CN115532185A - Polyaniline double-layer microcapsule with barrier property - Google Patents
Polyaniline double-layer microcapsule with barrier property Download PDFInfo
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- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
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- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
- B01J13/06—Making microcapsules or microballoons by phase separation
- B01J13/14—Polymerisation; cross-linking
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- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
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- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/006—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polymers provided for in C08G18/00
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- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/10—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polymers containing more than one epoxy radical per molecule
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Abstract
The invention discloses a preparation method of a polyaniline double-layer microcapsule with high barrier property, belonging to the field of microcapsule preparation. The invention uses light to solidify one step to prepare single-layer sulfonated light-cured resin microcapsule, through the electrostatic interaction between sulfonic acid group and aniline, aniline is absorbed to the surface of microcapsule, and initiates aniline polymerization to polymerize a layer of compact polyaniline shell layer on the surface of light-cured microcapsule, thus obtaining polyaniline/light-cured resin double-shell microcapsule; the polyaniline microcapsule has excellent solvent resistance, thermal stability and mechanical properties; the method has wide application range, is simple and easy to implement, has high preparation speed, can be carried out at normal temperature, and can be used for coating different core materials; has wide application prospect in the fields of anti-corrosion materials, self-repairing materials, coating materials, cosmetic preparations, medicines, agricultural chemicals, cleaning agents and the like.
Description
Technical Field
The invention relates to the field of microcapsule preparation, in particular to a preparation method of a polyaniline double-layer microcapsule with high barrier property.
Background
Microcapsules refer to a type of micro-container having a polymeric shell and used to encapsulate an active substance (liquid, gas or solid). Microcapsules generally consist of two parts: a core material (inner) which is an active material (e.g., dye, monomer, catalyst, curing agent, flame retardant, plasticizer, and nanoparticles), and a shell layer (outer) which serves to protect the core material, which is typically a polymer.
The microcapsule can isolate active substances from the external environment, prevent the active substances from being oxidized or inactivated, and simultaneously can control the release of the active substances or position the release of the active substances, so the microcapsule is widely used in the fields of medicine, agriculture, construction, chemical industry, food, biotechnology, cosmetics, electronics, textile, printing and the like. For example, in biomedical research, the excellent encapsulation effect and controlled release characteristics of microcapsules make them uniquely advantageous in drug delivery; in the food field, the survival rate of the microencapsulated probiotics in the processing process is greatly improved. In the cosmetic field, the stability and bioavailability of microencapsulated vitamins, sunscreens, moisturizers, fragrances are greatly enhanced.
In practical applications, the microcapsules need to have sufficient encapsulation stability, so as to ensure that the core material of the microcapsules does not run off during storage and manufacturing processes. In the practical application of the microcapsule, the solvent or high temperature may damage the shell layer of the microcapsule and make the speed of the core material greatly increased. For example, during the preparation process of the self-repairing composite material, the processing temperature is higher (more than 100 ℃) so that the self-repairing agent is easy to diffuse into the polymer matrix, and the self-repairing efficiency is reduced. Many organic solvents are used in the coating art to swell and destroy the microcapsule shell. In addition to thermal stability and solvent resistance, the microcapsules should also have good mechanical properties, although they must break under specific conditions, during normal handling, for example: high speed stirring, filtering, etc., the microcapsules should not rupture prematurely. Based on the above discussion, the microcapsules should therefore have sufficient mechanical, thermal and solvent stability at the same time.
To date, the vast majority of microcapsule shell layers are polymers such as urea formaldehyde, melamine resins, polyurethanes, polystyrenes, and the like. However, polymer microcapsules do not encapsulate a core material effectively for a long period of time under severe conditions, because they have relatively poor barrier properties against water, oxygen and small organic molecules. In recent years, double-layer microcapsules have been proposed to solve this problem. For example, the thermal stability of the UF/PU microcapsule is greatly enhanced by condensing urea-formaldehyde (UF) resin on the surface of the Polyurethane (PU) microcapsule to synthesize a double-layer UF/PU microcapsule.
Aniline consists of two parts, a benzene ring and an amino group, and is polymerized immediately after an initiator is added. The pi-pi stacking and hydrogen bonding in polyaniline makes it a compact film and has remarkable heat resistance and solvent resistance. Thus, it is possible to effectively prevent the release of the core material from the microcapsules at high temperatures and in solvents by depositing a dense and uniform polyaniline coating on the microcapsules. Besides improving the thermal stability and the solvent stability, the mechanical property of the microcapsule can be obviously improved by the polyaniline coating.
Referring to the scheme disclosed in CN 110484088A, since the ultraviolet irradiation curing speed is fast, the polymer after photo-crosslinking cannot be fast transferred to the surface of the microcapsule, so that the microcapsule is very thin, and the barrier property of the obtained microcapsule is poor. In addition, after emulsion is subjected to photocuring, a large amount of free sulfonate emulsifiers can adsorb a large amount of aniline to generate homogeneous polymerization in a water phase, so that a large amount of free polyaniline appears in the water phase, and is mixed with the polyaniline double-layer microcapsule, thereby causing difficulty in separation and purification of the microcapsule. Therefore, a method for simply, conveniently and efficiently preparing the polyaniline double-layer microcapsule with high barrier property is still lacked at present.
Disclosure of Invention
In view of this, the applicant has invented a method for preparing polyaniline double-layer microcapsules with high barrier properties, which has the advantages of excellent chemical stability and weather resistance of polyaniline, so that polyaniline also becomes a microcapsule with excellent solvent resistance, thermal stability and mechanical properties. Therefore, the method has wide application range, is simple and feasible; has wide application prospect in the fields of anti-corrosion materials, self-repairing materials, cosmetic preparations, medicaments, household products, agricultural chemicals, cleaning agents and the like.
A preparation method of polyaniline double-layer microcapsules with barrier property is characterized by comprising the following steps:
the method comprises the following steps: uniformly mixing the photocuring resin, the core material, the cross-linking agent, the solvent and the photoinitiator to form an oil phase, mixing the oil phase with a water phase containing the stabilizer to form a stable emulsion, and continuously stirring or heating the emulsion to completely remove the solvent so as to separate the photocuring resin, the cross-linking agent and the core material;
step two: adding sodium styrene sulfonate into the water phase, stirring, curing the emulsion under UV irradiation, washing by using deionized water to remove unreacted sodium styrene sulfonate, and preparing to obtain a single-layer sulfonated microcapsule;
step three: dropwise adding aniline into the aqueous dispersion of the sulfonated microcapsule, continuously stirring to enable the aniline to be completely adsorbed on the surface of the microcapsule, then adding an initiator under an ice bath condition to initiate aniline polymerization, and washing to obtain a polyaniline double-layer microcapsule;
the light-cured resin and the core material are mutually insoluble; the solvent has a boiling point of 80 ℃ or less and is a good solvent for the photocurable resin.
The photo-curable resin and the core material which are originally insoluble with each other form a homogeneous oil phase under the action of the cosolvent, and the homogeneous emulsion droplets can be prepared by dispersing the core material, the photo-curable resin and the cross-linking agent which are originally incompatible with each other into the water phase, after the cosolvent is completely volatilized, the core material, the photo-curable resin and the cross-linking agent which are originally incompatible with each other are subjected to phase separation, and the polymer shell layer gradually migrates to an oil-water interface along with the volatilization of the solvent to form a phase-separated emulsion, as shown in fig. 15.
In one embodiment, the mass ratio of the light-curable resin to the core material in the first step is 5: 1 to 1: 5,
the cross-linking agent accounts for 5-50 wt% of the light-cured resin,
the solvent is 3-8 times of the mass of the light-cured resin; the photoinitiator is 1wt% -10 wt% of the total mass of the light-cured resin and the cross-linking agent.
In one embodiment, the mass ratio of the oil phase to the water phase in the second step is 1: 10 to 2: 1, the concentration of the stabilizer is 0.5wt% to 6wt%, and the mass ratio of the sodium styrene sulfonate to the light-cured resin is 1: 2 to 1: 8.
In one embodiment, the mass ratio of the aniline to the sulfonated microcapsule in the third step is 1: 16 to 4: 1, and the molar ratio of the initiator to the aniline is 1: 2 to 4: 1.
In one embodiment, the light-curable resin is one or more of urethane acrylate, polyester acrylate, epoxy acrylate;
the cross-linking agent is one or more of tripropylene glycol diacrylate, 1, 6-hexanediol diacrylate, dipropylene glycol diacrylate, bisphenol A glycidyl dimethacrylate, triethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, diethylene glycol diacrylate phthalate, neopentyl glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate and 1, 3-butanediol diacrylate;
the solvent is a good solvent of the light-cured resin with a lower boiling point, and is preferably one or more of dichloromethane, trichloromethane, tetrachloromethane, ethyl acetate and butyl acetate;
the stabilizer is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polystyrene-maleic anhydride copolymer, polyethylene-maleic anhydride copolymer, polyoxyethylene-polyoxypropylene-polyoxyethylene triblock polymer, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, hexadecyl trimethyl ammonium bromide, span-80, span-60, tween-80, tween-60, monoglyceride fatty acid glyceride, N-dodecyl dimethylamine and Arabic gum;
in the first step, the photoinitiator is one or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, isopropylthioxanthone, ethyl 4- (N, N-dimethylamino) benzoate, benzophenone, 4-chlorobenzophenone, methyl o-benzoylbenzoate, diphenyliodonium salt hexafluorophosphate, isooctyl N, N-dimethylaminobenzoate, 4-methylbenzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4, 6-trimethylbenzoylphenylphosphinate;
in the third step, the initiator is one or a mixture of any more of ammonium persulfate, potassium persulfate, hydrogen peroxide and potassium permanganate.
In one embodiment, the core material in the first step is one or more of a self-repairing agent, an early warning agent and a lubricant;
in the third step, the initiator is one or a mixture of any more of ammonium persulfate, potassium persulfate, hydrogen peroxide and potassium permanganate.
In one embodiment, the self-repairing agent comprises one or a mixture of any of isocyanate, linseed oil, tung oil and epoxy resin.
In one embodiment, the pre-warning agent comprises one or a mixture of any more of 8-hydroxyquinoline, phenanthroline, 2, 7-dichlorofluorescein and benzoquinone.
In one embodiment, the lubricant comprises one or a mixture of any of linseed oil, tung oil, palm oil.
The second purpose of the invention is to provide a microcapsule, the grain diameter of the prepared microcapsule is 10-200 μm, the shell thickness is 5-80% of the grain diameter of the microcapsule, and the shell thickness is preferably 10-50% of the grain diameter of the microcapsule.
The third purpose of the invention is to provide the application of the microcapsule, and the application fields of the microcapsule comprise anticorrosion materials, self-repairing materials, cosmetic preparations, medicines, household products, agricultural chemicals and cleaning agents.
Has the advantages that:
according to the invention, firstly, the photo-curing resin, the cross-linking agent and the core material are separated in the solvent removal process, so that the time for the polymer to migrate to an oil-water interface is greatly increased, the finally obtained photo-curing resin has a thicker shell layer, and the thickness and height of the shell layer of the microcapsule can be adjusted by adjusting the mass ratio of the core material to the photo-curing resin. In addition, the sulfonated microcapsule is prepared by using the reactive sodium styrene sulfonate instead of conventional sulfonates, the sodium styrene sulfonate can be directly and stably grafted to the shell layer of the photocuring resin through covalent bonds, free sulfonates do not exist in the sulfonated microcapsule dispersion liquid after washing, so a large amount of aniline cannot be adsorbed and homogeneous polymerization in the water phase does not occur, free polyaniline does not exist in the water phase, and the preparation schematic diagram is shown in fig. 3.
Drawings
FIG. 1 is an SEM photograph of polyaniline microcapsules prepared in comparative example 1 (a is intact polyaniline microcapsules; b is broken polyaniline microcapsules)
FIG. 2 is a photomicrograph of the ultra-deep-field microscope for preparing polyaniline microcapsules in comparative example 1
FIG. 3 is a schematic diagram of the preparation of polyaniline double-layer microcapsules of the present invention
FIG. 4 is an SEM photograph of the polyaniline double-layer microcapsule prepared in example 1
FIG. 5 is a TGA curve of the polyaniline double-layer microcapsule prepared in example 1
FIG. 6 is a TGA curve of the polyaniline double-layer microcapsule prepared in example 1 at 250 deg.C
FIG. 7 shows the solvent barrier property of the polyaniline double-layer microcapsule prepared in example 1 in tetrahydrofuran
FIG. 8 shows the solvent barrier property of the polyaniline double-layer microcapsule prepared in example 2 in cyclohexane
FIG. 9 is a super-depth-of-field picture of the polyaniline double-layer microcapsule prepared in example 2 soaked in acetone for different times
FIG. 10 is an SEM photograph of the polyaniline double-layer microcapsule prepared in example 2 (A is a single-layer microcapsule; B is a polyaniline double-layer microcapsule) after being soaked in acetone
FIG. 11 is an SEM photograph of the polyaniline double-layer microcapsule prepared in example 3
FIG. 12 is a photograph showing the ultra-depth of field of the polyaniline double-layer microcapsule prepared in example 3 after being dispersed in an aqueous coating
FIG. 13 shows the mechanical properties of the polyaniline double-layer microcapsules prepared in example 3 characterized by nanoindenter
FIG. 14 shows the solvent barrier property of the polyaniline double-layer microcapsule prepared in example 3 in ethyl acetate
FIG. 15 is a fluorescent microscopic photograph before and after phase separation of an emulsion.
Detailed Description
The present invention will be further described with reference to the following examples.
The thermal stability detection method comprises the following steps: the thermal stability of the microcapsules was characterized using a thermogravimetric analyzer (TGA/1100 SF) with heating of the sample from 50 ℃ to 800 ℃ under an oxygen atmosphere at a heating rate of 20 ℃/min with a weight loss of 60 minutes in an isothermal process at 250 ℃ under an oxygen atmosphere.
The solvent barrier property test method comprises the following steps: 1000mL of solvent and 1wt% of microcapsules are well sealed in 1000mL vials at room temperature. After a certain time, the microcapsules are quickly extracted from the solvent. After heating the microcapsules at 70 ℃ for 2h, the weight of the microcapsules was recorded. Finally, the relative release percentage of the core material can be simply calculated as follows:
core material release% = (m) 1 -m 2 )/m 1 Per core material percentage is multiplied by 100%
m 1 Is the initial weight of the microcapsules, m 2 Is the remaining weight of the microcapsules after immersion in different solvents.
The mechanical property test method comprises the following steps: the mechanical properties of the photocurable resin and polyaniline double-layer microcapsules were tested using a nano indenter (Agilent, G200) with a diameter of 215 μm cylindrical plate indenter (poisson ratio of 0.07, modulus of 1141 GPa). The depth was set at 500nm and the force at 500 μ N. The reduced modulus and hardness were calculated using the hertz classical contact theory and the average of the three tests was calculated.
According to the invention, firstly, the photo-curing resin, the cross-linking agent and the core material are separated in the solvent removal process, so that the time for the polymer to migrate to an oil-water interface is greatly increased, the finally obtained photo-curing resin has a thicker shell layer, and the thickness and height of the shell layer of the microcapsule can be adjusted by adjusting the mass ratio of the core material to the photo-curing resin. The preparation method of the polyaniline double-layer microcapsule of the invention is shown in figure 3.
Example 1
The method comprises the following steps: uniformly mixing light-cured resin epoxy acrylate and core material linseed oil according to the mass ratio of 4: 1, wherein a cross-linking agent 1, 6-hexanediol diacrylate is 10wt% of the epoxy acrylate, a solvent dichloromethane is 4 times of the mass of the epoxy acrylate, and a photoinitiator 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide is 2wt% of the total mass of the epoxy acrylate and the 1, 6-hexanediol diacrylate and is used as an oil phase;
mixing the oil phase and the water phase containing 1wt% of polyvinyl alcohol according to a ratio of 1: 8, forming stable emulsion under high-speed stirring, continuously stirring the emulsion to completely remove the solvent, and separating the epoxy acrylate, the 1, 6-hexanediol diacrylate and the linseed oil to form a core-shell emulsion with the epoxy acrylate, the 1, 6-hexanediol diacrylate as shells and the linseed oil as a core;
step two: adding sodium styrene sulfonate and epoxy acrylate into a water phase of the emulsion according to the mass ratio of 8: 1, curing the emulsion by utilizing UV initiated polymerization to enable the epoxy acrylate, 1, 6-hexanediol diacrylate and the sodium styrene sulfonate in the water phase to be cured and crosslinked, and washing by utilizing deionized water to remove unreacted sodium styrene sulfonate to prepare the single-layer sulfonated microcapsule;
step three: slowly dripping aniline and epoxy acrylate into the single-layer sulfonated microcapsule dispersion liquid according to the mass ratio of 1: 16 to ensure that the aniline is completely adsorbed on the surface of the microcapsule;
under the ice bath condition, ammonium persulfate and aniline are added into a water phase according to the molar ratio of 1: 2 to initiate aniline polymerization, and after the reaction is finished and washed, the microcapsule with the polyaniline double-layer microcapsule is prepared, wherein an SEM picture of the microcapsule is shown in figure 4, the wall thickness of the polyaniline double-layer microcapsule is thicker than 5 microns, and the thermal stability of the microcapsule is shown in figures 5 and 6. The thermal stability of the microcapsules is very important for the storage and practical application of the microcapsules, and the thermal stability of the single-layer sulfonated microcapsules and the polyaniline double-layer microcapsules is researched under dynamic and isothermal conditions by TGA. Uncoated microcapsules began to lose weight at about 185 ℃ due to degradation of the polyepoxy acrylate shell and evaporation of the encapsulated core. Above 200 ℃, the core material linseed oil is volatile. For the PANI shell microcapsule, the initial weight loss of the microcapsule is about 293 ℃, namely the initial weight loss temperature of the microcapsule is obviously increased by 100 ℃ from 185 ℃ to 293 ℃, and only an additional PANI coating is needed.
The solvent resistance of the microcapsules in tetrahydrofuran is shown in fig. 7, and it can be seen that the final core material release rate of the single-layer microcapsules obtained in step two is greater than that of the microcapsules with polyaniline double layers, indicating that the solvent resistance of the polyaniline double layers is superior to that of the single-layer photocuring resin shell. For single-layer sulfonated microcapsules, collapse of the microcapsules is quite evident because most of the core material has been extracted. At the same time, severe adhesion between the microcapsules was also observed, which is due to the swelling of the polyacrylate shell. In sharp contrast, the polyaniline-coated microcapsules remained well spherical with no collapse or adhesion observed, indicating enhanced solvent resistance of the polyaniline-coated microcapsules.
Example 2
The method comprises the following steps: uniformly mixing urethane acrylate and linseed oil according to the mass ratio of 1: 1, wherein a crosslinking agent trimethylolpropane triacrylate is 25wt% of the urethane acrylate, ethyl acetate is 6 times of the mass of the urethane acrylate, and a photoinitiator 4-phenyl benzophenone is 5wt% of the total mass of the urethane acrylate and the trimethylolpropane triacrylate to obtain an oil phase;
mixing an oil phase and a water phase containing 3wt% of polyethylene oxide according to a ratio of 1: 5, stirring at a high speed to form a stable emulsion, continuously stirring the emulsion to completely remove the solvent, and separating polyurethane acrylate, trimethylolpropane triacrylate and linseed oil to form a core-shell emulsion with polyurethane acrylate, trimethylolpropane triacrylate as a shell and linseed oil as a core;
step two: adding sodium styrene sulfonate and polyurethane acrylate into the emulsion according to the mass ratio of 1: 1, curing the emulsion by utilizing UV initiated polymerization to enable the polyurethane acrylate and the trimethylolpropane triacrylate in an oil phase and the sodium styrene sulfonate in a water phase to be cured and crosslinked, and washing by utilizing deionized water to remove unreacted sodium styrene sulfonate to prepare a single-layer sulfonated microcapsule;
step three: slowly dripping aniline and polyurethane acrylate into the single-layer sulfonated microcapsule dispersion liquid according to the mass ratio of 1: 1 to ensure that the aniline is completely adsorbed on the surface of the microcapsule;
under the ice bath condition, adding hydrogen peroxide and aniline into a water phase according to the mol ratio of 1: 1 to initiate aniline polymerization, and after the reaction is finished and the polyaniline double-layer microcapsule is obtained after washing, wherein the solvent resistance of the microcapsule in cyclohexane is shown in figure 8. The super-depth-of-field pictures and the SEM photographs of the microcapsules immersed in acetone for different periods of time are shown in fig. 9 and 10, respectively, and it can be seen that the release rate of the core material of the single-layer microcapsule is greater than that of the microcapsules having polyaniline double layers, indicating that the solvent resistance of the polyaniline double layers is superior to that of the single-layer photocurable resin shell layer.
Example 3
The method comprises the following steps: uniformly mixing polyester acrylate and linseed oil according to the mass ratio of 1: 5, wherein a cross-linking agent dipentaerythritol hexaacrylate is 50wt% of the polyester acrylate, a solvent is 8 times of the polyester acrylate, and a photoinitiator methyl o-benzoylbenzoate is 10wt% of the total mass of the polyester acrylate and the dipentaerythritol hexaacrylate to serve as an oil phase;
mixing an oil phase and a water phase containing 6wt% of sodium dodecyl sulfate according to a ratio of 2: 1, stirring at a high speed to form a stable emulsion, continuously stirring the emulsion to completely remove the solvent, so that the polyester acrylate, the dipentaerythritol hexaacrylate and the linseed oil are separated to form a core-shell emulsion taking the polyester acrylate, the dipentaerythritol hexaacrylate as shells and the linseed oil as a core, wherein fluorescence micrographs of the emulsion before and after the solvent is removed are shown in figure 15, when the solvent is not removed, the emulsion is homogeneous, and the emulsion is in a phase separation state after the solvent is removed;
step two: adding sodium styrene sulfonate and polyester acrylate into emulsion according to the mass ratio of 1: 4, curing the emulsion by using electron beam to initiate polymerization, so that the polyester acrylate, dipentaerythritol hexaacrylate and sodium styrene sulfonate in an oil phase are cured and crosslinked, and washing by using deionized water to remove unreacted sodium styrene sulfonate, thereby preparing the single-layer sulfonated microcapsule;
step three: slowly dripping aniline and polyurethane acrylate into the single-layer sulfonated microcapsule dispersion liquid according to the mass ratio of 4: 1 to ensure that the aniline is completely adsorbed on the surface of the microcapsule;
under the ice bath condition, adding potassium permanganate and aniline into a water phase according to the molar ratio of 4: 1 to initiate aniline polymerization, and after the reaction is finished and the solution is washed, preparing the polyaniline double-layer microcapsule, wherein an SEM photo of the microcapsule is shown in figure 11, and the dispersibility of the microcapsule in different water-based coatings is shown in figure 12. The mechanical properties of the microcapsules are shown in fig. 13, the hardness and modulus of the single-layer photocuring resin obtained in the step two are both smaller than those of the polyaniline double-layer, and the average young's modulus and hardness of the single-layer sulfonated microcapsule shell are 86.23 +/-9.13 MPa and 4.66 +/-3.2 MPa respectively. The Young modulus and the hardness of the polyaniline double-layer microcapsule shell material are respectively increased to 362.31 +/-35.98 MPa and 39.89 +/-1.29 MPa, which are 4 times and 9 times of the uncoated microcapsule shell material. Therefore, it can be concluded that the polyaniline-coated microcapsules have better resistance to deformation.
The solvent resistance of the microcapsules in ethyl acetate is shown in fig. 14, the final core material release rate of the single-layer microcapsules is higher than that of the microcapsules with polyaniline double layers, and the solvent resistance of the polyaniline double layers is better than that of the single-layer photocuring resin shell layers.
Comparative example 1
With reference to the scheme disclosed in CN 110484088A, a polyaniline microcapsule is prepared:
(1) 480mg of sodium dodecyl sulfate was dissolved in 12mL of water as an aqueous phase by sonication, while 1.2mL of dimethylaminoethyl methacrylate (DMAEMA) (1.119 g, density: 0.933 g/mL), 1.2mL of Divinylbenzene (DVB) (1.102 g, density: 0.919 g/mL), 66.6mg of photoinitiator 1173% (3% of monomer mass), 3mL of Hexamethylene Diisocyanate (HDI) were dissolved in 0.6mL of ethyl acetate. Mixing the two phases at oil-water ratio of 1: 2, and emulsifying at 9000rpm for 3min by high-speed disperser to form stable oil-in-water (O/W) emulsion;
(2) Placing the emulsion prepared in the step (1) under ultraviolet light for illumination for 4min to polymerize an alkene monomer, dropwise adding 0.6mL of aniline into the microcapsule dispersion liquid after illumination, then adding 2mL of aqueous solution containing 735mg of ammonium persulfate (molar ratio of 1: 2 to aniline) and 50 mu L of hydrochloric acid (1M) to polymerize aniline, reacting for 16h at 10 ℃ under the action of mechanical stirring, alternately washing with water and ethanol, and drying to obtain polyaniline microcapsules loaded with active monomers;
as shown in fig. 1, is an SEM photograph of the prepared microcapsules, wherein a is the intact polyaniline microcapsules; b is broken polyaniline microcapsule. Because the ultraviolet irradiation curing speed is high, the polymer after photo-crosslinking can not be quickly transferred to the surface of the microcapsule, so that the microcapsule is very thin, and the barrier property of the obtained microcapsule is poor.
As shown in fig. 2, it is an ultra-deep-field microscope photograph of the polyaniline microcapsule prepared. After emulsion is subjected to photocuring, a large amount of free sulfonate emulsifiers can adsorb a large amount of aniline to generate homogeneous polymerization in a water phase, so that a large amount of free polyaniline appears in the water phase, and the free polyaniline is mixed with the polyaniline double-layer microcapsule, so that the core material has low relative content, and the efficient packaging of the core material cannot be realized.
Comparative example 2
Referring to Yaohui Ling, dian Zhai Chang, dian Zhai Guanglian, etc., the synthesis and performance characterization of polyaniline/poly (styrene-sodium styrene sulfonate) nano core-shell structure polymer by microemulsion method [ J ]. Shandong university Commission (science edition), 2008.
0.5g of Sodium Dodecyl Sulfate (SDS), 20g of deionized water, 0.06g of sodium styrene sulfonate, 0.6g of styrene monomer and 1.4g of n-amyl alcohol were added into a three-necked flask, nitrogen gas was introduced, and vigorous stirring was carried out for 1 hour to form a transparent microemulsion system. A50 mL volumetric flask was used to prepare a mixed solution of KPS and PVP, in which potassium persulfate (KPS) was 2.893g. 0.018g of polyvinylpyrrolidone (PVP) was used as initiator and dispersant, respectively (KPS and styrene monomer in a molar ratio of 1: 100, PVP represents 3% by mass of styrene monomer). Measuring the KPS and PVP mixed solution by microliter to 200 microliter, adding a microemulsion system, stirring uniformly, and reacting for 4 hours under the protection of nitrogen at 75 ℃ to obtain the polystyrene nano latex particles. The polystyrene latex was diluted 1-fold, and 20g was poured into a round-bottom flask. 0.045g FeCl was weighed 3 Pouring into a flask, stirring vigorously until FeCl is obtained 3 And completely dissolving. KPS 0.0363g and PVP 0.075g are weighed and prepared into a solution in a 100mL volumetric flask for later use. mu.L (0.0063 g) of aniline monomer was metered in microliter and added to the flask and stirred vigorously under nitrogen to mix the components well. Measuring KPS and PVP mixed solution by a microliter meter to 200 mu L, adding into a round-bottom flask, then putting the flask into an ice water bath, stirring violently under the condition of nitrogen protection, and reacting for 24h to obtain polyaniline-coated nanoparticles.
The above steps utilize sodium styrene sulfonate and Sodium Dodecyl Sulfate (SDS) as emulsifier to stabilize styrene monomer, and cross-link and fix on the surface of latex particle through covalent bond.
The invention does not use sodium styrene sulfonate as an emulsifier, and only adds the sodium styrene sulfonate as a sulfonation element into a water phase, namely, only grafts a sulfonic group on the surface of a microcapsule shell layer through the sodium styrene sulfonate with reactivity.
Once sodium styrene sulfonate is used as an emulsifier for preparing the emulsion before curing, after the rapid polymerization of photo-initiation, the sodium styrene sulfonate is bonded to the surface of the shell layer of the microcapsule by covalent bonds, so that the capability of stabilizing the oil phase is greatly reduced, a large amount of microcapsules are aggregated, and cannot be dispersed in matrix resin, and further cannot be practically applied.
Comparative example 3
Uniformly mixing epoxy acrylate and linseed oil according to the mass ratio of 4: 1, wherein a cross-linking agent 1, 6-hexanediol diacrylate is 10wt% of the epoxy acrylate, a photoinitiator 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide is 2wt% of the total mass of the epoxy acrylate and the 1, 6-hexanediol diacrylate, and the mixture is used as an oil phase;
mixing an oil phase and a water phase containing 1wt% of polyvinyl alcohol according to a ratio of 1: 8, stirring at a high speed to form a stable emulsion, adding sodium styrene sulfonate and epoxy acrylate into the water phase of the emulsion according to a mass ratio of 8: 1, curing the emulsion by utilizing UV-initiated polymerization to enable the epoxy acrylate, 1, 6-hexanediol diacrylate and the sodium styrene sulfonate in the water phase to be cured and crosslinked, and washing by utilizing deionized water to remove unreacted sodium styrene sulfonate, thus obtaining the porous microsphere.
After the stable emulsion is prepared in the steps, the emulsion is directly subjected to photo-initiated rapid curing, the obtained product is porous microspheres, microcapsules with a core-shell structure cannot be prepared, a core material cannot be stably packaged, and the core material is easy to leak.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (7)
1. A preparation method of polyaniline double-layer microcapsules with barrier property is characterized by comprising the following steps:
the method comprises the following steps: uniformly mixing the photo-curing resin, the core material, the cross-linking agent, the solvent and the photoinitiator to form an oil phase, mixing the oil phase with a water phase containing the stabilizer to form a stable emulsion, and continuously stirring or heating the emulsion to completely remove the solvent so as to separate the photo-curing resin, the cross-linking agent and the core material;
step two: adding sodium styrene sulfonate into the water phase, stirring, curing the emulsion under UV irradiation, washing by using deionized water to remove unreacted sodium styrene sulfonate, and preparing to obtain a single-layer sulfonated microcapsule;
step three: dropwise adding aniline into the aqueous dispersion of the sulfonated microcapsule, continuously stirring to enable the aniline to be completely adsorbed on the surface of the microcapsule, then adding an initiator under an ice bath condition to initiate aniline polymerization, and washing to obtain a polyaniline double-layer microcapsule;
the light-cured resin and the core material are not mutually soluble; the solvent has a boiling point of 80 ℃ or less and is a good solvent for the photocurable resin.
2. The method for preparing the polyaniline double-layer microcapsule with barrier property according to claim 1, wherein the photocurable resin is one or more of urethane acrylate, polyester acrylate and epoxy acrylate;
the cross-linking agent is one or more of tripropylene glycol diacrylate, 1, 6-hexanediol diacrylate, dipropylene glycol diacrylate, bisphenol A glycidyl dimethacrylate, triethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, diethylene glycol diacrylate phthalate, neopentyl glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate and 1, 3-butanediol diacrylate;
the solvent is a good solvent of the light-cured resin with a lower boiling point, the boiling point is below 80 ℃, and preferably one or more of dichloromethane, trichloromethane, ethyl acetate and butyl acetate;
the stabilizer is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polystyrene-maleic anhydride copolymer, polyethylene-maleic anhydride copolymer, polyoxyethylene-polyoxypropylene-polyoxyethylene triblock polymer, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, hexadecyl trimethyl ammonium bromide, span-80, span-60, tween-80, tween-60, monoglyceride fatty acid glyceride, N-dodecyl dimethylamine and Arabic gum;
in the first step, the photoinitiator is one or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, 2,4, 6-trimethylbenzoyl diphenylphosphine oxide, isopropyl thioxanthone, ethyl 4- (N, N-dimethylamino) benzoate, benzophenone, 4-chlorobenzophenone, methyl o-benzoylbenzoate, diphenyliodonium salt hexafluorophosphate, isooctyl N, N-dimethylaminobenzoate, 4-methylbenzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide, and ethyl 2,4, 6-trimethylbenzoyl phenylphosphinate;
in the first step, the core material is one or more of a self-repairing agent, an early warning agent and a lubricating agent;
in the third step, the initiator is one or a mixture of any more of ammonium persulfate, potassium persulfate, hydrogen peroxide and potassium permanganate.
3. The method for preparing polyaniline double-layer microcapsule with barrier property as claimed in claim 1 or 2, wherein the mass ratio of the photo-curing resin to the core material in the first step is 5: 1-1: 5,
the cross-linking agent accounts for 5-50 wt% of the light-cured resin,
the solvent is 3 to 8 times of the mass of the light-cured resin; the photoinitiator is 1wt% -10 wt% of the total mass of the light-cured resin and the cross-linking agent.
4. The method for preparing polyaniline double-layer microcapsule with barrier property as claimed in claim 1 or 2, wherein the mass ratio of the oil phase and the water phase in the second step is 1: 10-2: 1, the concentration of the stabilizer is 0.5wt% -6 wt%, and the mass ratio of the sodium styrene sulfonate and the light-cured resin is 1: 2-1: 8.
5. The method for preparing polyaniline double-layer microcapsule with barrier property according to claim 1 or 2, characterized in that the mass ratio of aniline to sulfonated microcapsule in the third step is 1: 16-4: 1, and the molar ratio of initiator to aniline is 1: 2-4: 1.
6. The polyaniline double-layer microcapsule with barrier property prepared by the method of any one of claims 1 to 5, characterized in that the prepared microcapsule has a particle size of 10 to 200 μm, a shell thickness of 5 to 80% of the particle size of the microcapsule, and preferably a shell thickness of 10 to 50% of the particle size of the microcapsule.
7. The microcapsules prepared by the method according to any one of claims 1 to 5 or the microcapsules of claim 6, wherein the microcapsules are applied to fields including anticorrosion materials, self-healing materials, cosmetic preparations, medicines, household products, agricultural chemicals and detergents.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115505332A (en) * | 2022-08-30 | 2022-12-23 | 江南大学 | Self-repairing anticorrosive coating containing polyaniline double-layer microcapsule |
| CN117050612A (en) * | 2023-10-12 | 2023-11-14 | 江苏金天辰新材料有限公司 | Corrosion-resistant composite aluminum foil for food packaging and processing technology thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115505332A (en) * | 2022-08-30 | 2022-12-23 | 江南大学 | Self-repairing anticorrosive coating containing polyaniline double-layer microcapsule |
| CN115505332B (en) * | 2022-08-30 | 2023-04-07 | 江南大学 | Self-repairing anticorrosive coating containing polyaniline double-layer microcapsule |
| CN117050612A (en) * | 2023-10-12 | 2023-11-14 | 江苏金天辰新材料有限公司 | Corrosion-resistant composite aluminum foil for food packaging and processing technology thereof |
| CN117050612B (en) * | 2023-10-12 | 2023-12-08 | 江苏金天辰新材料有限公司 | Corrosion-resistant composite aluminum foil for food packaging and processing technology thereof |
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