Photoresponsive Pickering emulsions stabilized by a spiropyran ionic liquid and UiO-66-NH2

Abstract

The present invention discloses a light-responsive Pickering emulsion that is synergistically stabilized by a spiropyran ionic liquid and UiO-66-NH2. The Pickering emulsion comprises an oil-water phase, and its stabilizer is a spiropyran ionic liquid and a metal-organic framework material UiO-66-NH2. The stable Pickering emulsion can undergo demulsification under additional visible light irradiation. When further irradiated with ultraviolet light, the system can be re-emulsified to form a stable Pickering emulsion. The Pickering emulsion provided by the present invention can be used for the Click reaction of hydrophilic azide compounds and terminal alkynyl compounds. Through reversible visible light and ultraviolet light regulation, the catalyst and spiropyran ionic liquid can be recycled, and the Pickering emulsion has application value in the fields of controlled drug release and sustainable catalysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of colloid and interface chemistry, and specifically relates to a light-responsive Pickering emulsion, in particular to a light-responsive Pickering emulsion synergistically stabilized by a class of spiropyran ionic liquids and a metal-organic framework material UiO-66-NH2. Background Art

[0002] Pickering emulsions are stable emulsion systems formed using solid particles as emulsifiers. They offer advantages such as low cost, low toxicity, minimal foaming, and strong interfacial stability, and have demonstrated promising applications in drug controlled release, chemical synthesis, material preparation, and wastewater treatment. Because surfactant particles adsorb at the oil / water interface, a key characteristic of Pickering emulsions is their high long-term stability, making demulsification difficult. Therefore, preparing Pickering emulsions with reversible emulsification and demulsification is both challenging and valuable.

[0003] In recent years, researchers have used stimuli-responsive nanoparticles to prepare Pickering emulsions. These systems can be used to construct Pickering emulsion systems that respond to external stimuli, such as pH-responsive, CO2-responsive, temperature-responsive, redox-responsive, magnetic-responsive, and light-responsive. These systems can achieve reversible regulation of emulsification and demulsification through external stimuli. However, most of these systems require complex synthetic steps to prepare nanoparticles that respond to external stimuli. Previous studies have shown that nanoparticles can synergistically emulsify oil and water phases with reversible surfactants, thereby preparing Pickering emulsion systems with reversible photoswitching capabilities. However, research on these simple and efficient systems is still limited.

[0004] Spiropyrans are a class of compounds with reversible photoactivation properties. By implanting spiropyran functional groups into the structure of ionic liquids, the ionic liquids can be imbued with reversible photoactivation properties, leveraging the amphiphilicity of the ionic liquids to regulate their emulsification capacity. Metal-organic frameworks (MOFs) are ordered porous materials self-assembled from metal clusters and organic ligands, which can be rendered amphiphilic through structural design. Based on this, the present invention attempts to design a type of Pickering emulsion based on MOF materials and photoresponsive spiropyran ionic liquids that synergistically stabilize the oil-water phase. This type of system avoids the complex synthesis of photoresponsive nanoparticles and allows reversible regulation of emulsion demulsification and re-emulsification through illumination. Based on this characteristic, this type of Pickering emulsion can be used for click reactions of azide compounds and terminal alkynyl compounds. Through reversible visible and ultraviolet light regulation, the MOF materials and ionic liquids can be recycled. This has application value in the fields of controlled drug release and sustainable catalysis. Currently, there are no relevant reports in this area. Summary of the Invention

[0005] The purpose of the present invention is to provide a simple, efficient, and reversibly photo-activated photoresponsive Pickering emulsion composed of a spiropyran ionic liquid and a metal-organic framework material UiO-66-NH2. The Pickering emulsion has strong stability and is responsive to both ultraviolet and visible light. It has application value in sustainable Click reactions of azide compounds and terminal alkynyl compounds. The Pickering emulsion can serve as an efficient and controllable microreactor for homogeneous reaction and heterogeneous separation.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a type of spiropyran ionic liquid and UiO-66-NH2 synergistically stabilized light-responsive Pickering emulsion, characterized in that: the Pickering emulsion includes two phases of oil and water, and its stabilizer is a spiropyran ionic liquid and a metal-organic framework material UiO-66-NH2, wherein the spiropyran ionic liquid is one or more of [C4SPDMEA]Br, [C6SPDMEA]Br or [C8SPDMEA]Br, and the stable Pickering emulsion can be demulsified under additional visible light irradiation. When further irradiated with ultraviolet light, the system can be re-emulsified to form a stable Pickering emulsion.

[0007] It is further defined that the structural formula of the spiropyran ionic liquid is:

[0008]

[0009] It is further defined that the oil phase in the oil-water two phases is one or more of benzene, toluene, xylene, ethyl acetate, dichloromethane, n-octane, n-hexane, n-heptane, n-decane or n-butanol, preferably a non-polar organic phase, specifically one or more of benzene, toluene, xylene, n-octane, n-hexane, n-decane or n-heptane, further preferably toluene.

[0010] It is further defined that the volume ratio of the oil and water phases is 1:0.1 to 1:10, specifically 1:0.5, 1:1, 1:2, 1:3, 2:3 or 2:5.

[0011] It is further defined that the concentration of the spiropyran ionic liquid in the Pickering emulsion is 7×10 -6 mol / kg~1×10 -4 mol / kg, and the content of the metal organic framework material UiO-66-NH2 is 0.01wt% to 0.4wt%.

[0012] It is further defined that the concentration of the spiropyran ionic liquid [C4SPDMEA]Br in the Pickering emulsion is 1×10 -5 mol / kg~1×10 -4 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.1wt% to 0.4wt%.

[0013] It is further defined that the concentration of the spiropyran ionic liquid [C6SPDMEA]Br in the Pickering emulsion is 1×10 -5 mol / kg~9×10 -5 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.01wt% to 0.4wt%.

[0014] It is further defined that the concentration of the spiropyran ionic liquid [C8SPDMEA]Br in the Pickering emulsion is 7×10 -6 mol / kg~5×10 -5 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.03wt% to 0.4wt%.

[0015] It is further defined that the Pickering emulsion can be used as a microreactor for the Click reaction of hydrophilic azide compounds and terminal alkynyl compounds, and can achieve the recycling of catalysts and spiropyran ionic liquids through reversible visible light and ultraviolet light regulation.

[0016] It is further defined that the specific process of the Pickering emulsion being able to be used as a microreactor for the Click reaction of hydrophilic azide compounds and terminal alkynyl compounds is as follows: adding the catalyst CuBr2 to the Pickering emulsion, then adding the azide compound and the terminal alkynyl compound and homogenizing them and reacting them at 40-50°C. After the reaction is completed, the reaction system is irradiated with visible light to break the emulsion, the product is in the water phase, the catalyst CuBr2 is precipitated, and the spiropyran ionic liquid is transferred to the oil phase.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: the Pickering emulsion provided by the present invention is highly stable, can be demulsified by irradiation with visible light, and can be re-emulsified by further irradiation with ultraviolet light to form a stable Pickering emulsion. The Pickering emulsion provided by the present invention can be used for the Click reaction of hydrophilic azide compounds and terminal alkynyl compounds. Through reversible regulation by visible and ultraviolet light, the catalyst and spiropyran ionic liquid can be recycled, and has application value in the fields of controlled drug release and sustainable catalysis. DETAILED DESCRIPTION

[0018] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention.

[0019] Example 1-51

[0020] 1 mL of spiropyran ionic liquids of different types and concentrations and 1 mL of UiO-66-NH2 dispersions of varying concentrations were placed in a wire-top bottle. 3 mL of toluene was added and homogenized at 10,000 rpm for 1 minute using a homogenizer to obtain stable Pickering emulsions. The compositions of the stable Pickering emulsions formed by different types and concentrations of spiropyran ionic liquids ([C4SPDMEA]Br, [C6SPDMEA]Br, [C8SPDMEA]Br) and varying concentrations of the metal-organic framework material UiO-66-NH2 are shown in Table 1.

[0021] Table 1 Composition of stable Pickering emulsions formed by different types and contents of spiropyran ionic liquids and UiO-66-NH2 dispersions

[0022]

[0023]

[0024] Example 52

[0025] [C6SPDMEA]Br (7×10 -5 mol.kg -1 ) / UiO-66-NH2(0.4wt%) / toluene / water system for 10 min, the system phase separation occurred, i.e., demulsification; further irradiation with LED point light UV lamp for 3 min, after stirring, the system was emulsified again to form a stable Pickering emulsion.

[0026] Example 53

[0027] [C8SPDMEA]Br (3×10 -5 mol·kg -1 ) / UiO-66-NH2(0.1wt%) / toluene / water system for 5 min, the system phase separated, i.e., demulsification occurred; further irradiation with an LED point light source UV lamp for 3 min, after stirring, the system was emulsified again to form a stable Pickering emulsion.

[0028] Example 54

[0029] [C4SPDMEA]Br (5×10 -5 mol·kg -1 ) / UiO-66-NH2(0.3wt%) / toluene / water system for 15 min, the system phase separation occurred, i.e., demulsification; further irradiation with LED point light UV lamp for 8 min, after stirring, the system was emulsified again to form a stable Pickering emulsion.

[0030] Examples 55-59

[0031] In [C6SPDMEA]Br(7×10 -5 mol.kg -1 ) / UiO-66-NH2 (0.4 wt%) / toluene / water, the catalyst CuBr2 was added, and then the azide compound and the terminal acetylenic compound were added and homogenized, and then reacted at 45°C for 18 hours. After the reaction, the reaction system was irradiated with visible light to break the emulsion. The product was in the aqueous phase, the catalyst CuBr2 and the metal-organic framework material UiO-66-NH2 were precipitated, and the ionic liquid [C6SPDMEA]Br was transferred to the oil phase. Different reaction raw materials were mixed in [C6SPDMEA]Br (7×10 -5 mol.kg -1The conversion rate of Click reaction in the Pickering emulsion formed by ) / UiO-66-NH2 (0.4wt%) / toluene / water is shown in Table 2.

[0032] Table 2 Conversion rate of Click reaction of different reaction raw materials in Pickering emulsion system

[0033]

[0034] The basic principles, main features and advantages of the present invention are shown and described above. Without departing from the spirit and scope of the present invention, the present invention may also be subject to various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A photoresponsive Pickering emulsion stabilized by spiropyran ionic liquid and UiO-66-NH2, characterized by: The Pickering emulsion includes an oil-water phase, and its stabilizer is a spiropyran ionic liquid and a metal-organic framework material UiO-66-NH2, wherein the spiropyran ionic liquid is one or more of [C4SPDMEA]Br, [C6SPDMEA]Br, or [C8SPDMEA]Br. The stable Pickering emulsion can be demulsified under additional visible light irradiation, and when further irradiated with ultraviolet light, the system can be re-emulsified to form a stable Pickering emulsion. The structural formula of the spiropyran ionic liquid is:

2. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The oil phase in the oil-water two phases is one or more of benzene, toluene, xylene, ethyl acetate, dichloromethane, n-octane, n-hexane, n-heptane, n-decane or n-butanol.

3. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The volume ratio of the oil and water phases is 1:0.1 to 1:

10.

4. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The concentration of the spiropyran ionic liquid in the Pickering emulsion is 7×10 -6 mol / kg~1×10 -4 mol / kg, and the content of the metal organic framework material UiO-66-NH2 is 0.01wt% to 0.4wt%.

5. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The concentration of the spiropyran ionic liquid [C4SPDMEA]Br in the Pickering emulsion is 1×10 -5 mol / kg~1×10 -4 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.1wt% to 0.4wt%.

6. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The concentration of the spiropyran ionic liquid [C6SPDMEA]Br in the Pickering emulsion is 1×10 -5 mol / kg~9×10 -5 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.01wt% to 0.4wt%.

7. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The concentration of the spiropyran ionic liquid [C8SPDMEA]Br in the Pickering emulsion is 7×10 -6 mol / kg~5×10 -5 mol / kg; the content of the metal organic framework material UiO-66-NH2 is 0.03wt% to 0.4wt%.

8. The photoresponsive Pickering emulsion synergistically stabilized by a spiropyran ionic liquid and UiO-66-NH2 according to claim 1, characterized in that: The Pickering emulsion can be used as a microreactor for Click reaction of hydrophilic azide compounds and terminal alkynyl compounds, and can realize the recycling of catalysts and spiropyran ionic liquids through reversible visible light and ultraviolet light regulation.

9. The photoresponsive Pickering emulsion stabilized synergistically by a spiropyran ionic liquid and UiO-66-NH2 according to claim 8, characterized in that: Catalyst CuBr2 is added to the Pickering emulsion, and then an azide compound and a terminal alkynyl compound are added and homogenized to react at 40-50°C. After the reaction is completed, the reaction system is irradiated with visible light to break the emulsion. The product is in the water phase, the catalyst CuBr2 is precipitated, and the spiropyran ionic liquid is transferred to the oil phase.

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