Preparation method of photo-thermal response type microcapsule

Abstract

The invention discloses a preparation method of a photo-thermal response type microcapsule, which comprises the following steps: adding a polymer capsule wall material into a first solvent, carrying out ultrasonic dissolution to obtain a solution containing the capsule wall material, weighing a second solvent, and recording the second solvent as an anti-solvent; dropwise adding a solvent into an anti-solvent, stirring and mixing to obtain a mixed solution, and treating the mixed solution by using a rotary evaporator to remove the solvent and part of the anti-solvent in the mixed solution to obtain a capsule wall particle dispersion; adding tris (hydroxymethyl) aminomethane into the capsule wall particle dispersion, adjusting the pH value, then adding a graft for grafting reaction, washing after the reaction, and then dispersing in deionized water to obtain a photo-thermal response type capsule wall particle dispersion; adjusting the solid content of the photo-thermal response type capsule wall particle dispersion, mixing with an embedding material solution, and then performing spray drying treatment to obtain the photo-thermal response type microcapsule. The photo-thermal response microcapsule prepared by the invention is relatively good in integrity and high in sphericity degree, and the breakage rate is less than or equal to 10%; and the particle size of the microcapsule is 0.1-100 [mu] m.

Description

Technical Field

[0001] The present invention relates to the technical field of microcapsule preparation. More specifically, it relates to a method for preparing a photothermal-responsive microcapsule. Background Art

[0002] Microcapsule technology, as a technique for encapsulating active substances in tiny containers, has shown great application potential in fields such as drug delivery, self-healing materials, and food preservation. In recent years, with the rapid development of nanotechnology and materials science, stimulus-responsive microcapsules, especially photothermal-responsive microcapsules, have attracted much attention because they can achieve controlled release under external light stimulation [Han Y-B, Shi L-L, Chen Z-G, et al. Preparation and properties of photothermal responsive fragrance microcapsules [J]. Journal of Applied Polymer Science, 2023, 140(41): e54535.]. Photothermal-responsive microcapsules refer to a type of microcapsules whose structure or properties can undergo reversible or irreversible changes under external light irradiation, thereby achieving controlled release of the encapsulated substances. Compared with traditional stimulus-responsive microcapsules such as pH-responsive and temperature-responsive ones, photothermal-responsive microcapsules have the following advantages: (1) Remote controllability: Light, as a non-contact stimulus source, can achieve precise remote control of the release behavior of microcapsules. (2) Spatiotemporal resolution: By adjusting parameters such as the wavelength, intensity, and irradiation time of light, precise spatiotemporal control of microcapsule release can be achieved.(3) Biocompatibility: Near-infrared light (NIR) has good tissue penetration and biocompatibility, making it have broad application prospects in the biomedical field

① Stoia D, Nistor M, Suciu M, et al. NIR photothermal-activated drug-conjugated microcapsules for in vitro targeted delivery and release: An alternative treatment of diabetic retinopathy[J]. International Journal of Pharmaceutics, 2023, 635:122700.; ② Cao Y, Shi J, Wu Z, et al. Gold nanorods / polydopamine-capped hollow hydroxyapatite microcapsules as remotely controllable multifunctional drug delivery platform[J]. Powder Technology, 2020, 372:486-496.; ③ Li H, Lin L, Su S, et al. Enhanced photothermal effect of functionalized HMPDA@AuNPs microcapsules for near-infrared theranostic treatment of tumor[J]. Journal of Materials Science, 2022, 57(15):7694-7705.

[0003] The working principle of the photothermal-responsive microcapsules is mainly based on the photothermal effect of the photothermal conversion materials. When the external light irradiates the microcapsules, the photothermal conversion materials absorb the light energy and convert it into heat energy, resulting in a local temperature increase of the microcapsules. The increase in temperature will trigger behaviors such as phase change, degradation, or swelling of the capsule wall material, thereby changing the permeability of the microcapsules or destroying their structure, and finally realizing the release of the encapsulated substances. Common preparation methods include interfacial polymerization, emulsion polymerization, layer-by-layer self-assembly, microfluidics, etc. Interfacial polymerization is a method of forming a polymer capsule wall on the surface of droplets through an interfacial polymerization reaction by dissolving two monomers containing different reactive groups in two immiscible solvents respectively. Hu et al. prepared polydopamine microcapsules through interfacial polymerization technology, which have photothermal conversion ability and size-dependent semipermeability. The photothermal effect can induce DNA denaturation and rearrangement and simulate the phase separation behavior of membraneless organelles. This microcapsule has important application prospects in the fields of synthetic biology and biomaterials, providing new ideas for exploring primitive abiotic cell structures [Hu C, Chen H, Zheng J, et al. Interfacial polymerization fabricated polydopamine capsules as a step toward a photothermal protocell model[J]. Advanced Functional Materials, 2025, 35(2): 2412408.]. Interfacial polymerization has the advantages of simple operation and easy control of the particle size and wall thickness of the microcapsules, but its disadvantage is the difficulty in selecting experimental monomers [Chen J, Xie J M, Chen M, et al. Study on the preparation of glyphosate isopropylamine salt microcapsules by interfacial polymerization[J]. Journal of Anhui Agricultural Sciences, 2012, 40(27): 13354 - 13357.; Wang D Z. Preparation and properties of osmanthus essential oil microcapsules by interfacial polymerization[D]. Tianjin: Tianjin University of Science and Technology, 2020.].

[0004] Emulsion polymerization is a method of forming microcapsules by dispersing monomers, intelligent materials, emulsifiers, etc. in an aqueous or oily phase through emulsion polymerization reactions. Wen et al. prepared intelligent-responsive microcapsules by Pickering emulsion polymerization for pheromone controlled release. Its encapsulation efficiency reached 80.3%, and the loading amount was 13.3%. It showed good controlled release effect and temperature responsiveness under simulated day-night temperature differences, and was expected to improve the utilization efficiency of pheromones [Wen Y, Yu S, Ge Z, et al. Temperature-responsive microcapsule hydrogel fabricated by Pickering emulsion polymerization for pheromones application[J]. Colloids and Surfaces, A: Physicochemical and Engineering Aspects, 2024, 684: 133127.]. This method can achieve uniform distribution of the photothermal conversion material in the capsule wall, but the particle size distribution of the microcapsules is relatively wide, and it is difficult to control the capsule wall thickness [Yang GX, Song XQ, Ye L, et al. Preparation of pmma / hd phase change heat storage microcapsules by emulsion polymerization[J]. Silk, 2015, 52(4): 9-13.]. Layer-by-layer self-assembly is a method of forming a multi-layered capsule wall by alternately depositing polyelectrolytes or nanoparticles with opposite charges on the template surface through intermolecular forces such as electrostatic interaction and hydrogen bond interaction. Xu et al. prepared intelligent hollow microcapsules composed of polyurethane amine, polystyrene sulfonic acid and gold nanoparticles by layer-by-layer self-assembly technology for multi-stimulus-responsive drug delivery. The microcapsules have thermal, acid and near-infrared light sensitivities, and their drug release behavior is regulated by pH, temperature and near-infrared light irradiation, showing good multi-stimulus response [Xu S, Shi J, Yang L, et al. Hollow PUA / PSS / au microcapsules with interdependent near-infrared / pH / temperature multiresponsiveness[J]. Journal of Applied Polymer Science, 2016, 133(7).]. This method can precisely control the thickness and composition of the capsule wall, but the preparation process is relatively cumbersome and it is difficult to achieve large-scale production [Zulipikel Payizila. Basic research on the controllable preparation of self-assembled polylactic acid microcapsules by spray drying and their applications[D]. Nanning: Guangxi University, 2024.; Tong WY, Gao CY. Preparation of layer-by-layer assembled microcapsules and their intelligent response and substance encapsulation and release properties[J]. Chemical Journal of Chinese Universities, 2008(7): 1285-1298.].The microfluidic method is a method that uses a microfluidic chip to precisely control the flow and mixing of fluids to achieve the controllable preparation of microcapsules. Kaufman et al. prepared graphene oxide microcapsules with photothermal and magnetic responses through microfluidic technology. The microcapsules utilize the photothermal effect of graphene oxide to achieve near-infrared light-triggered drug release, demonstrating application potential in the biomedical field [Kaufman G, Montejo K A, Michaut A, et al. Photoresponsive and magnetoresponsive graphene oxide microcapsules fabricated by droplet microfluidics[J]. ACS Applied Materials & Interfaces, 2017, 9(50):44192-44198.]. This method can prepare microcapsules with good monodispersity and complex structures, but the equipment cost is high, and it is difficult to achieve large-scale production [Pan Y, Xie S, Wang H, et al. Microfluidic construction of responsive photonic microcapsules of cholesteric liquid crystal for colorimetric temperature microsensors[J]. Advanced Optical Materials, 2023, 11(4):2202141.].

[0005] Although photothermal-responsive microcapsules exhibit many advantages and there are various preparation methods, the current preparation technologies still have a series of problems. For example, the operation process is generally complex, it is difficult to achieve continuous production, there are great difficulties in scale-up production, the control accuracy of the microcapsule particle size is insufficient, and the encapsulation efficiency needs to be further improved, etc. These problems limit the large-scale application and commercial promotion of photothermal-responsive microcapsules and urgently need to be solved by scientific researchers through technological innovation and optimization. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method for photothermal-responsive microcapsules. The photothermal-responsive microcapsules prepared by this preparation method have remarkable characteristics such as uniform particle size distribution, high embedding rate, high sphericity, and the microcapsule breakage rate ≤ 10%; they also have good photothermal conversion efficiency and controllable release performance.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows :

[0008] A preparation method for photothermal-responsive microcapsules, comprising the following steps:

[0009] S1. Preparation of the photothermal-responsive capsule wall particle dispersion

[0010] S1-1. Add the polymer capsule wall material into the first solvent and dissolve it by ultrasonic treatment to obtain a solution containing the capsule wall material; separately measure the second solvent, denoted as the anti-solvent;

[0011] S1-2. Drop the solution containing the capsule wall material into the anti-solvent, mix and stir to obtain a mixed solution, and use a rotary evaporator to evaporate the mixed solution to remove the solvent and part of the anti-solvent to obtain the capsule wall particle dispersion;

[0012] S1-3. Add tris(hydroxymethyl)aminomethane (Tris) to the capsule wall particle dispersion to adjust the pH, then add the grafting agent for grafting reaction, wash after the reaction, and then disperse it in deionized water to obtain the photothermal-responsive capsule wall particle dispersion;

[0013] S2. Preparation of the photothermal-responsive microcapsules

[0014] Adjust the solid content of the photothermal-responsive capsule wall particle dispersion, and then perform spray drying treatment to collect the photothermal-responsive microcapsules.

[0015] Preferably, in step S1-1, the polymer capsule wall material is one or more of starch, polylactic acid, polystyrene, chitosan, cellulose, poly(lactic-co-glycolic acid) (PLGA).

[0016] Preferably, in step S1-1, the first solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

[0017] Preferably, the second solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

[0018] Preferably, in step S1-1, the temperature of ultrasonic dissolution is 0-100 °C.

[0019] Preferably, in step S1-2, the volume ratio of the solvent phase to the anti-solvent phase is 0.01-50:1.

[0020] Preferably, in step S1-2, the stirring speed is 200-1500 r / min.

[0021] Preferably, in step S1-2, the stirring time is 1-12 h.

[0022] Preferably, in step S1-3, the pH = 7.5-14.

[0023] Preferably, in step S1-3, the grafted substance is one or more of polydopamine, polypyrrole, N-isopropylacrylamide and its polymers, polyethylene glycol, polyvinyl alcohol, polyacrylic acid, magnetite, polymethacrylic acid, titanium dioxide, cadmium sulfide.

[0024] Preferably, in step S1-3, the temperature of the grafting reaction is 0-100 °C.

[0025] Preferably, in step S1-3, the time of the grafting reaction is 6-48 h.

[0026] Preferably, in step S2, the solid content of the wall particle dispersion is 0.01-5%, the inlet temperature of spray drying is 70-180 °C, the outlet temperature is 45-150 °C, and the air volume intensity is 5-15 L / min.

[0027] Any range described in the present invention includes the end values and any values between the end values, as well as any sub-ranges constituted by any values between the end values or the end values.

[0028] Unless otherwise specified, each raw material in the present invention can be obtained by commercial purchase, and the equipment used in the present invention can be a conventional equipment in the field or can be referred to the existing technology in the field.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) The microcapsules prepared by the present invention can achieve different sustained-release effects according to the change of the photothermal environment and have a photothermal response.

[0031] 2) The microcapsules prepared by the present invention have good integrity, high sphericity, and the breakage rate ≤ 10%; the particle size of the microcapsules is 0.1-100 μm.

[0032] 3) The preparation method of the microcapsules of the present invention has a higher yield, low cost, easily available raw materials, is environmentally friendly, has a simple operation, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0034] Figure 1 It is the TEM image of the photothermal-responsive wall particles in Example 1.

[0035] Figure 2 It is the performance image of the photothermal-responsive wall particles in Example 1 under different light power conditions.

[0036] Figure 3 It is the performance image of the photothermal-responsive wall particles with different concentrations in Example 1.

[0037] Figure 4 SEM image of the unloaded photothermal-responsive microcapsules in Example 1;

[0038] Figure 5 SEM image of the photothermal-responsive microcapsules loaded with congo red in Example 2;

[0039] Figure 6 SEM image of the photothermal-responsive microcapsules loaded with abamectin in Example 3;

[0040] Figure 7 SEM image of the photothermal-responsive microcapsules loaded with pyrimethanil in Example 4;

[0041] Figure 8 SEM image of the photothermal-responsive microcapsules loaded with thiamethoxam in Example 5;

[0042] Figure 9 Sustained release performance diagram of the photothermal-responsive microcapsules loaded with abamectin in Example 3 under different temperature conditions;

[0043] Figure 10 Sustained release performance diagram of the photothermal-responsive microcapsules loaded with pyrimethanil in Example 4 under different temperature conditions;

[0044] Figure 11 Sustained release performance diagram of the photothermal-responsive microcapsules loaded with thiamethoxam in Example 5 under different temperature conditions. Detailed implementation manners

[0045] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0046] As an aspect of the present invention, a preparation method of a photothermal-responsive microcapsule of the present invention includes the following steps:

[0047] S1. Preparation of a photothermal-responsive wall particle dispersion

[0048] S1-1. Add a polymer wall material to a first solvent and dissolve it by ultrasonic treatment to obtain a solution containing the wall material; separately measure a second solvent, denoted as an anti-solvent;

[0049] S1-2. Drop the solution containing the wall material into the anti-solvent, mix and stir to obtain a mixed solution, and use a rotary evaporator to evaporate the mixed solution to remove the solvent and part of the anti-solvent to obtain a wall particle dispersion;

[0050] S1-3. Add tris(hydroxymethyl)aminomethane (Tris) to the vesicle wall particle dispersion to adjust the pH, then add the grafting agent for grafting reaction. After the reaction, wash and then disperse in deionized water to obtain a photothermal-responsive vesicle wall particle dispersion.

[0051] S2. Preparation of photothermal-responsive microcapsules

[0052] Adjust the solid content of the photothermal-responsive vesicle wall particle dispersion and perform spray drying treatment to collect the photothermal-responsive microcapsules.

[0053] According to some embodiments of the present invention, in step S1-1, the polymer vesicle wall material is one or more of starch, polylactic acid, polystyrene, chitosan, cellulose, and poly(lactic-co-glycolic acid) (PLGA).

[0054] According to some embodiments of the present invention, in step S1-1, the first solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

[0055] According to some embodiments of the present invention, the second solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

[0056] According to some embodiments of the present invention, in step S1-1, the temperature of ultrasonic dissolution is 0-100°C.

[0057] According to some embodiments of the present invention, in step S1-2, the volume ratio of the solvent phase to the antisolvent phase is 0.01-50:1.

[0058] According to some embodiments of the present invention, in step S1-2, the stirring speed is 200-1500 r / min.

[0059] According to some embodiments of the present invention, in step S1-2, the stirring time is 1-12 h.

[0060] According to some embodiments of the present invention, in step S1-3, the pH = 7.5-14.

[0061] According to some embodiments of the present invention, in step S1-3, the grafting agent is one or more of polydopamine, polypyrrole, N-isopropylacrylamide, polyethylene glycol, polyvinyl alcohol, polyacrylic acid, iron oxide, polymethacrylic acid, titanium dioxide, and cadmium sulfide.

[0062] According to some embodiments of the present invention, in step S1-3, the temperature of the grafting reaction is 0-100°C.

[0063] According to certain embodiments of the present invention, in step S1-3, the grafting reaction time is 6-48 h.

[0064] According to certain embodiments of the present invention, in step S2, the inlet temperature of the spray drying is 70-180 °C, the outlet temperature is 45-150 °C, and the air volume intensity is 5-15 L / min.

[0065] According to certain embodiments of the present invention,

[0066] Example 1

[0067] A preparation method of a photothermal-responsive microcapsule, comprising the following steps:

[0068] S1. Preparation of a photothermal-responsive capsule wall particle dispersion

[0069] S1-1. Add 0.23 g of the polymer capsule wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the capsule wall material polylactic acid. Measure deionized water and record it as the anti-solvent;

[0070] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min under the condition of 500 r / min to obtain a mixed solution, and use a rotary evaporator to treat the mixed solution to remove tetrahydrofuran and part of the deionized water to obtain a polylactic acid dispersion of capsule wall particles;

[0071] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the polylactic acid dispersion of capsule wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a photothermal-responsive capsule wall particle dispersion.

[0072] S2. Preparation of a photothermal-responsive microcapsule

[0073] S2-1. Adjust the solid content of the photothermal-responsive capsule wall particle dispersion to 0.05%, carry out spray drying treatment, the inlet temperature is 140 °C, the gas flow rate is 8 L / min, and the outlet temperature is 80 °C, and collect the photothermal-responsive microcapsule.

[0074] Figure 1 It is the TEM image of the photothermal-responsive capsule wall particles in Example 1.

[0075] Figure 2 It is the performance diagram of the photothermal-responsive capsule wall material under different light power conditions in Example 1;

[0076] Figure 3 It is the performance diagram of the photothermal-responsive capsule wall material with different concentrations in Example 1;

[0077] Figure 4 SEM image of the unloaded photothermal-responsive microcapsules in Example 1.

[0078] Example 2

[0079] A preparation method of photothermal-responsive microcapsules loaded with congo red, comprising the following steps:

[0080] S1. Preparation of photothermal-responsive capsule wall particle dispersion

[0081] S1-1. Add 0.23 g of the polymer capsule wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the capsule wall material polylactic acid. Measure deionized water and record it as the anti-solvent.

[0082] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min under the condition of 500 r / min to obtain a mixed solution. Use a rotary evaporator to treat the mixed solution to remove tetrahydrofuran and part of the deionized water, and obtain a polylactic acid dispersion of capsule wall particles.

[0083] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the polylactic acid dispersion of capsule wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a photothermal-responsive capsule wall particle dispersion.

[0084] S2. Preparation of photothermal-responsive microcapsules

[0085] S2-1. Adjust the solid content of the photothermal-responsive capsule wall particle dispersion to 0.05%, add 0.0575 g of congo red and carry out spray drying treatment. The inlet temperature is 140 °C, the gas flow rate is 8 L / min, and the outlet temperature is 80 °C. Collect the photothermal-responsive microcapsules loaded with congo red.

[0086] Figure 5 SEM image of the photothermal-responsive microcapsules loaded with congo red in Example 2.

[0087] Example 3

[0088] A preparation method of photothermal-responsive microcapsules loaded with avermectin, comprising the following steps:

[0089] S1. Preparation of photothermal-responsive capsule wall particle dispersion

[0090] S1-1. Add 0.23 g of the polymer wall material polylactic acid into 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the wall material polylactic acid. Measure deionized water and record it as the anti-solvent;

[0091] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, and stir and mix for 30 min under the condition of 500 r / min to obtain a mixed solution. Use a rotary evaporator to process the mixed solution to remove tetrahydrofuran and part of the deionized water, and obtain a dispersion of polylactic acid wall particles;

[0092] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the dispersion of polylactic acid wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a dispersion of photothermal-responsive wall particles.

[0093] S2. Preparation of photothermal-responsive microcapsules

[0094] S2-1. Adjust the solid content of the dispersion of photothermal-responsive wall particles to 0.05%, add 50 ml of 0.03 g of abamectin methanol solution for spray drying, with an inlet temperature of 140 °C, a gas flow rate of 8 L / min, and an outlet temperature of 80 °C, and collect the photothermal-responsive microcapsules loaded with abamectin.

[0095] Figure 6 SEM image of the photothermal-responsive microcapsules loaded with abamectin in Example 3;

[0096] Figure 9 Sustained-release performance diagram of the photothermal-responsive microcapsules loaded with abamectin in Example 3 under different temperature conditions.

[0097] Example 4

[0098] A preparation method of photothermal-responsive microcapsules loaded with pyrifenox includes the following steps:

[0099] S1. Preparation of photothermal-responsive wall particle dispersion

[0100] S1-1. Add 0.23 g of the polymer wall material polylactic acid into 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the wall material polylactic acid. Measure deionized water and record it as the anti-solvent;

[0101] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min at 500 r / min to obtain a mixed solution. Use a rotary evaporator to process the mixed solution to remove tetrahydrofuran and part of deionized water, and obtain a dispersion of polylactic acid as the wall particles;

[0102] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the dispersion of polylactic acid as the wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a dispersion of wall particles with photothermal response.

[0103] S2. Preparation of photothermal-responsive microcapsules

[0104] S2-1. Adjust the solid content of the dispersion of wall particles with photothermal response to 0.05%, add 50 ml of 0.03 g of pyridaben methanol solution for spray drying treatment. The inlet temperature is 140 °C, the gas flow rate is 8 L / min, and the outlet temperature is 80 °C. Collect the obtained photothermal-responsive microcapsules loaded with pyridaben.

[0105] Figure 7 This is the SEM image of the photothermal-responsive microcapsules loaded with pyridaben in Example 4;

[0106] Figure 10 This is the sustained-release performance graph of the photothermal-responsive microcapsules loaded with pyridaben in Example 4 under different temperature conditions.

[0107] Example 5

[0108] A preparation method of a photothermal-responsive microcapsule loaded with thiamethoxam, comprising the following steps:

[0109] S1. Preparation of a dispersion of photothermal-responsive wall particles

[0110] S1-1. Add 0.23 g of the polymer wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the wall material polylactic acid. Measure deionized water and record it as the anti-solvent;

[0111] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min at 500 r / min to obtain a mixed solution. Use a rotary evaporator to process the mixed solution to remove tetrahydrofuran and part of deionized water, and obtain a dispersion of polylactic acid as the wall particles;

[0112] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the polylactic acid dispersion of the capsule wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a photothermal-responsive capsule wall particle dispersion.

[0113] S2. Preparation of photothermal-responsive microcapsules

[0114] S2-1. Adjust the solid content of the photothermal-responsive capsule wall particle dispersion to 0.05%, add 0.03 g of thiamethoxam, and perform spray drying. The inlet temperature is 140 °C, the gas flow rate is 8 L / min, and the outlet temperature is 80 °C. Collect the photothermal-responsive microcapsules loaded with thiamethoxam.

[0115] Figure 7 SEM image of the photothermal-responsive microcapsules loaded with thiamethoxam in Example 5;

[0116] Figure 11 Sustained-release performance diagram of the photothermal-responsive microcapsules loaded with thiamethoxam in Example 5 under different temperature conditions.

[0117] Example 6

[0118] A preparation method of photothermal-responsive microcapsules, comprising the following steps:

[0119] S1. Preparation of photothermal-responsive capsule wall particle dispersion

[0120] S1-1. Add 0.23 g of the organic polymer capsule wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the capsule wall material polylactic acid. Measure deionized water and record it as the anti-solvent;

[0121] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix at 500 r / min for 30 min to obtain a mixed solution. Use a rotary evaporator to treat the mixed solution to remove tetrahydrofuran and part of the deionized water to obtain a polylactic acid dispersion of the capsule wall particles;

[0122] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the polylactic acid dispersion of the capsule wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a photothermal-responsive capsule wall particle dispersion.

[0123] S2. Preparation of photothermal-responsive microcapsules

[0124] S2-1. Adjust the solid content of the photothermal-responsive wall particle dispersion to 0.05%, divide it into three portions, and perform spray drying at an inlet temperature of 140 °C and an outlet temperature of 80 °C with gas flow rates of 5, 8, and 15 L / min respectively to collect the photothermal-responsive microcapsules.

[0125] Example 7

[0126] A method for preparing photothermal-responsive microcapsules, comprising the following steps:

[0127] S1. Preparation of photothermal-responsive wall particle dispersion

[0128] S1-1. Add 0.23 g of the polymer wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the wall material polylactic acid. Measure deionized water and record it as the anti-solvent.

[0129] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min at 500 r / min to obtain a mixed solution. Use a rotary evaporator to treat the mixed solution to remove tetrahydrofuran and part of the deionized water to obtain a polylactic acid dispersion of wall particles.

[0130] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the polylactic acid dispersion of wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a photothermal-responsive wall particle dispersion.

[0131] S2. Preparation of photothermal-responsive microcapsules

[0132] S2-1. Adjust the solid content of the photothermal-responsive wall particle dispersion to 0.05%, divide it into three portions, and perform spray drying at inlet temperatures of 110, 140, and 160 °C respectively, an outlet temperature of 80 °C, and a gas flow rate of 8 L / min to collect the photothermal-responsive microcapsules.

[0133] Example 8

[0134] A method for preparing photothermal-responsive microcapsules, comprising the following steps:

[0135] S1. Preparation of photothermal-responsive wall particle dispersion

[0136] S1-1. Add 0.23 g of the polymer wall material polylactic acid to 100 mL of tetrahydrofuran, and ultrasonically dissolve it at 70 °C to obtain a tetrahydrofuran solution containing the wall material polylactic acid. Measure deionized water and record it as the anti-solvent phase.

[0137] S1-2. Drop the tetrahydrofuran solution of polylactic acid into the anti-solvent at a ratio of 1:20, stir and mix for 30 min at 500 r / min to obtain a mixed solution. Use a rotary evaporator to treat the mixed solution to remove tetrahydrofuran and part of deionized water, and obtain a dispersion of polylactic acid as the capsule wall particles.

[0138] S1-3. Add 10 mmol of tris(hydroxymethyl)aminomethane (Tris) to the dispersion of polylactic acid as the capsule wall particles, adjust the pH to 9, then add polydopamine and react at 30 °C for 24 h. After washing three times, disperse it in deionized water to obtain a dispersion of the capsule wall particles with photothermal response.

[0139] S2. Preparation of microcapsules with photothermal response

[0140] S2-1. Adjust the solid content of the dispersion of the capsule wall particles with photothermal response to 0.05%, divide it into three parts, and carry out spray drying treatment. The inlet temperature is 140 °C, the outlet temperatures are 60, 80, and 100 °C respectively, and the gas flow rate is 8 L / min. Collect the obtained microcapsules with photothermal response.

[0141] Comparative Example 1

[0142] Repeated Example 1: The difference is that the inlet temperature in Step S2-1 is 40 °C.

[0143] The result is that the spray drying process is very slow, the moisture cannot be completely volatilized, and no microcapsules can be collected.

[0144] Comparative Example 2

[0145] Repeated Example 1: The difference is that the inlet temperature in Step S2-1 is 210 °C.

[0146] The result is that the spray drying process is very fast, and there are only a small number of microcapsules in the collection chamber.

[0147] Comparative Example 3

[0148] Repeated Example 1: The difference is that the air volume intensity in Step S2-1 is 20 L / min.

[0149] The result is that due to the excessive air volume, the obtained microcapsules have too small particle size and no microcapsules can be collected.

[0150] Comparative Example 4

[0151] Repeated Example 1: The difference is that the air volume intensity in Step S2-1 is 1 L / min.

[0152] As a result, due to the too small air volume, the obtained microcapsules adhered to the drying tower wall, and the microcapsules could not be collected.

[0153] Comparative Example 5

[0154] Repeat Example 1: The difference is that the outlet temperature in Step S2-1 is 30 °C.

[0155] As a result, due to the too low outlet temperature, the obtained drying process was very slow, the moisture could not be completely volatilized, and the microcapsules could not be collected.

[0156] Comparative Example 6

[0157] Repeat Example 1: The difference is that the pH in Step S1-3 is 2.5.

[0158] As a result, due to the too low pH, the photothermal-responsive capsule wall particle dispersion could not be prepared.

[0159] Comparative Example 7

[0160] Repeat Example 1: The difference is that the reaction temperature in Step S1-3 is -20 °C.

[0161] As a result, due to the too low temperature of the grafting reaction, the photothermal-responsive capsule wall particle dispersion could not be prepared.

[0162] Comparative Example 8

[0163] Repeat Example 1: The difference is that the reaction time in Step S1-3 is 96 h.

[0164] As a result, due to the too long grafting reaction time, the photothermal-responsive capsule wall particle dispersion could not be prepared.

[0165] Comparative Example 9

[0166] Repeat Example 1: The difference is that the solvent-to-antisolvent ratio in Step S1-2 is 150:1.

[0167] As a result, due to the too large solvent-to-antisolvent ratio, the photothermal-responsive capsule wall particle dispersion could not be prepared.

[0168] Comparative Example 10

[0169] Repeat Example 1: The difference is that the rotation speed in Step S1-2 is 3000 r / min.

[0170] As a result, due to the too large rotation speed of the stirring and mixing, the photothermal-responsive capsule wall particle dispersion could not be prepared.

[0171] Comparative Example 11

[0172] Repeat Example 1: The difference is that the reaction time in step S1-2 is 48 h.

[0173] The result is that due to the too long stirring and mixing time, the photothermal-responsive capsule wall particle dispersion cannot be prepared.

[0174] Comparative Example 12

[0175] Repeat Example 1: The difference is that the reaction temperature in step S1-1 is 250 °C.

[0176] The result is that due to the too high reaction temperature, the photothermal-responsive capsule wall particle dispersion cannot be prepared.

[0177] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing a photothermal responsive microcapsule, characterized in that: The steps include: S1. Preparation of photothermal responsive capsule wall particle dispersion S1-1, adding the polymer capsule wall material to the first solvent, dissolving it by ultrasonication, and obtaining a solution containing the capsule wall material; and measuring the second solvent, which is recorded as the anti-solvent; S1-2, adding the solution containing the capsule wall material dropwise into the anti-solvent, mixing and stirring to obtain a mixed solution, and evaporating the mixed solution using a rotary evaporator to remove the solvent and part of the anti-solvent to obtain a capsule wall particle dispersion; S1-3, adding tris(hydroxymethyl)aminomethane to the capsule wall particle dispersion, adjusting the pH, and then adding the grafted material to carry out a grafting reaction, washing after the reaction, and then dispersing in deionized water to obtain a photothermal responsive capsule wall particle dispersion; S2. Preparation of photothermal responsive microcapsules The solid content of the photothermal responsive capsule wall particle dispersion is adjusted, and then spray drying is performed to collect the photothermal responsive microcapsules.

2. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: In step S1-1, the polymer capsule wall material is one or more of starch, polylactic acid, polystyrene, chitosan, cellulose, and polylactic acid-glycolic acid copolymer.

3. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: In step S1-1, the first solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

4. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: The second solvent is one or more of deionized water, methanol, ethanol, acetone, tetrahydrofuran, benzene, and toluene.

5. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: In step S1-1, the temperature of the ultrasonic dissolution is 0-100°C.

6. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: In step S1-2, the volume ratio of the solvent phase to the anti-solvent phase is 0.01-50:

1.

7. The method for preparing the photothermal responsive microcapsule according to claim 1, characterized in that: In step S1-2, the stirring speed is 200-1500 r / min.

8. The method for preparing the photothermal responsive microcapsules according to claim 1, characterized in that: In step S1-2, the stirring time is 1-12 hours.

9. The method for preparing the photothermal responsive microcapsule according to claim 1, characterized in that: In step S1-3, the pH is 7.5-14; Preferably, in step S1-3, the grafted substance is one or more of polydopamine, polypyrrole, N-isopropylacrylamide, polyethylene glycol, polyvinyl alcohol, polyacrylic acid, ferrosoferric oxide, polymethacrylic acid, titanium dioxide, and cadmium sulfide; Preferably, in step S1-3, the temperature of the grafting reaction is 0-100°C; Preferably, in step S1-3, the grafting reaction time is 6-48 hours.

10. The method for preparing the photothermal responsive microcapsule according to claim 1, characterized in that: In step S2, the solid content of the capsule wall particle dispersion is 0.01-5%, the inlet temperature of the spray drying is 70-180°C, the outlet temperature is 45-150°C, and the air volume intensity is 5-15 L / min.

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