pH-responsive high-temperature-resistant hybrid intelligent drug release microcapsule, preparation method thereof and application thereof in power insulation materials

Abstract

This invention provides a pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsule, its preparation method, and its application in electrical insulation materials, relating to the field of electrical insulation materials. The preparation method of the microcapsules of this invention includes the following steps: weighing chitosan and adding it to an aqueous acetic acid solution, stirring to obtain an acidic chitosan solution; adding an isothiazolinone antibacterial agent solution dropwise to the acidic chitosan solution, performing high-speed shearing and ultrasonic dispersion to obtain a nano / submicron emulsion; adding tetraethyl orthosilicate dropwise to the emulsion, stirring, adjusting the pH value to form a hybrid gel shell; dispersing the hybrid gel shell in anhydrous ethanol; adding a silane coupling agent; adding a zinc salt solution, stirring to obtain a microcapsule slurry; adding the microcapsule slurry to a growth solution, and reacting to obtain the target microcapsules. The microcapsules of this invention have a core-shell-skin three-layer structure and, when used in outdoor electrical insulation materials, can achieve intelligent response and long-term inhibition of algae, mold, and microbial attachment and growth.

Description

Technical Field

[0001] This invention relates to the field of electrical insulation materials, and in particular to a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule, its preparation method, and its application in electrical insulation materials. Background Technology

[0002] Outdoor electrical insulation equipment (such as ceramic insulators and composite insulators) is highly susceptible to algae and mold growth due to prolonged exposure to humid environments. According to current research, this biofouling absorbs moisture and inorganic salts, forming conductive pathways on the insulator surface and potentially causing flashover accidents, seriously threatening power grid safety.

[0003] Currently, the main solution to this problem relies on adding bactericides to coatings or rubber, but this has the following significant drawbacks: (1) Organic antifungal agents are lost quickly and have a short lifespan: Although commonly used organic antifungal agents such as DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) have high bactericidal efficiency, they are prone to "leaching" under outdoor rainwater rinsing, resulting in an effective protection period of less than 2 years, which cannot meet the 7-10 year maintenance cycle requirements of power equipment.

[0004] (2) Poor temperature resistance and difficult to process: Many high-efficiency organic antifungal agents or ordinary polymer microcapsules cannot withstand the high temperature (usually 150℃-170℃) during the vulcanization of silicone rubber (HTV), which causes the agent to decompose or the capsule to break and become ineffective during processing.

[0005] (3) Limitations of inorganic and photocatalysts: Copper ions (Cu) 2+ Although it resists algae, it can easily cause discoloration (blackening / greening) of the insulator surface and reduce surface resistance; simple photocatalysts (such as TiO2) are ineffective on cloudy or rainy days or on the backlit side and cannot cope with all-weather biological erosion.

[0006] Although microencapsulation technology has been used for sustained-release bactericides, their shells are mostly pure polymers, which cannot withstand the high temperatures of silicone rubber vulcanization. Inorganic-coated microcapsules, while heat-resistant, lack environmental responsiveness, leading to premature leakage or failure to release the agent as needed. Currently, there is no microencapsulation system that combines high-temperature stability, pH-intelligent response, high insulation, and long-lasting antimicrobial properties suitable for outdoor power insulation applications. Summary of the Invention

[0007] In view of this, the present invention proposes a pH-responsive, high-temperature resistant hybrid smart drug release microcapsule and its application in electrical insulation materials.

[0008] This invention designs a composite microcapsule (Z-pH-MC) with a three-layer "core-shell-skin" structure, combining the high efficiency of organic bactericides, the heat resistance of an inorganic framework, and the auxiliary protective function of zinc oxide to achieve an intelligent mechanism of "locking in the drug at high temperatures and automatically releasing it upon contact with acid." The core of this invention is not to provide new bactericidal active substances, but to construct an environmentally responsive carrier system. Through the multi-level structural design of the microcapsule, it achieves spatiotemporal controllable release of existing high-efficiency bactericides (isothiazolinones), thereby solving the problems of rapid loss and thermal inactivation under harsh operating conditions.

[0009] 1. Structural Composition (1) Core: High concentration of DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one). As the core bactericidal "ammunition", it has a broad-spectrum killing effect on molds and algae.

[0010] (2) Shell: Modified chitosan / silica (SiO2) interpenetrating network structure.

[0011] (3) Hedgehog Armor: Hedgehog nano zinc oxide provides zinc ion release and physical damage to assist in antibacterial action, with a dual function.

[0012] This invention utilizes the sol-gel method to introduce an inorganic SiO2 rigid framework between pH-sensitive chitosan polymer chains. The hedgehog-like nano-zinc oxide armor provides triple functionality.

[0013] On the one hand, it has a temperature-resistant function: the SiO2 framework supports the shell, raising its thermal decomposition temperature to over 200℃, ensuring it does not crack during rubber vulcanization; on the other hand, it has a smart response function: the shell retains the protonation properties of chitosan. When algae / molds grow and secrete organic acids (oxalic acid, citric acid, pH < 6.5), the shell swells, the micropores open, and the internal agents are released.

[0014] (4) Skin: Nano-ZnO (nano-hedgehog) chemically grafted onto the surface. Nano-ZnO is anchored to the outermost layer of the microcapsule using a silane coupling agent. On the one hand, it provides insulation and safety: ZnO is a semiconductor and, compared to metallic copper powder, does not reduce the volume resistivity of the substrate. On the other hand, it serves as the first line of defense: shielding against ultraviolet radiation to protect the internal organic agents and providing basic antibacterial capabilities through photocatalysis.

[0015] Main mechanism: (1) The amino group (-NH2) of chitosan in the shell is protonated to -NH under acidic conditions. 3+This leads to an increase in electrostatic repulsion between molecular chains, causing the shell to swell and opening the nanopores in the SiO2 network, thereby triggering the release of the core material. This process can be reversibly shut off when pH>6.5, achieving intelligent regulation of "release on demand and release without pollution". (2) Hedgehog-shaped nano zinc oxide supplements the release of zinc ions.

[0016] 2. Preparation process (1) Oil phase preparation: Dissolve DCOIT in a hydrophobic solvent, add emulsifier, and prepare O / W (oil-in-water) emulsion.

[0017] (2) Construction of hybrid shell: Chitosan solution and silicon source (such as tetraethyl orthosilicate TEOS) are added to the aqueous phase. The pH value is adjusted to initiate the hydrolysis and condensation of TEOS, and a SiO2 network is generated in situ during the gelation of chitosan to encapsulate the oil phase droplets.

[0018] (3) Surface functionalization (cortex grafting): The surface of the hybrid shell is modified with organic functional groups by silane coupling agent, and then zinc ions are adsorbed as crystal nuclei for ZnO growth. ZnO nanostructure growth: Under low temperature hydrothermal conditions, a dense needle-like ZnO array is grown in situ on the surface of microcapsules by utilizing the slow release and morphology guidance effect of HMTA, forming the final sea urchin-like structure.

[0019] (4) Post-processing: Filter, wash and spray dry to obtain a white powder with good flowability.

[0020] This invention achieves multi-level, structured construction from the inside out (oil phase core material → organic-inorganic hybrid shell → inorganic nanoarray) by combining physical emulsification, chemical hybridization, surface grafting and hydrothermal growth techniques, ultimately obtaining composite microcapsules with sustained-release and enhanced protective functions.

[0021] The technical solution of this invention is specifically implemented as follows: a method for preparing pH-responsive, high-temperature resistant hybrid smart drug-release microcapsules, comprising the following steps: (1) Weigh out chitosan and add it to an aqueous solution of acetic acid. Stir magnetically at room temperature to obtain an acidic chitosan solution. The chitosan is completely dissolved and the solution is transparent and viscous.

[0022] (2) The isothiazolinone antibacterial agent solution, with the isothiazolinone antibacterial agent as the core material, is slowly added dropwise to the chitosan acidic solution in step (1), and a high-speed shear emulsifier is turned on for shearing, and then ultrasonically dispersed to obtain a nano / submicron emulsion, which forms an O / W emulsion (physical coating).

[0023] In this solution, the solvent for isothiazolinone antibacterial agents is ethyl acetate or xylene; the oil phase is pulverized into micron-sized droplets, or even submicron-sized droplets; because chitosan is amphiphilic (possessing both hydrophilic and hydrophobic groups), it automatically adsorbs onto the oil-water interface, forming the first "liquid soft shell" to prevent oil droplets from merging.

[0024] (3) Add tetraethyl orthosilicate (TEOS) to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH value to 4.5-5.5, keep warm at 40-50℃ for 3-4 hours to form a hybrid gel shell; if the pH value is too high, chitosan will precipitate instantly; slowly add dilute ammonia to make it gel slowly.

[0025] The following chemical reactions occur: Hydrolysis: TEOS hydrolyzes in an acidic environment to generate silanol groups (Si-OH); Hydrogen bond induction: -OH and -NH2 on the chitosan chain form hydrogen bonds with Si-OH, inducing the enrichment of silicon source in the chitosan network; Dehydration condensation: As the reaction proceeds (held at 40-50℃ for 3-4 hours), dehydration occurs between Si-OH to form a -Si-O-Si-inorganic rigid framework, which may also partially graft with chitosan.

[0026] Result: The originally soft chitosan layer transformed into a "chitosan-silica hybrid gel shell." This structure retains both the pH sensitivity of chitosan (swells in acid) and the heat resistance of SiO2.

[0027] (4) Disperse the product obtained in step (3) in anhydrous ethanol, add silane coupling agent to obtain dispersion, add zinc salt solution to the dispersion, stir to obtain microcapsule slurry; The surface of the silica shell undergoes "hydroxylation" and "grafting" pretreatment in step one, allowing the originally inert SiO2 shell to develop "hands" capable of capturing zinc ions. Specifically, one end of the silane (Si-OR) hydrolyzes and forms a covalent bond (Si-O-Si) with the SiO2 network of the capsule shell; the other end (organic functional groups) extends into the external solution. These functional groups effectively adsorb subsequent zinc ions (Zn). 2+ Adding a zinc salt solution allows zinc ions to be "anchored" to the surface of the microcapsules through coordination, forming extremely small ZnO crystal nuclei (seeds).

[0028] (5) Prepare the growth solution, which is made from zinc salt and hexamethylenetetramine (HMTA) and water; add the microcapsule slurry from step (4) to the growth solution, heat to 85-95℃, and stir at a constant temperature; after the reaction, filter, wash with water, and vacuum dry to obtain the target microcapsules. Among them, ZnO is induced to grow into needle-like structures at low temperature to protect DCOIT from decomposition.

[0029] HMTA is a key "slow-release agent" and "morphology modifier." When heated, it slowly releases ammonia (NH3), providing an alkaline environment. Simultaneously, it adsorbs onto specific crystal faces of ZnO, forcing ZnO to grow only along the c-axis (longitudinal direction), thus forming "needles." After the reaction, the tiny crystal nuclei on the microcapsule surface "germinate" outwards, growing into a dense array of needles approximately 100-300 nm long and 20-50 nm in diameter, forming a "hedgehog" morphology.

[0030] Further, in step (1), the degree of deacetylation of the chitosan is ≥85%; the volume concentration of the acetic acid aqueous solution is 1%-2.5%; The mass-to-volume ratio of chitosan to aqueous acetic acid is 1.8-2.2 g : 90-110 ml.

[0031] Further, in step (2), the solvent of the isothiazolinone antibacterial agent solution is ethyl acetate or xylene; the concentration of the isothiazolinone antibacterial agent solution is 3-30 wt%; and the mass ratio of the isothiazolinone antibacterial agent to chitosan is 2-6:1.

[0032] Further, in step (2), the isothiazolinone antibacterial agent is at least one of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, and 2-n-octyl-4-isothiazolin-3-one.

[0033] Further, in step (2), the high-speed shear emulsifier has a rotation speed of 8000-15000 rpm and a shearing time of 10-15 minutes; the ultrasonic dispersion time is 5-10 minutes.

[0034] Furthermore, the mass-volume ratio of chitosan in step (1) to tetraethyl orthosilicate in step (3) is 2g:5-8ml.

[0035] Furthermore, between steps (3) and (4) are the following steps: glutaraldehyde or genipin is added to the hybrid gel shell of step (3) for cross-linking and curing, filtered, and the filter cake is collected to obtain DCOIT / SiO2 hybrid microcapsules; this step "locks" the chitosan molecular chains through chemical bonds to prevent chain slippage at the high temperature of rubber vulcanization.

[0036] Furthermore, the amount of glutaraldehyde or genipin added is 0.4%-0.6% of the mass of the hybrid gel shell.

[0037] Further, in step (4), the coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane; the amount of the coupling agent added is 2%-5% of the mass of the product obtained in step (3); The concentration of the zinc salt solution is 8%-12%wt, preferably 10wt; the amount of zinc salt solution added is 3%~30% of the mass of the product obtained in step (3); Stirring time is 20-40 minutes.

[0038] Furthermore, in step (5), the concentrations of zinc salt and hexamethylenetetramine in the growth solution are both 0.05-0.1 mol / L; the reaction time is 2-4 h; and the vacuum drying temperature is 60-80 °C. Furthermore, in steps (4) and (5), the zinc salt is at least one of zinc nitrate, zinc acetate, zinc sulfate, zinc chloride, and zinc gluconate.

[0039] A pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule is prepared by any one of the preparation methods described in this invention.

[0040] The application of the pH-responsive, high-temperature resistant hybrid smart drug-release microcapsules described in this invention in electrical insulation materials.

[0041] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention designs a composite microcapsule (Z-pH-MC) with a three-layer structure of "core-shell-skin", which combines the high efficiency of organic bactericides, the heat resistance of inorganic skeletons, and the auxiliary protective function of zinc oxide to achieve an intelligent mechanism of "locking in the drug at high temperature and releasing it automatically when exposed to acid". This invention constructs an environmentally responsive carrier system, which achieves spatiotemporal controllable release of existing high-efficiency bactericides through the multi-level structural design of microcapsules, thereby solving the problems of rapid loss and thermal inactivation of bactericides under harsh working conditions.

[0042] (2) The present invention has a core-shell-skin three-layer structure of intelligent responsive microcapsules, which are suitable for use in outdoor electrical insulation materials such as high temperature vulcanized silicone rubber and room temperature vulcanized (RTV) anti-flashover coatings, for long-term inhibition of algae, mold and microbial attachment and growth.

[0043] (3) The microcapsule release mechanism of this invention: pH threshold triggering (intelligent and controllable), which means that it is only released when acidic metabolites are produced by biological waste, and is not consumed when sterile. This product can extend its service life compared with the prior art. The concentration gradient of the prior art products diffuses naturally (uncontrollable).

[0044] (4) The microcapsules of this invention have excellent temperature resistance. They can withstand temperatures above 180℃ (with SiO2 skeleton protection) and can be directly added to high-temperature vulcanized silicone rubber (HTV) to make insulators, filling the gap in rubber anti-algae materials. In contrast, existing products have a temperature resistance of <120℃ and are prone to volatility / decomposition.

[0045] (5) The microcapsules of this invention have excellent anti-leaking properties. The microcapsule locks in the superhydrophilic nano zinc oxide agent, which is encapsulated, and the outer ZnO layer is hydrophilic, achieving surface cleaning through self-cleaning and maintaining the surface function. In contrast, existing products are easily washed away and leached by rainwater.

[0046] (6) The microcapsules of this invention meet the appearance inspection requirements of power equipment and do not affect the insulation performance. In contrast, existing products containing copper are prone to discoloration or containing carbon are prone to conductivity. Attached Figure Description

[0047] Figure 1 : Flowchart of the microcapsule preparation process of this invention.

[0048] Figure 2 (a) Synthesized silica-coated DCOIT nanocapsules (approximately 10-60 nm). (b) Electron micrograph of hedgehog-shaped zinc oxide composite capsules grown directly on nano-silica microparticles (the outer contour of the hedgehog-shaped zinc oxide nanoparticles is 500 nm). (c) and (d) are composite capsules with larger particle sizes (the outer contour of the hedgehog-shaped nano-zinc oxide is 1-3 micrometers). The concentrations of NaOH and TEG can be controlled to achieve control over the size of the hedgehog capsules.

[0049] Figure 3 High-resolution transmission electron microscopy (TEM) image (left) of the hedgehog-like pointed structure and its local electron diffraction pattern (right). Specific analysis reveals that the zinc oxide on the surface is a single-crystal zinc oxide with a hexagonal wurtzite structure.

[0050] Figure 4 (a) Hedgehog-shaped nano-zinc oxide particles coated with silica; (b) XRD pattern of pure nano-zinc oxide; The weak broad peak at 20 degrees in (a) is amorphous silica.

[0051] Figure 5 Temperature resistance comparison chart (TGA curve): Comparison of the stability of pure chitosan microcapsules and the hybrid microcapsules of the present invention at 180°C. Mass loss is relative to the chitosan and DCOIT portions (volatile portions), excluding the zinc oxide and silicon oxide portions.

[0052] Figure 6 pH-responsive release curves demonstrate a significant difference in release rates between neutral (pH 7) and slightly acidic (pH 5-6) environments. Detailed Implementation

[0053] Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods; Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0054] The Chinese meanings of some of the abbreviations in this invention are as follows: DCOIT: 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one; Silane coupling agent KH-570: γ-methacryloyloxypropyltrimethoxysilane; Silane coupling agent APTES: 3-aminopropyltriethoxysilane.

[0055] HMTA: Hexamethylenetetramine.

[0056] The process flow diagram for the preparation of microcapsules in this invention is as follows: Figure 1 As shown.

[0057] A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule includes the following steps: (1) Raw material preparation: Weigh chitosan, dissolve it in 1%-2.0% v / v acetic acid aqueous solution, stir magnetically at room temperature for 2-4 hours to obtain an acidic chitosan solution.

[0058] (2) Emulsion and primary coating: The oil phase of DCOIT is added dropwise to the chitosan solution and emulsified by high-speed shear emulsifier (8000-15000 rpm, 10-15 minutes); high-power ultrasonic dispersion (5 minutes) is used to obtain nano / submicron emulsion, in which chitosan is adsorbed at the oil-water interface.

[0059] (3) Hybrid shell formation: Add tetraethyl orthosilicate (TEOS) dropwise to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH value to 4.5-5.5; keep warm at 40-50℃ and stir for 3-4 hours, TEOS hydrolyzes, hydrogen bonds are induced and condensed to form a "chitosan-silica" hybrid gel shell.

[0060] (4) Enhance temperature resistance (optional step): Add glutaraldehyde or genipin to the hybrid gel shell of step (3) for cross-linking and curing, filter, collect filter cake, and obtain DCOIT / SiO2 hybrid microcapsules. (5) Surface modification and seed anchoring: Disperse the microcapsules in anhydrous ethanol; add silane coupling agent (such as KH-570 or APTES); then add zinc acetate solution and stir for 30 minutes. Zinc ions are anchored on the surface to form ZnO crystal nuclei, and microcapsule slurry is obtained. (6) ZnO nanostructure growth: Prepare an equimolar aqueous solution of Zn(NO3)2 and HMTA (growth solution), add the surface-modified microcapsules to the growth solution, and perform a hydrothermal reaction at 85-95℃ for 2-4 hours; needle-shaped ZnO arrays (about 100-300nm long) grow on the surface, filter, wash with water, and vacuum dry at 60-80℃ to obtain the final product, anti-algae microcapsules.

[0061] Example 1 A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule includes the following steps: (1) Weigh 2.0g of chitosan (degree of deacetylation ≥ 85%) and add it to 100ml of acetic acid aqueous solution (1.5% v / v). Stir magnetically for 3 hours at room temperature until the chitosan is completely dissolved and the solution is transparent and viscous, thus obtaining an acidic chitosan solution.

[0062] (2) Add 3-30wt% DCOIT solution (about 10g) dropwise to the chitosan acidic solution in step (1). The solvent of DCOIT solution is ethyl acetate. The mass ratio of DCOIT to chitosan is 4:1. Turn on the high-speed shear emulsifier and shear at 10000 rpm for 12 minutes. Then use high power (1000W) ultrasonic dispersion for 5 minutes to obtain nano / submicron emulsion.

[0063] (3) Slowly add 5-8 ml of tetraethyl orthosilicate to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH to 5.0; keep warm at 45℃ and stir for 3.5 hours to obtain a hybrid gel shell, wherein the emulsion is the core and the gel is the shell.

[0064] (4) Disperse the hybrid gel shell from step (3) in anhydrous ethanol; add silane coupling agent to obtain a dispersion; add zinc acetate solution to the dispersion and stir for 30 minutes to obtain microcapsule slurry; The coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the amount of the coupling agent added is 3.5% of the mass of the hybrid gel shell; the amount of the zinc acetate solution added is 3% of the mass of the hybrid gel shell. (5) Prepare the growth solution, which is prepared by zinc nitrate and hexamethylenetetramine with water. The concentrations of zinc nitrate and hexamethylenetetramine in the growth solution are both 0.08 mol / L. Add the microcapsule slurry from step (4) to the growth solution, heat to 90°C, and stir at a constant temperature for 3 hours. After the reaction, filter, wash with water, and vacuum dry at 70°C to obtain the target microcapsules.

[0065] Example 2 The difference from Example 1 is the addition of a "strengthening temperature resistance" step.

[0066] A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule includes the following steps: (1) Weigh 2.0g of chitosan (degree of deacetylation ≥ 85%) and add it to 100ml of acetic acid aqueous solution (1.5% v / v). Stir magnetically for 3 hours at room temperature until the chitosan is completely dissolved and the solution is transparent and viscous, thus obtaining an acidic chitosan solution.

[0067] (2) Add 3-30wt% DCOIT solution (about 10g) dropwise to the chitosan acidic solution in step (1). The solvent of DCOIT solution is ethyl acetate. The mass ratio of DCOIT to chitosan is 4:1. Turn on the high-speed shear emulsifier and shear at 10000 rpm for 12 minutes. Then use high power (1000W) ultrasonic dispersion for 5 minutes to obtain nano / submicron emulsion.

[0068] (3) Slowly add 5-8 ml of tetraethyl orthosilicate to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH to 5.0; keep warm at 45℃ and stir for 3.5 hours to form a hybrid gel shell, in which the emulsion is the core and the gel is the shell.

[0069] (4) Add glutaraldehyde or genipin to the hybrid gel shell of step (3) for cross-linking and curing, filter, collect the filter cake, and obtain DCOIT / SiO2 hybrid microcapsule filter cake. The amount of glutaraldehyde or genipin added is 0.5% of the mass percentage of the hybrid gel shell.

[0070] (5) Disperse the cross-linked and cured DCOIT / SiO2 hybrid microcapsule filter cake from step (4) in anhydrous ethanol; add silane coupling agent to obtain a dispersion; add zinc acetate solution to the dispersion and stir for 30 minutes to obtain microcapsule slurry; The coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the amount of the coupling agent added is 3.5% of the mass of the hybrid microcapsule filter cake; the amount of the zinc acetate solution added is 3% of the mass of the hybrid microcapsule filter cake. (6) Prepare the growth solution, which is prepared by zinc nitrate and hexamethylenetetramine with water. The concentrations of zinc nitrate and hexamethylenetetramine in the growth solution are both 0.08 mol / L. Add the microcapsule slurry from step (5) to the growth solution, heat to 90°C, and stir at a constant temperature for 3 hours. After the reaction, filter, wash with water, and vacuum dry at 70°C to obtain the target microcapsules.

[0071] Example 3 A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule includes the following steps: (1) Weigh 2.0g of chitosan (degree of deacetylation ≥ 85%) and add it to 100ml of acetic acid aqueous solution (1% v / v). Stir magnetically for 2 hours at room temperature until the chitosan is completely dissolved and the solution is transparent and viscous, thus obtaining an acidic chitosan solution.

[0072] (2) Add 3-30wt% DCOIT solution (about 10g) dropwise to the chitosan acidic solution in step (1). The solvent of DCOIT solution is ethyl acetate. The mass ratio of DCOIT to chitosan is 2:1. Turn on the high-speed shear emulsifier and shear at 8000 rpm for 15 minutes. Then use high power (1000W) ultrasonic dispersion for 5 minutes to obtain nano / submicron emulsion.

[0073] (3) Slowly add 5-8 ml of tetraethyl orthosilicate to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH value to 4.5; keep warm at 40℃ and stir for 4 hours to form a hybrid gel shell, in which the emulsion is the core and the gel is the shell.

[0074] (4) Add glutaraldehyde or genipin to the hybrid gel shell of step (3) for cross-linking and curing, filter, collect the filter cake, and obtain DCOIT / SiO2 hybrid microcapsule filter cake. The amount of glutaraldehyde or genipin added is 0.5% of the mass percentage of the hybrid gel shell.

[0075] (5) Disperse the cross-linked and cured DCOIT / SiO2 hybrid microcapsule filter cake from step (4) in anhydrous ethanol; add silane coupling agent to obtain a dispersion; add zinc acetate solution to the dispersion and stir for 30 minutes to obtain microcapsule slurry; The coupling agent is at least one of γ-methacryloxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane; the amount of the coupling agent added is 2% of the mass of the hybrid microcapsule filter cake; the amount of the zinc acetate solution added is 3% of the mass of the hybrid microcapsule filter cake. (6) Prepare the growth solution, which is prepared by zinc nitrate and hexamethylenetetramine with water. The concentrations of zinc nitrate and hexamethylenetetramine in the growth solution are both 0.05 mol / L. Add the microcapsule slurry from step (5) to the growth solution, heat to 85°C, and stir at a constant temperature for 4 hours. After the reaction, filter, wash with water, and vacuum dry at 60°C to obtain the target microcapsules.

[0076] Example 4 A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule includes the following steps: (1) Weigh 2.0g of chitosan (degree of deacetylation ≥ 85%) and add it to 100ml of acetic acid aqueous solution (2.0% v / v). Stir magnetically for 4 hours at room temperature until the chitosan is completely dissolved and the solution is transparent and viscous, thus obtaining an acidic chitosan solution.

[0077] (2) Add 3-30wt% DCOIT solution (about 10g) dropwise to the chitosan acidic solution in step (1). The solvent of DCOIT solution is xylene; the mass ratio of DCOIT to chitosan is 6:1; turn on the high-speed shear emulsifier and shear at 15000 rpm for 10 minutes; then use high power (1000W) ultrasonic dispersion for 5 minutes to obtain nano / submicron emulsion.

[0078] (3) Slowly add 5-8 ml of tetraethyl orthosilicate to the emulsion in step (2), keep stirring, slowly add dilute ammonia to adjust the pH to 5.5; keep warm at 50°C and stir for 3 hours to form a hybrid gel shell.

[0079] (4) Add glutaraldehyde or genipin to the hybrid gel shell of step (3) for cross-linking and curing, filter, collect the filter cake, and obtain DCOIT / SiO2 hybrid microcapsule filter cake. The amount of glutaraldehyde or genipin added is 0.5% of the mass percentage of the hybrid gel shell.

[0080] (5) Disperse the cross-linked and cured DCOIT / SiO2 hybrid microcapsule filter cake from step (4) in anhydrous ethanol; add silane coupling agent to obtain a dispersion; add zinc acetate solution to the dispersion and stir for 30 minutes to obtain microcapsule slurry; The coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane; the amount of the coupling agent added is 5% of the mass of the hybrid microcapsule filter cake; the amount of the zinc acetate solution added is 5% of the mass of the hybrid microcapsule filter cake. (6) Prepare the growth solution, which is prepared by zinc nitrate and hexamethylenetetramine with water. The concentrations of zinc nitrate and hexamethylenetetramine in the growth solution are both 0.1 mol / L. Add the microcapsule slurry from step (5) to the growth solution, heat to 95°C, and stir at a constant temperature for 2 hours. After the reaction, filter, wash with water, and vacuum dry at 80°C to obtain the target microcapsules.

[0081] The structure and properties of the microcapsules prepared in Example 1 were tested, and the results are as follows: (1) Microstructure: Scanning electron microscope images such as Figure 2 As shown, the coated silicon dioxide nanoparticles are approximately 50-50 nm in size, while the regrown hedgehog-like zinc oxide nanoparticles reach 500 nm in size. High-resolution transmission electron microscopy (HRTEM) results are shown below. Figure 3As shown, in the hedgehog-like structure, the tips of the spines have a diameter of approximately 10-30 nanometers.

[0082] (2) Phase structure: XRD test structure as follows Figure 4 As shown, silicon oxide is mainly amorphous, while nano-zinc oxide is wurtzite zinc oxide, consistent with the results of high-resolution transmission electron microscopy.

[0083] (3) Temperature resistance test: such as Figure 5 As shown, TGA thermogravimetric analysis revealed that the microcapsule weight loss rate was <5% after being kept at 180℃ for 30 minutes (indicating that the core material did not leak).

[0084] (4) pH response release curve: pH-responsive release assay: Take 1g of microcapsules and place them in PBS buffer solutions with pH 7.0 and 5.0 respectively. Shake well and place in a constant temperature drying phase at 37℃. Take the supernatant at 10, 30 and 50 days respectively, and test the Zn content by ICP-MS for comparison.

[0085] like Figure 6 As shown, the cumulative release rate over 30 days was <2% in pH 7.0 buffer solution and >60% in pH 5.0 (simulating algal acid environment) buffer solution. This demonstrates a significant difference in release rate between neutral (pH 7) and slightly acidic (pH 5-6) environments. This indicates that the device possesses a pH-responsive intelligent switch with automatic antibacterial, antifungal, and antialgal functions.

[0086] Meanwhile, Examples 2-4 add a "strengthening temperature resistance" step. Examples 2-4 can all achieve the purpose of the present invention, and their performance is better than that of Example 1.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule, characterized in that, Includes the following steps: (1) Weigh out chitosan, add it to an aqueous acetic acid solution, stir, and obtain an acidic chitosan solution; (2) Add the isothiazolinone antibacterial agent solution dropwise to the chitosan acidic solution in step (1); turn on the high-speed shear emulsifier for shearing; then disperse by ultrasonication to obtain a nano / submicron emulsion; (3) Add tetraethyl orthosilicate to the emulsion in step (2), keep stirring, adjust the pH value to 4.5-5.5, keep stirring at 40-50℃ to form a hybrid gel shell; (4) Disperse the product obtained in step (3) in anhydrous ethanol; add silane coupling agent to obtain a dispersion; add zinc salt solution to the above dispersion and stir to obtain microcapsule slurry; (5) Prepare the growth solution, which is prepared by zinc salt and hexamethylenetetramine with water; add the microcapsule slurry from step (4) into the growth solution, heat to 85-95℃, and stir at a constant temperature; after the reaction, filter, wash with water, and vacuum dry to obtain the target microcapsules.

2. The preparation method of the pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, In step (1), the degree of deacetylation of the chitosan is ≥85%; the volume concentration of the acetic acid aqueous solution is 1%-2.5%. The mass-to-volume ratio of chitosan to aqueous acetic acid is 1.8-2.2 g : 90-110 ml.

3. The preparation method of the pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, In step (2), the solvent for the isothiazolinone antibacterial agent solution is ethyl acetate or xylene; The concentration of the isothiazolinone antibacterial agent solution is 3-30 wt%; The mass ratio of the isothiazolinone antibacterial agent to chitosan is 2-6:1; The isothiazolinone antibacterial agent is at least one of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, and 2-n-octyl-4-isothiazolin-3-one; The high-speed shear emulsifier has a rotation speed of 8000-15000 rpm and a shearing time of 10-15 minutes; the ultrasonic dispersion time is 5-10 minutes.

4. The preparation method of the pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, The mass-to-volume ratio of chitosan in step (1) to tetraethyl orthosilicate in step (3) is 2g:5-8ml; In step (3), the heat preservation and stirring time is 3-4 hours.

5. The preparation method of the pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, Between steps (3) and (4), the following steps are also included: glutaraldehyde or genipin is added to the hybrid gel shell of step (3) for cross-linking and curing, filtered, and the filter cake is collected to obtain hybrid microcapsules.

6. The preparation method of the pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule according to claim 5, characterized in that, The amount of glutaraldehyde or genipin added in step (4) is 0.4%-0.6% of the mass of the hybrid gel shell.

7. The method for preparing pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, In step (4), the coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane; the amount of the coupling agent added is 2%-5% of the mass of the product obtained in step (3); The concentration of the zinc salt solution is 8%-12%wt, and the amount of zinc salt solution added is 3%~30% of the mass of the product obtained in step (3); the zinc salt is at least one of zinc nitrate, zinc acetate, zinc sulfate, zinc chloride and zinc gluconate; Stirring time is 20-40 minutes.

8. The method for preparing pH-responsive, high-temperature resistant hybrid intelligent drug-release microcapsules according to claim 1, characterized in that, In step (5), the concentrations of zinc salt and hexamethylenetetramine in the growth solution are both 0.05-0.1 mol / L; the reaction time is 2-4 h; the vacuum drying temperature is 60-80 °C; and the zinc salt is at least one of zinc nitrate, zinc acetate, zinc sulfate, zinc chloride, and zinc gluconate.

9. A pH-responsive, high-temperature resistant hybrid smart drug-release microcapsule, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the pH-responsive, high-temperature resistant hybrid smart drug-release microcapsules as described in claim 9 in electrical insulation materials.

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