CN114653314A - Method for preparing self-assembled microcapsule - Google Patents
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Abstract
The invention discloses a method for preparing self-assembled microcapsules, which comprises the following steps: dissolving a surfactant in deionized water, weighing a polymerization monomer, and dissolving an initiator in the deionized water; under the nitrogen atmosphere, circularly conveying the surfactant solution and the monomer mixture to a supergravity rotating packed bed, and mixing to obtain a pre-emulsion; adding an initiator solution into the pre-emulsion to perform polymerization reaction, and dialyzing to remove impurities after the reaction is finished to obtain a colloidal particle aqueous dispersion; circularly introducing the mixture of the colloidal particle aqueous dispersion, the oil phase and the emulsifier into a supergravity rotating packed bed to strengthen the emulsification process to obtain emulsion; and heating the emulsion, centrifuging, washing and drying to obtain the microcapsule. The particle size of the colloid particles prepared by the invention is small and is uniformly distributed, and the particle size is 10-200 nm; the polymerization reaction time can be shortened by 20-50%; the microcapsule has controllable size and porosity, good appearance, regular spherical shape, and particle diameter of 0.1-10 μm.
Description
Technical Field
The invention relates to the technical field of microcapsule preparation; and more particularly, to a method of preparing self-assembling microcapsules.
Background
Microcapsules refer to solid particulate products in which a solid, liquid or gas is entrapped inside, using a natural or synthetic polymer material as the wall material, and the particle size is usually in the range of 1-1000 μm. The special core-shell structure of the microcapsule ensures that the microcapsule has the performance of protecting core substances from escaping to the outside and being not influenced by the invasion of the outside environment. According to the release characteristics of different wall materials to the core material, the slow release, instant release or lasting preservation effect of the core material is realized on the premise of keeping the original characteristics of the core material substance, and the purpose of controlling the release of the core material is achieved. At present, the preparation and embedding technology of the microcapsule is widely applied to the fields of medicine, food, textile and the like.
Ramsden at the beginning of the 20 th century[1]And Pickering[2]The self-assembly process of colloidal particles on an oil-water interface is reported for the first time, and a stable Pickering emulsion is formed ([1 ]]Ramsden W.Separation of solids in the surface-layers of solutions and“suspensions”(observations on surface-membranes,bubbles,emulsions,and mechanical coagulation):Preliminary account[J].Proceedings of the Royal Society ofLondon,1903,72:156–164；[2]Pickering S U.Emulsions[J]Journal of the Chemical Society, Transactions,1907,91: 2001-. 90 s, Velev et al[3-5]Self-assembled microcapsules were prepared using Pickering emulsion, the colloidal particles of the shell of which were immobilized by deposition of polyelectrolyte ([3 ]]Velev O D,Furusawa K,Nagayama K.Assembly oflatex particles by using emulsion droplets as templates.1.microstructured hollow spheres[J].Langmuir,1996,12:2374–2384；[4]Velev O D,Furusawa K,Nagayama K.Assembly of latex particles by using emulsion droplets as templates.2.ball-like and composite aggregates[J].Langmuir,1996,12:2385–2391；[5]Velev O D,Nagayama K.Assembly oflatex particles by using emulsion droplets.3.reverse(water in oil)system[J]Langmuir,1997,13: 1856-. Subsequently, Dinsmore et al[6]A method for heat-fixing the shell of microcapsules is invented, in which the colloidal particles are heated to a temperature above the glass transition temperature, so that the polymer colloidal particles are melted and cross-linked together to form self-assembled microcapsules ([6 ]]Dinsmore AD,Hsu M F,Nikolaides M G,Marquez M,BauschAR,Weitz D A.Colloidosomes:selectively permeable capsules composed of colloidal particles[J]Science,2002,298: 1006-1009). Router et al[7]Further invented is a method for preparing self-assembled microcapsules at low temperature, which changes the melting and cross-linking degree of the shell colloidal particles of the microcapsules by controlling the heating temperature and the heating time, thereby achieving different slow release rates ([7 ]]Samia
Alexander F.Routh.Fabrication of colloidosomes at low temperature for the encapsulation ofthermally sensitive compounds[J]Journal of colloid and Interface Science,2008,317: 121-129.). Keen et al[8]The self-assembly microcapsule prepared by Pickering emulsion is embedded with macromolecular substances such as amylase, lactobacillus, saccharomycetes and the like, so that the activity of an embedded object is limited, and small molecular substances can be exchanged inside and outside the microcapsule ([8 ]]Polly H R Keen.Encapsulation of biological material in colloidosomes[D]London: University of Cambridge, 2013.). The porosity and the slow release rate of the self-assembly microcapsule prepared by the method can be regulated and controlled, the preparation process is relatively simple, and the biological toxicity is low.
However, the current microcapsule preparation method still has the following problems: 1) the preparation efficiency of the capsule wall material is low; 2) the particle size of the capsule wall material particles is not uniform; 3) the release of the embedded substance cannot be effectively controlled; 4) the stability of the microcapsule product is not high.
Disclosure of Invention
The invention aims to provide a method for preparing self-assembled microcapsules. The method can obtain stable pre-emulsion of surfactant aqueous solution and monomer at the stage of capsule wall material, can regulate and control the particle size of prepared colloidal particles, and greatly shortens the reaction time of polymerization reaction; in the subsequent microcapsule preparation stage, the formed water-in-oil type Pickering emulsion is more stable, and the prepared microcapsules have smaller and more uniform particle size; the size and porosity of the microcapsule are flexibly controlled by changing the conditions of the size of colloidal particles, the heating time of emulsion, the heating temperature and the like so as to embed different small molecular substances and achieve the effect of different slow release rates; the microcapsule prepared by the method is in a regular spherical shape, and the particle diameter is 0.1-10 μm.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method of making self-assembling microcapsules comprising the steps of:
1) dissolving a surfactant in deionized water to obtain a surfactant solution; weighing the polymerization monomers to obtain a monomer mixture; dissolving an initiator in deionized water to obtain an initiator solution;
2) under the nitrogen atmosphere, circularly conveying the surfactant solution and the monomer mixture to a supergravity rotating packed bed, and mixing to obtain a pre-emulsion;
3) adding an initiator solution into the pre-emulsion to perform polymerization reaction, and dialyzing to remove impurities after the reaction is finished to obtain colloidal particle water dispersion serving as a capsule wall material;
4) circularly introducing the mixture of the colloidal particle water dispersion, the oil phase and the emulsifier into a supergravity rotating packed bed to strengthen the emulsification process to obtain microemulsion or nano emulsion;
5) heating the emulsion, centrifuging, washing with deionized water, dispersing in water to obtain water phase microcapsule, or washing and directly drying to obtain microcapsule solid particles.
According to certain embodiments of the invention, in step 1), the surfactant is selected from one or more of the following: sodium dodecyl sulfate, polyvinyl alcohol, polyethylene oxide, ammonium salts (such as dodecyl ammonium chloride), quaternary ammonium salts (such as hexadecyl trimethyl ammonium bromide).
According to some embodiments of the invention, in step 1), the surfactant is used in an amount of 0.1 to 8 wt% of the total mass of the monomers; more preferably, the surfactant is used in an amount of 0.5 to 5 wt% based on the total mass of the monomers.
According to certain embodiments of the invention, in step 1), the polymerized monomers are selected from one or more of the following: styrene, butyl acrylate, methacrylic acid, acrylic acid, methyl methacrylate, butyl methacrylate, dimethyl methacrylate, dimethylaminoethyl methacrylate, allylamine hydrochloride, acrylamide, n-butyl cyanoacrylate, isopropylacrylamide, vinylpyridine.
According to certain embodiments of the invention, in step 1), the initiator is selected from one or more of the following: potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, and azobisisopropylimidazoline.
According to some embodiments of the invention, in step 1), the initiator is used in an amount of 0.1 to 5 wt% based on the total mass of the monomers; more preferably, the initiator is used in an amount of 0.5 to 3.5 wt% based on the total mass of the monomers.
According to certain embodiments of the invention, in step 2), the mixture cycle time is 5-150 min; more preferably, the mixture cycle time is from 5 to 120 min.
According to some embodiments of the present invention, in step 2), the rotation speed of the rotor of the supergravity rotating packed bed is 300-; more preferably, the rotor speed is 500-. And regulating the rotating speed of the rotor by using a frequency modulation speed changer.
According to some embodiments of the invention, in step 3), the polymerization temperature is 60 to 95 ℃ and the polymerization time is 0.5 to 10 hours; more preferably, the polymerization temperature is 70-90 ℃ and the polymerization time is 1-5 h.
According to some embodiments of the invention, in step 3), the initiator solution is added into the pre-emulsified solution to perform a polymerization reaction, and the circulating operation of the hypergravity rotating packed bed is maintained in the process;
according to some embodiments of the present invention, in step 3), the particle size of the colloidal particles is 10 to 200nm, the glass transition temperature of the colloidal particles can be controlled according to the mixture ratio of the polymerized monomers, and the polymer colloidal particles are spherical, dispersed in water, and have good dispersibility.
According to certain embodiments of the present invention, in step 4), the aqueous colloidal particle dispersion has a solids content of 0.5 to 5% by weight.
According to certain embodiments of the invention, in step 4), the oil phase is selected from one or more of the following: sunflower seed oil, soybean oil, peanut oil, isohexadecane, isoamyl acetate, isopropyl myristate, castor oil, perilla oil, olive oil and palm oil.
According to certain embodiments of the invention, in step 4), the emulsifier is selected from one or more of the following: polyglycerol-3-polyricinoleate, sorbitan oleate, sucrose polystearate, diglycerol polypropylene glycol ether, polyoxyethylene oleate and lecithin.
According to certain embodiments of the present invention, in step 4), the volume usage ratio of the aqueous colloidal particle dispersion, the oil phase and the emulsifier is 1:100: 1-2.5.
According to some embodiments of the invention, in step 4), the emulsification process time is 5-120 min; more preferably, the emulsification process time is 5-90 min.
According to some embodiments of the invention, in step 5), the heating temperature is 20 to 60 ℃ and the heating time is 1 to 30 min.
Any range recited herein is intended to include the endpoints and any number between the endpoints and any subrange subsumed therein or defined therein.
The starting materials of the present invention are commercially available, unless otherwise specified, and the equipment used in the present invention may be any equipment conventionally used in the art or may be any equipment known in the art.
Compared with the prior art, the invention has the following beneficial effects:
1) the colloidal particles prepared by the method have small particle size and uniform distribution, are 10-200nm, have adjustable glass transition temperature and greatly shorten polymerization reaction time;
2) the invention can flexibly control the size and the porosity of the microcapsule through the change of the particle size of the colloidal particles, the change of the heating temperature of the emulsion, the change of the heating time of the emulsion and the like so as to achieve the effect of different slow release rates;
3) the self-assembly microcapsule prepared by the invention has good balling property, polymer nano particles are densely and regularly arranged on the surface of the microcapsule, more than or equal to 90 percent of the microcapsule is in a regular spherical shape, and the particle size is between 0.1 and 10 mu m;
4) the preparation method of the microcapsule has the advantages of higher yield, low cost, low biological toxicity, simple and convenient operation and easy industrial production.
Drawings
The following detailed description of the embodiments of the invention is provided in connection with the accompanying drawings
FIG. 1 is a scanning electron micrograph of colloidal particles of the wall material obtained in example 1;
FIG. 2 is a scanning electron micrograph of the self-assembled microcapsules prepared in example 1 at 500rpm of the rotating packed bed;
FIG. 3 is a scanning electron micrograph of a self-assembled microcapsule prepared in example 1 at a rotating packed bed speed of 1000 rpm;
FIG. 4 is a scanning electron micrograph of the self-assembled microcapsule prepared in example 1 at 1500rpm of the rotating packed bed;
FIG. 5 is a scanning electron micrograph of self-assembled microcapsules prepared in example 1 at 2500rpm of the rotating packed bed;
FIG. 6 is a confocal microscope of microcapsules embedding allure red dye in example 2;
FIG. 7 is a scanning electron microscope image of the self-assembled microcapsule prepared in comparative example 1;
FIG. 8 is a scanning electron microscope image of the self-assembled microcapsule prepared in comparative example 3;
fig. 9 is a scanning electron microscope image of the colloidal particles prepared in comparative example 5.
Fig. 10 is a scanning electron microscope image of the colloidal particles prepared in comparative example 8.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
As one aspect of the present invention, a method for preparing a self-assembled microcapsule, comprises the steps of:
1) dissolving a surfactant in deionized water to obtain a surfactant solution; weighing the polymerization monomers to obtain a monomer mixture; dissolving an initiator in deionized water to obtain an initiator solution;
2) under the nitrogen atmosphere, circularly conveying the surfactant solution and the monomer mixture to a supergravity rotating packed bed, and mixing to obtain a pre-emulsion;
3) adding an initiator solution into the pre-emulsion to perform polymerization reaction, and dialyzing to remove impurities after the reaction is finished to obtain a colloidal particle water dispersion serving as a capsule wall material;
4) circularly introducing the mixture of the colloidal particle aqueous dispersion, the oil phase and the emulsifier into a supergravity rotating packed bed to strengthen the emulsification process to obtain microemulsion or nano emulsion;
5) heating the emulsion, centrifuging, washing with deionized water, dispersing in water to obtain water phase microcapsule, or washing and directly drying to obtain microcapsule solid particles.
In certain embodiments, in step 1), the surfactant is selected from one or more of the following: sodium dodecyl sulfate, polyvinyl alcohol, polyethylene oxide, ammonium salts (e.g., dodecyl ammonium chloride), quaternary ammonium salts (e.g., cetyl trimethyl ammonium bromide). The presence of the surfactant reduces the oil-water interfacial tension, so that the monomer is dispersed into fine droplets, and a protective layer is formed on the surfaces of the droplets, so that the pre-emulsion is stable; the raw materials of other surfactants have poor emulsification effect and are difficult to degrade.
In certain embodiments, in step 1), the surfactant is used in an amount of 0.1 to 8 wt% based on the total mass of the monomers; more preferably, the surfactant is used in an amount of 0.5 to 5 wt% based on the total mass of the monomers. Outside the dosage range, the emulsification effect cannot be achieved if the dosage is less; in many cases, severe foaming is easily caused in the reaction process, the prepared colloid particles are seriously adhered, and the surfactant is difficult to clean.
In certain embodiments, in step 1), the polymerized monomer is selected from one or more of the following: styrene, butyl acrylate, methacrylic acid, acrylic acid, methyl methacrylate, butyl methacrylate, dimethyl methacrylate, dimethylaminoethyl methacrylate, allylamine hydrochloride, acrylamide, n-butyl cyanoacrylate, isopropylacrylamide, vinylpyridine. Other polymerization monomer raw materials are not suitable to be used as capsule wall materials, the self-assembly behavior in the emulsion is poor, the appearance of the prepared microcapsule is poor, and the yield is too low.
In certain embodiments, in step 1), the initiator is selected from one or more of the following: potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, and azobisdiisopropylimidazoline. Other initiator raw materials have higher decomposition temperature and lower decomposition rate.
In certain embodiments, in step 1), the initiator is used in an amount of 0.1 to 5 wt% based on the total mass of the monomers; more preferably, the initiator is used in an amount of 0.5 to 3.5 wt% based on the total mass of the monomers. Outside the dosage range, the reaction is not easy to initiate if the dosage is less, and the reaction can not be normally carried out; the reaction rate is too fast to control.
In certain embodiments, in step 2), the mixture cycle time is from 5 to 150 min; more preferably, the mixture cycle time is from 5 to 120 min. Outside this time range, a stable pre-emulsion is not formed at low; at high, the impurities increase and the machine loss is serious.
In some embodiments, in step 2), the rotation speed of the rotor of the supergravity rotating packed bed is 300-; more preferably, the rotor speed is 500-2500rpm, or 1000-2500 rpm. And regulating the rotating speed of the rotor by using a frequency modulation speed changer. Outside the rotating speed range, the mixing effect is general at low speed, and the formed liquid drops are large and uneven; at high, the impurities increase and the machine loss is serious.
In certain embodiments, in step 3), the polymerization temperature is 60 to 95 ℃ and the polymerization time is 0.5 to 10 hours; more preferably, the polymerization temperature is 70-90 ℃ and the polymerization time is 1-5 h. Outside the temperature range, the reaction rate is very slow at low temperature, and is very fast at high temperature, so that the control is difficult, and the product dispersibility is poor; outside the time range, the reaction is not complete at low temperature, and the appearance of the product is easy to be deteriorated at high temperature and stirring for a long time at high temperature.
In some embodiments, in step 3), the particle size of the colloidal particles is 10 to 200nm, the glass transition temperature of the colloidal particles can be controlled according to different proportions of the polymerized monomers, and the polymer colloidal particles are spherical, are dispersed in water, and have good dispersibility.
In certain embodiments, the aqueous dispersion of colloidal particles in step 4) has a solids content of 0.5 to 5 wt%. Outside the dosage range, a small dosage results in insufficient capsule wall materials and low microcapsule yield; many of the scattered colloidal particles are not fully utilized.
In certain embodiments, in step 4), the oil phase is selected from one or more of the following: sunflower seed oil, soybean oil, peanut oil, isohexadecane, isoamyl acetate, isopropyl myristate, castor oil, perilla oil, olive oil and palm oil. In the water-in-oil Pickering emulsion, the oil phase serves as the continuous phase. Other oil phase raw materials have high biological toxicity and high cost.
In certain embodiments, in step 4), the emulsifier is selected from one or more of the following: polyglycerol-3-polyricinoleate, sorbitan oleate, sucrose polystearate, diglycerol polypropylene glycol ether, polyoxyethylene oleate and lecithin. After the emulsifier is added to the oil-water system, the water and oil can be mixed with each other to form a completely dispersed emulsion. The selection of other emulsifier materials has poor emulsifying effect and is difficult to clean.
In certain embodiments, in step 4), the volume usage ratio of the aqueous colloidal particle dispersion, the oil phase, and the emulsifier is from 1:100:1 to 2.5.
In certain embodiments, in step 4), the emulsification process time is 5-120 min; more preferably, the emulsification process time is 5-90 min. Outside this time frame, a stable emulsion is not formed; at high, the impurities increase and the machine loss is serious.
In some embodiments, in step 5), the heating temperature is 20 to 60 ℃, the heating time is 1 to 30min, and the temperature is outside the temperature range, when the temperature is low, the colloidal particles cannot be melted, and the microcapsules cannot be prepared, and when the temperature is high, the melting degree of the colloidal particles is extremely high, and the porosity of the microcapsules is extremely low; outside this time range, the colloidal particles are not completely melted at low temperatures and do not change significantly when heated for long periods at high temperatures.
Example 1
Method for preparing self-assembled microcapsule
Dissolving 0.4g of sodium dodecyl sulfate in 180mL of deionized water; mixing 30g of methyl methacrylate, 9.6g of butyl acrylate and 0.4g of acrylic acid; starting the supergravity rotating device, and adjusting the rotating speed to 1500 rpm; starting a feeding pump, conveying the surfactant solution and the monomer mixture into a rotary packed bed together, and circulating for 60min to obtain the pre-emulsion. Dissolving 0.4g of potassium persulfate in 20mL of deionized water, adding the potassium persulfate into the pre-emulsion to initiate polymerization reaction, controlling the reaction temperature at 85 ℃, controlling the reaction time to be 2 hours, keeping the reaction process under a nitrogen atmosphere, and starting 3 ℃ for circulating condensed water. And subpackaging the prepared colloidal particle water dispersion into a dialysis bag for dialysis, removing unreacted monomers, emulsifying agents and other impurities, and obtaining the required capsule wall material after one week. FIG. 1 is a scanning electron micrograph of the synthesized colloidal particles having a particle size of about 59 nm.
Deionized water was added to adjust the solids content of the aqueous colloidal particle dispersion to 2 wt%. Mixing 2mL of the mixture with 200mL of sunflower seed oil and 5mL of sorbitan oleate, dividing the mixture into four parts, conveying the four parts into a rotary packed bed for mixing and strengthening, adjusting the rotating speed of the rotary packed bed to be 500rpm, 1000rpm, 1500rpm and 2500rpm respectively, and circulating for 60 min. The resulting emulsion was heated in a water bath at 48 ℃ for 15 min. Centrifuging, and washing with deionized water to obtain the self-assembled microcapsule dispersed in water.
FIG. 2 is a scanning electron microscope image of microcapsules prepared by rotating a packed bed at 500rpm, under which the sorbitan oleate is used in an excessive amount and is difficult to clean, and the appearance of the microcapsules is not very regular. FIG. 3 is a scanning electron microscope image of microcapsules prepared at 1000rpm of a rotating packed bed, wherein most of the microcapsules prepared under the condition are regular spheres and the surface of the microcapsules is slightly wrinkled. FIG. 4 is a scanning electron microscope image of microcapsules prepared at a rotating speed of 1500rpm of a rotating packed bed, and under the condition, the surface colloid particles of the microcapsules are regularly arranged and have good appearance. FIG. 5 is a scanning electron microscope image of microcapsules prepared at 2500rpm of a rotating packed bed, under which the microcapsules are regularly spherical and the surface colloidal particles have a high degree of melting.
Example 2
Method for preparing self-assembly microcapsule embedded allure red dye
Dissolving 0.8g of sodium dodecyl sulfate in 180mL of deionized water; respectively proportioning different monomers into methyl methacrylate: butyl acrylate: acrylic acid 65:34:1, 75:24:1, 85:14:1, the total mass of the monomer mixture being 40 g; starting the supergravity rotating device, and adjusting the rotating speed to 1500 rpm; starting a feeding pump, conveying the surfactant solution and the monomer mixture into a rotary packed bed together, and circulating for 60min to obtain the pre-emulsion. Dissolving 0.8g of potassium persulfate in 20mL of deionized water, adding the potassium persulfate into the pre-emulsion to initiate polymerization reaction, controlling the reaction temperature at 85 ℃, controlling the reaction time to be 2 hours, keeping the reaction process under a nitrogen atmosphere, and starting 3 ℃ for circulating condensed water. And subpackaging the prepared colloidal particle water dispersion into a dialysis bag for dialysis, removing unreacted monomers, emulsifying agents and other impurities, and obtaining the required capsule wall material after one week.
The glass transition temperature Tg of the polymer can be calculated by using the glass transition temperature of the monomer homopolymer and according to the Fox equation shown in the formula (1).
In the formula, w1，2，3…nIs the mass fraction, Tg, of the monomer 1, 2, 3 … n1，2，3…nIs the Tg in K for a homopolymer of monomer 1, 2, 3 … n. The actual glass transition temperature of the polymer was determined by differential scanning calorimetry. Table 1 shows colloidal particles prepared with different monomer ratiosThe glass transition temperature of (a) can be seen to be close to the theoretical calculated value and the actual measured value.
Table 1: glass transition temperature of colloidal particles prepared with different monomer ratios
Deionized water was added to adjust the solids content of the aqueous colloidal particle dispersion to 2 wt%. 0.04g of allura red was weighed and dissolved in 2mL of the above aqueous colloidal particle dispersion. Mixing the mixture of the above allura red with 200mL of sunflower seed oil and 5mL of sorbitan oleate, conveying to a rotary packed bed for mixing and strengthening, adjusting the rotation speed of the rotary packed bed to 1500rpm respectively, and circulating for 30 min. The resulting emulsion was heated in a water bath at 48 ℃ for 15 min. Centrifuging, and washing with deionized water to obtain the self-assembled microcapsule dispersed in water.
FIG. 6 is a confocal microscope image of microcapsules encapsulating decoy red dye, from which it can be seen that the dye was successfully embedded.
Example 3
Method for preparing self-assembly type microcapsule embedding adriamycin hydrochloride
Dissolving 1.0g of sodium dodecyl sulfate in 180mL of deionized water; mixing 25.6g of styrene, 14g of butyl acrylate and 0.4g of acrylic acid; starting the supergravity rotating device, and adjusting the rotating speed to 1500 rpm; and starting a feed pump, conveying the surfactant solution and the monomer mixture into a rotary packed bed together, and circulating for 30min to obtain the pre-emulsion. Dissolving 1.0g of ammonium persulfate in 20mL of deionized water, adding the dissolved ammonium persulfate into the pre-emulsion to initiate polymerization reaction, controlling the reaction temperature at 80 ℃, controlling the reaction time to be 4 hours, keeping the reaction process under a nitrogen atmosphere, and starting 3 ℃ for circulating condensed water. And subpackaging the prepared colloidal particle water dispersion into a dialysis bag for dialysis, removing unreacted monomers, emulsifying agents and other impurities, and obtaining the required capsule wall material after one week.
Deionized water was added to adjust the solids content of the aqueous colloidal particle dispersion to 2 wt%. 0.04g of doxorubicin hydrochloride was weighed and dissolved in 2mL of the above aqueous colloidal particle dispersion. Mixing the mixture of the dissolved adriamycin hydrochloride with 200mL of sunflower seed oil and 5mL of sucrose polystearate, conveying the mixture into a rotary packed bed for mixing and strengthening, adjusting the rotating speed of the rotary packed bed to be 1500rpm respectively, and circulating for 30 min. The resulting emulsion was heated in a water bath at 48 ℃ for 30 min. Centrifuging, washing with deionized water, and drying to obtain self-assembled microcapsule solid particles.
Example 4
Method for preparing self-assembled microcapsule
Dissolving 0.4g of polyvinyl alcohol in 180mL of deionized water; 6.4g of styrene, 3.5g of butyl methacrylate and 0.1g of acrylic acid are mixed; starting the supergravity rotating device, and adjusting the rotating speed to 800 rpm; and starting a feed pump, conveying the surfactant solution and the monomer mixture into a rotary packed bed together, and circulating for 10min to obtain the pre-emulsion. 0.4g of azodiisopropyl imidazoline is dissolved in 20mL of deionized water, and is added into the pre-emulsion to initiate polymerization reaction, the reaction temperature is controlled at 70 ℃, the reaction time is 10 hours, and the reaction process is always in a nitrogen atmosphere and is started to circulate condensed water at 3 ℃. And subpackaging the prepared colloidal particle water dispersion into a dialysis bag for dialysis, removing unreacted monomers, emulsifying agents and other impurities, and obtaining the required capsule wall material after one week.
Deionized water was added to adjust the solids content of the aqueous colloidal particle dispersion to 0.5 wt%. Mixing 2mL and 200mL perilla oil with 3mL, 4mL and 5mL sorbitan oleate respectively, delivering the mixture to a rotary packed bed for mixing and strengthening, adjusting the rotation speed of the rotary packed bed to 1500rpm respectively, and circulating for 45 min. The resulting emulsion was heated in a water bath at 48 ℃ for 15 min. Centrifuging, and washing with deionized water to obtain the self-assembled microcapsule dispersed in water.
Example 5
Method for preparing self-assembled microcapsule
0.4g of dodecyl ammonium chloride is dissolved in 180mL of deionized water; mixing 6.4g of acrylamide, 33.2g of dimethylsecretly marked ethyl methacrylate and 0.4g of acrylic acid; starting the supergravity rotating device, and adjusting the rotating speed to 800 rpm; starting a feeding pump, conveying the surfactant solution and the monomer mixture into a rotary packed bed together, and circulating for 60min to obtain the pre-emulsion. 0.4g of azodiisopropyl imidazoline is dissolved in 20mL of deionized water, and is added into the pre-emulsion to initiate polymerization reaction, the reaction temperature is controlled at 70 ℃, the reaction time is 4 hours, and the reaction process is always in a nitrogen atmosphere and is started to circulate condensed water at 3 ℃. And subpackaging the prepared colloidal particle water dispersion into a dialysis bag for dialysis, removing the monomers, the emulsifier and other impurities which are not used completely, and obtaining the required capsule wall material after one week.
Deionized water was added to adjust the solids content of the aqueous colloidal particle dispersion to 4 wt%. Mixing 2mL of the mixture with 200mL of olive oil and 5mL of lecithin, delivering the mixture to a rotary packed bed for mixing and strengthening, adjusting the rotating speed of the rotary packed bed to be 1500rpm respectively, and circulating for 30 min. The obtained emulsion was divided into four portions, and heated in water bath at 40 deg.C, 44 deg.C, 52 deg.C, and 56 deg.C for 15 min. Centrifuging, and washing with deionized water to obtain the self-assembled microcapsule dispersed in water. As the heating temperature of the emulsion increases, the degree of melting of the colloidal particles on the surface of the microcapsule increases, and the porosity of the microcapsule decreases.
Comparative example 1
Example 1 was repeated: except that deionized water was added to adjust the aqueous colloidal particle dispersion to a solids content of 5.6 wt%, the microcapsule product yield of this comparative example was less than 50%, and there were also a number of loose colloidal particles that were not self-assembled. Scanning electron micrograph of the microcapsule prepared with dispersion solid content of 5.6 wt% is shown in FIG. 7.
Comparative example 2
Example 1 was repeated: except that deionized water was added to adjust the aqueous colloidal particle dispersion to a solids content of 0.4 wt%, the microcapsule product yield of this comparative example was less than 20%, and the amount of wall material added was too small.
Comparative example 3
Example 1 was repeated: the difference is that the emulsifier sorbitan oleate is 6mL, the dosage is too much, the washing is difficult, most of prepared microcapsule products are not regular spheres, and a scanning electron microscope picture is shown in figure 8.
Comparative example 4
Example 1 was repeated: the difference is that 1mL of sorbitan oleate serving as an emulsifier is used, the dosage is too small, a stable Pickering emulsion is difficult to form, and the yield of the prepared microcapsule product is extremely low.
Comparative example 5
Example 1 was repeated: the difference is that 1.6g of surfactant sodium dodecyl sulfate is used, namely 4 wt% of the total mass of the monomers, and the prepared colloidal particles have poor appearance and poor dispersibility. The scanning electron microscope image of the product is shown in FIG. 9.
Comparative example 6
Example 1 was repeated: the difference is that the total mass of the monomers is 5g, the solid content of the prepared colloidal particle water dispersion is too low, and a complicated concentration process is needed for the subsequent preparation of the microcapsule.
Comparative example 7
Example 1 was repeated: the only difference is that the mixing cycle time of the pre-emulsification process was 150min, too much impurities were introduced into the sample, and the solid content of the prepared aqueous colloidal particle dispersion was too low.
Comparative example 8
Example 1 was repeated: except that no high gravity rotating packed bed was used in the preparation of the wall material and the polymerization was carried out in a conventional stirred tank. The polymerization reaction is finished in 4h, the reaction cannot be completed in 2h, the particle size of the prepared colloidal particles is large, the particle size distribution range is wide, and a scanning electron microscope image is shown in fig. 10.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Not all embodiments are exhaustive. All obvious changes and modifications which are obvious to the technical scheme of the invention are covered by the protection scope of the invention.
Claims (10)
1. A method for preparing self-assembled microcapsules, comprising the steps of:
1) dissolving a surfactant in deionized water to obtain a surfactant solution; weighing the polymerization monomers to obtain a monomer mixture; dissolving an initiator in deionized water to obtain an initiator solution;
2) under the nitrogen atmosphere, circularly conveying the surfactant solution and the monomer mixture to a supergravity rotating packed bed, and mixing to obtain a pre-emulsion;
3) adding an initiator solution into the pre-emulsion to perform polymerization reaction, and dialyzing to remove impurities after the reaction is finished to obtain a colloidal particle water dispersion serving as a capsule wall material;
4) circularly introducing the mixture of the colloidal particle aqueous dispersion, the oil phase and the emulsifier into a supergravity rotating packed bed to strengthen the emulsification process to obtain microemulsion or nano emulsion;
5) heating the emulsion, centrifuging, washing with deionized water, dispersing in water to obtain water phase microcapsule, or washing and directly drying to obtain microcapsule solid particles.
2. The method for preparing self-assembled microcapsules according to claim 1, characterized in that: in step 1), the surfactant is selected from one or more of the following substances: sodium dodecyl sulfate, polyvinyl alcohol, polyethylene oxide, ammonium salt and quaternary ammonium salt.
3. The process for preparing self-assembling microcapsules according to claim 1, wherein: in the step 1), the dosage of the surfactant is 0.1-8 wt% of the total mass of the monomers; more preferably, the surfactant is used in an amount of 0.5 to 5 wt% based on the total mass of the monomers.
4. The process for preparing self-assembling microcapsules according to claim 1, wherein: in step 1), the polymerized monomer is selected from one or more of the following substances: styrene, butyl acrylate, methacrylic acid, acrylic acid, methyl methacrylate, butyl methacrylate, dimethyl methacrylate, dimethylaminoethyl methacrylate, allylamine hydrochloride, acrylamide, n-butyl cyanoacrylate, isopropylacrylamide, vinylpyridine.
5. The process for preparing self-assembling microcapsules according to claim 1, wherein: in step 1), the initiator is selected from one or more of the following substances: potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, and azobisisopropylimidazoline.
6. The process for preparing self-assembling microcapsules according to claim 1, wherein: in the step 1), the using amount of the initiator is 0.1-5 wt% of the total mass of the monomers; more preferably, the initiator is used in an amount of 0.5 to 3.5 wt% based on the total mass of the monomers.
7. The process for preparing self-assembling microcapsules according to claim 1, wherein: in the step 2), the circulation time of the mixture is 5-150 min; more preferably, the mixture cycle time is from 5 to 120 min;
preferably, in the step 2), the rotating speed of the rotor of the supergravity rotating packed bed is 300-5000 rpm; more preferably, the rotor speed is 500-.
8. The process for preparing self-assembling microcapsules according to claim 1, wherein: in the step 3), the polymerization reaction temperature is 60-95 ℃, and the polymerization reaction time is 0.5-10 h; more preferably, the polymerization temperature is 70-90 ℃ and the polymerization time is 1-5 h;
preferably, in the step 3), the initiator solution is added into the pre-emulsified solution to carry out polymerization reaction, and the circulating operation of the super-gravity rotating packed bed is kept in the process;
preferably, in the step 3), the particle size of the colloidal particles is 10-200 nm.
9. The process for preparing self-assembling microcapsules according to claim 1, wherein: in step 4), the solid content of the aqueous colloidal particle dispersion is 0.5 to 5 wt%;
preferably, in step 4), the oil phase is selected from one or more of the following: sunflower seed oil, soybean oil, peanut oil, isohexadecane, isoamyl acetate, isopropyl myristate, castor oil, perilla oil, olive oil and palm oil;
preferably, in step 4), the emulsifier is selected from one or more of the following: polyglycerol-3-polyricinoleate, sorbitan oleate, sucrose polystearate, diglycerol polypropylene glycol ether, polyoxyethylene oleate and lecithin;
preferably, in the step 4), the volume using ratio of the colloidal particle water dispersion, the oil phase and the emulsifier is 1:100: 1-2.5;
preferably, in the step 4), the emulsifying process time is 5-120 min; more preferably, the emulsification process time is 5-90 min.
10. The method for preparing self-assembled microcapsules according to claim 1, characterized in that: in the step 5), the heating temperature is 20-60 ℃, and the heating time is 1-30 min.
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