Preparation method and application of polymer emulsifier

Abstract

The invention discloses a preparation method and application of a high-molecular emulsifier, acrylamide and nano calcium carbonate are dispersed in a mixed solution of ethylene glycol monomethyl ether and water as a water phase, ethylene glycol dimethacrylate and 2, 4, 6-(trimethylbenzoyl)-diphenyl phosphine oxide are added in toluene as an oil phase, and the high-molecular emulsifier is prepared by a hydrothermal method. Dispersing the water phase and the oil phase in a homogenizer to form Pickering emulsion, polymerizing the emulsion under ultraviolet light, demulsifying, adding acid to remove calcium carbonate, and washing and drying the product to obtain the macromolecular emulsifier. The method has the advantages that the operation method is simple, the reaction condition is mild, the plant essential oil emulsion can be stabilized by using a very small amount of the microsphere emulsifier, and the method has a wide application prospect in the field of polymer emulsifiers.

Description

Technical Field

[0001] The invention belongs to the field of polymer functional materials and relates to a method for preparing a polymer emulsifier based on Pickering emulsion polymerization and its application Background Art

[0002] Emulsions are thermodynamically unstable systems in which immiscible liquids are dispersed into another liquid under the action of surfactants. Pickering emulsions are new emulsions that use solid particles instead of surfactants as emulsifiers. Compared with traditional emulsions, they have the advantages of low production cost, fewer adverse reactions, low toxicity and good biocompatibility.

[0003] Essential oils are aromatic, oily volatile substances found in plant materials (such as fruits, barks, seeds, pulp, peels, roots and whole plants). These substances are formed in the cytoplasm and usually exist in the form of tiny droplets sandwiched between cells. Essential oils have a fairly good antibacterial effect as a natural preservative. They also have the advantages of safety, non-toxicity and environmental protection. At present, they have been widely used as preservatives in foods such as fruits, vegetables, juices, milk, beef, chicken, etc. However, due to the poor water solubility and stability of essential oils, their application range in food storage and preservation is limited. In some current studies, nanoemulsions combining pullulan and cinnamon essential oil (Yifu Chu, ChengCheng Gao, Xiaoya Liu, Ni Zhang, Tian Xu, Xiao Feng, Yuling Yang, Xinchun Shen, Xiaozhi Tang, LWT-Food Science and Technology 122 (2020) 109054) can be used to prevent cinnamon essential oil from agglomerating and evaporating. The emulsion can be evenly applied to the surface of strawberries to extend the storage time of strawberries at room temperature. Carvacrol has been recognized as an effective growth inhibitor of food pathogens. Stabilizing carvacrol oil in nanoemulsions (Motta Felício and others, Letters in Applied Microbiology, Volume 72, Issue 3, 1 March 2021, Pages 299–306) solves the shortcomings of carvacrol oil, which has poor water solubility and is easily decomposed when exposed to air. Although these methods have solved the shortcomings of poor water solubility and volatility of essential oils, they all use surfactants to prepare nanoemulsions, and the addition of surfactants may cause harm to human health.

[0004] In order to solve the above problems, the present invention is improved on the basis of the above work by utilizing the Pickering emulsion polymerization technology developed by this research group, and a highly stable nanoemulsion is prepared in an environmentally friendly manner without using surfactants, and a variety of plant essential oils can be stabilized. Summary of the invention

[0005] The purpose of the present invention is to provide a polymer emulsifier prepared based on Pickering emulsion polymerization and its preparation method and application

[0006] The technical solution adopted by the present invention is:

[0007] (1) preparing a certain proportion of ethylene glycol methyl ether and water, and dissolving the monomer and nano calcium carbonate in the solution as the aqueous phase;

[0008] (2) adding a crosslinking agent and an initiator into toluene as an oil phase;

[0009] (3) The solution obtained in (2) is added to the solution in (1), and after homogenization, the mixture is placed under a predetermined light source to undergo a polymerization reaction to obtain a polymer.

[0010] (4) The polymer obtained by the reaction is treated and then dried.

[0011] Preferably according to the present invention, the volume ratio of ethylene glycol methyl ether to water in step (1) is 1:1-4:1.

[0012] Preferably according to the present invention, the particle size of the nano calcium carbonate in step (1) is 100-500 nm; the nano calcium carbonate accounts for 0.5-3% of the total solution mass.

[0013] Preferably, according to the present invention, the volume ratio of the oil phase in step (2) to the water phase in step (1) is 1:6-1:2.

[0014] Preferably according to the present invention, the homogenization time in step (3) is 2-5 min, and the rotation speed is 12000-15000 rpm.

[0015] According to the preferred embodiment of the present invention, the light source in step (3) is ultraviolet light with a light intensity of 200 μW / cm 2 ; The polymerization time is 2-3h.

[0016] Preferably according to the present invention, the theoretical solid content (excluding nano-calcium carbonate) of the polymer microspheres prepared by the Pickering emulsion polymerization method is 5-10%.

[0017] Compared with the prior art, the polymer emulsifier of the present invention has the following beneficial effects:

[0018] The method of the present invention utilizes a new type of polymer emulsifier prepared by the Pickering emulsion polymerization method to solve the problem that plant essential oils are easily volatile in the air. The preparation method provided by the present invention greatly reduces the amount of emulsifier used and improves the stability of the plant essential oil emulsion, so that its antibacterial performance can be stably exerted. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the water contact angle of nano-calcium carbonate;

[0020] Figure 2 is the water contact angle of the polymer emulsifier (including nano calcium carbonate);

[0021] Figure 3 is the water contact angle of the polymer emulsifier;

[0022] Figure 4 This is the SEM picture of the polymer emulsifier;

[0023] Figure 5 This is an optical microscope image of cinnamaldehyde emulsion stabilized by a polymer emulsifier;

[0024] Figure 6 This is an optical microscope image of eugenol emulsion stabilized by a polymer emulsifier;

[0025] Figure 7 is the release curve of cinnamaldehyde emulsion;

[0026] Figure 8 This is a graph showing the inhibitory effect of cinnamaldehyde emulsion on the growth of Bacillus subtilis;

[0027] Fig. 9 This is a graph showing the inhibitory effect of eugenol emulsion on the growth of Bacillus subtilis; DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0029] Example 1

[0030] Step 1, take 9 ml of ethylene glycol methyl ether and 3 ml of pure water and mix them as the aqueous phase, add 0.0670 g of acrylamide and 0.1547 g of calcium carbonate into the aqueous phase, and ultrasonicate for 5 minutes;

[0031] Step 2, adding 0.7472 g of ethylene glycol dimethacrylate and 0.0082 g of 2,4,6-(trimethylbenzoyl)-diphenylphosphine oxide into 4 ml of toluene as an oil phase;

[0032] Step 3, the aqueous phase and the oil phase are mixed, and treated at 12000-15000 rpm for 2 min in a high-speed homogenizer to obtain a Pickering emulsion;

[0033] Step 4: Place the prepared emulsion at 200 μw / cm 2 The reaction was stirred under ultraviolet light for 2 h;

[0034] Step 5, add 3 ml of methanol to break the emulsion, remove the upper clear liquid after centrifugation, add 3 ml of 1 mol / L hydrochloric acid to the lower solid layer, and stir for 24 hours;

[0035] Step 6: The product was first washed with methanol:acetic acid = 9:1 (v / v), then washed with pure water, and then placed in a 40°C drying oven for constant temperature drying for 24 hours to obtain a polymer emulsifier. The yield was 78%, and the water contact angle was 46.1°.

[0036] Comparative Example 1

[0037] The same as Example 1, except that hydrochloric acid was not added for stirring in step 5. The water contact angle of the final polymer emulsifier was 48.7°.

[0038] Example 2

[0039] 0.010 g of the polymer emulsifier prepared in Example 1 was dispersed in 10 ml of pure water as the aqueous phase, 0.5 ml of cinnamaldehyde was added to the aqueous phase, and the mixture was homogenized at 12000 rpm for 2 min using a homogenizer to obtain a cinnamaldehyde emulsion.

[0040] Comparative Example 2

[0041] Same as Example 2, except that the oil phase is 0.5 ml of eugenol. Finally, a eugenol emulsion is obtained.

[0042] Example 3

[0043] 100 μL of Bacillus subtilis liquid was dropped into a 60 mm culture dish containing culture medium and evenly coated, an Oxford cup was placed at the center of the culture dish, and 50 μL of the cinnamaldehyde emulsion prepared in Example 2 was dropped into the Oxford cup, the culture dish was sealed and placed in a bacterial culture phase at 37° C. for 24 h, and the diameter of the inhibition zone was recorded.

[0044] Comparative Example 3

[0045] Same as Example 3, except that the emulsion used is the eugenol emulsion prepared in Comparative Example 3.

[0046] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. The present invention provides a preparation method and application of a polymer emulsifier, characterized in that: The steps include: (1) Adding nano-calcium carbonate and acrylamide to a mixed solution of water and ethylene glycol methyl ether to obtain an aqueous phase; adding ethylene glycol dimethacrylate and 2,4,6-trimethylbenzoyldiphenoxyphosphine to toluene to obtain an oil phase; and dispersing the aqueous phase and the oil phase through a high-speed homogenizer to obtain a Pickering emulsion. (2) placing the Pickering emulsion obtained in step (1) under ultraviolet light, stirring at room temperature for reaction, adding methanol to break the emulsion, adding hydrochloric acid to remove calcium carbonate, centrifuging the product, washing, and drying to obtain a polymer emulsifier.

2. The preparation method and application of a polymer emulsifier according to claim 1, characterized in that: In step (1), the aqueous phase is a mixed solution of ethylene glycol methyl ether and water in a volume ratio of 1:1-4:1, and the volume ratio of the oil phase to the aqueous phase is 1:6-1:

2.

3. The preparation method and application of a polymer emulsifier according to claim 1, characterized in that: In step (1), the nano calcium carbonate accounts for 0.5-3% of the total solution mass.

4. The preparation method and application of a polymer emulsifier according to claim 1, characterized in that: In step (1), the solid content of the prepared polymer emulsifier (excluding nano calcium carbonate) is 5-10%.

5. The preparation method and application of a polymer emulsifier according to claim 1, characterized in that: In step (1), the rotation speed of the high-speed homogenizer is 8000-14000 rpm, and the dispersion time is 1-5 min.

6. The preparation method and application of a polymer emulsifier according to claim 1, characterized in that: In step (2), the light intensity of the UV light is 200 μw / cm 2 .

7. Use of the polymer emulsifier according to claims 1 to 6 in preparing essential oil emulsions.

8. The use according to claim 7, characterized in that: The polymer emulsifier is dispersed in water, and dispersed with cinnamaldehyde and eugenol by a high-speed homogenizer to obtain a Pickering emulsion, characterized in that the volume of water to cinnamaldehyde and eugenol is 20:1-2:1; the mass ratio of the polymer emulsifier to the total solution is 0.0001:1-0.01:1; the speed of the high-speed homogenizer is 8000-14000rpm, and the dispersion time is 1-5min.

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