CN113457566B

CN113457566B - Method for preparing Janus particles and morphology regulation and control method

Info

Publication number: CN113457566B
Application number: CN202110664048.2A
Authority: CN
Inventors: 黄才利; 陈静怡; 程泉勇; 朱天任; 余祥
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2022-04-01
Anticipated expiration: 2041-06-16
Also published as: CN113457566A

Abstract

The invention discloses a method for preparing Janus particles and a morphology regulating method, and belongs to the technical field of polymer composite materials. Dropping a first polymer solution containing a monomer, a co-crosslinking agent and a photoinitiator on the surface of the super-hydrophobic substrate to form a liquid drop, wherein the liquid drop on the substrate is in a sphere shape because the liquid drop can present a large contact angle on the surface of the super-hydrophobic substrate; then, a second polymer solution containing the monomer, the co-crosslinking agent and the photoinitiator is dripped on the surface of the liquid droplet to form a mixed liquid droplet, and the mixed liquid droplet is subjected to phase separation to form a spherical Janus liquid droplet; the Janus droplets are then converged into hydrogel Janus particles under ultraviolet illumination. The method effectively solves the problems that a large amount of organic solvent is consumed for synthesizing Janus particles, the morphology is difficult to regulate and control, the equipment is complex and the like, and can be used for synthesizing the Janus particles with complex morphology meeting the requirements of users.

Description

Method for preparing Janus particles and morphology regulation and control method

Technical Field

The invention relates to the technical field of polymer composite materials, in particular to a method for preparing Janus particles and a morphology regulating method, and particularly relates to a simple organic solvent-free Janus particle synthesis method and a new idea for regulating the morphology of Janus particles, which can be applied to the field of drug transportation.

Background

Janus particles are a separate colloid having two or more different chemical properties or compositions. As the Janus particles have asymmetric structures, different functional characteristics can be integrated, and more synergistic functions can be executed, so that the Janus particles have wide application prospects and can be applied to the fields of corresponding carriers of the environment, self-assembly, micro-rheological probes, solid surfactants and the like. Meanwhile, due to the difference of the sensing ability and the response ability of the Janus particles relative to external stimuli, a new idea is provided for the next generation of novel intelligent materials.

The lack of central symmetry of Janus particles is a great challenge in the synthesis process, and therefore, the method has great significance in the research of the synthesis method. The synthesis of Janus particles can be divided into two categories, regardless of the various materials and techniques used: surface modification and regionalization synthesis. Surface modification methods are methods of making isotropic particles anisotropic on a surface by means of surface modification, typically by using masks, templates and geometrical constraints imposed by adjacent particles, sometimes in combination with physical vapor deposition and photolithography techniques. While the compartmentalization method builds Janus particles from scratch, the synthesized particles are anisotropic in composition and are typically prepared by microfluidic and electrohydrodynamic spraying, chemical synthesis, and polymer self-assembly. These methods may have different mechanisms and concerns, with their own advantages and disadvantages, but since the compartmentalization approach allows more complex design of Janus particles, the predominant current synthesis approach is compartmentalized synthesis. However, organic solvents are inevitably used in the process of regionalization synthesis, so that research on a method for synthesizing all-water-system Janus particles without involving organic solvents is necessary. Meanwhile, when talking about the synthesis of Janus particles, there are two important issues to be solved: one is the ability to control the geometry of the Janus particles, i.e., the relative volumes of their two sides. Another is the ability to mass produce Janus particles, which is critical to technology applications. Various methods for synthesizing Janus particles have been developed so far, but only a few methods can solve both problems at the same time.

Taking the current microfluidic technology as an example, two different liquids are jetted side by side without mixing, and the droplet formed by the jet break-up contains two different parts, and finally polymerized or crosslinked into solid particles by means of ultraviolet light or thermal polymerization. In this technique, it is important to separate the two different phases. This is usually achieved by controlling the fluid flows to remain laminar, causing them to flow in parallel and leaving a sharp boundary, which requires rapid polymerization after droplet formation to reduce mixing of the two phases. However, the Janus particles of the all-water system prepared by this method have so far required the consumption of a large amount of organic solvent. Low throughput is another problem because the flow rate is slow to avoid mixing the different phases by convection. At present, other methods have respective advantages, but the factors such as particle size, monodispersity, yield, device complexity, applicability and the like are difficult to be considered simultaneously.

Disclosure of Invention

The invention aims to solve the technical problems that a large amount of organic solvent is consumed for synthesizing Janus particles, the appearance is difficult to regulate and control, equipment is complex and the like in the prior art, and aims to provide a simple, effective and environment-friendly preparation method of the Janus particles in the full-water system, and the geometric shapes of the Janus particles can be further controlled, so that the Janus hydrogel particles with biocompatibility, environmental protection and adjustable appearance are prepared, and various design requirements are met.

According to a first aspect of the present invention, there is provided a method of preparing Janus particles, comprising the steps of:

(1) adding a first water-soluble monomer, a first water-soluble co-crosslinking agent and a first water-soluble photoinitiator into an aqueous solution of a first polymer capable of forming an all-aqueous phase separation system to obtain a first mixture solution; dropwise adding the first mixture solution to the surface of the super-hydrophobic substrate to form droplets;

(2) adding a second water-soluble monomer, a second water-soluble co-crosslinking agent and a second water-soluble photoinitiator into an aqueous solution of a second polymer capable of forming a full-aqueous-phase separation system to obtain a second mixture solution; dropwise adding the second mixture solution to the surface of the liquid drop formed in the step (1) to form a mixed liquid drop, wherein the mixed liquid drop is subjected to phase separation to form a spherical Janus liquid drop;

the first water-soluble monomer is the same as or different from the second water-soluble monomer; the first water-soluble co-crosslinking agent and the second water-soluble co-crosslinking agent are the same or different; the first water-soluble photoinitiator is the same as or different from the second water-soluble photoinitiator; the first polymer and the second polymer are polymers with different molecular weights, wherein the polymer with the small molecular weight is mainly positioned at the upper phase of the Janus droplets, and the polymer with the large molecular weight is mainly positioned at the lower phase of the Janus droplets;

(3) and (3) carrying out ultraviolet irradiation on the spherical Janus droplets obtained in the step (2) to respectively polymerize the first water-soluble monomer and the second water-soluble monomer to form hydrogel Janus particles.

Preferably, the superhydrophobic substrate is a superamphiphobic substrate.

Preferably, the molecular weight of the polymer with small molecular weight in the first polymer and the second polymer is 18500-22000, and the molecular weight of the polymer with large molecular weight in the first polymer and the second polymer is 450000-650000.

Preferably, the polymer with small molecular weight in the first polymer and the second polymer is polyethylene glycol, polypropylene glycol or polyethylene glycol diacrylate, and the polymer with large molecular weight in the first polymer and the second polymer is dextran, polyvinyl alcohol or polyvinylpyrrolidone;

the first water-soluble monomer and the second water-soluble monomer are each independently selected from the group consisting of N-isopropylacrylamide, N-N-dimethylacrylamide, polyethylene glycol diacrylate, and maleylated dextran.

Preferably, the first water-soluble co-crosslinking agent and the second water-soluble co-crosslinking agent are each independently selected from N-N-methylene bisacrylamide, diethylenetriamine and diisocyanate;

the first and second water-soluble photoinitiators are each independently selected from the group consisting of 2, 2-diethoxypropiophenone, 2-hydroxy-2-methyl-1- [4- (2-hydroxyethoxy) phenyl ] -1-propanone, and 4-acryloyloxybenzophenone.

According to another aspect of the present invention, there is provided a method for regulating the morphology of a Janus particle, comprising the steps of:

(2) adding a second water-soluble monomer, a second water-soluble co-crosslinking agent and a second water-soluble photoinitiator into an aqueous solution of a second polymer capable of forming a full-aqueous-phase separation system to obtain a second mixture solution; dropwise adding the second mixture solution to the surface of the liquid drop formed in the step (1) to form a mixed liquid drop, wherein the mixed liquid drop is subjected to phase separation to form a spherical Janus liquid drop with a phase separation boundary line;

(3) carrying out ultraviolet irradiation on the spherical Janus droplets obtained in the step (2) to respectively polymerize the first water-soluble monomer and the second water-soluble monomer to form hydrogel Janus particles;

setting the point of the concentration of the first polymer and the second polymer in the mixed liquid drop, which corresponds to the line of the two-water phase diagram, as point A, the intersection point of the line and the coexistence curve, which is close to the horizontal axis, as point B, the intersection point of the line and the coexistence curve, which is close to the vertical axis, as point C, and the distance between point A and point B is compared with the distance between point A and point C, namely the volume ratio of the upper phase to the lower phase; the volume ratio of the upper phase to the lower phase is controlled by controlling the concentration of the first polymer and the second polymer in the mixed liquid droplet.

Preferably, as the concentration of the polymer having a small molecular weight in the first polymer and the second polymer in the mixed droplet increases and the concentration of the polymer having a large molecular weight in the first polymer and the second polymer in the mixed droplet does not change or decreases, the phase boundary line of the formed spherical Janus droplet shifts downward.

Preferably, as the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplet decreases, and the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplet does not change or increases, the phase boundary line of the formed spherical Janus droplet moves upward.

Preferably, as the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplet increases and the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplet does not change, the phase boundary line of the formed spherical Janus droplet moves upward.

Preferably, as the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplet is decreased and the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplet is not changed, the phase boundary line of the formed spherical Janus droplet is shifted downward.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

(1) the invention utilizes the steric hindrance effect generated by the incompatibility of the first polymer and the second polymer to form a double aqueous phase system, and the preparation method is simple and environment-friendly.

(2) The Janus particle prepared according to the invention has the advantages of simple operation, no need of complicated instruments, no organic solvent, biocompatibility, controllable morphology and the like. Therefore, the invention can be used for synthesizing Janus particles with complex shapes meeting the requirements of users, and can be applied to the research in the field of biological medicine for the scientific research in the aspects of bearing, transporting and releasing medicines.

(3) Compared with a microfluidic method, the method has the technical effects of no need of organic solvent and complex equipment, capability of synthesizing Janus particles in a customized manner and the like.

(4) According to the idea of regulating the Janus particle morphology, the system line in the phase diagram is used as a morphology regulating tool, so that the experimental conditions required for achieving the morphology can be determined according to the actual design requirements of the Janus particle morphology, and the finally-obtained morphology effect of the Janus particle can be accurately analyzed according to the existing experimental parameters.

Drawings

Fig. 1 is a two-water phase diagram.

FIG. 2 is a plot of critical mass concentration data points and fitted coexistence plots for a 5 wt% PEG solution having a DEX mass of 0.5g as determined by the cloud point method.

FIG. 3 is a data point for the critical mass concentration of a 10 wt% PEG solution at 0.5g DEX by cloud point method.

FIG. 4 is a critical mass concentration data point for a 20 wt% PEG solution at 0.5g DEX mass as determined by the cloud point method.

FIG. 5 is a critical mass concentration data point for a DEX mass of 0.1g, 15 wt% PEG solution as determined by the cloud point method.

FIG. 6 is a critical mass concentration data point for a 30 wt% PEG solution at a DEX mass of 0.1g as determined by the cloud point method.

FIG. 7 is a critical mass concentration data point for a 40 wt% PEG solution at 0.1g DEX mass as determined by the cloud point method.

FIG. 8 shows PEG (18500-^-1) With DEX (450000-^-1) Fitted coexistence plot of system measurements at room temperature.

FIG. 9 is an experimental graph of a tether measurement; wherein a is the height ratio of the upper phase and the lower phase in the sample bottle when the initial state (11.98 percent and 2.01 percent) of the PEG/DEX system reaches phase equilibrium; b is the height ratio of the upper phase and the lower phase in the sample bottle when the initial state (10.31%, 1.74%) of the PEG/DEX system reaches phase equilibrium; the c picture shows the height ratio of the upper phase and the lower phase in the sample bottle when the initial state (9.12 percent and 1.48 percent) of the PEG/DEX system reaches phase equilibrium; the d-diagram shows the height ratio of the upper and lower phases in the sample bottle when the initial state of the PEG/DEX system (8.02%, 1.33%) reaches phase equilibrium.

FIG. 10 shows PEG (18500-^-1)/DEX(450000-650000g·mol^-1) And (4) a system phase diagram. The coexistence curve determined in FIG. 8 and the line determined in FIG. 9 were combined together to form a two-aqueous phase diagram of the complete PEG/DEX system.

FIG. 11 is a topographical view of a Janus droplet formed by continuously dropping 10 wt% PEG solution after fixing 15 wt% DEX solution volume on the surface of a super-amphiphobic substrate. The initial DEX solution volume was 10. mu.l and the topography was taken by OCA instruments.

FIG. 12 is a topographical view of a Janus droplet formed by continuously dropping a 15 wt% DEX solution after fixing a 10 wt% PEG solution volume on the surface of a super-amphiphobic substrate. The initial PEG solution volume is 10 u l, morphology by OCA instrument.

FIG. 13 is a Janus drop profile plot of the PEG/DEX addition sequence and PEG/DEX volume ratio.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The polyethylene glycol (PEG), the Dextran (DEX), the N, N-Dimethylacrylamide (DMA), the N-isopropylacrylamide (NIPAm), the N, N-methylenebisacrylamide (BIS) and the 2, 2-diethoxyacetophenone are all purchased in the market.

According to the purpose of the invention, the simple synthesis method of the Janus particle is provided, and the method comprises the following specific steps:

(1) firstly, injecting a certain volume of PEG solution added with NIPAm monomer, BIS co-crosslinking agent and photoinitiator on the surface of a super-amphiphobic substrate prepared by using soot by using an injector, wherein the PEG solution on the substrate is spherical because the liquid drop can present a large contact angle on the surface of the super-amphiphobic substrate.

(2) And injecting a certain volume of DEX solution added with NIPAm monomer, BIS co-crosslinking agent and photoinitiator onto the PEG liquid drop on the substrate by using an injector, wherein the PEG solution/DEX solution can form an all-water system, and a spherical Janus liquid drop can be formed by phase separation, wherein the upper phase is a PEG-rich phase, and the lower phase is a DEX-rich phase.

(3) The Janus droplets are then converged into hydrogel Janus particles under ultraviolet illumination.

In some embodiments, the PEG solution/DEX solution system can also optionally be any solution that can form an all water system in the present invention.

In some embodiments, in addition to adding NIPAm monomers to the PEG solution (or DEX solution), water soluble monomers such as N-N-Dimethylacrylamide (DMA) monomers can be added. Similarly, the co-crosslinking agent and the photoinitiator only need to meet the photocuring requirement of the all-water system.

In some embodiments, the soot-based super-amphiphobic substrate used in the present invention can be replaced with any super-hydrophobic substrate as long as the droplets are guaranteed to be spherical on the surface of the substrate.

The superamphiphobic substrates of the present invention may be prepared by reference to Deng X, Mammen L, Butt H, et al, candle root as a template for a transparent turbo coating [ J ] Science,2012,335:67-70.

According to the invention, a new idea for controlling the geometric shape of the Janus particle is also provided, and the principle of morphology adjustment is as follows:

the phase separation behavior of a two-water phase system can be expressed by a phase diagram. Assuming that the initial mass concentrations of polymer X and polymer Y are at point 2, assuming that the PEG/DEX all-water system phase diagram has been determined (fig. 1), the mass concentrations of polymers X and Y in the upper phase are at 1 point and the mass concentrations of polymers X and Y in the lower phase are at 3 points when phase equilibrium is reached. When the double-water-phase system with the initial concentration at any point on the same line reaches the phase equilibrium, the concentrations of the upper phase and the lower phase are the same, the concentration of the upper phase is point 1, and the concentration of the lower phase is point 3. In addition, the volume ratio of the upper phase and the lower phase of the two-water-phase system in the balancing process can be obtained according to the lever principle, for example: for point 2, when the system reaches equilibrium, the volume ratio of the upper phase to the lower phase of the system is V_t:V_bLength of line segment 32: the length of line segment 12. Therefore, the volume ratio of the PEG/DEX solution added initially can be adjusted to control the concentration of the initial state point of the system, and then the upper-lower phase volume ratio of the Janus droplets when phase equilibrium is reached is judged under the initial concentration according to the phase diagram. Therefore, the upper and lower phase morphology of the finally formed Janus particle can be determined by controlling the concentration of the initial state point, and the effect of morphology control is achieved.

The method for regulating and controlling the Janus particle morphology comprises the following steps:

the first water-soluble monomer is the same as or different from the second water-soluble monomer; the first water-soluble co-crosslinking agent and the second water-soluble co-crosslinking agent are the same or different; the first water-soluble photoinitiator is the same as or different from the second water-soluble photoinitiator; the first polymer and the second polymer are polymers with different molecular weights, wherein the polymer with the small molecular weight is positioned at the upper phase of the Janus droplets, and the polymer with the large molecular weight is positioned at the lower phase of the Janus droplets;

setting the point of the concentration of the first polymer and the second polymer in the mixed liquid drop, which corresponds to the line of the two-water phase diagram, as a point A, the intersection point of the line and the coexistence curve, which is close to the X axis, as a point B, the intersection point of the line and the coexistence curve, which is close to the Y axis, as a point C, and the distance between the point A and the point B is compared with the distance between the point A and the point C, namely the volume ratio of the upper phase to the lower phase; the volume ratio of the upper phase to the lower phase is controlled by controlling the concentration of the first polymer and the second polymer in the mixed liquid droplet.

As the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplets increases and the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplets does not change or decreases, the phase boundary line of the formed spherical Janus droplets moves downward.

As the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplet decreases, and the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplet does not change or increases, the phase boundary line of the formed spherical Janus droplet moves upward.

As the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplet increases and the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplet does not change, the phase separation boundary of the formed spherical Janus droplet moves upward.

As the concentration of the polymer having a large molecular weight among the first polymer and the second polymer in the mixed droplets decreases and the concentration of the polymer having a small molecular weight among the first polymer and the second polymer in the mixed droplets does not change, the phase boundary of the formed spherical Janus droplets shifts downward.

Example 1

Taking 0.5g DEX (dextran) in a 25ml glass sample bottle, adding 2ml deionized water for dissolving, adding a magneton for stirring, and clarifying the solution;

the injector sucks 5 wt% of PEG (polyethylene glycol) solution, records the scale of the injector, continuously injects the PEG solution until the solution is turbid (the concentration of the mixed aqueous two-phase solution is just on the coexisting curve), records the scale of the injector, and can obtain a group of PEG solution volumes consumed by the aqueous two-phase solution from clarification to turbidity;

adding a proper amount of deionized water until the solution is clear, continuously injecting the PEG solution until the solution is turbid, recording the scales of the injector, and obtaining a group of PEG solution volumes consumed by the double-water-phase solution from the clear state to the turbid state; repeated operation is carried out, experimental data are recorded, and multiple groups of PEG solution volumes consumed when the turbidity critical point is reached can be obtained. The concentration of the critical point of turbidity (both on the coexistence curve) was calculated.

And (4) sorting the turbid critical concentration data points, and fitting a final coexistence curve by taking the DEX mass concentration as an abscissa and the PEG mass concentration as an ordinate.

The coexistence curve is shown in fig. 2, before the PEG solution is not added dropwise, only 0.5g of DEX and 2ml of deionized water are present in the sample bottle, the mass solubility of DEX at this time is the maximum, the mass concentration of DEX is continuously decreased and is continuously decreased from 19 wt% to about 3 wt% in the process of continuously adding the PEG solution, and the mass concentration of PEG is continuously increased and is continuously increased from 0.1 wt% to about 2.9 wt%. However, in general, the mass concentration of DEX is in the high concentration region and the mass concentration of PEG is in the low concentration region in the coexistence curve measured with 0.5g DEX and 5 wt% DEX.

Examples 2,3, 4, 5, 6 and 7

The six critical mass concentration data points of FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7 can be obtained by repeating the experimental procedure of example 1 with 0.5g DEX and 10 wt%, 0.5g DEX and 20 wt% PEG solution, and 0.1g DEX and 15 wt%, 30 wt%, and 40 wt% PEG solution, respectively.

In the coexistence curves of fig. 3 and 4, the DEX mass concentration is in the high concentration region, and the PEG mass concentration is in the low concentration region. In the coexistence curves of fig. 5, 6, and 7, the DEX mass concentration is in the low concentration region, and the PEG mass concentration is in the high concentration region. The data in the low DEX concentration region and the data in the high DEX concentration region are integrated together, so that a coexistence curve in a complete PEG/DEX system phase diagram can be obtained, as shown in FIG. 8.

The position and shape of the two-water phase diagram coexistence curve are mainly related to the relative molecular mass of the polymer: the higher the relative molecular weight of DEX, the lower the concentration required for phase separation; the larger the relative molecular mass difference between the two polymers, the more asymmetric the shape of the coexisting curve. Therefore, theoretically, the molecular weights of the PEG and DEX reagents used in the experiment are greatly different, the coexistence curve should be a curve which is extremely asymmetric and is very close to the coordinate axis, and the final experiment result also verifies the point.

Example 8

0.25g of 10 wt% PEG solution and 1g of 15 wt% DEX solution are added into four 5ml sample bottles, 0.0g, 0.2g, 0.4g and 0.6g of deionized water are added into the bottles, and the bottles are sealed by sealing films.

Shaking for 30s, standing for layering, and recording the height ratio (h) of the upper phase and the lower phase when an obvious phase separation boundary line appears in the sample bottle and the upper phase and the lower phase are clear and transparent and the full water system reaches a phase equilibrium state_PEG：h_DEX) Because the sample bottle is a regular cylinder and the cross-sectional areas of the upper phase and the lower phase are the same, the upper phase and the lower phase are the sameProduct ratio (V)_PEG：V_DEX) I.e. its height ratio (h)_PEG：h_DEX)。

As shown in fig. 9, the mass concentrations of PEG and DEX in the four sample vials were (11.98%, 2.1%), (10.31%, 1.74%), (9.12%, 1.48%), (8.02%, 1.33%), respectively, and a distinct phase boundary was observed when the aqueous two-phase system in the vial reached phase equilibrium. At this time, a height ratio of the upper phase to the lower phase was measured with a steel ruler.

Example 9

In the phase diagram, the mass concentrations of the polymers in the upper and lower phases are the same when any point on the line reaches an equilibrium state, except for the volume ratio of the upper and lower phases, which can be calculated by the lever principle. That is, an initial concentration of the system corresponds to only one equilibrium state, the line of the point is unique, the volume ratio of the upper phase to the lower phase is also unique, and the line can be drawn by combining the lever principle. Namely, an initial state point is determined, and the final volume ratio of the upper phase and the lower phase is measured to determine a series line. The sample bottle used in the experiment is a regular cylinder, the cross sectional areas of the two phases are the same, therefore, the height ratio of the upper phase and the lower phase is that four initial state points are selected for the volume ratio experiment, corresponding to four different tying lines, and then combined with the coexistence curve measured in the example 8 to form a complete two-aqueous-phase diagram, as shown in fig. 10.

Example 10

Preparing a PEG solution (m) with NIPAm as a monomer_10wt％_PEG＝5g，m_NIPAm＝1.131g，m_BIS0.0308g, 2, 2-diethoxyacetophenone: 0.08 wt%), DEX solution with NIPAm as monomer (m)_15wt％_DEX＝5g，m_NIPAm＝1.131g，m_BIS0.0308g, 2, 2-diethoxyacetophenone: 0.08 wt%). Replacing the needle head with a quantitative needle head with the diameter of 0.25mm by using two 1ml medical syringes, and respectively sucking a PEG solution taking NIPAm as a monomer and a DEX solution taking NIPAm as a monomer;

the super-amphiphobic substrate is placed on a platform of an OCA instrument, 5 mu l of DEX solution taking NIPAm as a monomer is dripped on the super-amphiphobic substrate by utilizing a quantitative control system on the instrument, at the moment, the coating has extremely low adhesion to water, water drops are difficult to be spread, and the DEX solution is spherical on the super-amphiphobic substrate.

And dripping the PEG solution with NIPAm as a monomer into the DEX liquid drop on the substrate, standing for 5min, irradiating for 3min by ultraviolet light, and waiting until the solution is completely photocured to form Janus particles.

Example 11

Preparation of a PEG solution (m) with DMA as a monomer_10wt％PEG＝10g，m_DMA＝0.99g，m_BIS0.03g, 2, 2-diethoxyacetophenone: 0.08 wt.%) DEX solution (m) with DMA as monomer_15wt％DEX＝10g，m_DMA＝0.99g，m_BIS0.03g, 2, 2-diethoxyacetophenone: 0.08 wt%). Using two 1ml medical syringes, replacing the needle heads with quantitative needle heads with the diameter of 0.25mm, and respectively sucking a PEG solution taking DMA as a monomer and a DEX solution taking DMA as a monomer;

the super-amphiphobic substrate is placed on a platform of an OCA instrument, 5 mu l of DEX solution taking DMA as a monomer is dripped on the super-amphiphobic substrate by utilizing a quantitative control system on the instrument, at the moment, the coating has extremely low adhesion to water, the water drops are difficult to spread, and the DEX solution is spherical on the super-amphiphobic substrate.

And dripping the PEG solution taking the DMA as the monomer into DEX liquid drops on the substrate, standing for 5min, irradiating for 3min by ultraviolet light, and waiting until the solution is completely photocured to form Janus particles.

Example 12

Using two 1ml medical syringes, replacing the needle with a quantitative needle with the diameter of 0.25mm, and respectively sucking 10 wt% of PEG solution and 15 wt% of DEX solution;

the super-amphiphobic substrate is placed on a platform of an OCA instrument, 10 mu l of 15 wt% DEX solution is dripped on the super-amphiphobic substrate by utilizing a quantitative control system on the instrument, at the moment, the coating has extremely low adhesion to water, the water drops are difficult to spread, and the DEX solution is spherical on the super-amphiphobic substrate.

And then continuously dropping 10 wt% of PEG solution into the DEX liquid drop on the substrate, judging according to phase diagram calculation, if the initial concentration of the PEG/DEX system is positioned above a coexistence curve (a two-phase region), phase separation behavior occurs, the upper phase is a PEG-rich phase with a smaller molecular weight, the lower phase is a DEX-rich phase with a larger molecular weight, spherical Janus liquid drops are formed, the volume of the added PEG solution is recorded, and the appearance diagrams of different Janus liquid drops are photographed by using an OCA instrument after phase equilibrium.

With V_DEX:V _PEG10 μ l: for example, 2. mu.l, the initial concentration of the system (12.5%, 1.67%) can be calculated to be above the coexistence curve according to the phase diagram, in the two-phase region, but at equilibrium the phase volume is too small to observe a distinct phase boundary in the OCA instrument (second droplet in the first row of FIG. 11). When V is_DEX:V _PEG10 μ l: at 10. mu.l, the initial concentration of the system was calculated to be (7.5%, 5%) on the coexistence curve according to the phase diagram, in the two-phase region, and V_t：V_b<1, lower phase volume is smaller than upper phase volume, a phase boundary line is observed in the OCA instrument that is relatively lower (sixth droplet in the first row of fig. 11). With the dripping of the PEG solution, the overall DEX concentration is continuously reduced, the PEG concentration is continuously increased, and V is_b：V_tThe continuous reduction is reflected in the OCA topography map, namely the process of continuously pressing down the phase boundary.

Example 13

The experimental procedure is similar to that of example 10, 10. mu.l of 10 wt% PEG solution is quantitatively dripped on the super-amphiphobic coating, 15 wt% DEX solution is continuously dripped on the basis of the PEG solution, the volume of the added DEX solution is recorded, and after phase equilibrium, different Janus droplets are photographed by using an OCA instrument.

V_DEX：V _PEG6 μ l: at 10. mu.l, the initial concentration of the system was calculated to be (5.63%, 6.25%) which was on the coexistence curve according to the phase diagram and located in the two-phase region, V_b：V_t<1, i.e. the volume of the upper phase is greater than the volume of the lower phase, a lower phase boundary comparison was observed in the OCA instrument (third panel of the first row of fig. 12). When V is_DEX:V_PEG11 μ l: at 10. mu.l, the initial concentration of the system was calculated to be (7.86%, 4.76%) on the coexistence curve according to the phase diagram, in the two-phase region, and V_b：V_t>1, i.e. the lower phase volume is greater than the upper phase volume, in an OCA instrumentA relatively high phase separation line was observed (fig. 12 for the last droplet in the first row). Along with the dropwise addition of the DEX solution, the overall DEX concentration is continuously increased, the PEG concentration is continuously reduced, and V_b：V_tThe increase is reflected in the OCA topography map, which is the process that the phase boundary lines are increasing continuously.

Example 14

Quantitatively dripping 1 mu l of 10 wt% PEG solution on the super-amphiphobic coating, dripping 9 mu l of 15 wt% DEX solution on the basis, and after phase equilibrium, shooting the topography of different Janus drops by using an OCA instrument. Adjusting different PEG/DEX volume ratios (V)_PEG：V_DEXThe experiment was repeated 1:9, 2:8, 3:7, 4:6, 5:5 observing the effect of different PEG/DEX volume ratios on Janus droplet morphology.

As can be seen from the results of OCA apparatus shooting (as shown in fig. 13), for the same system, the sizes and shapes of the Janus droplets finally formed by adding PEG first and adding DEX first are the same, and the phase boundary positions are the same, so the adding order of PEG and DEX has no influence on the appearance of the final Janus droplets, because the phase equilibrium is a thermodynamic state, and when the conditions of initial concentration, pressure, temperature, etc. of the polymer in the system are determined, the phase equilibrium state is unique and is not related to the adding order in actual operation. Further, as can be seen from fig. 13, in the initial state, the larger the mass concentration of PEG, the smaller the mass concentration of DEX, the larger the volume of the PEG-rich phase (upper phase) at the phase equilibrium, and the higher the phase boundary line, but the mass concentration of DEX cannot be made too small, and must be higher than the minimum concentration (above the coexistence curve) at which two phases can be formed.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method of making Janus particles comprising the steps of:

the first water-soluble monomer is the same as or different from the second water-soluble monomer; the first water-soluble co-crosslinking agent and the second water-soluble co-crosslinking agent are the same or different; the first water-soluble photoinitiator is the same as or different from the second water-soluble photoinitiator; the first polymer and the second polymer are polymers with different molecular weights, wherein the polymer with the small molecular weight is mainly positioned at the upper phase of the Janus droplets, and the polymer with the large molecular weight is mainly positioned at the lower phase of the Janus droplets; the polymer with small molecular weight in the first polymer and the second polymer is polyethylene glycol, polypropylene glycol or polyethylene glycol diacrylate, and the polymer with large molecular weight in the first polymer and the second polymer is dextran, polyvinyl alcohol or polyvinylpyrrolidone;

2. The method of making a Janus particle of claim 1, wherein the superhydrophobic substrate is a superamphiphobic substrate.

3. The method of claim 1 or 2, wherein the molecular weight of the polymer with a lower molecular weight of the first polymer and the second polymer is 18500-22000, and the molecular weight of the polymer with a higher molecular weight of the first polymer and the second polymer is 450000-650000.

4. The method of making a Janus particle of claim 3, wherein the first water soluble monomer and the second water soluble monomer are each independently selected from the group consisting of N-isopropylacrylamide, N-dimethylacrylamide, polyethylene glycol diacrylate, and maleylated dextran.

5. The method of making Janus particles of claim 4, wherein the first water-soluble co-crosslinker and the second water-soluble co-crosslinker are each independently selected from the group consisting of N-N-methylene bisacrylamide, diethylenetriamine, and diisocyanate;

6. A method for regulating Janus particle morphology is characterized by comprising the following steps:

the polymer with small molecular weight in the first polymer and the second polymer is polyethylene glycol, polypropylene glycol or polyethylene glycol diacrylate, and the polymer with large molecular weight in the first polymer and the second polymer is dextran, polyvinyl alcohol or polyvinylpyrrolidone;

7. The method for regulating and controlling the morphology of Janus particles as claimed in claim 6, wherein the phase boundary line of the formed spherical Janus droplets shifts downward as the concentration of the low molecular weight polymer of the first polymer and the second polymer in the mixed droplets increases and the concentration of the high molecular weight polymer of the first polymer and the second polymer in the mixed droplets does not change or decreases.

8. The method for regulating and controlling the morphology of Janus particles of claim 6, wherein the phase boundary of the formed spherical Janus droplets moves upwards as the concentration of the low molecular weight polymer of the first polymer and the second polymer in the mixed droplets decreases and the concentration of the high molecular weight polymer of the first polymer and the second polymer in the mixed droplets does not change or increases.

9. The method for regulating and controlling the morphology of Janus particles as claimed in claim 6, wherein the phase separation line of the formed spherical Janus droplets moves upwards as the concentration of the polymer with large molecular weight in the first polymer and the second polymer in the mixed droplets increases and the concentration of the polymer with small molecular weight in the first polymer and the second polymer in the mixed droplets does not change.

10. The method for regulating and controlling the morphology of Janus particles as claimed in claim 6, wherein the phase boundary of the formed spherical Janus droplets shifts downward as the concentration of the polymer with large molecular weight in the first polymer and the second polymer in the mixed droplets decreases and the concentration of the polymer with small molecular weight in the first polymer and the second polymer in the mixed droplets does not change.