A method for preparing a janus water-based microgel

Abstract

The application discloses a preparation method of Janus water-based microgel and belongs to the technical field of microgel. The Janus water-based microgel is successfully prepared based on vortex oscillation into emulsion and ultraviolet light irradiation. 1. Solution preparation: polymerization monomers / crosslinking agent / initiator are weighed, and an oil phase solution containing Span 80 surfactant is prepared; an ATPS aqueous solution is prepared; 2. Preparation of Janus emulsion droplets; 3. Preparation of Janus water-based microgel; 4. Washing of Janus water-based microgel. The oil phase and surfactant used in the application are cheap and easy to obtain, the preparation method is simple, and through the change of the components of the double water phase and the type of the surfactant, Janus water-based microgels with different morphologies can be obtained. The Janus water-based microgel prepared in the application is expected to be used for drug encapsulation and treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the preparation of a gel, in particular to a preparation method of Janus water-based microgel. BACKGROUND

[0002] The preparation method of Janus water-based microgel is mainly microfluidic technology, which can realize the change of various topological structures of the gel. However, the microfluidic device is expensive and the preparation speed is slow, which is difficult to realize industrialized preparation. Therefore, we have developed a one-step vortex method to prepare Janus water-based microgel. The Janus emulsion is prepared in batches by a vortex, and the Janus microgel is prepared by polymerization in the Janus emulsion as a template, realizing the batch preparation of Janus water-based microgel.

[0003] At present, the polymerization methods of microgels mainly include photopolymerization, ionic crosslinking and thermal polymerization. Among them, ionic crosslinking is mainly used to prepare physical gels, which uses the interaction between ions and polymers to enhance the gel network; thermal polymerization uses thermal initiators such as ammonium persulfate and sodium persulfate to initiate chain polymerization to form a three-dimensional network. Because the stability of the reverse emulsion in a high-temperature environment is difficult to guarantee, thermal polymerization is not an ideal polymerization method. Photopolymerization uses a photo initiator to initiate chain polymerization, and is widely used in the preparation of microgels and solid particles due to its rapid preparation.

[0004] For example, the patent for invention with publication number CN103788267A discloses a method for preparing Janus particles. Two kinds of partially immiscible polymerizable monomers and a surfactant aqueous solution are emulsified at one time to prepare a Janus emulsion, and then the polymerizable monomers in the emulsion droplets are polymerized by light initiation to prepare Janus particles composed of two different organic substances. For example, the patent for invention with publication number CN115418006A discloses a microgel based on acrylated gelatin, its preparation method and its application. A microfluidic method combined with an online photopolymerization reaction is used to prepare a kind of acrylated gelatin microgel in high throughput, and its application in the encapsulation of bioactive substances. First, acrylated gelatin microdroplets are prepared in high throughput using droplet microfluidic technology, then a visible light source matched with a photo initiator is placed above the microfluidic channel to realize the online continuous production of GelA microdroplets and the solidification to form microgel particles.

[0005] At present, these methods need to be further improved in terms of production process, production capacity and morphology control. SUMMARY

[0006] The purpose of the present application is to provide a method for preparing Janus water-based microgel which is simple and efficient and is conducive to industrial production.

[0007] Technical scheme: A preparation method of Janus water-based microgel, comprising the following steps:

[0008] (1) Construction of aqueous two-phase system containing polymerizable monomer: sodium sulfate and polyethylene glycol or dextran and polyethylene glycol (PEG) are added to deionized water to dissolve and centrifuge to form an aqueous two-phase system ATPS solution, and a polymerizable monomer, a crosslinking agent, and an initiator are added to the ATPS and stirred to dissolve and centrifuge to obtain a monomer-added ATPS aqueous solution;

[0009] (2) Preparation of Janus emulsion and Janus microgel: an oil solution containing a surfactant is prepared, the monomer-added ATPS aqueous solution is added to the oil solution containing the surfactant, a vortex shaker is used to shake into a milk, the emulsion is placed in a photochemical reaction device, and a UV lamp is used for light stirring to obtain a Janus microgel;

[0010] (3) Drying of the Janus microgel: the obtained Janus microgel after light irradiation is washed and dried to obtain a Janus microgel.

[0011] In the preparation method, the polymerizable monomer in step (1) is acrylamide, polyethylene glycol diacrylate, or N-isopropyl acrylamide; the crosslinking agent is N,N'-methylene bisacrylamide; and the initiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0012] In the preparation method, the surfactant in step (2) is Span 80; the oil phase is liquid paraffin or sunflower seed oil; the emulsification speed of the vortex shaker is 2000-20000 rpm, and the emulsification time is 1-5 min.

[0013] In the method, if a rotor is used as a stirrer in step (1), the rotation speed is 500-1000 rpm.

[0014] In the preparation method, the wavelength of the UV lamp in step (3) is 300-400 nm.

[0015] In the preparation method, the washing in step (3) is an alternating washing and drying of the Janus water-based microgel with ethanol and petroleum ether.

[0016] In the preparation method, the mass concentration of the polymerizable monomer in step (1) is 5%-30%, the mass fraction of the initiator in the monomer is 0.1%-3%, and the mass concentration of the crosslinking agent accounts for 1%-20% of the monomer concentration.

[0017] In the preparation method, the oil / water mass ratio in step (2) is 10 / 1-2 / 1, and the concentration of the surfactant Span 80 in the oil is 1%-5%.

[0018] The preparation method, the mass concentration of PEG 8000 in step (1) is 10%-25%, the mass concentration of DEX 10000 is 10%-25%, and the mass concentration of sodium sulfate is 10%-25%.

[0019] The preparation method, the molecular weight of PEG is selected from 2000-25000, and the molecular weight of DEX is selected from 2000-25000.

[0020] The Janus emulsion is prepared by one-step vortex method by one-time emulsification of the aqueous two-phase system added with the polymerization monomer and the oil solution added with the surfactant, polymerization is carried out in the Janus emulsion by ultraviolet light polymerization to form a three-dimensional network structure, and thus the Janus water-based microgel is obtained, the morphology of which can be controlled by changing the proportion of the aqueous two-phase, and the particle size can be controlled by the rotating speed of the vortex.

[0021] The polymerization monomer includes but is not limited to acrylamide, N-isopropyl acrylamide and polyethylene glycol diacrylate.

[0022] The initiator includes but is not limited to 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropanone, which is a common cleavage type photoinitiator, has simple structure, is easy to synthesize and has high initiation activity.

[0023] The crosslinking agent includes but is not limited to N,N'-methylene bisacrylamide.

[0024] The Janus water-based microgel preparation process is shown in Figure 1 .

[0025] The Janus water-based microgel prepared in the application is verified by an optical microscope, the particle size of the prepared Janus water-based microgel is proved by a laser particle size analyzer, the morphology of the prepared Janus water-based microgel is verified by a scanning electron tunneling microscope (SEM), the groups of the dried microgel are characterized by an infrared spectrometer, and the rheological performance of the prepared microgel is tested by a rotary rheometer.

[0026] The preparation of Janus water-based microgel is based on Janus emulsion, which relies on the preparation of aqueous two-phase system. When two polymers, one polymer and one lyophile salt, or two salts (one is discrete salt and the other is lyophile salt) are mixed together at a suitable concentration or at a specific temperature, an aqueous two-phase system is formed. The two phases are mostly composed of water and non-volatile components, thus avoiding the use of volatile organic components. In the aqueous two-phase system, the two molecules compete for water molecules to form a phase interface, and the ability of the two molecules to compete for water molecules is different, and the hydrophilicity is different, resulting in different phase interface positions. The aqueous two-phase system described in the present application includes salt solution and polymer solution, polymer and polymer solution, and salt solution and polymer solution are sodium sulfate and PEG 8000, and polymer and polymer are DEX 10000 and PEG 8000.

[0027] Beneficial effects: (1) Janus microgel is prepared by using Janus emulsion as a polymer template, and the obtained double-sided microgel has controllable morphology. The size of Janus water-based microgel can be controlled by the speed of vortex, which is beneficial to expand the application field of Janus. (2) The preparation method is simple, and the polymerization speed of the polymerization method is rapid, which can mass-produce Janus water-based microgel, is easy to realize industrialization, and the oil phase in the preparation process can be separated and reused. (3) The Janus microgel prepared by the method has two independent microchambers, which can load substances and realize functionalization. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the preparation flow chart of Janus water-based microgel prepared in examples 1-8;

[0029] Figure 2 is the microscope image of Janus water-based microgel prepared in example 1;

[0030] Figure 3 is the SEM image of Janus water-based microgel prepared in example 1;

[0031] Figure 4 is the rheological property test image of Janus water-based microgel prepared in example 1;

[0032] Figure 5 is the infrared spectrum of Janus water-based microgel prepared in example 1;

[0033] Figure 6 is the microscope image of Janus emulsion and Janus water-based microgel prepared in example 2;

[0034] Figure 7is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 3;

[0035] Figure 8 is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 4;

[0036] Figure 9 is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 5;

[0037] Figure 10 is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 6;

[0038] Figure 11 is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 7;

[0039] Figure 12 is a microscope image of the Janus emulsion and Janus water-based microgel prepared in Example 8;

[0040] Figure 13 is a particle size analysis chart of the Janus water-based microgel prepared in Examples 1 to 3;

[0041] Figure 14 is a microgel friction performance test chart of the separated aqueous two-phase; (wherein a is a photo of the Janus microgel dissolved in water; b is the friction performance test of pure water, PEG microgel aqueous solution, DEX microgel aqueous solution, Janus microgel aqueous solution; c is the average friction coefficient of pure water, PEG microgel aqueous solution, DEX microgel aqueous solution, Janus microgel aqueous solution; b and c are test results under a load of 10N, a time of 20min, a stroke of 1mm, and a frequency of 1Hz;)

[0042] Figure 15 is a microscope image of the Janus water-based microgel prepared in Example 4. DETAILED DESCRIPTION

[0043] The present application is further described in the following examples and by reference to the data. It should be understood that these examples are only given to illustrate the present application and are not intended to limit the scope of the present application in any way.

[0044] In the following examples, various processes and methods that are not described in detail are conventional methods known in the art.

[0045] Example 1

[0046] Dextrans (DEX 1000) and PEG8000 were dissolved in deionized water to form an aqueous two-phase (ATPS) solution, and acrylamide, N,N'-methylenebisacrylamide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone were added to the solution to obtain an aqueous solution of monomers, and the final solution contained 15wt% acrylamide, 2wt% N,N'-methylenebisacrylamide, 1wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10wt% PEG 8000, and 10wt% DEX 10000. 1% Span 80 surfactant was added to liquid paraffin, and the mass ratio of the aqueous two-phase solution of monomers to the Span 80 liquid paraffin solution was 1:4. The weighed aqueous two-phase solution was placed in a separatory funnel and allowed to stand for 1 hour, then the lower solution was removed by opening the piston, and then a small amount of the upper solution was removed to ensure that no lower solution remained, and the entire upper solution was poured out. The prepared aqueous two-phase system had a PEG:DEX volume ratio of 7:3, and the total mass was 5g. The vortex speed was 3000rpm, and the vortex time was 3min in a 10mL centrifuge tube.

[0047] The obtained Janus reverse emulsion was irradiated under a 300W ultraviolet lamp for 1h to initiate polymerization of acrylamide to form a three-dimensional network.

[0048] The polymerized solution was washed with petroleum ether and ethanol solution alternately five times, and vacuum dried at 25°C to obtain a Janus water-based microgel.

[0049] Verification: Figure 2 The microscope photo of the prepared Janus water-based microgel, Figure 3 The SEM photo of the prepared Janus water-based microgel, Figure 4 The rheological test of the emulsion before and after irradiation, Figure 5 The infrared spectrum of the Jansu water-based microgel after vacuum drying.

[0050] From Figure 2 Figure 3 It can be seen that the Janus microgel prepared by the application has a micro-morphology.

[0051] From Figure 4 It can be seen that after irradiation, a linear viscoelastic zone formed by the gel is obviously present.

[0052] From Figure 5 It can be seen that 3190cm -1 is the characteristic absorption peak of associated -NH2, 2926cm -1 is the anti-symmetrical stretching vibration absorption peak of methylene, and 2856cm -1 is the characteristic absorption peak of symmetrical stretching vibration of methylene, and 1667cm-1 characteristic absorption peak of carbonyl group, 1451 cm -1 characteristic absorption peak of methylene deformation, indicating the polymerization of acrylamide in the reaction.

[0053] Example 2

[0054] 1. 15wt% acrylamide, 2wt% N,N'-methylene bisacrylamide, 1wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10wt% PEG 8000, 10wt% DEX 10000 were dissolved in deionized water to form a two-phase aqueous solution, 1% Span 80 surfactant was added to liquid paraffin, and the mass ratio of the two-phase aqueous solution to the Span 80 liquid paraffin solution was 1:4. The weighed two-phase aqueous solution was placed in a separatory funnel and allowed to stand for 1 hour, then the piston was opened, the lower layer solution was taken out, then a small part of the upper layer solution was discharged to ensure that there was no lower layer solution remaining, and the entire upper layer solution was poured out from the top. The prepared two-phase aqueous phase had a PEG:DEX volume ratio of 7:3, and the total mass was 5g. The vortex speed was 10000rpm and the vortex time was 3min in a 10mL centrifuge tube.

[0055] 2. The obtained Janus reverse emulsion was irradiated under a 300W ultraviolet lamp for 1h to initiate the polymerization of acrylamide to form a three-dimensional network.

[0056] 3. The polymerized solution was washed with petroleum ether and ethanol solution alternately five times, and vacuum dried at 25°C to obtain a Janus water-based microgel.

[0057] 4. Verification: Figure 6 is a microscope photo of the prepared Janus water-based microgel.

[0058] Example 3

[0059] 1. 15wt% acrylamide, 2wt% N,N'-methylene bisacrylamide, 1wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10wt% PEG 8000, 10wt% DEX 10000 were dissolved in deionized water to form a two-phase aqueous solution, 1% Span 80 surfactant was added to liquid paraffin, and the mass ratio of the two-phase aqueous solution to the Span 80 liquid paraffin solution was 1:4. The weighed two-phase aqueous solution was placed in a separatory funnel and allowed to stand for 1 hour, then the piston was opened, the lower layer solution was taken out, then a small part of the upper layer solution was discharged to ensure that there was no lower layer solution remaining, and the entire upper layer solution was poured out from the top. The prepared two-phase aqueous phase had a PEG:DEX volume ratio of 7:3, and the total mass was 5g. The vortex speed was 10000rpm and the vortex time was 3min in a 10mL centrifuge tube.

[0060] 2. The obtained Janus reverse emulsion was irradiated under 300W UV light for 1h to initiate the polymerization of acrylamide to form a three-dimensional network.

[0061] 3. The polymerized solution was washed with petroleum ether and ethanol solution alternately for five times, and dried under vacuum at 25°C to obtain Janus water-based microgel.

[0062] 4. Verification: Figure 7 The microscope photos of the prepared Janus water-based microgel. The Janus emulsion and Janus water-based microgel prepared in Examples 1-3 were subjected to particle size analysis, and the results are shown in Figure 13

[0063] Example 4

[0064] 15wt% acrylamide, 2wt% N,N'-methylene bisacrylamide, 1wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10wt% PEG 8000, 10wt% Na2SO4 were dissolved in deionized water to form a two-phase aqueous solution, 1% Span 80 surfactant was added to liquid paraffin, and the mass ratio of two-phase aqueous solution to Span 80 liquid paraffin solution was 1:4. The weighed two-phase aqueous solution was placed in a separatory funnel and allowed to stand for 1 hour, then the piston was opened, the lower solution was taken out, then a small part of the upper solution was discharged to ensure that there was no lower solution residue, and the whole upper solution was poured out from the top. The prepared two-phase aqueous phase had a PEG: DEX volume ratio of 7:3, and the total mass was 5g. The vortex speed was 3000rpm and the vortex time was 3min in a 10mL centrifuge tube.

[0065] Verification: Figure 15 The microscope photos of the prepared Janus water-based microgel.

[0066] Example 5

[0067] ​1. Dissolve 15 wt% acrylamide, 2 wt% N,N'-methylenebisacrylamide, 1 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10 wt% PEG 8000, 10 wt% DEX 10000 in deionized water to form a aqueous two-phase solution, add 1% Span 80 surfactant to liquid paraffin, weigh the aqueous two-phase solution and the Span 80 liquid paraffin solution in a mass ratio of 1:4. Weigh the aqueous two-phase solution and place it in a separatory funnel, let it stand for 2 hours, then open the piston, take out the lower layer solution, then pour out the upper layer solution to ensure that there is no lower layer solution left. The prepared aqueous two-phase has a PEG:DEX volume ratio of 4:1, and the total mass is 5g. In a 10mL centrifuge tube, the vortex speed is 3000rpm, and the vortex time is 3min.

[0068] 2. Irradiate the obtained Janus reverse emulsion under a 300W ultraviolet lamp for 1h to initiate acrylamide polymerization to form a three-dimensional network.

[0069] 3. Wash the polymerized solution with petroleum ether and ethanol solution alternately five times, and dry it under vacuum at 25°C to obtain a Janus water-based microgel.

[0070] 4. Verification: Figure 8 The microscope photo of the prepared Janus water-based microgel.

[0071] Example 6

[0072] 1. Dissolve 15 wt% acrylamide, 2 wt% N,N'-methylenebisacrylamide, 1 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10 wt% PEG 8000, 10 wt% DEX 10000 in deionized water to form a aqueous two-phase solution, add 1% Span 80 surfactant to liquid paraffin, weigh the aqueous two-phase solution and the Span 80 liquid paraffin solution in a mass ratio of 1:4. Weigh the aqueous two-phase solution and place it in a separatory funnel, let it stand for 4 hours, then open the piston, take out the lower layer solution, then pour out the upper layer solution to ensure that there is no lower layer solution left. The prepared aqueous two-phase has a PEG:DEX volume ratio of 1:1, and the total mass is 5g. In a 10mL centrifuge tube, the vortex speed is 3000rpm, and the vortex time is 3min.

[0073] 2. Irradiate the obtained Janus reverse emulsion under a 300W ultraviolet lamp for 1h to initiate acrylamide polymerization to form a three-dimensional network.

[0074] 3. The polymerized solution was washed with petroleum ether and ethanol solution alternately for five times, and dried in vacuum at 25 °C to obtain Janus water-based microgel.

[0075] 4. Verification: Figure 9 The microscope photo of the prepared Janus water-based microgel.

[0076] Example 7

[0077] 1. 15wt% acrylamide, 2wt% N,N'-methylenebisacrylamide, 1wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10wt% PEG 8000, 10wt% DEX 10000 were dissolved in deionized water to form a two-phase aqueous solution, 1% Span 80 surfactant was added to liquid paraffin, and the mass ratio of two-phase aqueous solution to Span 80 liquid paraffin solution was 1:1. The weighed two-phase aqueous solution was placed in a separatory funnel and left to stand for 8 hours, then the lower solution was taken out by opening the piston, and then a small part of the upper solution was discarded to ensure that there was no lower solution residue, and the whole upper solution was poured out from the top. The prepared two-phase aqueous phase had a PEG: DEX volume ratio of 1:4, and the total mass was 5g. The vortex speed was 3000rpm and the vortex time was 3min in a 10mL centrifuge tube.

[0078] 2. The obtained Janus reverse emulsion was irradiated under a 300W ultraviolet lamp for 1h to initiate polymerization of acrylamide to form a three-dimensional network.

[0079] 3. The polymerized solution was washed with petroleum ether and ethanol solution alternately for five times, and dried in vacuum at 25 °C to obtain Janus water-based microgel.

[0080] 4. Verification: Figure 10 The microscope photo of the prepared Janus water-based microgel.

[0081] Example 8

[0082] 1. Dissolve 15 wt% polyethylene glycol diacrylate, 2 wt% N,N'-methylenebisacrylamide, 1 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 10 wt% PEG 8000, 10 wt% DEX 10000 in deionized water to form an aqueous two-phase solution, add 1% Span 80 surfactant to liquid paraffin, weigh the aqueous two-phase solution and the Span 80 liquid paraffin solution in a mass ratio of 1:4. Weigh the aqueous two-phase solution and place it in a separatory funnel, let it stand for 4 hours, then open the stopcock, remove the lower solution to ensure that there is no lower solution remaining, then pour out the entire upper solution from the top after discarding a small amount of the upper solution. The PEG:DEX volume ratio in the prepared aqueous two-phase system is 1:1, and the total mass is 5 g. In a 10 mL centrifuge tube, the vortex speed is 3000 rpm, and the vortex time is 3 min.

[0083] 2. Irradiate the obtained Janus reverse emulsion under a 300 W ultraviolet lamp for 1 h to initiate polymerization of polyethylene glycol diacrylate to form a three-dimensional network.

[0084] 3. Wash the polymerized solution with petroleum ether and ethanol solution alternately five times, and vacuum dry at 25°C to obtain a Janus water-based microgel.

[0085] 4. Verification: Figure 11 The microscope photo of the prepared Janus water-based microgel.

[0086] Example 9

[0087] 1. Dissolve 15 wt% acrylamide, 2 wt% N,N'-methylenebisacrylamide, 1 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 1 wt% TiO2, 10 wt% PEG 8000, 10 wt% DEX 10000 in deionized water to form an aqueous two-phase solution, add 1% Span 80 surfactant to liquid paraffin, weigh the aqueous two-phase solution and the Span 80 liquid paraffin solution in a mass ratio of 1:4. Weigh the aqueous two-phase solution and place it in a separatory funnel, let it stand for 4 hours, then open the stopcock, remove the lower solution to ensure that there is no lower solution remaining, then pour out the entire upper solution from the top after discarding a small amount of the upper solution. The PEG:DEX volume ratio in the prepared aqueous two-phase system is 1:1, and the total mass is 5 g. In a 10 mL centrifuge tube, the vortex speed is 3000 rpm, and the vortex time is 3 min.

[0088] 2. Irradiate the obtained Janus reverse emulsion under a 300 W ultraviolet lamp for 1 h to initiate polymerization of acrylamide to form a three-dimensional network.

[0089] 3. The polymerized solution was washed with petroleum ether and ethanol solution alternately for five times, and dried in vacuum at 25°C to obtain Janus water-based microgel.

[0090] 4. Verification: Figure 12 The microscope photo of the prepared Janus water-based microgel.

[0091] Example 10

[0092] Friction test performance of Janus microgel aqueous solution under constant load

[0093] The Janus microgel prepared in Example 1 was taken, the particle content was 10wt%, the friction pair was selected as 304 stainless steel ball with a diameter of 4.5mm and 304 stainless steel plate with a size of 30x12mm, the load was constant at 10N, the sliding frequency was 1Hz, the amplitude was 1mm, and the test time was 20min, and the test was carried out by a friction and wear testing machine.

[0094] Verification: As shown in Figure 14 a, the dispersion of Janus microgel particles in water; Figure 14 b-c are the test results of the friction coefficient between the friction pairs under the conditions of constant load of 10N, sliding frequency of 1Hz and amplitude of 1mm. The results show that the Janus microgel prepared by the present application has good anti-friction effect.

Claims

1. A process for the preparation of a Janus water-based microgel, characterized in that, It comprises the following steps: (1) Construction of aqueous two-phase system containing polymerization monomer: two reagents of sodium sulfate and polyethylene glycol, or two reagents of dextran and polyethylene glycol are added to deionized water to dissolve and centrifuge to form an aqueous two-phase system ATPS solution, and the polymerization monomer, crosslinking agent and initiator are added to the ATPS to stir, dissolve and centrifuge to obtain an aqueous solution of monomer-added ATPS; (2) Preparation of Janus emulsion and Janus microgel: an oil solution containing a surfactant is prepared, the aqueous solution of monomer-added ATPS is added to the oil solution containing the surfactant, a vortex shaker is used to shake into a milk, the emulsion is placed in a photochemical reaction device, and a UV lamp is used for light irradiation and stirring to obtain a Janus microgel; (3) Drying of Janus microgel: the obtained Janus microgel after light irradiation is washed and dried to obtain a Janus microgel.

2. The preparation method according to claim 1, characterized in that, In step (1), the polymerization monomer is acrylamide, polyethylene glycol diacrylate or N-isopropyl acrylamide; the crosslinking agent is N,N'-methylene bisacrylamide; and the initiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

3. The preparation method according to claim 1, characterized in that, In step (2), the surfactant is Span 80; the oil phase in the oil solution is liquid paraffin or sunflower seed oil; the emulsification speed of the vortex shaker is 2000-20000 rpm, and the emulsification time is 1-5 min.

4. The method of claim 1, wherein, In step (1), if a rotor is used as a stirrer, the rotation speed is 500-1000 rpm.

5. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (2), the wavelength of the UV lamp is 300-400 nm.

6. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (3), the washing is an alternating washing and drying of ethanol and petroleum ether to obtain a Janus water-based microgel.

7. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (1), the mass concentration of the polymerization monomer is 5%-30%, the mass fraction of the initiator in the monomer is 0.1%-3%, and the mass concentration of the crosslinking agent accounts for 1%-20% of the monomer concentration.

8. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (2), the oil / water mass ratio is 10 / 1-2 / 1, the surfactant is Span 80, and the concentration of Span 80 in the oil is 1%-5%.

9. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (1), the polyethylene glycol is PEG 8000 with a mass concentration of 10%-25%, the dextran is DEX 10000 with a mass concentration of 10%-25%, and the mass concentration of sodium sulfate is 10%-25%.

10. The method of claim 1, wherein, The molecular weight of the polyethylene glycol is selected from 2000-25000, and the molecular weight of the dextran is selected from 2000-25000.

Images