Method for preparing high-stability w / o / w-type multiple pickering emulsion on basis of janus particles, and use

Abstract

The present invention relates to the technical field of colloid and interface chemistry, and disclosed are a method for preparing a high-stability W / O / W-type multiple Pickering emulsion on the basis of Janus particles, and a use. The present invention uses alkylsilanes of different chain lengths to modify SiO2, thereby preparing Janus particles having distinct hydrophilic and hydrophobic properties, which jointly stabilize a multiple emulsion; and different types of Janus particles are adsorbed on different oil-water interfaces, fully exerting the interfacial activity and amphiphilicity of the Janus particles, thereby preparing a high-stability multiple emulsion. The multiple emulsion of the present invention has excellent stability, and remains stable under conditions such as long-term storage, strong acids and bases, and high-concentration electrolytes, thereby effectively expanding the practical application of the multiple emulsion.

Description

A method for preparing highly stable W / O / W type multiple Pickering emulsions based on Janus particles and its application Technical Field

[0001] This invention relates to a method and application for preparing highly stable W / O / W type multiple Pickering emulsions based on Janus particles, belonging to the field of colloid and interface chemistry technology. Background Technology

[0002] Multiple emulsions (MPEs), also known as composite emulsions, are multilayer emulsions formed by dispersing one emulsion in another continuous phase. They combine the advantages of traditional oil-in-water and water-in-oil emulsions, enabling the simultaneous encapsulation of both water-soluble and oil-soluble substances. Multiple emulsions are commonly classified into water-in-oil-in-water (W / O / W) and oil-in-water-in-oil (O / W / O) types. Their unique structure makes them widely used in the food industry, cosmetics, biopharmaceuticals, and agriculture. The stability of multiple emulsions is controlled by multiple factors, including their preparation process, emulsifiers, oil phase, and aqueous phase. Because multiple emulsions have a more complex system than single emulsions, their excess surface free energy is thermodynamically unstable. Therefore, preparing stable and controllable multiple emulsions is crucial for their application.

[0003] The emulsifiers in multiple emulsions mainly consist of small-molecule surfactants, polymeric emulsifiers, natural macromolecules, and colloidal particles. Multiple emulsions stabilized by small-molecule surfactants often have poor stability; polymeric emulsifiers have excellent stability and swelling properties, which can greatly improve the stability of emulsions, but their biocompatibility is poor; using natural macromolecules alone requires a high concentration to obtain a stable multiple emulsion.

[0004] With the deepening research on Pickering emulsions, solid particle-stabilized Pickering emulsions exhibit higher stability due to the difficulty in desorption of particles adsorbed at the interface. Among these, amphiphilic Janus particles, which are colloidal particles with two different surface properties, stabilize emulsions with excellent stability; their adsorption energy at the oil-water interface is three times that of homogeneous particles. The surface asymmetry of Janus particles allows for precise control of their hydrophilicity and hydrophobicity, and some researchers have prepared emulsions with moderate wettability (θ...). ow While stabilizing multiple emulsions in one step using colloidal particles with a latitude of ≈90° is a simple and convenient process, it also presents several disadvantages, including the need for strict control of particle wettability, competition between particles at the two interfaces, poor emulsion reproducibility, and difficulty in controlling the distribution of each phase (e.g., W1 / O / W2 type). Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing highly stable multiple Pickering emulsions based on Janus particles. Janus particles with varying hydrophilicity and hydrophobicity are prepared by modifying SiO2 with alkylsilanes of different chain lengths, collectively stabilizing the multiple emulsion. Different types of Janus particles are adsorbed at different oil-water interfaces, fully utilizing the interfacial activity and amphiphilicity of the Janus particles to prepare highly stable multiple emulsions, effectively expanding the practical applications of multiple emulsions.

[0006] The first objective of this invention is to provide a method for preparing multiple Pickering emulsions, the method comprising the steps of:

[0007] (1) Aminated silica particles (SiO2) were dispersed in toluene solution, and octacarbonsilane and triethylamine were added to react. After washing and drying, hydrophilic Janus-SiO2 nanoparticles were obtained. The mass ratio of aminated silica particles, octacarbonsilane and triethylamine was 1:2-3:1.2-1.5. The volume ratio of aminated silica particles to toluene solution was 1g:40-60mL.

[0008] Aminated silica particles were dispersed in a toluene solution, and octadecylsilane and triethylamine were added to react. The resulting hydrophobic Janus-SiO2 nanoparticles were washed and dried. The mass ratio of aminated silica particles, octadecylsilane, and triethylamine was 1:7-10:1.2-1.5. The volume ratio of aminated silica particles to toluene solution was 1 g:40-60 mL.

[0009] (2) The hydrophobic Janus-SiO2 nanoparticles were mixed with liquid paraffin and dispersed; water was added and homogenized to obtain a water-in-oil pre-emulsion (W / O pre-emulsion); wherein the ratio of hydrophobic Janus-SiO2 nanoparticles, liquid paraffin and water was 1g:30~35mL:5~10mL.

[0010] (3) Mix hydrophilic Janus-SiO2 nanoparticles with water and disperse them; add water-in-oil pre-emulsion and homogenize to obtain multiple Pickering emulsion (W / O / W emulsion); wherein the ratio of hydrophilic Janus-SiO2 nanoparticles, water and water-in-oil pre-emulsion is 1g:80~100mL:80~100mL.

[0011] In one implementation, the water may be deionized water.

[0012] In one embodiment, the method for preparing the aminated silica particles in step (1) includes:

[0013] (1) Disperse silica particles in an aqueous solution of cationic surfactant and sonicate; add paraffin wax, heat to melt and homogenize to obtain an oil-in-water emulsion; cool the oil-in-water emulsion, wash and dry to obtain paraffin-silica particle balls;

[0014] (2) Disperse paraffin-silica particles in methanol solution, add diaminosilane, and react; add chloroform to wash away paraffin, wash and dry to obtain aminated silica particles;

[0015] Optionally, the concentration of the cationic surfactant aqueous solution in step (1) is 0.05–0.1 g / L;

[0016] Optionally, in step (1), the ratio of silica particles, cationic surfactant aqueous solution and paraffin is 1g: 50-80mL: 5-10g;

[0017] Optionally, in step (1), homogenization is performed at 13,000–17,000 rpm for 8–12 min;

[0018] Optionally, in step (1), the heating and melting process involves heating at 70–80°C until the paraffin wax is completely melted.

[0019] Optionally, in step (2), the mass ratio of paraffin-silica granules to diaminosilane is 1:180-200;

[0020] Optionally, in step (2), the ratio of paraffin-silica granules, methanol and chloroform is 1g: 2-6mL: 10-15mL;

[0021] Optionally, the reaction in step (2) is carried out at 150-250 rpm for 10-14 hours.

[0022] In one embodiment, the cationic surfactant in step (1) includes one or more of lauryltrimethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and dihexadecyldimethylammonium chloride;

[0023] In step (1), the diaminosilane includes one or more of N-aminoethyl-γ-aminopropyltrimethoxysilane, N-aminoethyl-γ-aminopropyltriethoxysilane, N-aminoethyl-3-aminopropylmethyldimethoxysilane, and N-(2-aminoethyl)-3-(trimethoxysilyl)propylamine;

[0024] The reaction in step (1) is carried out at room temperature for 2 to 4 hours.

[0025] In one embodiment, the octacarbon silane includes n-octyltrimethoxysilane, n-octyltriethoxysilane, and trimethoxy(octyl)silane;

[0026] Octadecylsilanes include octadecyltrichlorosilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane.

[0027] In one embodiment, the homogenization in step (2) is 9000-13000 rpm for 2-3 min; the homogenization in step (3) is 15000-17000 rpm for 2-3 min.

[0028] A second object of the present invention is to provide a multiple Pickering emulsion prepared by any of the above methods.

[0029] A third objective of this invention is to provide the application of the above-described multiple Pickering emulsion in the preparation of food, pharmaceuticals, or cosmetics.

[0030] In one embodiment, the application in food preparation includes the preparation of emulsifiers and preservatives;

[0031] Applications in pharmaceutical preparation include the preparation of drug delivery carriers and drug solvents;

[0032] Its applications in cosmetics include the preparation of face creams, lotions, and serums.

[0033] In one embodiment, the above application is to prepare food, pharmaceuticals, or cosmetics using multiple Pickering emulsions as raw materials.

[0034] In one embodiment, the above-mentioned multiple Pickering emulsion is used as a food emulsifier to prepare gummy candies, including the following steps:

[0035] Add gelatin to deionized water and stir until fully swollen; add maltitol and low-methoxyl pectin in sequence, and stir while keeping warm until there are no particles; slowly add the above-mentioned multiple Pickering emulsion while stirring to make the system uniform; add flavoring, stir evenly, and then degas under vacuum to remove air bubbles; pour the liquid into a silicone mold and let it stand at room temperature to initially solidify; transfer it to a cold storage for curing, demold it, and dry it in an oven to remove surface free water to obtain the soft candy food.

[0036] In one embodiment, gelatin is added to deionized water at 50–70°C and stirred for 20–40 minutes until fully swollen; maltitol and low-methoxyl pectin are added sequentially, and the mixture is kept at 40–60°C and stirred until no particles are present; the above-mentioned multiple Pickering emulsion is slowly added while stirring to make the system uniform; an appropriate amount of flavoring is added, and after stirring evenly, vacuum degassing is performed to remove air bubbles; the liquid is poured into a silicone mold (temperature maintained at 35–45°C), and allowed to stand at room temperature for 20–40 minutes for initial solidification; it is then transferred to a cold storage at 2–4°C for curing, and after demolding, it is dried in an oven at 30–50°C for 1–3 hours to remove surface free water, thus obtaining the soft candy food.

[0037] In one embodiment, the above-mentioned multiple Pickering emulsion serves as a functional ingredient delivery carrier, including the following steps:

[0038] (1) Take hydrophobic Janus-SiO2 and add it to liquid paraffin containing coenzyme Q10. Sonicate until completely dispersed, then add vitamin C aqueous solution and homogenize to obtain W / O colostrum.

[0039] (2) Add hydrophilic Janus-SiO2 to deionized water and sonicate until completely dispersed. Then add W / O colostrum and homogenize to obtain W / O / W multiple Pickering emulsion that simultaneously encapsulates vitamin C and coenzyme Q10.

[0040] (3) After pre-freezing, vacuum freeze-drying is performed to obtain a delivery carrier containing vitamin C and coenzyme Q10.

[0041] In one implementation, vitamin C can be replaced with other water-soluble functional ingredients, and coenzyme Q10 can be replaced with fat-soluble functional ingredients.

[0042] In one embodiment, the concentration of the water-soluble functional component is 1–10 mg / mL, and the concentration of the fat-soluble functional component is 1–10 mg / mL.

[0043] In one embodiment, the preparation of a moisturizing face cream using the above-mentioned multiple Pickering emulsion includes the following steps:

[0044] (1) Add hydrophobic Janus-SiO2 to liquid paraffin and sonicate until completely dispersed. Then add deionized water containing glycerol and hyaluronic acid, homogenize, and obtain W / O colostrum.

[0045] (2) Add hydrophilic Janus-SiO2 to deionized water and sonicate until completely dispersed. Then add W / O primary emulsion and homogenize to obtain W2 / O / W1 multiple emulsion.

[0046] In one embodiment, the concentration of glycerol in the deionized water in step (1) is 5-15% w / w, and the concentration of hyaluronic acid is 0.1-0.5% w / w.

[0047] The fourth objective of this invention is to provide a method for simultaneously improving the stability, strong acid and alkali resistance, and high-concentration electrolyte resistance of multiple Pickering emulsions. This method involves preparing multiple Pickering emulsions using hydrophilic Janus-SiO2 nanoparticles and hydrophobic Janus-SiO2 nanoparticles, including the following steps:

[0048] (1) Aminated silica particles were dispersed in toluene solution, and octacarbonsilane and triethylamine were added to react. After washing and drying, hydrophilic Janus-SiO2 nanoparticles were obtained. The mass ratio of aminated silica particles, octacarbonsilane and triethylamine was 1:2-3:1.2-1.5. The volume ratio of aminated silica particles to toluene solution was 1g:40-60mL.

[0049] Aminated silica particles were dispersed in a toluene solution, and octadecylsilane and triethylamine were added to react. The resulting hydrophobic Janus-SiO2 nanoparticles were washed and dried. The mass ratio of aminated silica particles, octadecylsilane, and triethylamine was 1:7-10:1.2-1.5. The volume ratio of aminated silica particles to toluene solution was 1 g:40-60 mL.

[0050] (2) The hydrophobic Janus-SiO2 nanoparticles were mixed with liquid paraffin and dispersed; water was added and homogenized to obtain a water-in-oil primary emulsion; wherein the ratio of hydrophobic Janus-SiO2 nanoparticles, liquid paraffin and water was 1g:30~35mL:5~10mL.

[0051] (3) Mix hydrophilic Janus-SiO2 nanoparticles with water and disperse them; add water-in-oil pre-emulsion and homogenize to obtain multiple Pickering emulsions; wherein the ratio of hydrophilic Janus-SiO2 nanoparticles, water and water-in-oil pre-emulsion is 1g:80~100mL:80~100mL.

[0052] In one embodiment, the reaction in step (1) is carried out at room temperature for 2 to 4 hours;

[0053] In step (2), the homogenization is performed at 9000-13000 rpm for 2-3 minutes; in step (3), the homogenization is performed at 15000-17000 rpm for 2-3 minutes.

[0054] The beneficial effects of this invention are:

[0055] (1) In this invention, Janus particles with different hydrophilicity and hydrophobicity are used as emulsifiers to stabilize multiple emulsions. During the particle modification process, only the chain length of the hydrophobic alkyl silane is changed. Compared with the one-step stabilization of multiple emulsions by Janus particles, it is not necessary to strictly control the hydrophilic and lipophilic balance of the particles. The prepared multiple emulsions can regulate the properties of the internal and external aqueous phases.

[0056] (2) The multi-emulsion prepared by the present invention has a distinct structure, uniform particle size distribution, high internal phase content, and Janus particles with different hydrophilic and hydrophobic properties arranged on different oil-water interfaces, making full use of the interfacial activity and amphiphilicity of Janus particles; the prepared multi-emulsion has excellent stability and remains stable under long-term storage, strong acid and strong alkali and high concentration electrolyte conditions, which can effectively expand the practical application of multi-emulsion.

[0057] Specifically:

[0058] (1) The emulsion prepared by the present invention did not show significant changes in particle size after being stored at room temperature for 60 days;

[0059] (2) The emulsion prepared by the present invention remains stable at pH 1.51 and 13.06, without breaking down and with obvious multiple structures;

[0060] (3) The emulsion prepared in this invention is used in high-concentration electrolytes (3.6 × 10⁻⁶). 5 The structure remains stable and unaffected at concentrations of mg / L NaCl. Attached Figure Description

[0061] Figure 1 shows the effect of octylsilane addition on the contact angle of hydrophilic Janus-SiO2 particles.

[0062] Figure 2 shows the infrared spectra of the prepared hydrophilic and hydrophobic Janus-SiO2, aminated SiO2 and unmodified SiO2.

[0063] Figure 3 shows the thermogravimetric curves of the prepared hydrophilic and hydrophobic Janus-SiO2 and unmodified SiO2.

[0064] Figure 4 shows the microscopic images of the oil-water emulsions prepared by staining the oil-water phases with Nile Red and fluorescein sodium, respectively, under an upright fluorescence microscope.

[0065] Figure 5 shows the appearance and microscopic images of the multiple emulsions after being placed at room temperature for 60 days.

[0066] Figure 6 shows the appearance and microstructure of the multiple emulsions under acidic and alkaline conditions.

[0067] Figure 7 shows the appearance and microstructure of the multiple emulsion at saturated NaCl concentration.

[0068] Figure 8 shows the effect of octadecylsilane addition on the contact angle and emulsification properties of hydrophobic Janus-SiO2 particles.

[0069] Figure 9 shows the appearance of stable W / O emulsions with different concentrations of hydrophobic Janus-SiO2 particles.

[0070] Figure 10 shows the appearance and microstructure of W / O / W multiple emulsions prepared with different concentrations of hydrophilic Janus-SiO2 particles;

[0071] Figure 11 shows the charge of hydrophilic Janus-SiO2 particles at different pH values. Detailed Implementation

[0072] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0073] Test method:

[0074] 1. Method for detecting emulsion particle size:

[0075] Take 10 μL of emulsion, disperse it in 3 mL of deionized water, drop it onto a glass slide, observe the droplet morphology using a super depth-of-field microscope and take pictures, and use Nano Measurer software to count the emulsion particle size.

[0076] 2. Methods for testing emulsion emulsification rate

[0077] The total height of the emulsion layer and the system were measured separately and substituted into the formula EI = H. e / H t Calculate the emulsion emulsification rate (EI) by multiplying by 100%; H e H represents the height of the upper emulsion layer. t This represents the total height of the liquid.

[0078] 3. Particle infrared detection method

[0079] 30 mg of granular powder was ground with KBr and then compressed into tablets. The compositional changes on the particle surface were analyzed using Fourier transform infrared spectroscopy.

[0080] 4. Particle thermogravimetric analysis method

[0081] Weigh approximately 7 mg of particles into a crucible and use a thermogravimetric analyzer in a nitrogen atmosphere to determine the thermal stability of the particles by heating from 30 °C to 850 °C at a rate of 15 °C / min.

[0082] Raw materials used in the examples:

[0083] Hexadecyltrimethylammonium bromide was purchased from: Maclean Biotech Co., Ltd., CAS No. 57-09-0;

[0084] SiO2 was purchased from Aladdin Biochemical Technology Co., Ltd., CAS number 7631-86-9;

[0085] Diaminosilane was purchased from Adamas Beta (Shanghai) Chemical Reagent Co., Ltd., CAS No. 1760-24-3;

[0086] Octacarbon silane was purchased from Adamas Beta (Shanghai) Chemical Reagent Co., Ltd., CAS No. 3069-40-7;

[0087] Octadecsilane was purchased from Adamas Beta (Shanghai) Chemical Reagent Co., Ltd., CAS No. 112-04-9;

[0088] Triethylamine was purchased from Sinopharm Chemical Reagent Co., Ltd., CAS number 121-44-8;

[0089] Liquid paraffin was purchased from Sinopharm Chemical Reagent Co., Ltd., CAS number 8012-95-1.

[0090] Example 1: Preparation of hydrophilic Janus-SiO2

[0091] The steps for preparing hydrophilic Janus-SiO2 are as follows:

[0092] (1) Disperse 0.5g SiO2 in 40mL of 0.08g / L hexadecyltrimethylammonium bromide (CTAB) aqueous solution and sonicate for 20min; add 5g sliced ​​paraffin and heat in an 80℃ water bath until completely melted, then homogenize at 15000r / min for 10min to obtain an O / W type emulsion; rapidly solidify the paraffin under an ice bath, wash to remove residual CTAB and free SiO2, and dry to obtain paraffin-silica particle spheres;

[0093] (2) Take 10g of paraffin-silica granules and disperse them in 30mL of methanol solution. Add 0.06g of diaminosilane and react slowly (200r / min) for 12h. Wash off the paraffin with 100mL of chloroform and centrifuge with ethanol three times. After drying, obtain aminated SiO2 powder.

[0094] (3) Take 0.1g of aminated SiO2 and disperse it in 5mL of toluene solution, add 0.05g of octacarbon silane and triethylamine (mass ratio of octacarbon silane and triethylamine is 1:1.5), react at room temperature (15~30℃) for 4h, centrifuge and wash three times with toluene, and dry to obtain hydrophilic Janus-SiO2 nanoparticles.

[0095] The effect of different amounts of octacarbon silane on the contact angle was investigated, and the results are shown in Figure 1. The results show that as the amount of octacarbon silane increases, the hydrophobicity of the particles gradually increases. When the amount of octacarbon silane reaches 0.05g, the increase in the hydrophobic angle slows down. Therefore, 0.05g is the optimal amount of octacarbon silane, at which point the particle-water-air contact angle is 52.7°.

[0096] Example 2: Preparation of hydrophobic Janus-SiO2

[0097] The steps for preparing hydrophobic Janus-SiO2 are as follows:

[0098] (1) Disperse 0.5g SiO2 in 40mL of 0.08g / L hexadecyltrimethylammonium bromide (CTAB) aqueous solution and sonicate for 20min; add 5g sliced ​​paraffin and heat in an 80℃ water bath until completely melted, then homogenize at 15000r / min for 10min to obtain an O / W type emulsion; rapidly solidify the paraffin under an ice bath, wash to remove residual CTAB and free SiO2, and dry to obtain paraffin-silica particle spheres;

[0099] (2) Take 10g of paraffin-silica granules and disperse them in 30mL of methanol solution. Add 0.06g of diaminosilane and react slowly (200r / min) for 12h. Wash off the paraffin with 100mL of chloroform and centrifuge with ethanol three times. After drying, obtain aminated SiO2 powder.

[0100] (3) Take 0.1g of aminated SiO2 and disperse it in 5mL of toluene solution. Add 0.015g of octadecylsilane and triethylamine (mass ratio of octadecylsilane to triethylamine is 1:1.5). React at room temperature for 2h. Wash three times with toluene by centrifugation and dry to obtain hydrophobic Janus-SiO2 nanoparticles.

[0101] The contact angle of hydrophobic Janus-SiO2 nanoparticles was measured, and the results showed that when the amount of octadecylsilane added was 0.015 g, the particle-water-air contact angle was 114.7°.

[0102] The aminated SiO2 powder, hydrophilic Janus-SiO2 nanoparticles and hydrophobic Janus-SiO2 nanoparticles prepared in Examples 1 and 2 were tested for their infrared spectra and thermogravimetric curves. The results are shown in Figures 2 and 3, respectively.

[0103] Infrared spectroscopy results show that, compared with unmodified SiO2, aminated SiO2, hydrophilic and hydrophobic Janus-SiO2 exhibit significant differences at 2850 cm⁻¹. -1 and 2929cm -1 The characteristic peaks at the point are symmetric and antisymmetric stretching vibrations of the CH bond. Thermogravimetric results show that before 200℃, unmodified SiO2, aminated SiO2, and both Janus-SiO2 particles all exhibit significant weight loss, which is due to the loss of adsorbed water on the particle surface. The weight loss of the two Janus-SiO2 particles near 300℃ is mainly due to the decomposition of amino groups, and the decomposition of alkyl chains after 400℃, indicating that diaminosilane and alkylsilane were successfully grafted onto the SiO2 surface.

[0104] Example 3: Preparation of W / O / W Multiple Pickering Emulsion

[0105] 1. Preparation of W / O / W multiple Pickering emulsion, the steps are as follows:

[0106] (1) Take 0.18g of hydrophobic Janus-SiO2 prepared in Example 2 and add it to 6mL of liquid paraffin. Sonicate for 5min until completely dispersed, then add 1.5mL of deionized water (W2) and homogenize at 13000r / min for 3min to obtain W / O primary emulsion.

[0107] (2) Take 0.045g of the hydrophilic Janus-SiO2 prepared in Example 1 and add it to 3mL of deionized water (W1). Sonicate until completely dispersed, then add 3g of W / O primary emulsion and homogenize at 16000r / min for 2min to obtain about 5mL of W2 / O / W1 multiple emulsion.

[0108] 2. Emulsion property testing

[0109] (1) Particle size

[0110] The W2 / O / W1 multiple emulsion prepared in Example 3 was used to observe the droplet morphology using a super depth-of-field microscope, and the droplet size was statistically analyzed using Nano Measurer 1.2 software.

[0111] The results showed that the particle size of the multiple emulsion was 52.4 μm, the particle size distribution was uniform, and it had obvious multiple structures.

[0112] (2) Emulsion type

[0113] Before emulsion preparation, deionized water was stained with sodium fluorescein and liquid paraffin was stained with Nile red. The concentration of the staining agent was 0.1 wt%. After homogenization, the emulsion was observed under an upright fluorescence microscope with excitation wavelengths of 480 nm and 552 nm, respectively.

[0114] The results are shown in Figure 4. The results indicate that the inner and outer phases of the emulsion are green and the middle phase is red, indicating that the prepared emulsion has a distinct W / O / W multiphase structure.

[0115] (3) Long-term stability testing

[0116] The W2 / O / W1 multiple emulsion prepared in Example 3 was placed at room temperature for 60 days. During this period, the appearance and microstructure of the emulsion were observed, and the total height of the emulsion layer and liquid was measured. The result was calculated using the formula EI = H. e / H t Calculate the emulsification rate (EI) by multiplying by 100%, where H... e To determine the height of the upper emulsion after the system stabilizes, H t This represents the total height of the liquid.

[0117] The results are shown in Figure 5. The results show that the emulsion emulsion rate is 63.17%, which is lower than that of the freshly prepared emulsion (80.49%). However, the average particle size of the emulsion is about 57.2 μm and has not changed significantly. The experimental results show that the prepared multi-emulsion has good long-term stability.

[0118] (4) Acid and alkali resistance test

[0119] By changing the pH of aqueous phases W1 and W2 to 1.51 (as acidic conditions) and pH to 13.06 (as alkaline conditions), respectively, acidic W / O / W multiple emulsions (prepared from an aqueous phase at pH 1.51, liquid paraffin, hydrophobic Janus-SiO2, and hydrophilic Janus-SiO2) and alkaline W / O / W multiple emulsions (prepared from an aqueous phase at pH 13.06, liquid paraffin, hydrophobic Janus-SiO2, and hydrophilic Janus-SiO2) were prepared according to the steps of Examples 1, 2, and 3. The charge of these emulsions at different pH conditions was determined using a Zeta potential analyzer and a particle size analyzer.

[0120] As shown in Figure 6, the emulsion could be formed under both slightly acidic and slightly alkaline conditions. Although some particles settled (slightly turbid), the emulsion remained stable, did not break down, and showed obvious multiple structures. When the pH of the aqueous phase was 1.51, the average particle size of the emulsion was 80.3 μm; when the pH of the aqueous phase was 13.06, the average particle size of the emulsion was 65.7 μm.

[0121] The stability (agglomeration, sedimentation) of particles in the aqueous phase is related to the absolute value of their zeta potential. A larger absolute value indicates stronger electrostatic repulsion between particles, resulting in greater stability. Particles with a zeta potential closer to 0 are more prone to agglomeration and sedimentation. Figure 11 shows the zeta potential detection results for hydrophilic Janus-SiO2 nanoparticles. The results indicate that the absolute value of the zeta potential gradually decreases with increasing pH. At pH less than 9, the zeta potential is greater than 10 mV, indicating a large absolute value and no particle sedimentation in the emulsion system. Around pH 13, the zeta potential is approximately 0, indicating weak electrostatic repulsion between particles, making agglomeration and sedimentation more likely. This results in turbidity in the aqueous phase, a decrease in the number of particles in the emulsion layer, and a slight increase in particle size. Under slightly acidic conditions in the aqueous phase, the protonation of amino groups on the particle surface is enhanced, increasing hydrophilicity and also causing particle sedimentation in the system. In summary, the results demonstrate that the W / O / W multi-emulsion prepared in Example 3 exhibits excellent acid and alkali resistance.

[0122] (5) Electrolyte resistance

[0123] Based on Example 3, the concentration of deionized water in steps (1) and (2) was changed to 10. 3 10 4 10 53.6×10 5 mg / L (concentration of 3.6 × 10 mg / L) 5 A NaCl aqueous solution (at a concentration of mg / L, which is a saturated solution) was prepared, and the remaining steps were the same as in Example 3. W / O / W multiple emulsions containing different concentrations of electrolytes were prepared, and the appearance and particle size of the emulsions were tested.

[0124] When the NaCl concentration is 3.6 × 10 5 The results at mg / L are shown in Figure 7. The results show that the saturated NaCl concentration has no effect on emulsification, and the average droplet size is 62.3 μm, indicating that the multi-pickering emulsion based on Janus particles has excellent electrolyte resistance.

[0125] Comparative Example 1: Changing the amount of octadecylsilane

[0126] Based on Example 2, the amount of octadecylsilane was changed to 0.005g, 0.015g, 0.022g, and 0.04g, while the remaining steps were the same as in Example 2, to prepare hydrophobic Janus-SiO2.

[0127] Take the hydrophobic Janus-SiO2 prepared in Comparative Example 1 and Example 2, and prepare an emulsion as follows:

[0128] Add 0.03 g of hydrophobic Janus-SiO2 to 3 mL of liquid paraffin, sonicate until the particles are completely dispersed, then add 3 mL of deionized water and homogenize at 13000 r / min for 3 min.

[0129] The results are shown in Figure 8. The results show that when the amount added is 0.005 g, the particle-water-air contact angle is less than 90°, and the emulsion is of the O / W type. When the amount added is greater than 0.04 g, the contact angle is 137.6°. Under this condition, the particle emulsifier prepared by high-speed homogenization separates the oil and water phases without emulsion formation. It can be seen that too little or too much octadecylsilane cannot form a stable W / O emulsion.

[0130] Comparative Example 2: Changing the amount of hydrophobic Janus-SiO2 added

[0131] Based on Example 3, the amount of hydrophobic Janus-SiO2 added in step (1) was changed to 0.06g, 0.12g, 0.18g, and 0.24g, respectively, to obtain W / O emulsions with hydrophobic particle concentrations of 1wt%, 2wt%, 3wt%, and 4wt%, respectively. The remaining steps were the same as in Example 3.

[0132] The emulsion results are shown in Figure 9. Keeping the oil-water (i.e., liquid paraffin and deionized water W2) volume ratio constant (4:1), when the concentration of hydrophobic Janus-SiO2 particles is less than 3 wt%, an oil phase precipitates in the upper layer; when it is greater than or equal to 3 wt%, no aqueous or oil phase precipitates. When the particle concentration is 4 wt%, the emulsion viscosity is very high and the fluidity is not conducive to the removal of W / O primary emulsion. Considering all factors, the concentration of hydrophobic Janus-SiO2 particles is 3 wt%.

[0133] Comparative Example 3: Changing the amount of hydrophilic Janus-SiO2 added

[0134] Based on Example 3, the amount of hydrophilic Janus-SiO2 added in step (2) was changed to 0.0075g, 0.015g, 0.03g, 0.045g, and 0.0525g, respectively, to obtain W / O / W multiple emulsions with hydrophilic particle concentrations of 0.25wt%, 0.5wt%, 1.0wt%, 1.5wt%, and 1.75wt%, respectively. The remaining steps were the same as in Example 3.

[0135] The emulsion results are shown in Figure 10. With a fixed water-to-emulsion mass ratio of 5:5, the multiple emulsion can be stabilized at a low concentration of hydrophilic Janus-SiO2 particles (0.25 wt%). At this point, the emulsion particle size is relatively large, about 93.7 μm. As the particle concentration increases, the emulsion particle size gradually decreases, and there is no significant change after 1.5 wt%. This condition is selected as the optimal dosage.

[0136] Comparative Example 4: W / O / W Multiple Emulsions Prepared Using Conventional Particles

[0137] Based on Example 3, the added hydrophilic and hydrophobic Janus-SiO2 was replaced with commercially available surface-uniform modified SiO2 particles. The hydrophilic SiO2 was modified with hexadecylsilane, with a C content of 0.9-1.8%. The hydroxyl groups on the SiO2 surface were partially replaced, reducing hydrophilicity, but some silanol groups were still retained, making it hydrophilic overall. The hydrophobic SiO2 was modified with dichlorodimethylsilane, with a C content of 0.7-1.3%. It had very few silanol groups and was oleophilic overall. The remaining steps were the same as in Example 3, and an emulsion was prepared.

[0138] The results showed that when these two types of particles were selected as emulsifiers to prepare multiple emulsions, the pH of the aqueous phase < 7.6 had no effect on the emulsion, but when the pH ≥ 7.6, the prepared emulsion was unstable and demulsification occurred quickly.

[0139] Changing the NaCl concentration in the aqueous phase revealed that c(NaCl) ≤ 10 4 At a concentration of mg / L, the emulsion particle size increases significantly with increasing NaCl concentration; concentrations exceeding this have a significant impact on emulsion stability.

[0140] The results showed that the multiple emulsions stabilized by both types of particles had poor acid and alkali resistance and electrolyte resistance.

[0141] Example 4: Application of W / O / W multi-pickering emulsions in the preparation of food, pharmaceuticals, or cosmetics

[0142] The W / O / W multi-pickering emulsion prepared in Example 3 was used to prepare food, pharmaceuticals, or cosmetics, as follows:

[0143] 1. As a food emulsifier

[0144] Formula: 48g maltitol, 2g low-methoxyl pectin, 10mL W / O / W multi-pickering emulsion, 5g gelatin, and appropriate amount of flavoring. Preparation method is as follows:

[0145] Gelatin was added to deionized water at 60°C and stirred for 30 minutes until fully swollen. Maltitol and low-methoxyl pectin were added sequentially, and the mixture was kept at 50°C and stirred until no particles were present. The W / O / W multiple Pickering emulsion prepared in Example 3 was slowly added while stirring to ensure uniformity. Flavoring was added, and the mixture was stirred evenly before vacuum degassing to remove air bubbles. The mixture was poured into a silicone mold (temperature maintained at 40°C) and allowed to stand at room temperature for 30 minutes for initial solidification. It was then transferred to a 4°C cold storage for curing, demolded, and dried in a 40°C oven for 2 hours to remove surface free water, yielding the soft candy.

[0146] 2. Preparation of functional ingredient delivery carriers

[0147] Instead of the deionized water (W2) in Example 3, vitamin C aqueous solution (vitamin C concentration of 3 mg / mL) was used. Coenzyme Q10 was dissolved in liquid paraffin to obtain a coenzyme Q10 liquid paraffin solution (coenzyme Q10 concentration of 5 mg / mL) instead of the liquid paraffin in Example 3. Other conditions were the same as in Example 3. A W / O / W multiple Pickering emulsion simultaneously encapsulating vitamin C and coenzyme Q10 was prepared. After pre-freezing at -18°C for 24 hours, it was freeze-dried under vacuum at -60°C to obtain the functional component delivery carrier.

[0148] 3. Moisturizing face cream

[0149] Glycerin and sodium hyaluronate were added to deionized water (glycerin concentration 10% w / w, hyaluronic acid concentration 0.4% w / w) instead of the deionized water (W2) in Example 3. Other conditions were the same as in Example 3 to obtain a W / O / W multi-pickering emulsion. Preservatives were added, and the mixture was stirred for 30 minutes to make the system homogeneous. The mixture was then placed in a sterile container and allowed to stand for 24 hours to obtain a moisturizing cream.

[0150] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing multiple Pickering emulsions, characterized in that, The method includes the following steps: (1) Aminated silica particles were dispersed in toluene solution, and octacarbonsilane and triethylamine were added to react. After washing and drying, hydrophilic Janus-SiO2 nanoparticles were obtained. The mass ratio of aminated silica particles, octacarbonsilane and triethylamine was 1:2-3:1.2-1.

5. The volume ratio of aminated silica particles to toluene solution was 1g:40-60mL. Aminated silica particles were dispersed in a toluene solution, and octadecylsilane and triethylamine were added to react. After washing and drying, hydrophobic Janus-SiO2 nanoparticles were obtained. The mass ratio of aminated silica particles, octadecylsilane and triethylamine was 1:7-10:1.2-1.5; the volume ratio of aminated silica particles to toluene solution was 1g:40-60mL. (2) The hydrophobic Janus-SiO2 nanoparticles were mixed with liquid paraffin and dispersed; water was added and homogenized to obtain a water-in-oil primary emulsion; wherein the ratio of hydrophobic Janus-SiO2 nanoparticles, liquid paraffin and water was 1g:30~35mL:5~10mL. (3) Mix hydrophilic Janus-SiO2 nanoparticles with water and disperse them; add water-in-oil pre-emulsion and homogenize to obtain multiple Pickering emulsions; wherein the ratio of hydrophilic Janus-SiO2 nanoparticles, water and water-in-oil pre-emulsion is 1g:80~100mL:80~100mL.

2. The method according to claim 1, characterized in that, The preparation method of aminated silica particles in step (1) includes: (1) Disperse silica particles in an aqueous solution of cationic surfactant and sonicate; add paraffin wax, heat to melt and homogenize to obtain an oil-in-water emulsion; cool the oil-in-water emulsion, wash and dry to obtain paraffin-silica particle balls; (2) Disperse paraffin-silica particles in methanol solution, add diaminosilane and react; add chloroform to wash away paraffin, wash and dry to obtain aminated silica particles.

3. The method according to claim 2, characterized in that, In step (1), the concentration of the cationic surfactant aqueous solution is 0.05-0.1 g / L.

4. The method according to claim 2, characterized in that, In step (1), the ratio of silica particles, cationic surfactant aqueous solution and paraffin is 1g: 50-80mL: 5-10g.

5. The method according to claim 2, characterized in that, In step (1), the homogenization is performed at 13000-17000 rpm for 8-12 minutes.

6. The method according to claim 2, characterized in that, In step (1), the heating and melting process involves heating the paraffin wax at 70-80°C until it is completely melted.

7. The method according to claim 2, characterized in that, In step (2), the mass ratio of paraffin-silica granules to diaminosilane is 1:180-200.

8. The method according to claim 2, characterized in that, In step (2), the ratio of paraffin-silica granules, methanol and chloroform is 1g: 2-6mL: 10-15mL.

9. The method according to claim 2, characterized in that, In step (2), the reaction is carried out at 150-250 rpm for 10-14 hours.

10. The method according to claim 2, characterized in that, The cationic surfactant in step (1) includes one or more of lauryltrimethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and dihexadecyldimethylammonium chloride; In step (1), the diaminosilane includes one or more of N-aminoethyl-γ-aminopropyltrimethoxysilane, N-aminoethyl-γ-aminopropyltriethoxysilane, and N-aminoethyl-3-aminopropylmethyldimethoxysilane; The reaction in step (1) is carried out at room temperature for 2 to 4 hours.

11. The method according to claim 1, characterized in that, Octacarbon silanes include n-octyltrimethoxysilane and n-octyltriethoxysilane; Octadecylsilanes include octadecyltrichlorosilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane.

12. The method according to claim 1, characterized in that, In step (2), the homogenization is performed at 9000-13000 rpm for 2-3 minutes; in step (3), the homogenization is performed at 15000-17000 rpm for 2-3 minutes.

13. The multiple Pickering emulsion prepared by the method according to any one of claims 1 to 12.

14. The use of the multi-pickering emulsion of claim 13 in the preparation of food, pharmaceutical or cosmetic products.

15. The application according to claim 14, characterized in that, Applications in food preparation include the preparation of emulsifiers and preservatives; Applications in pharmaceutical preparation include the preparation of drug delivery carriers and drug solvents; Its applications in cosmetics include the preparation of face creams, lotions, and serums.

16. The application according to claim 13 or 14, characterized in that, The application involves using multiple Pickering emulsions as raw materials to prepare food, pharmaceuticals, or cosmetics.

Images