Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules and its preparation method and application

Abstract

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. Water and an aldehyde-containing pyrrolidone block copolymer precursor are formulated into an aqueous solution, hydrocarbon oil and fluorocarbon oil are formulated into a mixed oil phase, and the fluoroalkylamine precursor can be added to the aqueous solution or the mixed oil phase. Thereafter, the aqueous solution and the mixed oil phase are mixed and emulsified to obtain the corresponding emulsion. After in-situ solidification of some components in the emulsion, micro-nanoparticles with controllable morphology can also be obtained. 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.

Description

Technical Field

[0001] The present 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] An emulsion is a thermodynamically unstable coarse dispersion system consisting of one liquid dispersed in another immiscible liquid. Surfactants are typically used as emulsifiers to stabilize the emulsion droplets. Emulsions are widely used in pharmaceutical formulations such as pharmaceuticals and pesticides, household chemicals such as cosmetics and coatings, advanced materials preparation, and oil development. Emulsions primarily include oil-in-water and water-in-oil. Under certain conditions, multiple emulsions such as water-in-oil-in-water and oil-in-water-in-oil can also form. Oil-in-water emulsions formed by mixing two immiscible oil phases are also called Janus emulsions. Janus emulsions offer a natural advantage as templates for the preparation of asymmetric micro- and nanomaterials. However, the ability to control the morphology, size, and stability of Janus emulsions using simple methods remains an urgent challenge.

[0003] Currently, there are two main methods for preparing Janus emulsions. One is direct emulsification, which involves directly emulsifying a mixture of two oil phases, water, and a surfactant under high shear. However, the droplet morphologies of the Janus emulsions produced by this method are diverse and non-spherical. Another approach utilizes the maximum solubility temperature of the two oil phases. Specifically, Janus emulsions are prepared by emulsifying above the solubility temperature and then allowing the emulsion to separate automatically below the solubility temperature. This method produces uniform, spherical Janus emulsions, but it places high demands on the emulsification system and often results in extremely complex compositions. The mechanism of Janus emulsion formation indicates that the morphology of a Janus emulsion is primarily influenced by the relative interfacial tensions between the two oil phases and the water phase, as well as between the oil phase itself. Utilizing the interfacial activity of small-molecule surfactants to modulate these relative interfacial tensions is undoubtedly an effective and widely adopted strategy. However, Janus emulsions prepared using small-molecule surfactants suffer from insufficient stability due to the rapid exchange of surfactants between the interfacial phase and the bulk phase. Therefore, it is extremely challenging to give Janus emulsions better stability while achieving controllable structure and morphology of Janus emulsions, which is also crucial for the application of Janus emulsions 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 to solve the problems currently faced by Janus emulsions, such as complex systems, 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 its preparation method and application. Based on the dynamic covalent bond strategy, amphiphilic macromolecules are formed in situ, so that the amphiphilic macromolecular aggregates can be enriched at the two-phase interface 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 solutions of the embodiments of the present application, a dynamic covalently bonded block copolymer can be constructed in situ in aqueous solution using an aldehyde-containing pyrrolidone block copolymer precursor and a fluoroalkylamine precursor. This type of dynamic covalently bonded block copolymer is amphiphilic, and the aggregates formed by this type of dynamic covalently bonded block copolymer in aqueous solution can act as an emulsifier to stabilize the mixed phase of hydrocarbon oil and fluorocarbon oil, thereby forming a Pickering-type Janus emulsion. This emulsion system has a simple composition, controllable droplet morphology, and the emulsifier can be enriched at the interface between the two phases, effectively improving 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] Wherein, 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 example, by specifying the specific structures of the aldehyde-containing pyrrolidone block copolymer precursor and the fluoroalkylamine precursor, the surface activity and micellization capacity of the corresponding aqueous solutions can be adjusted to enhance the dynamic stability of the emulsion system. Furthermore, based on the precursors used in this example, the interfacial curvature can be more easily adjusted, thereby improving the morphological controllability of the emulsion.

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

[0016] In this embodiment, the aggregates formed by the dynamically covalently bonded block copolymer in aqueous solution can more effectively stabilize the mixed oil phase formed by the hydrocarbon oil and fluorocarbon oil, thereby improving the stability of the emulsion system. Specifically, when hydrocarbon-containing polymerizable oil monomers and fluorocarbon-containing polymerizable oil monomers are selected as the hydrocarbon oil and fluorocarbon oil, respectively, micro-nanoparticles 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-described embodiments, by varying the precursor molar ratio, precursor concentration, and volume ratio of the two oil phases, a transition from a hydrocarbon-in-water-in-fluorocarbon-oil Pickering composite emulsion, a fluorocarbon-in-water-in-hydrocarbon-oil Pickering Janus emulsion, to a hydrocarbon-in-water-in-fluorocarbon-oil Pickering composite emulsion can be achieved. Furthermore, by regulating the molar ratio of the two precursors, the precursor concentration, and the volume ratio of the two oil phases, the curvature of the interface between the hydrocarbon and fluorocarbon oil phases within the resulting emulsion can be controlled, thereby regulating the morphology of the two oil phases within the droplets.

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

[0022] An aqueous solution and a mixed oil phase are prepared at predetermined temperatures 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; and the aqueous solution or the mixed oil phase further contains the fluoroalkylamine precursor;

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

[0024] In the technical solution 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 enrich them at the water-oil interface as a soft particle Pickering emulsifier, thereby stabilizing 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.; and 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. After standing, a uniform and stable Pickering-type Janus emulsion is formed.

[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-nanoparticles, micro-nanoparticles with controllable morphology can be obtained.

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

[0030] An aqueous solution and a mixed oil phase are prepared at predetermined temperatures 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 using ultraviolet light, and then filtered to obtain micro-nano particles.

[0032] In this embodiment, by selecting a polymerizable oil monomer as the oil phase and adding a photoinitiator during the preparation of the emulsion, the polymerizable monomer in the droplets can be in situ polymerized and solidified 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] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0035] Figure 1 Schematic diagram of the droplet morphology transition of the emulsion in the examples of this application;

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

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

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

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

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

[0041] Figure 7 These are 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-nanoparticles prepared in Examples 43 to 46 of the present application. DETAILED DESCRIPTION

[0043] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended 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 those skilled in the art 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" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0045] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, 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, difficult to control the emulsion droplet morphology, and poor emulsion stability, which limit the application of Janus emulsions in related fields. Currently, it is necessary to develop a preparation method with a simple system, which is convenient for effectively controlling the droplet morphology of Janus emulsions and maintaining good stability, in order to solve the above problems.

[0047] Pickering emulsion uses amphiphilic solid particles as emulsifiers and has extremely high stability. 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. 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 thus 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, as well as its preparation method and application. 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, 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 solution 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 is amphiphilic, 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, effectively improving the dynamic stability of the emulsion system.

[0050] Furthermore, 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 By defining the specific structure of CA, the surface activity and micellization ability of the corresponding aqueous solution can be adjusted to improve the dynamic stability of the emulsion system, and the interfacial curvature can be adjusted to improve the morphological controllability of the emulsion. In the early experiments of this application, it was found that changing the structure of the corresponding precursor and the values ​​of a, b, m, and n would affect the formation of the corresponding emulsion. As a result, the transition process from the water-in-hydrocarbon oil-in-fluorocarbon oil Pickering composite emulsion, the water-in-fluorocarbon oil and hydrocarbon oil Pickering Janus emulsion to the water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion was difficult to occur, which was not conducive to the regulation of the emulsion morphology. 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] Furthermore, in some embodiments, the hydrocarbon oil comprises a medium-chain alkane or a polymerizable oil monomer containing hydrocarbons, and the fluorocarbon oil comprises a medium-chain fluorocarbon alkane or a polymerizable oil monomer containing fluorocarbons; 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 preferably be hexane or heptane, and the polymerizable oil monomer containing hydrocarbons may preferably be 1,6-hexanediol diacrylate; the medium-chain fluorocarbon alkane may preferably be perfluorohexane or ethyl perfluorobutyl ether (HFE 7200), and the polymerizable oil monomer containing fluorocarbons may preferably be perfluorooctyl ethyl acrylate or perfluorodecyl ethyl acrylate.

[0059] In the technical solutions of the embodiments of the present application, the aggregates formed by the dynamically covalently bonded block copolymer in 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. Specifically, when hydrocarbon-containing polymerizable oil monomers and fluorocarbon-containing polymerizable oil monomers are selected as the hydrocarbon oil and the fluorocarbon oil, respectively, micro-nanoparticles 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 parameters such as 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 emulsion can also be adjusted to adjust 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 Indicates the concentration of aldehyde-containing pyrrolidone block copolymer precursor in water, HC represents hydrocarbon oil, FC represents fluorocarbon oil, and V represents HC / V FC 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, which can transform the emulsion into a water-in-hydrocarbon oil-in-fluorocarbon oil Pickering composite emulsion, a water-in-fluorocarbon oil and hydrocarbon oil Pickering Janus emulsion, and a water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion. The transformation diagram is shown in FIG. Figure 1 As shown. In 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. At the same time, by adjusting V HC / V FC , and can also change the ratio of HC to FC within the emulsion droplets. On this basis, by adjusting various parameters, the morphology of the emulsion droplets can be effectively controlled. On this basis, it is also possible to prepare micro-nanoparticles with controllable morphology to meet the application needs of different scenarios.

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

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

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

[0066] In the technical solution 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 added to the mixed oil phase. The present application prepares the corresponding aqueous solution and mixed oil phase separately, 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 process of water-oil mixing, thereby forming a dynamic covalent bond block copolymer in situ in the aqueous solution, and enriching it at the water-oil two-phase interface as a soft particle Pickering emulsifier, thereby stabilizing 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] Furthermore, in some embodiments, the predetermined temperature of the aqueous solution and the mixed oil phase is 40-60° C.; and 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 thoroughly mixed and emulsified at a certain shear rate, and then allowed to stand to form a uniform and stable Pickering-type Janus emulsion. The standing temperature is preferably 20-30°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 of the components in the emulsion droplets.

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

[0073] An aqueous solution and a mixed oil phase are prepared at predetermined temperatures respectively; wherein the aqueous solution contains water and a pyrrolidone block copolymer precursor containing an aldehyde group; the mixed oil phase contains a hydrocarbon oil, a fluorocarbon oil, and a photoinitiator; the aqueous solution or the mixed oil phase further 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 to the mixed oil phase and emulsified to obtain a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules. The emulsion is stirred and photopolymerized using ultraviolet light, and then filtered to obtain micro-nano particles.

[0075] In the technical solution of the embodiment of the present application, by selecting a polymerizable oil monomer 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 monomer in the droplets after the emulsion is formed, thereby preparing micro-nanoparticles with controllable morphology.

[0076] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[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 a mass concentration of c em The mixture is 0.5% and a certain amount of fluoroalkylamine precursor is added to form a dynamic covalent amphiphilic macromolecule in situ in the aqueous solution, which is then heated 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 was all n-heptane, the fluorocarbon oil (FC) was all perfluorohexane, the fluoroalkylamine precursor was all 1H,1H-perfluorooctylamine, and the structural formula of the aldehyde-containing pyrrolidone block copolymer precursor was as follows:

[0083]

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

[0085] The only difference between Examples 1-8 is the molar ratio (R) of the amino groups in the fluoroalkylamine precursor to the aldehyde groups in the aldehyde-containing pyrrolidone block copolymer precursor. The R values ​​in Examples 1-8 are 0, 0.25, 0.5, 0.75, 1, 1.5, 2, and 2.5, respectively. R = 0 indicates that no fluoroalkylamine precursor was 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 images, and a2 to h2 are dark field images. For the convenience of observation, in the preparation process of each embodiment, coumarin-6 was 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 Pickering composite emulsion; when R increases to 0.25-0.75, a water-in-fluorocarbon oil and hydrocarbon oil Pickering 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 Pickering composite emulsion, indicating that the morphology of the droplets in the emulsion can be effectively controlled 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 the formation of Pickering Janus emulsion.

[0088] Examples 9 to 17

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

[0090] S1. dissolving the aldehyde-containing pyrrolidone block copolymer precursor in water to a concentration of c em 0.5% and heated 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 is obtained.

[0093] Compared to Examples 1-8, Examples 9-17 only changed the method of adding the fluoroalkylamine precursor. The specific types of the raw materials were the same as in Examples 1-8 and are not further described here. The only difference between Examples 9-17 is the R value. The R values ​​in Examples 9-17 are 0, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, and 10, respectively.

[0094] The optical microscope pictures of the emulsions prepared in Examples 9 to 17 are as follows: Figure 3 shown. Figure 3 In the figures, 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 The morphological changes of emulsions and Figure 2 Similarly, 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. By adjusting the R value, the morphology of the droplets in the emulsion can be effectively controlled.

[0095] Furthermore, in Examples 9 to 17, the fluoroalkylamine precursor was added to the mixed oil phase, and a Pickering-type Janus emulsion of fluorocarbon oil and hydrocarbon oil in water was formed in the R value range 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 was 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 , R values ​​are different between different embodiments, and the remaining raw materials, steps and parameters are consistent with those of Examples 9 to 17 and 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 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 pictures of the emulsions prepared 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 lies in changing 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 pictures of the emulsions prepared 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 As the emulsion gradually changes into a water-in-fluorocarbon oil-in-hydrocarbon oil Pickering composite emulsion, it is shown 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 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 were different, and the volume ratios of HC to FC were different between Examples 31 to 34. The remaining raw materials, steps and parameters were the same as 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 prepared 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 embodiment, 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 and FC in the droplet changes, indicating that by adjusting V HC / V FC The value can be adjusted to further control the ratio and morphology of HC and FC in the droplets on the basis of forming Pickering-type Janus emulsion.

[0108] Examples 35 to 42

[0109] Examples 35 to 42 provide a method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules, which is similar to that of 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 were all P 72 D3. c in Examples 35 to 38 em The values ​​are all constant at 0.5%. The only difference between the examples is the R value. The R values ​​in Examples 35 to 38 are 0, 1, 5, and 10, respectively; the c values ​​in Examples 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 Examples 39 to 42 are 0, 1, 5, and 10, respectively.

[0111] The optical microscope pictures of the emulsions prepared 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 embodiment, 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] Examples 43 to 46

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

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

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

[0116] S3. The aqueous solution was added to the mixed oil phase and emulsified at a shear rate of 2800 rpm for 2 minutes. The mixture was allowed to stand at 25°C to obtain a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules. The emulsion was irradiated with ultraviolet light at a wavelength of 365 nm. After photopolymerization for 5 minutes, the obtained micro-nanoparticles were 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 to d1 are optical microscope images of the micro-nano particles in Examples 43 to 46, and a2 to d2 are SEM images of the micro-nano particles in Examples 43 to 46, respectively.

[0119] It can be seen from Examples 43 to 46 that, based on the preparation of a Pickering-type Janus emulsion, asymmetric micro-nanoparticles 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 strong 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, the fluoroalkylamine precursor can be added to the aqueous solution or the mixed oil phase, and then the aqueous solution and the mixed oil phase are mixed and emulsified to obtain the corresponding emulsion. After some components in the emulsion are solidified in situ, micro-nanoparticles with controllable morphology can be obtained. 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 merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine 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: It includes hydrocarbon oil, fluorocarbon oil, water and emulsifier; the emulsifier includes aldehyde-containing pyrrolidone block copolymer precursor and fluoroalkylamine precursor; 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; in, a The value of is 72 or 103, b is an integer between 3 and 15, m and n They are all integers between 6 and 10.

2. 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.

3. 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.

4. 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%.

5. 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.

6. A method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to any one of claims 1 to 5, characterized in that: The steps include: An aqueous solution and a mixed oil phase are prepared at predetermined temperatures 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; and the aqueous solution or the mixed oil phase further contains the fluoroalkylamine precursor; The aqueous solution is added to the mixed oil phase, and after emulsification, a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules is obtained.

7. The method for preparing a Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to claim 6, 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.

8. Use of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules according to any one of claims 1 to 5 in the preparation of micro-nanoparticles.

9. The use of the Pickering-type Janus emulsion based on dynamic covalent amphiphilic macromolecules in the preparation of micro-nanoparticles according to claim 8, characterized in that: The preparation method of the micro-nano particles comprises: An aqueous solution and a mixed oil phase are prepared at predetermined temperatures 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 using ultraviolet light, and then filtered to obtain micro-nano particles.

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