Pickering type Janus emulsion based on dynamic covalent amphiphilic macromolecules as well as preparation method and application of Pickering type Janus emulsion

Abstract

The invention provides a Pickering type Janus emulsion based on dynamic covalent amphiphilic macromolecules as well as a preparation method and application of the Pickering type Janus emulsion. The emulsion comprises hydrocarbon oil, fluorocarbon oil, water and an emulsifier, the emulsifier comprises a pyrrolidone block copolymer precursor containing an aldehyde group and a fluoroalkylamine precursor. Water and an aldehyde group-containing pyrrolidone block copolymer precursor are prepared into an aqueous solution, hydrocarbon oil and fluorocarbon oil are prepared into a mixed oil phase, a fluoroalkylamine precursor can be added into the aqueous solution or the mixed oil phase, and then the aqueous solution and the mixed oil phase are mixed and emulsified to prepare a corresponding emulsion. After part of the components in the emulsion are cured in situ, micro-nano particles with controllable forms can be obtained. According to the invention, the dynamic covalent bond block copolymer is constructed in situ in the aqueous solution, and the dynamic covalent bond block copolymer is used as an emulsifier to stabilize the mixed oil phase of hydrocarbon oil and fluorocarbon oil, so that the Pickering type Janus emulsion with controllable form and excellent stability is formed by a simple system.

Description

Technical Field

[0001] The invention relates to the technical field of colloid and interface chemistry, and in particular to a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules and a preparation method and application thereof. Background Art

[0002] Emulsion is a thermodynamically unstable coarse dispersion system formed by a liquid dispersed in another immiscible liquid. Surfactants are usually used as emulsifiers to stabilize the emulsion droplets. Emulsions are widely used in many fields such as pharmaceutical preparations such as medicines and pesticides, daily chemical products such as cosmetics and coatings, advanced material preparation, and oil development. Emulsions mainly include two types: water-in-oil and oil-in-water. Under certain conditions, multiple emulsions such as water-in-oil-in-water and oil-in-water-in-oil can also be formed. Water-in-oil emulsions formed by two immiscible mixed oil phases are also called Janus emulsions. Janus emulsions have natural advantages as templates in the preparation of asymmetric micro-nano materials. How to use simple methods to control the morphology, size and stability of Janus emulsions is still an urgent problem to be solved.

[0003] At present, there are two main methods for preparing Janus emulsions. One is the direct emulsification method, that is, the mixture of two oil phases, water and surfactant is directly emulsified under high-speed shear, but the droplet morphology of the Janus emulsion prepared by this method is diverse and not spherical. Another scheme is to use the highest solubility temperature between the two oil phases, that is, to prepare Janus emulsions by emulsifying above the solubility temperature and then placing the emulsion below the solubility temperature to make the two oil phases automatically separate. The Janus emulsion prepared by this method has a uniform morphology and a regular spherical shape, but it has high requirements for the emulsification system, so the composition is often extremely complex. From the perspective of the formation mechanism of Janus emulsions, the morphology of Janus emulsion liquid is mainly affected by the relative size of the interfacial tension between the two oil phases and water and between the oil phases. It is undoubtedly an effective strategy to use the interfacial activity of small molecule surfactants to regulate the relative size of the interfacial tension, which is also the currently commonly adopted scheme. However, the Janus emulsion prepared based on small molecule surfactants has insufficient stability due to the rapid exchange of surfactants between the interface phase and the bulk phase. Therefore, it is extremely challenging to give Janus emulsion better stability while achieving controllable structure and morphology of Janus emulsion, which is also crucial for the application of Janus emulsion in related fields.

[0004] In view of this, it is extremely important to develop a simple preparation technology that can effectively regulate the morphology of Janus emulsions and make them stable in order to solve the problems currently faced by Janus emulsions, such as complex system, cumbersome manipulation of emulsion droplet morphology, and poor emulsion stability. This will greatly promote its application in related fields. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules and a preparation method and application thereof. The amphiphilic macromolecules are formed in situ based on the dynamic covalent bond strategy, so that the amphiphilic macromolecular aggregates can be enriched at the interface of the two phases as soft particle Pickering emulsifiers, thereby constructing a Pickering-type Janus emulsion with controllable morphology and excellent stability with a simple system.

[0006] In a first aspect, an embodiment of the present application provides a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, comprising hydrocarbon oil, fluorocarbon oil, water and an emulsifier; the emulsifier comprises an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor.

[0007] In the technical solution of the embodiment of the present application, a dynamic covalent bond block copolymer can be constructed in situ in an aqueous solution by using an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor. This type of dynamic covalent bond block copolymer has an amphiphilic type, and the aggregates formed by this type of dynamic covalent bond block copolymer in an aqueous solution can be used as an emulsifier to stabilize the mixed oil phase of hydrocarbon oil and fluorocarbon oil, thereby forming a Pickering-type Janus emulsion. The emulsion system has a simple composition, controllable droplet morphology, and the emulsifier can be enriched at the interface between the two phases, which effectively improves the dynamic stability of the emulsion system.

[0008] In some embodiments, the structural formula of the aldehyde-containing pyrrolidone block copolymer precursor is shown in Formula 1, and the structural formula of the fluoroalkylamine precursor is shown in Formula 2 or Formula 3;

[0009] Formula 1:

[0010]

[0011] Formula 2: CF3(CF2) m-2 CH2NH2;

[0012] Formula 3: CF3(CF2) n-3 CH2CH2NH2;

[0013] Among them, the value of a is 72 or 103, b is an integer between 3 and 15, and m and n are both integers between 6 and 10.

[0014] In this embodiment, by defining the specific structures of the aldehyde-containing pyrrolidone block copolymer precursor and the fluoroalkylamine precursor, the surface activity and micellization ability of the corresponding aqueous solution can be adjusted to improve the dynamic stability of the emulsion system. In addition, based on the precursor used in this embodiment, it is easier to adjust the interface curvature to improve the morphological controllability of the emulsion.

[0015] In some embodiments, the hydrocarbon oil includes one of a medium-chain alkane or a polymerizable oil monomer containing hydrocarbon, and the fluorocarbon oil includes one of a medium-chain fluorocarbon alkane or a polymerizable oil monomer containing fluorocarbon. Preferably, the number of carbon atoms in the medium-chain alkane and the medium-chain fluorocarbon alkane is 6 to 12, the polymerizable oil monomer containing hydrocarbon is 1,6-hexanediol diacrylate, and the polymerizable oil monomer containing fluorocarbon is perfluorooctyl ethyl acrylate or perfluorodecyl ethyl acrylate.

[0016] In this embodiment, the aggregates formed by the dynamic covalent bond block copolymer in the aqueous solution can more effectively stabilize the mixed oil phase formed by the hydrocarbon oil and the fluorocarbon oil, thereby improving the stability of the emulsion system. Wherein, when a polymerizable oil monomer containing hydrocarbon and a polymerizable oil monomer containing fluorocarbon are respectively selected as the hydrocarbon oil and the fluorocarbon oil, micro-nano particles with controllable morphology can be prepared by in-situ polymerization and curing of the corresponding monomers.

[0017] In some embodiments, the molar ratio of the amino groups in the fluoroalkylamine precursor to the aldehyde groups in the aldehyde-containing pyrrolidone block copolymer precursor is 0.25-10.

[0018] In some embodiments, the mass concentration of the aldehyde-containing pyrrolidone block copolymer precursor in water is 0.05% to 1.5%.

[0019] In some embodiments, the volume ratio of the hydrocarbon oil to the fluorocarbon oil is 3:7 to 6:4.

[0020] In the above embodiments, with the change of the precursor molar ratio, the precursor concentration and the volume ratio of the two oil phases, the transformation from the water-in-hydrocarbon oil-in-fluorocarbon oil type Pickering composite emulsion, the water-in-fluorocarbon oil and hydrocarbon oil Pickering type Janus emulsion to the water-in-fluorocarbon oil-in-hydrocarbon oil type Pickering composite emulsion can be achieved. On this basis, by regulating the molar ratio of the two precursors, the concentration of the precursors and the volume ratio of the two oil phases, the curvature of the interface between the hydrocarbon oil and the fluorocarbon oil in the formed emulsion can be controlled, thereby regulating the morphology of the two oil phases in the droplets.

[0021] In a second aspect, the present application provides a method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, comprising the following steps:

[0022] An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and the aldehyde-containing pyrrolidone block copolymer precursor; the mixed oil phase contains the hydrocarbon oil and the fluorocarbon oil; the aqueous solution or the mixed oil phase also contains the fluoroalkylamine precursor;

[0023] The aqueous solution is added into the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained.

[0024] In the technical scheme of the embodiment of the present application, by first preparing the corresponding aqueous solution and mixed oil phase separately, and then mixing and emulsifying them, the aldehyde-containing pyrrolidone block copolymer precursor and the fluoroalkylamine precursor can form a dynamic covalent bond block copolymer in water during the emulsification process, and make them enriched at the water-oil two-phase interface as a soft particle Pickering emulsifier, which has a stabilizing effect on the hydrocarbon oil and fluorocarbon oil in the mixed oil phase, forming a water-in-oil Pickering type Janus emulsion, and improving the stability of the emulsion.

[0025] In some embodiments, the predetermined temperature of the aqueous solution and the mixed oil phase is 40-60° C.; the emulsification method is: emulsification at a shear rate of 2500-3000 rpm for 1-2 min.

[0026] In this embodiment, the aqueous solution and the mixed oil phase are heated separately, mixed, and then fully mixed and emulsified at a certain shear rate, and a uniform and stable Pickering-type Janus emulsion is formed after standing.

[0027] In a third aspect, the embodiments of the present application provide an application of a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules in the preparation of micro-nanoparticles.

[0028] In this embodiment, since the curvature of the interface between the hydrocarbon oil phase and the fluorocarbon oil phase in the droplets of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is controllable, when the emulsion is used to prepare micro-nano particles, micro-nano particles with controllable morphology can be obtained.

[0029] In some embodiments, the method for preparing the micro-nano particles comprises:

[0030] An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and the aldehyde-containing pyrrolidone block copolymer precursor; the mixed oil phase contains the hydrocarbon oil, the fluorocarbon oil and a photoinitiator; the aqueous solution or the mixed oil phase further contains the fluoroalkylamine precursor; the hydrocarbon oil is a polymerizable oil monomer containing hydrocarbons, and the fluorocarbon oil is a polymerizable oil monomer containing fluorocarbons;

[0031] The aqueous solution is mixed with the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained. The emulsion is stirred and photopolymerized with ultraviolet light, and then filtered to obtain micro-nano particles.

[0032] In this embodiment, by selecting polymerizable oil monomers as the oil phase and adding a photoinitiator during the preparation of the emulsion, the polymerizable monomers in the droplets can be in situ polymerized and cured by photopolymerization after the emulsion is formed, thereby preparing micro-nanoparticles with controllable morphology.

[0033] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a schematic diagram of the droplet morphology transformation of the emulsion in the embodiment of the present application;

[0036] Figure 2 The laser confocal microscope images of the emulsions prepared in Examples 1 to 8 of the present application;

[0037] Figure 3 Optical microscope images of the emulsions prepared in Examples 9 to 17 of the present application;

[0038] Figure 4 Optical microscope images of the emulsions prepared in Examples 18 to 26 of the present application;

[0039] Figure 5 Optical microscope images of the emulsions prepared in Examples 27 to 30 of the present application;

[0040] Figure 6Optical microscope images of the emulsions prepared in Examples 31 to 34 of the present application;

[0041] Figure 7 Optical microscope images of the emulsions prepared in Examples 35 to 42 of the present application;

[0042] Figure 8 These are optical microscope images and SEM images of the micro-nano particles prepared in Examples 43 to 46 of the present application. DETAILED DESCRIPTION

[0043] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0045] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] Existing Janus emulsions usually face problems such as complex system, inconvenient control of emulsion droplet morphology, and poor emulsion stability, which limit the application of Janus emulsions in related fields. It is currently necessary to develop a preparation method with a simple system that is easy to effectively control the droplet morphology of Janus emulsions and maintain good stability to solve the above problems.

[0047] Pickering emulsion uses amphiphilic solid particles as emulsifiers, and its stability is extremely high. The present application synthesizes amphiphilic macromolecular aggregates, which can be enriched at the interface of the two phases as a soft particle Pickering emulsifier, thereby giving the emulsion system excellent dynamic stability. For covalent amphiphilic macromolecules of a given structure, the amphiphilicity of the macromolecules caused by their clear hydrophilic and hydrophobic segments is determined, and the amphiphilic macromolecules formed in situ based on the dynamic covalent bond strategy of the present application can be arbitrarily combined by changing the structure of the two segments in a manner similar to building blocks, thereby achieving real-time regulation of the amphiphilicity of the macromolecules, and then achieving controllable regulation of the emulsion morphology. Based on this, the present application provides a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, and a preparation method and application thereof, by allowing an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor to form a dynamic covalent bond block copolymer in situ in water, so that the aggregates formed in the aqueous solution act as an emulsifier to stabilize the mixed oil phase of hydrocarbon oil and fluorocarbon oil, thereby constructing a Pickering-type Janus emulsion with controllable morphology and excellent stability with a simple system.

[0048] In a first aspect, an embodiment of the present application provides a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, comprising hydrocarbon oil, fluorocarbon oil, water and an emulsifier; the emulsifier comprises an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor.

[0049] In the technical scheme of the embodiment of the present application, a dynamic imine bond can be formed between the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor and the amino group in the fluoroalkylamine precursor, thereby forming a dynamic imine covalent bond type block copolymer in situ in an aqueous solution. The copolymer has an amphiphilic type, and its amphiphilicity and the surface activity and micellization ability of the formed aqueous solution can be regulated by adjusting the structure of each precursor. In addition, the aggregates formed by the copolymer in the aqueous solution can be used as an emulsifier to stabilize the mixed oil phase of hydrocarbon oil and fluorocarbon oil, thereby forming a water-in-oil Pickering type Janus emulsion. The emulsion system is simple in composition, the droplet morphology is controllable, and the emulsifier can be enriched at the interface between the two phases, which effectively improves the dynamic stability of the emulsion system.

[0050] Further, in some embodiments, the structural formula of the aldehyde-containing pyrrolidone block copolymer precursor is shown in Formula 1, and the structural formula of the fluoroalkylamine precursor is shown in Formula 2 or Formula 3;

[0051] Formula 1:

[0052]

[0053] Formula 2: CF3(CF2) m-2CH2NH2;

[0054] Formula 3: CF3(CF2) n-3 CH2CH2NH2;

[0055] Wherein, a represents the degree of polymerization of the pyrrolidone block, which is 72 or 103, b represents the degree of polymerization of the aldehyde block, which is an integer between 3 and 15, and m and n both represent the number of carbon atoms in the structural formula of the fluoroalkylamine precursor, which are integers between 6 and 10.

[0056] In the following, for the convenience of description, P a D b The aldehyde-containing pyrrolidone block copolymer precursor shown in Formula 1 is represented by FC m A represents the fluoroalkylamine precursor shown in formula 2, and FC n CA represents a fluoroalkylamine precursor represented by Formula 3.

[0057] In the technical solution of the embodiment of the present application, by a D b , FC m A. FC n The specific structure of CA is limited, and the surface activity and micellization ability of the corresponding aqueous solution can be adjusted to improve the dynamic stability of the emulsion system, and it is convenient to adjust the interface curvature and improve the morphological controllability of the emulsion. In the preliminary experiments of this application, it was found that if the structure of the corresponding precursor and the values ​​of a, b, m, and n are changed, the formation of the corresponding emulsion will be affected, resulting in the difficulty of the transformation process from the water-in-hydrocarbon oil-in-fluorocarbon oil type Pickering composite emulsion, the water-in-fluorocarbon oil and hydrocarbon oil Pickering type Janus emulsion to the water-in-fluorocarbon oil-in-hydrocarbon oil type Pickering composite emulsion in this application, which is not conducive to the regulation of the morphology of the emulsion. Specifically, when the aldehyde content in the aldehyde-containing pyrrolidone block copolymer precursor is too high or the number of carbon atoms in the fluoroalkylamine precursor is too high, the ability of the formed copolymer to completely regulate the interface within the emulsion will be enhanced, so that the reversal of the interface curvature can only occur within a very narrow ratio and concentration range, making it difficult to achieve a controllable transformation of the interface curvature, thereby affecting the controllability of the emulsion morphology.

[0058] Further, in some embodiments, the hydrocarbon oil includes one of a medium-chain alkane or a polymerizable oil monomer containing hydrocarbon, and the fluorocarbon oil includes one of a medium-chain fluorocarbon alkane or a polymerizable oil monomer containing fluorocarbon; wherein the number of carbon atoms in the medium-chain alkane and the medium-chain fluorocarbon alkane is 6 to 12. More specifically, the medium-chain alkane may be preferably hexane or heptane, and the polymerizable oil monomer containing hydrocarbon is preferably 1,6-hexanediol diacrylate; the medium-chain fluorocarbon alkane may be preferably perfluorohexane or ethyl perfluorobutyl ether (HFE 7200), and the polymerizable oil monomer containing fluorocarbon is preferably perfluorooctyl ethyl acrylate or perfluorodecyl ethyl acrylate.

[0059] In the technical solution of the embodiment of the present application, the aggregates formed by the dynamic covalent bond block copolymer in the aqueous solution can more effectively stabilize the mixed oil phase formed by the hydrocarbon oil and the fluorocarbon oil, thereby improving the stability of the emulsion system. Wherein, when a polymerizable oil monomer containing hydrocarbon and a polymerizable oil monomer containing fluorocarbon are respectively selected as the hydrocarbon oil and the fluorocarbon oil, micro-nano particles with controllable morphology can be prepared by in-situ polymerization and curing of the corresponding monomers.

[0060] Furthermore, in some embodiments, the molar ratio of the amino group in the fluoroalkylamine precursor to the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor is 0.25-10; the mass concentration of the aldehyde-containing pyrrolidone block copolymer precursor in water is 0.05%-1.5%; and the volume ratio of hydrocarbon oil to fluorocarbon oil is 3:7-6:4.

[0061] In the technical solution of the embodiment of the present application, since a dynamic covalent bond block copolymer is constructed, the surface activity and micellization ability of the aqueous solution can be regulated by adjusting the molar ratio of the two precursors, the concentration of the precursors, and the volume ratio of the two oil phases, and the curvature of the interface between the hydrocarbon oil and the fluorocarbon oil in the emulsion, thereby adjusting the specific morphology of the droplets in the emulsion. For ease of description, R is used below to represent the molar ratio of the amino group in the fluoroalkylamine precursor to the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor, and c is used to represent the molar ratio of the amino group in the fluoroalkylamine precursor to the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor. em It indicates the concentration of aldehyde-containing pyrrolidone block copolymer precursor in water, HC indicates hydrocarbon oil, FC indicates fluorocarbon oil, and V HC / V FC It represents the volume ratio of hydrocarbon oil to the fluorocarbon oil.

[0062] Specifically, the present application has found through research that under specific precursor conditions, by increasing R or c within a certain range em, the emulsion can be transformed from a water-in-hydrocarbon oil-in-fluorocarbon oil type Pickering composite emulsion, a water-in-fluorocarbon oil and hydrocarbon oil Pickering type Janus emulsion to a water-in-fluorocarbon oil-in-hydrocarbon oil type Pickering composite emulsion. The transformation diagram is shown in Figure 1 As shown in Figure 2, during this process, the interfacial curvature between the HC phase and the FC phase in the emulsion droplet (with the FC phase as a reference) can undergo a continuous transition from positive to negative. HC / V FC , and can also change the ratio of HC to FC in the emulsion droplets. On this basis, by adjusting various parameters, the morphology of the droplets in the emulsion can be effectively controlled. On this basis, micro-nano particles with controllable morphology can also be prepared to meet the application needs in different scenarios.

[0063] In a second aspect, the present application provides a method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, comprising the following steps:

[0064] An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and a pyrrolidone block copolymer precursor containing an aldehyde group; the mixed oil phase contains hydrocarbon oil and fluorocarbon oil; the aqueous solution or the mixed oil phase also contains a fluoroalkylamine precursor;

[0065] The aqueous solution is mixed with the mixed oil phase and emulsified to obtain a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules.

[0066] In the technical scheme of the embodiment of the present application, the fluoroalkylamine precursor can be added to the aqueous solution or to the mixed oil phase, and more preferably to the mixed oil phase. The present application prepares the corresponding aqueous solution and the mixed oil phase respectively, and then mixes and emulsifies them, so that the fluoroalkylamine precursor in the aqueous solution or the mixed oil phase can form a dynamic imine bond with the aldehyde-containing pyrrolidone block copolymer precursor in the aqueous solution during the emulsification of water and oil, thereby forming a dynamic covalent bond block copolymer in situ in the aqueous solution, and enriching it at the interface between the water and oil phases as a soft particle Pickering emulsifier, which has a stabilizing effect on the hydrocarbon oil and fluorocarbon oil in the mixed oil phase, forming a water-in-oil Pickering type Janus emulsion, and improving the stability of the emulsion.

[0067] Further, in some embodiments, the predetermined temperature of the aqueous solution and the mixed oil phase is 40-60° C.; the emulsification method is: emulsification at a shear rate of 2500-3000 rpm for 1-2 min.

[0068] In the technical solution of the embodiment of the present application, the aqueous solution and the mixed oil phase are heated separately, mixed and then fully mixed and emulsified at a certain shear rate, and then left to stand to form a uniform and stable Pickering-type Janus emulsion, preferably at a temperature of 20 to 30°C.

[0069] Furthermore, in some embodiments, the volume ratio between the aqueous solution and the mixed oil phase can be adjusted as needed, and can be preferably 3:7 to 6:4; the mass concentration of the aldehyde-containing pyrrolidone block copolymer precursor in the aqueous solution is preferably 0.05% to 1.5%, and the amount of the fluoroalkylamine precursor is determined based on the molar ratio of the amino group to the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor, and the molar ratio is preferably 0.25 to 10; the volume ratio of hydrocarbon oil to fluorocarbon oil in the mixed oil phase is preferably 3:7 to 6:4.

[0070] In a third aspect, the embodiments of the present application provide an application of a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules in the preparation of micro-nanoparticles.

[0071] In the technical solution of the embodiment of the present application, since the interface curvature between the hydrocarbon oil phase and the fluorocarbon oil phase in the droplets of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is controllable, micro-nanoparticles with controllable morphology can be obtained by solidifying some components in the emulsion droplets.

[0072] Furthermore, in some embodiments, the method for preparing the micro-nano particles comprises:

[0073] An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and a pyrrolidone block copolymer precursor containing an aldehyde group; the mixed oil phase contains hydrocarbon oil, fluorocarbon oil and a photoinitiator; the aqueous solution or the mixed oil phase also contains a fluoroalkylamine precursor; the hydrocarbon oil is a polymerizable oil monomer containing hydrocarbons, and the fluorocarbon oil is a polymerizable oil monomer containing fluorocarbons;

[0074] The aqueous solution is added into the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained. The emulsion is stirred and photopolymerized by ultraviolet light, and micro-nano particles are obtained after filtration.

[0075] In the technical solution of the embodiment of the present application, by selecting polymerizable oil monomers as the oil phase and adding a photoinitiator during the preparation of the emulsion, photopolymerization can be used to in situ polymerize and solidify the polymerizable monomers in the droplets after the emulsion is formed, thereby preparing micro-nanoparticles with controllable morphology.

[0076] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0077] Examples 1 to 8

[0078] Examples 1 to 8 of the present application respectively provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule, each comprising the following steps:

[0079] S1. Mix hydrocarbon oil (HC) and fluorocarbon oil (FC) in a volume ratio of 1:1 and heat to 50° C. to obtain a mixed oil phase;

[0080] S2. dissolving the aldehyde-containing pyrrolidone block copolymer precursor in water to make the mass concentration of the precursor c em 0.5%, and then adding a certain amount of fluoroalkylamine precursor to form dynamic covalent amphiphilic macromolecules in situ in the aqueous solution, and heating it to 50°C to obtain an aqueous solution;

[0081] S3. Take an aqueous solution and a mixed oil phase in a volume ratio of 1:1, add the aqueous solution to the mixed oil phase, and emulsify at a shear rate of 2800 rpm for 1 minute. After standing at 25°C, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules can be obtained.

[0082] The hydrocarbon oil (HC) used in Examples 1 to 8 is all n-heptane, the fluorocarbon oil (FC) is all perfluorohexane, the fluoroalkylamine precursor is all 1H,1H-perfluorooctylamine, and the structural formula of the aldehyde-containing pyrrolidone block copolymer precursor is as follows:

[0083]

[0084] In Examples 1 to 8, the value of a is 103, the value of b is 10, and it is represented as P 103 D 10 .

[0085] The difference between Examples 1 to 8 is only the molar ratio (R) of the amino group in the fluoroalkylamine precursor to the aldehyde group in the aldehyde-containing pyrrolidone block copolymer precursor. The R values ​​in Examples 1 to 8 are 0, 0.25, 0.5, 0.75, 1, 1.5, 2, and 2.5, respectively. R = 0 means that no fluoroalkylamine precursor is added.

[0086] The laser confocal microscopy images of the emulsions prepared in Examples 1 to 8 are as follows: Figure 2 shown. Figure 2 In the figure, the scale bar is 70 μm, a1 to h1 are bright field shots, and a2 to h2 are dark field shots. For the convenience of observation, in the preparation process of each embodiment, coumarin-6 is solubilized in aqueous micelles before emulsification. Figure 2 It can be seen that when other conditions are exactly the same, as the R value gradually increases from 0 to 2.5, the emulsion transforms in the manner of water-in-hydrocarbon oil-in-fluorocarbon oil Pickering composite emulsion, water-in-fluorocarbon oil and hydrocarbon oil Pickering Janus emulsion to water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion.

[0087] Specifically, when R=0, the emulsion is a water-in-hydrocarbon oil-in-fluorocarbon oil type Pickering composite emulsion; when R increases to 0.25-0.75, a water-in-fluorocarbon oil and hydrocarbon oil Pickering type Janus emulsion is formed; thereafter, when R continues to increase to 1-2.5, it gradually transforms into a water-in-fluorocarbon oil-in-hydrocarbon oil type Pickering composite emulsion, indicating that the morphology of droplets in the emulsion can be effectively regulated by adjusting the R value. When HC is n-heptane, FC is perfluorohexane, the fluoroalkylamine precursor is 1H,1H-perfluorooctylamine and is added to the aqueous solution, and the aldehyde-containing pyrrolidone block copolymer precursor is P 103 D 10 , c em When the content of fluorocarbon oil in water and hydrocarbon oil in water is 0.5%, adjusting the R value to 0.25-0.75 is more conducive to forming a Pickering-type Janus emulsion.

[0088] Examples 9 to 17

[0089] Examples 9 to 17 respectively provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule, each comprising the following steps:

[0090] S1. Dissolve the aldehyde-containing pyrrolidone block copolymer precursor in water to make the concentration of the precursor c em 0.5%, and heating it to 50°C to obtain an aqueous solution;

[0091] S2. hydrocarbon oil (HC) and fluorocarbon oil (FC) are mixed in a volume ratio of 1:1, a certain amount of fluoroalkylamine precursor is added, and the mixture is heated to 50° C. to obtain a mixed oil phase;

[0092] S3. The aqueous solution is added to the mixed oil phase and emulsified at a shear rate of 2800 rpm for 1 minute. After standing at 25°C, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules can be obtained.

[0093] Compared with Examples 1 to 8, Examples 9 to 17 only change the method of adding the fluoroalkylamine precursor, and the specific types of each raw material are the same as those of Examples 1 to 8, which are not repeated here. The difference between Examples 9 to 17 is only the R value. The R values ​​in Examples 9 to 17 are 0, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, and 10, respectively.

[0094] The optical microscope images of the emulsions obtained in Examples 9 to 17 are as follows: Figure 3 shown. Figure 3 In the figure, the scale bars are all 200 μm. For the convenience of observation, in the preparation process of each example, Sudan Red 7B was dissolved in HC before emulsification. Figure 3 Morphological changes of emulsions and Figure 2 Similar to the above, when other conditions are exactly the same, with the gradual increase of R value, the emulsion transforms in the manner of water-in-hydrocarbon oil-in-fluorocarbon oil Pickering composite emulsion, water-in-fluorocarbon oil and hydrocarbon oil Pickering Janus emulsion to water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion. The morphology of droplets in the emulsion can be effectively controlled by adjusting the R value.

[0095] Moreover, in Examples 9 to 17, the fluoroalkylamine precursor is added to the mixed oil phase, and the Pickering-type Janus emulsion of water-in-fluorocarbon oil and hydrocarbon oil can be formed in the range of R value of 0.25 to 1. Compared with the method of adding the fluoroalkylamine precursor to the aqueous solution in Examples 1 to 8, the adjustment range of the R value is broadened.

[0096] Examples 18 to 26

[0097] Examples 18 to 26 provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule. The difference from the preparation method in Examples 9 to 17 is that the type of fluoroalkylamine precursor and the c em , the R values ​​between different embodiments are different, and the remaining raw materials, steps and parameters are consistent with those of embodiments 9 to 17, which will not be repeated here.

[0098] The fluoroalkylamine precursors used in Examples 18 to 26 are all 1H,1H-perfluorohexylamine, and the precursor P 103 D 10 The concentration of c emThe difference between Examples 18 to 26 is only the R value, and the R values ​​in Examples 18 to 26 are 0, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, and 10, respectively.

[0099] The optical microscope images of the emulsions obtained in Examples 18 to 26 are as follows: Figure 4 shown. Figure 4 In the figure, the scale bar is 200 μm. For the convenience of observation, in the preparation process of each embodiment, Sudan Red 7B was dissolved in HC before emulsification. Figure 4 It can be seen that when R=0, the emulsion is a water-in-hydrocarbon oil-in-fluorocarbon oil type Pickering composite emulsion; when R increases to 0.25-10, a water-in-fluorocarbon oil and hydrocarbon oil Pickering type Janus emulsion is formed, which further broadens the adjustment range of the R value compared to Examples 9-17. Based on this, when HC is n-heptane, FC is perfluorohexane, the fluoroalkylamine precursor is 1H,1H-perfluorohexylamine and is added to the mixed oil phase, and the aldehyde-containing pyrrolidone block copolymer precursor is P 103 D 10 , c em When the content of fluorocarbon oil in water and hydrocarbon oil in water is 1%, adjusting the R value to 0.25-10 is conducive to the formation of Pickering Janus emulsion.

[0100] Examples 27 to 30

[0101] Examples 27 to 30 provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule. Compared with Example 22 (R=1), the difference is that the type of fluoroalkylamine precursor and the c em The remaining raw materials, steps and parameters are the same as those in Example 22 and will not be repeated here.

[0102] The fluoroalkylamine precursors used in Examples 27 to 30 are all 1H, 1H, 2H, 2H-perfluorodecylamine, and the R value is constant at 1. The only difference between Examples 27 to 30 is that c em Different, c in Examples 27 to 30 em The values ​​are 0.05%, 0.15%, 0.25% and 0.50% respectively.

[0103] The optical microscope images of the emulsions obtained in Examples 27 to 30 are as follows: Figure 5 shown. Figure 5 In the figure, the scale bar is 200 μm. For the convenience of observation, in the preparation process of each embodiment, Sudan Red 7B was dissolved in HC before emulsification. Figure 5 It can be seen that when c em=0.05%, the emulsion is a Pickering type Janus emulsion of fluorocarbon oil and hydrocarbon oil in water. em The emulsion gradually transformed into a water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion, indicating that by em When HC is n-heptane, FC is perfluorohexane, the fluoroalkylamine precursor is 1H, 1H, 2H, 2H-perfluorodecylamine and added to the mixed oil phase, and the aldehyde-containing pyrrolidone block copolymer precursor is P 103 D 10 , when R=1, c em Adjusting the value to 0.05% is conducive to the formation of a Pickering-type Janus emulsion of fluorocarbon oil and hydrocarbon oil in water.

[0104] Examples 31 to 34

[0105] Examples 31 to 34 respectively provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule. Compared with Example 26 (R=10), the difference lies in that the types of HC, FC and aldehyde-containing pyrrolidone block copolymer precursors and the c em The values ​​and emulsification time are different, and the volume ratios of HC to FC are different between Examples 31 to 34. The remaining raw materials, steps and parameters are consistent with those in Example 26 and will not be repeated here.

[0106] The HC used in Examples 31 to 34 was 1,6-hexanediol diacrylate, the FC was ethyl perfluorobutyl ether (HFE 7200), and the aldehyde-containing pyrrolidone block copolymer precursor was P 103 D 15 , c em The values ​​are all constant at 1.5%, the R values ​​are all constant at 10, and the emulsification time is all 2 minutes. The only difference between Examples 31 to 34 is that V HC / V FC Different, V in Examples 31 to 34 HC / V FC They are 3 / 7, 4 / 6, 5 / 5, and 6 / 4 respectively.

[0107] The optical microscope images of the emulsions obtained in Examples 31 to 34 are as follows: Figure 6 shown. Figure 6 In the figure, the scale bar is 100 μm. For the convenience of observation, in the preparation process of each example, Sudan Red 7B was dissolved in HC before emulsification. Figure 6 It can be seen that the emulsions in each embodiment are all Pickering-type Janus emulsions of fluorocarbon oil and hydrocarbon oil in water. HC / VFC The ratio of HC to FC in the droplets changes, indicating that by adjusting V HC / V FC The value can be adjusted to further regulate the ratio and morphology of HC and FC in the droplets on the basis of forming a Pickering-type Janus emulsion.

[0108] Embodiments 35 to 42

[0109] Examples 35 to 42 provide a method for preparing a Pickering-type Janus emulsion based on a dynamic covalent amphiphilic macromolecule, which is similar to Example 33 (V HC / V FC =5 / 5), the difference is that the type of aldehyde-containing pyrrolidone block copolymer precursor and c em The remaining raw materials, steps and parameters are the same as those in Example 33 and will not be repeated here.

[0110] The aldehyde-containing pyrrolidone block copolymer precursors used in Examples 35 to 42 are all P 72 D3. c in Examples 35 to 38 em The values ​​are all constant at 0.5%. The only difference between the embodiments is the R value. The R values ​​in embodiments 35 to 38 are 0, 1, 5, and 10, respectively; the c values ​​in embodiments 39 to 42 are em The values ​​are all constant at 1.0%. The only difference between the embodiments is the R value. The R values ​​in embodiments 39 to 42 are 0, 1, 5, and 10, respectively.

[0111] The optical microscope images of the emulsions obtained in Examples 35 to 42 are as follows: Figure 7 shown. Figure 7 In the figure, the scale bar is 100 μm. For the convenience of observation, in the preparation process of each example, Sudan Red 7B was dissolved in HC before emulsification. Figure 7 It can be seen that when c em When the R value is different, even the same R value will show different forms, but the overall change law is still similar. When the R value is 1, both can form a Pickering-type Janus emulsion of fluorocarbon oil and hydrocarbon oil in water.

[0112] Embodiments 43 to 46

[0113] Examples 43 to 46 respectively provide a method for preparing micro-nano particles, each comprising the following steps:

[0114] S1. Dissolve the aldehyde-containing pyrrolidone block copolymer precursor in water to make the concentration of the precursor c em 1.0%, and heating it to 50°C to obtain an aqueous solution;

[0115] S2. hydrocarbon oil (HC) and fluorocarbon oil (FC) are mixed in a volume ratio of 1:1, and then a certain amount of fluoroalkylamine precursor and photoinitiator 1-hydroxycyclohexyl phenyl ketone are added, and the mixture is heated to 50° C. to obtain a mixed oil phase;

[0116] S3. The aqueous solution is added to the mixed oil phase and emulsified at a shear rate of 2800 rpm for 2 minutes, and allowed to stand at 25°C to obtain a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules; the emulsion is irradiated with ultraviolet light at a wavelength of 365 nm, and after photopolymerization for 5 minutes, the obtained micro-nanoparticles are collected.

[0117] The hydrocarbon oil (HC) used in Examples 43 to 46 was 1,6-hexanediol diacrylate, the fluorocarbon oil (FC) was ethyl perfluorobutyl ether (HFE 7200), the fluoroalkylamine precursor was 1H,1H-perfluorohexylamine, and the aldehyde-containing pyrrolidone block copolymer precursor was P 72 D3, the mass concentration of 1-hydroxycyclohexyl phenyl ketone in the mixed oil phase is 4% 。 The only difference between Examples 43 to 46 is the R value. The R values ​​in Examples 43 to 46 are 1, 3, 5, and 10, respectively.

[0118] The optical microscope images and SEM images of the micro-nano particles obtained in Examples 43 to 46 are as follows: Figure 8 shown. Figure 8 In the figure, a1~d1 are optical microscope images of the micro-nano particles in Examples 43~46, and a2~d2 are SEM images of the micro-nano particles in Examples 43~46, respectively.

[0119] It can be seen from Examples 43 to 46 that, based on the preparation of the Pickering-type Janus emulsion, micro-nanoparticles with an asymmetric structure can be obtained by in-situ polymerization and curing of the monomer 1,6-hexanediol diacrylate using a photoinitiator, and the morphology of the micro-nanoparticles can be adjusted by the R value, with high controllability.

[0120] In summary, the present application provides a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules and its preparation method and application. The emulsion includes hydrocarbon oil, fluorocarbon oil, water and an emulsifier; the emulsifier includes an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor. By preparing water and an aldehyde-containing pyrrolidone block copolymer precursor into an aqueous solution, preparing hydrocarbon oil and fluorocarbon oil into a mixed oil phase, and adding a fluoroalkylamine precursor to the aqueous solution or the mixed oil phase, the aqueous solution and the mixed oil phase are then mixed and emulsified to obtain a corresponding emulsion, and some components in the emulsion can be cured in situ to obtain micro-nano particles with controllable morphology. The present application constructs a dynamic covalent bond block copolymer in situ in an aqueous solution, so that it acts as an emulsifier to stabilize the mixed oil phase of hydrocarbon oil and fluorocarbon oil, thereby forming a Pickering-type Janus emulsion with controllable morphology and excellent stability in a simple system.

[0121] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, characterized in that: The invention comprises hydrocarbon oil, fluorocarbon oil, water and emulsifier; the emulsifier comprises an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor.

2. The Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 1, characterized in that: The structural formula of the aldehyde-containing pyrrolidone block copolymer precursor is shown in Formula 1, and the structural formula of the fluoroalkylamine precursor is shown in Formula 2 or Formula 3; Formula 1: Formula 2: CF3(CF2) m-2 CH2NH2; Formula 3: CF3(CF2) n-3 CH2CH2NH2; Among them, the value of a is 72 or 103, b is an integer between 3 and 15, and m and n are both integers between 6 and 10.

3. The Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 1, characterized in that: The hydrocarbon oil includes one of medium-chain alkanes or polymerizable oil monomers containing hydrocarbons, and the fluorocarbon oil includes one of medium-chain fluorocarbon alkanes or polymerizable oil monomers containing fluorocarbons.

4. The Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 1, characterized in that: The molar ratio of the amino groups in the fluoroalkylamine precursor to the aldehyde groups in the aldehyde-containing pyrrolidone block copolymer precursor is 0.25-10.

5. The Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 1, characterized in that: The mass concentration of the aldehyde-containing pyrrolidone block copolymer precursor in water is 0.05% to 1.5%.

6. The Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 1, characterized in that: The volume ratio of the hydrocarbon oil to the fluorocarbon oil is 3:7 to 6:

4.

7. A method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to any one of claims 1 to 6, characterized in that: The steps include: An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and the aldehyde-containing pyrrolidone block copolymer precursor; the mixed oil phase contains the hydrocarbon oil and the fluorocarbon oil; the aqueous solution or the mixed oil phase also contains the fluoroalkylamine precursor; The aqueous solution is added into the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained.

8. The method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 7, characterized in that: The predetermined temperature of the aqueous solution and the mixed oil phase is 40-60° C.; the emulsification method is: emulsification at a shear rate of 2500-3000 rpm for 1-2 minutes.

9. Use of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to any one of claims 1 to 6 in the preparation of micro-nano particles.

10. The use of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules in the preparation of micro-nano particles according to claim 9, characterized in that: The preparation method of the micro-nano particles comprises: An aqueous solution and a mixed oil phase at a predetermined temperature are prepared respectively; wherein the aqueous solution contains water and the aldehyde-containing pyrrolidone block copolymer precursor; the mixed oil phase contains the hydrocarbon oil, the fluorocarbon oil and a photoinitiator; the aqueous solution or the mixed oil phase further contains the fluoroalkylamine precursor; the hydrocarbon oil is a polymerizable oil monomer containing hydrocarbons, and the fluorocarbon oil is a polymerizable oil monomer containing fluorocarbons; The aqueous solution is mixed with the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained. The emulsion is stirred and photopolymerized with ultraviolet light, and then filtered to obtain micro-nano particles.

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