one embodiment of the present invention, the mass fraction of the initiator relative to the monomer is 5%-8%.

[0021] In one embodiment of the present invention, an initiator is added and the reaction continues for 3 - 6 h. Specifically, 4 h can be selected.

[0022] In one embodiment of the present invention, PNT-MoS2 NMs exhibit an irregular network structure and have a smooth surface.

[0023] In one embodiment of the present invention, the preparation method of the PNT-MoS2 NMs specifically includes:

[0024] The monomers N-isopropylacrylamide (NIPAm), N-tert-butylacrylamide (TBA), the crosslinking agent N,N'-methylenebisacrylamide (BIS), and the surfactant sodium dodecyl sulfate (SDS) are dissolved in a 0.5 mg / mL MoS2 dispersion. After mixing evenly, it is heated to 70 °C under nitrogen protection and kept warm for 30 minutes. Subsequently, an ammonium persulfate (APS) solution is quickly injected into the reaction solution, and the reaction continues for 4 hours. Finally, after the reaction ends, the naturally cooled product is loaded into a dialysis bag (MWCO = 10000, 45 mm) and placed in a large beaker containing 5 L of ultrapure water for dialysis for 5 days, during which the ultrapure water is changed 3 times a day to remove unreacted monomers and surfactants, obtaining purified PNT-MoS2 NMs.

[0025] The present invention also provides the application of the above temperature-sensitive regulated molybdenum disulfide composite nanomaterial in crop chilling injury control.

[0026] In one embodiment of the present invention, the nanomaterial is a PNT-modified molybdenum disulfide nanocomposite.

[0027] In one embodiment of the present invention, the application is to disperse PNT-MoS2 NMs in water to obtain a suspension; then the suspension is sprayed on the crop leaves.

[0028] In one embodiment of the present invention, the crop is a vegetable. Specifically, it includes green leafy vegetables such as lettuce, spinach, coriander, and green vegetables.

[0029] In one embodiment of the present invention, the plant is a crop, including corn, soybean, rice, etc.

[0030] In one embodiment of the present invention, the concentration of the suspension is 200 - 500 mg / L; preferably 500 mg / L.

[0031] The present invention also provides the application of the above temperature-sensitive regulated molybdenum disulfide composite nanomaterial in the preparation of a crop antifreeze agent.

[0032] In one embodiment of the present invention, the crop antifreeze agent further includes any one or more of the following: inorganic salts, saccharide substances, organic alcohol substances, etc.

[0033] In one embodiment of the present invention, the inorganic salts include any one or more of the following: potassium dihydrogen phosphate, potassium nitrate.

[0034] In one embodiment of the present invention, the saccharide substances include any one or more of the following: glucose, sucrose, trehalose.

[0035] In one embodiment of the present invention, the organic alcohol substances include any one or more of the following: propylene glycol, ethylene glycol.

[0036] The main content of the present invention includes:

[0037] (1) Prepare temperature-sensitive regulated molybdenum disulfide composite nanomaterials (PNT-MoS2 NMs);

[0038] (2) Through in vitro experiments, explore the photothermal properties of molybdenum disulfide nanomaterials (MoS2 NMs), PNT-MoS2 NMs, and molybdenum disulfide large particles (MoS2 BPs) at different concentrations;

[0039] (3) Through in vitro experiments, explore the temperature-sensitive properties of PNT-MoS2 NMs;

[0040] (4) By means of foliar spraying, apply different concentrations of MoS2 NMs, PNT-MoS2 NMs, and plant antifreeze agents to corn and soybeans, and explore their effects on enhancing the cold resistance of corn and soybeans.

[0041] [Beneficial effects]

[0042] The present invention disperses PNT-MoS2 NMs in water to obtain a suspension; then sprays the suspension on the leaves of corn and soybeans. By means of foliar spraying, the cold resistance of corn and soybeans can be regulated, the cold resistance of corn and soybeans can be enhanced, and the above-ground and underground biomass of cold-damaged corn and soybean seedlings can be significantly increased, having excellent application prospects. The effects of different materials on enhancing the cold resistance of corn and soybeans are as follows: 500 mg / L PNT-MoS2 NMs > 200 mg / L PNT-MoS2 NMs ≈ 200 mg / L MoS2 NMs > 1667 mg / L plant antifreeze agent > 500 mg / L MoS2 NMs.

[0043] Furthermore, the temperature-sensitive regulated molybdenum disulfide composite nanomaterials have a significant temperature-sensitive regulation function, which can avoid photothermal damage caused by excessive use. Description of the drawings

[0044] Figure 1(A) SEM images of PNT-MoS2 NMs; (B) elemental distribution images of PNT-MoS2 NMs.

[0045] Figure 2 Photothermal heating curves (A-C) of different concentrations of MoS2 NMs, PNT-MoS2 NMs, and MoS2 BPs under sunlight irradiation, and the photothermal heating curve (D) of 500 mg / L MoS2 NMs, PNT-MoS2 NMs, MoS2 BPs, and deionized water under sunlight irradiation.

[0046] Figure 3 Relationship between the hydrodynamic diameter and temperature of 500 mg / L PNT-MoS2 NMs (A) and phenotypic images of PNT-MoS2 NMs at 4 °C - 25 °C - 4 °C (B).

[0047] Figure 4 Effects of foliar application of MoS2 NMs, PNT-MoS2 NMs, PNT, PNT+Mo+S, and plant antifreeze agents on (A) aboveground and underground biomass of maize and (B) aboveground and underground biomass of soybean under low temperature stress. Detailed implementation manners

[0048] The following further describes the present invention in conjunction with specific embodiments.

[0049] The embodiments provided below are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit their execution order. Obvious improvements made by those skilled in the art to the present invention in combination with the existing well-known common sense also fall within the scope of protection required by the present invention.

[0050] The structure of N-isopropylacrylamide involved in the present invention is shown as follows:

[0051]

[0052] The structure of N-tert-butylacrylamide involved in the present invention is shown as follows:

[0053]

[0054] The structure of N,N'-methylenebisacrylamide involved in the present invention is shown as follows:

[0055]

[0056] The structure of sodium dodecyl sulfate involved in the present invention is shown as follows:

[0057]

[0058] Preparation of Thermosensitive Regulated Molybdenum Disulfide Composite Nanomaterials in Example 1

[0059] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat to 70 °C under nitrogen protection and keep warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and the reaction continues for 4 hours. Finally, after the reaction is completed, load the naturally cooled product into a dialysis bag (MWCO = 10000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified molybdenum disulfide composite nanomaterials, denoted as PNT-MoS2 NMs.

[0060] Material Characterization:

[0061] Characterize the morphology and elemental distribution of PNT-MoS2 NMs using a scanning electron microscope (SEM). The results show that PNT-MoS2 NMs exhibit an irregular network structure, with no significant difference from the SEM image of PNT NMs in the illustration, and the surface is smooth, proving that MoS2 NMs are wrapped in PNT NMs. At the same time, the addition of MoS2 NMs does not change the structure of PNT NMs ( Figure 1 A). Figure 1 Figure B is the SEM-EDS elemental distribution image of PNT-MoS2 NMs. It can be seen that sulfur (S) and molybdenum (Mo) elements are evenly distributed in PNT NMs and are in the same position, further indicating that MoS2 NMs are evenly distributed in PNT NMs.

[0062] Photothermal Properties of Different Concentrations of MoS2 NMs, PNT-MoS2 NMs, and MoS2 BPs in Example 2

[0063] Disperse the PNT-MoS2 NMs obtained in Example 1 in water to prepare PNT-MoS2 NMs suspensions with concentrations of 50, 100, 200, and 500 mg / L.

[0064] Disperse molybdenum disulfide nanomaterials (MoS2 NMs) and molybdenum disulfide large particles (MoS2 BPs) in water to prepare solutions with concentrations of 50, 100, 200, and 500 mg / L.

[0065] Take 2 mL of the solution and place it in a centrifuge tube. Under sunlight irradiation, use an infrared thermal imager to record the temperature change and the imaging image, with pure water as the control.

[0066] Among them, molybdenum disulfide nanomaterials (MoS2 NMs) were prepared by the following method: Dissolve 0.35 g of Na2MoO4·2H2O in 60 mL of ultrapure water, and use 1 mol / L HCl to adjust the pH to 6.5, and stir for 10 minutes. At the same time, dissolve 0.4 g of L-cysteine in 80 mL of ultrapure water. After complete dissolution, mix the above two solutions and stir for 40 minutes. Subsequently, transfer the mixed solution to a stainless steel hydrothermal reaction kettle with a 200 mL Teflon inner liner and react at 200 °C for 15 hours. After the reaction, centrifuge to collect the black precipitate, and wash it alternately with deionized water and absolute ethanol for multiple times. Finally, dry it at 80 °C for 12 hours to obtain molybdenum disulfide nanomaterials. The MoS2 NMs exhibit a typical flaky structure with an average size of 173.82 ± 15.20 nm.

[0067] The purity of molybdenum disulfide large particles (MoS2 BPs) is GR, and the CAS is 1317-33-5, which can be purchased from Beijing Innochem Science & Technology Co., Ltd.

[0068] The results show that under the same irradiation time, as the concentrations of MoS2 NMs and PNT-MoS2 NMs increase, their temperatures also increase significantly. The temperature of 500 mg / L MoS2 NMs rises to 42.5 °C after 200 min of sunlight irradiation; the temperature of PNT-MoS2 NMs reaches 34 °C after 200 min of sunlight irradiation at a concentration of 500 mg / L ( Figure 2 A, B). The photothermal effects of the three materials are in the order of MoS2 NMs > PNT-MoS2 NMs > MoS2 BPs ( Figure 2 C, D).

[0069] Example 3 Thermosensitive performance of PNT-MoS2 NMs

[0070] Disperse the PNT-MoS2 NMs obtained in Example 1 in water to prepare a 500 mg / L PNT-MoS2 NMs suspension.

[0071] Ice-bath and ultrasonicate the suspension for 1 h to make it evenly dispersed. Subsequently, use a nanoparticle size analyzer to measure its hydrodynamic diameter at different temperatures (6 - 38 °C), and measure it once every 2 °C. Before the test, keep the PNT-MoS2 NMs solution at the test temperature for 10 minutes to achieve swelling equilibrium. Measure 4 times at each temperature, and take the average value as the hydrodynamic diameter.

[0072] The results showed that the hydrodynamic diameter of PNT-MoS2 NMs decreased with the increase of temperature, showing good thermosensitive properties. At lower temperatures, hydrogen bonds were formed between the amide groups in PNT-MoS2 NMs and water molecules, causing the molecular chains to fully stretch, resulting in a larger hydrodynamic diameter; when the temperature exceeded 24.2 °C, the interaction between isopropyl groups increased, and the hydrogen bond interaction between amide groups and water molecules weakened. PNT-MoS2 NMs showed a contracted state, resulting in a smaller hydrodynamic diameter ( Figure 3 A). When the ambient temperature changed from 4 °C to 25 °C and then back to 4 °C, PNT-MoS2 NMs could undergo reversible phase transitions, specifically manifested as the transformation of "solution-solid-solution" ( Figure 3 B).

[0073] Example 4 Application of PNT-MoS2 NMs in regulating the cold resistance of corn and soybean

[0074] The PNT-MoS2 NMs obtained in Example 1 were dispersed in water to prepare 200 and 500 mg / L PNT-MoS2 NMs suspensions.

[0075] Maize (Zea mays L.) and soybean (Glycine max L.) were used as the test crops. First, the seeds of maize (Dafeng 30) and soybean (Zhonghuang 57) were disinfected with 5% sodium hypochlorite solution for 5 min, and then rinsed with deionized water several times. The disinfected seeds were soaked in deionized water for 6 h (maize) and 3 h (soybean) respectively, and then placed in a seedling tray lined with moist filter paper and germinated in the dark at a temperature of 25 °C. When the maize and soybean seedlings grew to about 3 cm, maize and soybean seedlings with consistent growth were selected and transplanted into flower pots containing 600 g of soil. When the maize had three leaves and one core and the soybean had two pairs of compound leaves unfolded, suspensions of PNT-MoS2 NMs at different concentrations (200 and 500 mg / L) were sprayed on their leaves at a rate of 5 mL per day for 5 consecutive days. The healthy control group (Healthy) and the chilling injury control group (Cold) were sprayed with an equal volume of deionized water. Healthy plants sprayed with 500 mg / L PNT-MoS2 NMs suspension (Healthy+5PMo), 500 mg / L PNT suspension (500PNT), 500 mg / L PNT+Na2SO4+Na2MoO4 suspension (500PNT+Mo+S), and 1667 mg / L commercially available plant antifreeze (Plant antifreeze, commercial recommended concentration) were used as controls. Two days later, the maize and soybean were placed in a light incubator for low temperature stress, with the day / night temperature set at 10 / 8 °C, the light / dark cycle at 14 / 10 h, the relative humidity at 60% ± 5%, and the light intensity at 16800 Lux. The day / night temperature in the incubator of the healthy control group was 25 / 20 °C, and the other environmental conditions remained the same. After one week, the photosynthetic parameters, chlorophyll fluorescence parameters, and relative chlorophyll content of maize and soybean were measured. Then, destructive sampling was carried out, and the fresh weight of the crops was recorded.

[0076] The results showed that foliar application of 200 mg / L MoS2 NMs, 200 mg / L PNT-MoS2, 500 mg / L PNT-MoS2, and plant antifreeze all significantly increased the aboveground biomass and underground biomass of chilling-injured maize and soybean seedlings. Among them, the 500 mg / L PNT-MoS2 treatment group showed the best cold resistance performance, significantly increasing the aboveground biomass (69%, 41%) and underground biomass (142%, 76%) of chilling-injured maize and soybean seedlings, which was better than the equivalent amount of MoS2 NMs, PNT, PNT+Mo+S, and plant antifreeze ( Figure 4 ). The results showed that 500 mg / L PNT-MoS2 had the best effect on enhancing the cold resistance of maize and soybean, and was significantly better than the enhancement effect of traditional plant antifreeze. The specific results are shown in Table 1.

[0077] Table 1 Results of Different Antifreeze Agents in Regulating the Cold Resistance of Maize and Soybean

[0078]

[0079] Example 5

[0080] Dissolve 0.76 g of monomer N-isopropylacrylamide (NIPAm), 0.38 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N’-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, load the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0081] Example 6

[0082] Dissolve 0.91 g of monomer N-isopropylacrylamide (NIPAm), 0.23 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N’-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, load the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0083] Example 7

[0084] Dissolve 0.91 g of monomer N-isopropylacrylamide (NIPAm), 0.23 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the potassium persulfate (KPS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, load the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0085] Example 8

[0086] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, load the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0087] Example 9

[0088] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.02 g of crosslinker N,N'-methylenebisacrylamide (BIS), and 0.04 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat to 70 °C under nitrogen protection and keep warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days, replacing the ultrapure water 3 times a day during this period to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0089] Example 10

[0090] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinker N,N'-methylenebisacrylamide (BIS), and 0.03 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat to 70 °C under nitrogen protection and keep warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days, replacing the ultrapure water 3 times a day during this period to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0091] Example 11

[0092] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.03 g of surfactant sodium dodecyl sulfate (SDS) in 400 mL of 0.1 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days, changing the ultrapure water 3 times a day during this period to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0093] Example 12

[0094] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.03 g of surfactant sodium dodecyl sulfate (SDS) in 40 mL of 1 mg / mL MoS2 dispersion. After mixing evenly, heat it to 70 °C under nitrogen protection and keep it warm for 30 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days, changing the ultrapure water 3 times a day during this period to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0095] Example 13

[0096] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.03 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 90 °C under nitrogen protection and keep it warm for 20 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0097] Example 14

[0098] Dissolve 0.86 g of monomer N-isopropylacrylamide (NIPAm), 0.28 g of N-tert-butylacrylamide (TBA), 0.03 g of crosslinking agent N,N'-methylenebisacrylamide (BIS), and 0.03 g of surfactant sodium dodecyl sulfate (SDS) in 80 mL of 0.5 mg / mL MoS2 dispersion. After mixing evenly, heat it to 60 °C under nitrogen protection and keep it warm for 60 minutes. Subsequently, quickly inject the ammonium persulfate (APS) solution (0.06 g, dissolved in 5 mL of ultrapure water) into the reaction solution, and continue the reaction for 4 hours. Finally, after the reaction is completed, put the naturally cooled product into a dialysis bag (MWCO = 10,000, 45 mm), and place it in a large beaker containing 5 L of ultrapure water for dialysis for 5 days. During this period, change the ultrapure water 3 times a day to remove unreacted monomers and surfactants, and obtain purified PNT-MoS2 NMs.

[0099] Example 15: Application of PNT-MoS2 NMs to Regulate the Cold Resistance of Rice

[0100] Disperse the PNT-MoS2 NMs obtained in Example 1 in water to prepare a 500 mg / L PNT-MoS2 NMs suspension; then apply it to the leaves of rice, and the experimental process is the same as that in Example 4.

[0101] The results show that PNT-MoS2 NMs have the effect of enhancing the cold resistance of rice.

[0102] Example 16: Application of PNT-MoS2 NMs to Regulate the Cold Resistance of Vegetables

[0103] The PNT-MoS2 NMs obtained in Example 1 were dispersed in water to prepare a 500 mg / L PNT-MoS2 NMs suspension; then it was applied to the leaves of vegetables (green leafy vegetables such as lettuce, spinach, coriander, and green vegetables), and the experimental process was the same as that in Example 4.

[0104] The results showed that PNT-MoS2 NMs had the effect of enhancing the cold resistance of various vegetables.

[0105] Application of thermosensitive regulated molybdenum disulfide composite nanomaterials in the preparation of crop antifreezes

[0106] A crop antifreeze contains the following components: the thermosensitive regulated molybdenum disulfide composite nanomaterials obtained in Example 1, inorganic salts, saccharide substances, and organic alcohol substances. Among them: the inorganic salt is potassium dihydrogen phosphate, the saccharide substance is trehalose, and the organic alcohol substance is propylene glycol.

[0107] Application of thermosensitive regulated molybdenum disulfide composite nanomaterials in the preparation of crop antifreezes

[0108] A crop antifreeze contains the following components: the thermosensitive regulated molybdenum disulfide composite nanomaterials obtained in Example 1, inorganic salts, saccharide substances, and organic alcohol substances. Among them: the inorganic salt is potassium nitrate, the saccharide substances are glucose and sucrose, and the organic alcohol substance is ethylene glycol.

[0109] The examples provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit their execution order. Obvious improvements made by those skilled in the art in combination with the existing common general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. A temperature-sensitive regulated molybdenum disulfide composite nanomaterial for crop chilling injury regulation, characterized in that, The preparation method of the temperature-sensitive regulated molybdenum disulfide composite nanomaterial comprises the following steps: Mix a monomer, a crosslinking agent, a surfactant and a MoS2 dispersion, and heat for reaction for a period of time; then add an initiator and continue the reaction for a period of time; after the reaction is completed, cool and dialyze to obtain the temperature-sensitive regulated molybdenum disulfide composite nanomaterial; Wherein, the monomer is N-isopropylacrylamide, N-tert-butylacrylamide.

2. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, characterized in that The mass ratio of N-isopropylacrylamide to N-tert-butylacrylamide in the monomer is (2-4):

1.

3. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, wherein The crosslinking agent is N,N'-methylenebisacrylamide, and the mass fraction of the crosslinking agent relative to the monomer is 2%-5%.

4. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, wherein, The surfactant is sodium dodecyl sulfate, and the mass fraction of the surfactant relative to the monomer is 2%-5%.

5. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, characterized in that, The concentration of the MoS2 dispersion is 0.1-1.0 mg / mL.

6. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, characterized in that, The mass fraction of MoS2 relative to the monomer is 2%-5%.

7. The temperature-sensitive regulated molybdenum disulfide composite nanomaterial according to claim 1, characterized in that The temperature of the heating reaction is 60-90 °C, and the time is 20-60 min.

8. The temperature-responsive regulated molybdenum disulfide composite nanomaterial according to claim 1, wherein, The initiator is selected from any one or more of the following: ammonium persulfate, azobisisobutyronitrile, potassium persulfate.

9. The thermosensitive regulation molybdenum disulfide composite nanomaterial according to claim 1, wherein The mass fraction of the initiator relative to the monomer is 5%-8%.

10. The temperature-sensitive regulated molybdenum disulfide composite nanomaterial according to claim 1, characterized in that, Add the initiator and continue the reaction for 3-6 h.

11. Application of the temperature-sensitive regulated molybdenum disulfide composite nanomaterial according to any one of claims 1-10 in crop chilling injury control.

12. The application according to claim 11, characterized in that The said application is to disperse PNT-MoS2 NMs in water to obtain a suspension; then spray the suspension on the crop leaves.

13. The application according to claim 11, characterized in that, The said crops are vegetables, corn, soybeans, rice.

14. The application according to claim 11, wherein, The concentration of the suspension is 200-500 mg / L.

15. Application of the temperature-sensitive regulated molybdenum disulfide composite nanomaterial according to any one of claims 1-10 in the preparation of a crop antifreeze.

16. The application according to claim 15, characterized in that, The said crop antifreeze further comprises any one or more of the following: inorganic salts, saccharide substances, organic alcohol substances; wherein: The inorganic salts include any one or more of the following: potassium dihydrogen phosphate, potassium nitrate; The saccharide substances include any one or more of the following: glucose, sucrose, trehalose; The organic alcohol substances include any one or more of the following: propylene glycol, ethylene glycol.

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