Preparation method and application of beta-cyclodextrin-polyurethane double-shell microcapsule

Abstract

This invention discloses a method for preparing β-cyclodextrin-polyurethane double-shell microcapsules and their applications. The method includes using polyurethane and β-cyclodextrin as wall materials, introducing epoxy groups into the shell material, using plant essential oil as the core material, and preparing double-shell microcapsules through interfacial polymerization. Further, the microcapsules are applied to cotton fabrics through an impregnation process to prepare functional textiles with dual functions of odor adsorption and fragrance sustained release, prolonging the fresh scent retention time of the textiles and effectively removing odors. The β-cyclodextrin-polyurethane double-shell microcapsules prepared by this invention can be applied in home textiles, curtains, sportswear, and leather products.

Description

Technical Field

[0001] This invention belongs to the field of chemical material preparation technology, specifically relating to a method for preparing β-cyclodextrin-polyurethane double-shell microcapsules and their application. Background Technology

[0002] With the improvement of living standards, people's functional demands for textiles are increasing. Although traditional textiles can meet basic wearing comfort, they have significant limitations in dealing with odors, antibacterial properties, and health care. Odor problems are particularly prominent in wearable textiles, interior decoration, and the medical field. Long-term odor accumulation not only affects the user experience but may also lead to health problems. Therefore, developing textiles with odor absorption and slow-release fragrance functions is particularly important and has significant practical implications.

[0003] Cyclodextrins are oligosaccharide compounds produced by the degradation of starch by cyclodextrin glucosyltransferase in Bacillus. There are three structures: α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. β-Cyclodextrin (β-CD) is a versatile, cost-effective, and environmentally friendly natural product with a moderate molecular pore size and a hydrophobic internal cavity and hydrophilic external surface. β-Cyclodextrin can selectively form complexes with guest molecules of matching cavity size through weak interactions such as hydrophobicity, hydrogen bonding, and van der Waals forces. Due to their natural origin, cyclodextrins exhibit excellent biocompatibility compared to chemically synthesized organic compounds. They also exhibit host-guest adsorption properties, making them widely used in textiles, food, and agriculture. However, the single functional group in the β-cyclodextrin molecule limits the scope of chemical reactions. In previous studies, several methods have been proposed to modify β-cyclodextrin, increasing the number of its active functional groups and expanding its application range.

[0004] In the prior art, Chinese invention patent (application number: CN201911235816.1) provides a catnip essential oil / naphthalene-acylated β-cyclodextrin microcapsule and its preparation method. This microcapsule uses catnip essential oil as the core material and naphthalene-acylated β-cyclodextrin as the wall material. At a certain temperature, the microcapsule can control the release rate and uniformity of the catnip essential oil, thus solving the problem of controllable release rate of the encapsulated catnip essential oil. However, this preparation method is relatively complex and is not a double-shell structure, making the essential oil prone to leakage. Chinese invention patent (application number: CN202110814410.X) provides a fragrance microcapsule prepared using hydroxypropyl-β-cyclodextrin and mannitol as wall materials and lavender fragrance as the core material, prepared using spray drying technology. The prepared lavender fragrance microcapsule has a sea urchin-like morphology, a rough surface, and exhibits low hygroscopicity and a high dissolution rate. However, the microcapsules prepared by this method have poor sealing performance and the core material is prone to leakage. At the same time, the host-guest adsorption effect of cyclodextrin is not utilized in the application of microcapsules. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a β-cyclodextrin-polyurethane double-shell microcapsule.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a β-cyclodextrin-polyurethane double-shell microcapsule, characterized in that: the microcapsule has a core-shell structure, wherein the core material is plant essential oil, the inner wall material is polyurethane, and the outer shell material is modified β-cyclodextrin.

[0009] As a preferred embodiment of the β-cyclodextrin-polyurethane double-shell microcapsule of the present invention, the plant essential oil includes one or more of lemon essential oil, peppermint essential oil, jasmine essential oil, gardenia essential oil, and lavender essential oil.

[0010] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing β-cyclodextrin-polyurethane double-shell microcapsules.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0012] Modified β-cyclodextrin is obtained by mixing β-cyclodextrin, anhydrous N,N-dimethylformamide-anhydrous dimethyl sulfoxide mixture, sodium hydroxide, and brominated olefins, centrifuging the mixture, washing the precipitate with acetone, filtering, and drying.

[0013] The mercapto-modified glycidyl methacrylate is obtained by mixing 3-mercapto-1,2-propanediol, glycidyl methacrylate, acetone, and diphenylphosphine.

[0014] Isophorone diisocyanate, acetone, dibutyltin dilaurate, 1,4-butanediol, 3-mercapto-1,2-propanediol, and the above-mentioned mercapto-modified glycidyl methacrylate were dissolved, mixed, and reacted. The resulting product was then removed by rotary evaporation to remove acetone, yielding a polyurethane prepolymer.

[0015] The emulsifier is dissolved in deionized water to form an aqueous phase; the polyurethane prepolymer, polyethylene glycol, and plant essential oil are ultrasonically mixed to form an oil phase; the mixed oil phase is added to the aqueous phase, and ultrasonic emulsification is performed to form a stable oil-in-water emulsion.

[0016] Polyurethane microcapsules can be obtained by dissolving modified β-cyclodextrin in deionized water and diphenylphosphine in ethanol, and then mixing and reacting them with the above oil-in-water emulsion.

[0017] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the β-cyclodextrin, the anhydrous N,N-dimethylformamide-anhydrous dimethyl sulfoxide mixture, sodium hydroxide, and the brominated olefin is 1–5:20–50:3–5:5–10.

[0018] In a preferred embodiment of the preparation method described in this invention, the brominated olefin includes one or more of brominated propylene, brominated butene, brominated pentylene, and brominated hexene; the emulsifier is one or more of sodium dodecylbenzenesulfonate, polyoxyethylene sorbitan monooleate, sodium dodecyl sulfate, polyoxyethylene-8-octylphenyl ether, polyoxyethylene sorbitan monolaurate, sorbitan fatty acid ester, and polyvinyl alcohol.

[0019] In a preferred embodiment of the preparation method described in this invention, the mass ratio of 3-mercapto-1,2-propanediol, glycidyl methacrylate, acetone, and diphenylphosphine is 1–5:1–5:1.5–6:20–50:0.1–0.5.

[0020] In a preferred embodiment of the preparation method described in this invention, the mass ratio of isophorone diisocyanate, acetone, dibutyltin dilaurate, 1,4-butanediol, 3-mercapto-1,2-propanediol, and mercapto-modified glycidyl methacrylate is 10–20:20–60:0.1–0.4:0.5–2:0.1–0.7:0.5–2.

[0021] In a preferred embodiment of the preparation method described in this invention, the mass ratio of sodium dodecylbenzenesulfonate to deionized water in the aqueous phase is 0.1–0.5:60–150; and the mass ratio of polyurethane prepolymer, polyethylene glycol, and plant essential oil in the oil phase is 2–6:2–5:1–6.

[0022] As a preferred embodiment of the preparation method described in this invention, the modified β-cyclodextrin, deionized water, diphenylphosphine, and ethanol are in a mass ratio of 1.5–6:10–50:0.05–0.2:1–5.

[0023] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of β-cyclodextrin-polyurethane double-shell microcapsules in textiles.

[0024] The polyurethane microcapsules are dispersed in deionized water to obtain a microcapsule dispersion; pure cotton fabric is immersed in the dispersion and then dried to obtain cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0025] Beneficial effects of this invention:

[0026] The β-cyclodextrin-polyurethane double-shell microcapsules prepared by this invention not only have the dual function of adsorbing odors but also releasing fragrances and masking odors, effectively synergistically covering and removing "aging odors." The double-shell structure design increases the airtightness of the shell, making the core material less prone to leakage and ultimately extending the service life of the microcapsules. The epoxy groups introduced into the shell material of the microcapsules can increase the covalent bonds between the microcapsules and the fabric, thereby improving their fastness to the fabric. The β-cyclodextrin / polyurethane double-shell microcapsules can be used in home textiles, health textiles, sportswear, home decoration, and leather products. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 This is a structural characterization diagram of the modified cyclodextrin of this invention. Figure 1 (a) Infrared spectra of β-CD and allyl β-CD; Figure 1 (b) is the 1H NMR spectrum of β-CD. Figure 1 (c) is the 1H NMR spectrum of allyl β-CD.

[0029] Figure 2 These are SEM images and EDS spectra of the microcapsules of this invention. Among them, Figure 2 (a) is a SEM image of polyurethane microcapsules; Figure 2 (bd) is a SEM image of the β-CD-polyurethane double-shell microcapsule; Figure 2 (e) is the particle size distribution histogram of polyurethane microcapsules; Figure 2 (f) is the particle size distribution histogram of β-CD / polyurethane double-shell microcapsules; Figure 2 (g) shows the EDS energy spectrum and elemental distribution of β-CD / polyurethane double-shell microcapsules.

[0030] Figure 3 These are the infrared spectra and thermogravimetric analysis diagrams of the microcapsules of this invention. Figure 3 (a) Infrared spectra of polyurethane prepolymer and β-CD / polyurethane double-shell microcapsules; Figure 3 (b) shows the thermogravimetric analysis curves of peppermint essential oil, blank microcapsules, and β-CD / polyurethane double-shell microcapsules; Figure 3 (c) shows the differential thermogravimetric curves of peppermint essential oil and β-CD / polyurethane double-shell microcapsules.

[0031] Figure 4 These are SEM images and EDS spectra of cotton fabrics before and after microcapsule treatment according to the present invention. Figure 4 (a) is a cold field emission scanning electron microscope image of the original cotton fabric; Figure 4 (b, c) are cold field emission scanning electron microscope images of cotton fabrics treated with β-CD / polyurethane double-shell microcapsules; Figure 4 (d) EDS energy spectrum and elemental distribution map of cotton fabric treated with β-CD / polyurethane double-shell microcapsules.

[0032] Figure 5 This invention relates to the adsorption performance testing of microcapsule-treated fabrics. Figure 5 (a) The odor adsorption mechanism of β-CD / polyurethane double-shell microcapsules; Figure 5 (b) is the standard absorbance-concentration curve of citral; Figure 5 (c) Adsorption performance of treated cotton fabric and blank cotton fabric for citral; Figure 5 (d) shows the adsorption performance of citral on cotton fabrics before and after microcapsule treatment with β-CD modification; Figure 5 (e) is the absorbance-concentration curve of the standard trans-2-nonenal; Figure 5 (f) Adsorption performance of trans-2-nonenal on treated cotton fabric and blank cotton fabric; Figure 5 (g) represents the adsorption performance of trans-2-nonenal on cotton fabrics treated with microcapsules before and after β-CD modification.

[0033] Figure 6 This invention relates to the microcapsule finishing of fabrics to improve their cyclic adsorption performance and wash fastness. Among other things, Figure 6 (a) is the cyclic adsorption curve of citral on the treated cotton fabric; Figure 6 (b) is the cyclic adsorption curve of trans-2-nonenal on the treated cotton fabric; Figure 6 (c) shows the adsorption curves of citral on cotton fabrics before and after washing. Figure 6 (d) shows the adsorption curves of trans-2-nonenal on cotton fabrics before and after washing.

[0034] Figure 7 This invention relates to the testing of the antibacterial properties of microcapsule-treated fabrics. Figure 7 (a) is a diagram of the antibacterial mechanism of β-CD / polyurethane double-shell microcapsules; Figure 7 (b) Images of the growth of Staphylococcus aureus and Escherichia coli on different sample surfaces; Figure 7 (c) is a graph showing the bacterial inhibition rate after different sample treatments; Figure 7 (d) Images of Staphylococcus aureus and Escherichia coli growing on different sample surfaces; Figure 7 (e) shows the bacterial inhibition rate after treatment of different samples and different number of days of storage. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available. See Table 1 for details.

[0039] Table 1

[0040]

[0041]

[0042] Example 1

[0043] (1) Add 1 part β-cyclodextrin and 20 parts anhydrous N,N-dimethylformamide / anhydrous dimethyl sulfoxide (V / V ratio 1:1) to a beaker and dissolve them completely. Then add 3 parts sodium hydroxide and stir at room temperature for 1 h. Then allow the system to cool naturally to 5°C. Using a dropping funnel, slowly add 5 parts bromobutene to the system in two portions while stirring. Stir vigorously for 24 h. After the reaction is complete, centrifuge and wash the precipitate several times with acetone, filter, and dry to obtain modified β-cyclodextrin.

[0044] (2) Take 1 part of 3-mercapto-1, 1 part of 2-propanediol, 1.5 parts of glycidyl methacrylate and 20 parts of acetone in a three-necked flask, sonicate to mix them evenly, add 0.1 parts of diphenylphosphine, and react at 40°C for 3-7 hours to obtain mercapto-modified glycidyl methacrylate for later use.

[0045] (3) 10 parts of isophorone diisocyanate and 20 parts of acetone were ultrasonically dissolved and mixed evenly in a three-necked flask. 0.1 parts of dibutyltin dilaurate were added, and the mixture was preheated in an oil bath at 65°C. Further, 0.5 parts of 1,4-butanediol, 0.1 parts of 3-mercapto-1, 0.1 parts of 2-propanediol, and 0.5 parts of the above-mentioned mercapto-modified glycidyl methacrylate were dissolved and mixed, and added to the three-necked flask. The reaction was continued for 2 hours. The acetone was removed by rotary evaporation of the obtained product to obtain the polyurethane prepolymer.

[0046] (4) Dissolve 0.1 parts of polyoxyethylene dehydrated sorbitan monooleate in 60 parts of deionized water to form an aqueous phase; place 2 parts of polyurethane prepolymer, 2 parts of polyethylene glycol, and 1 part of gardenia essential oil in a beaker and ultrasonically mix evenly to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask and stir evenly. Then, dissolve 1.5 parts of modified β-cyclodextrin in 10 parts of deionized water and 0.05 parts of diphenylphosphine in 1 part of ethanol, and add them dropwise to the preheated three-necked flask. After reacting at 50°C for 3 hours, β-cyclodextrin-polyurethane double-shell microcapsules can be obtained.

[0047] (5) Take 0.2g of the prepared β-cyclodextrin-polyurethane double-shell microcapsules and disperse them in 20 parts of deionized water to obtain a microcapsule dispersion; immerse a pure cotton fabric (5cm×5cm) in the dispersion for 10min and dry it at 50℃ to obtain cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0048] Example 2

[0049] (1) Add 4 parts of β-cyclodextrin and 45 parts of anhydrous N,N-dimethylformamide / anhydrous dimethyl sulfoxide (V / V ratio 1:1) to a beaker and dissolve them completely. Then add 4 parts of sodium hydroxide and stir at room temperature for 2.5 h. Allow the system to cool naturally to 8 °C. Using a dropping funnel, slowly add 5.7 mL of heptamethrin in two portions while stirring. Stir vigorously for 40 h. After the reaction is complete, centrifuge and wash the precipitate several times with acetone, filter, and dry to obtain modified β-cyclodextrin.

[0050] (2) Take 4 parts of 3-mercapto-1, 4 parts of 2-propanediol, 5 parts of glycidyl methacrylate and 40 parts of acetone in a three-necked flask, mix them evenly by sonication, add 0.4 parts of diphenylphosphine, and react at 70°C for 6 hours to obtain mercapto-modified glycidyl methacrylate for later use.

[0051] (3) 18 parts of isophorone diisocyanate and 50 parts of acetone were ultrasonically dissolved and mixed evenly in a three-necked flask. 0.35 parts of dibutyltin dilaurate were added, and the mixture was preheated in an oil bath at 80°C. Further, 1.8 parts of 1,4-butanediol, 0.6 parts of 3-mercapto-1, 0.6 parts of 2-propanediol, and 1.8 parts of the above-mentioned mercapto-modified glycidyl methacrylate were dissolved and mixed, and added to the three-necked flask. The reaction was continued for 4.5 h. The obtained product was removed by rotary evaporation to obtain the polyurethane prepolymer.

[0052] (4) Dissolve 0.4 parts of sodium dodecyl sulfate in 120 parts of deionized water to form an aqueous phase; place 5 parts of prepolymer, 4 parts of polyethylene glycol, and 5 parts of lavender essential oil in a beaker and ultrasonically mix evenly to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask and stir evenly. Then, dissolve 5 parts of modified β-cyclodextrin in 40 parts of deionized water and 0.15 parts of diphenylphosphine in 4 parts of ethanol, and add them dropwise to the preheated three-necked flask. After reacting at 70°C for 5 hours, β-cyclodextrin-polyurethane double-shell microcapsules can be obtained.

[0053] (5) Disperse 0.8 g of the prepared β-cyclodextrin-polyurethane double-shell microcapsules in 40 parts of deionized water to obtain a microcapsule dispersion. Immerse a pure cotton fabric (5 cm × 5 cm) in the dispersion for 30 min and dry it at 70 °C to obtain a cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0054] Example 3

[0055] (1) Add 5 parts of β-cyclodextrin and 50 parts of anhydrous N,N-dimethylformamide / anhydrous dimethyl sulfoxide (V / V ratio 1:1) to a beaker and dissolve them completely. Then add 5 parts of sodium hydroxide and stir at room temperature for 3 hours. Allow the system to cool naturally to 10°C. Using a dropping funnel, slowly add 10 parts of bromohexene in two portions while stirring. Stir vigorously for 48 hours. After the reaction is complete, centrifuge and wash the precipitate several times with acetone, filter, and dry to obtain modified β-cyclodextrin.

[0056] (2) Take 5 parts of 3-mercapto-1, 5 parts of 2-propanediol, 6 parts of glycidyl methacrylate and 50 parts of acetone in a three-necked flask, mix them evenly by sonication, add 0.5 parts of diphenylphosphine, and react at 80°C for 7 hours to obtain mercapto-modified glycidyl methacrylate for later use.

[0057] (3) 20 parts of isophorone diisocyanate and 60 parts of acetone were ultrasonically dissolved and mixed evenly in a three-necked flask. 0.4 parts of dibutyltin dilaurate were added, and the mixture was preheated in an oil bath at 85°C. Further, 2 parts of 1,4-butanediol, 0.7 parts of 3-mercapto-1, 0.7 parts of 2-propanediol, and 2 parts of the above-mentioned mercapto-modified glycidyl methacrylate were dissolved and mixed, and added to the three-necked flask. The reaction was continued for 5 hours. The acetone was removed by rotary evaporation of the obtained product to obtain the polyurethane prepolymer.

[0058] (4) Dissolve 0.5 parts of polyoxyethylene-8-octylphenyl ether in 150 parts of deionized water to form an aqueous phase; place 6 parts of prepolymer, 5 parts of polyethylene glycol, and 6 parts of jasmine essential oil in a beaker and ultrasonically mix them evenly to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask and stir evenly. Then, dissolve 6 parts of modified β-cyclodextrin in 50 parts of deionized water and 0.2 parts of diphenylphosphine in 5 parts of ethanol, and add them dropwise to the preheated three-necked flask. After reacting at 80°C for 6 hours, β-cyclodextrin-polyurethane double-shell microcapsules can be obtained.

[0059] (5) Disperse 1g of the prepared β-cyclodextrin-polyurethane double-shell microcapsules in 50 parts of deionized water to obtain a microcapsule dispersion. Immerse a pure cotton fabric (5cm×5cm) in the dispersion for 30min and dry it at 80℃ to obtain cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0060] Example 4

[0061] (1) Add 3 parts of β-cyclodextrin and 35 parts of anhydrous N,N-dimethylformamide / anhydrous dimethyl sulfoxide (V / V ratio 1:1) to a beaker and dissolve them completely. Then add 4 parts of sodium hydroxide and stir at room temperature for 2 hours. Allow the system to cool naturally to 7°C. Using a dropping funnel, slowly add 7 parts of bromopentene in two portions while stirring. Stir vigorously for 36 hours. After the reaction is complete, centrifuge and wash the precipitate several times with acetone, filter, and dry to obtain modified β-cyclodextrin.

[0062] (2) Take 3 parts of 3-mercapto-1, 3 parts of 2-propanediol, 3 parts of glycidyl methacrylate and 35 parts of acetone in a three-necked flask, mix them evenly by sonication, add 0.3 parts of diphenylphosphine, and react at 60°C for 5 hours to obtain mercapto-modified glycidyl methacrylate for later use.

[0063] (3) 15 parts of isophorone diisocyanate and 40 parts of acetone were ultrasonically dissolved and mixed evenly in a three-necked flask. 0.3 parts of dibutyltin dilaurate were added, and the mixture was preheated in an oil bath at 75°C. Further, 1.3 parts of 1,4-butanediol, 0.4 parts of 3-mercapto-1, 0.4 parts of 2-propanediol, and 1.2 parts of the above-mentioned mercapto-modified glycidyl methacrylate were dissolved and mixed, and added to the three-necked flask. The reaction was continued for 3 hours. The acetone was removed by rotary evaporation of the obtained product to obtain the polyurethane prepolymer.

[0064] (4) Dissolve 0.3 parts of polyoxyethylene sorbitan monolaurate in 100 parts of deionized water to form an aqueous phase; place 4 parts of prepolymer, 4 parts of polyethylene glycol, and 4 parts of lemon essential oil in a beaker and ultrasonically mix evenly to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask and stir evenly. Then, dissolve 4 parts of modified β-cyclodextrin in 30 parts of deionized water and 0.1 parts of diphenylphosphine in 3 parts of ethanol, and add them dropwise to the preheated three-necked flask. After reacting at 60°C for 4 hours, β-cyclodextrin-polyurethane double-shell microcapsules can be obtained.

[0065] (5) Disperse 0.6 g of the prepared β-cyclodextrin-polyurethane double-shell microcapsules in 35 parts of deionized water to obtain a microcapsule dispersion. Immerse a pure cotton fabric (5 cm × 5 cm) in the dispersion for 20 min and dry it at 65 °C to obtain a cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0066] Example 5

[0067] (1) Add 1.5 parts of β-cyclodextrin and 25 parts of anhydrous N,N-dimethylformamide / anhydrous dimethyl sulfoxide (V / V ratio 1:1) to a beaker and dissolve them completely. Then add 3.5 parts of sodium hydroxide and stir at room temperature for 1 hour. Allow the system to cool naturally to 5°C. Using a dropping funnel, slowly add 6 parts of bromopropene in two portions while stirring. Stir vigorously for 24-48 hours. After the reaction is complete, centrifuge and wash the precipitate several times with acetone, filter, and dry to obtain modified β-cyclodextrin.

[0068] (2) Take 2 parts of 3-mercapto-1, 2 parts of 2-propanediol, 2 parts of glycidyl methacrylate and 25 parts of acetone in a three-necked flask, sonicate to mix them evenly, add 0.2 parts of diphenylphosphine, and react at 50°C for 4 hours to obtain mercapto-modified glycidyl methacrylate for later use.

[0069] (3) 12 parts of isophorone diisocyanate and 30 parts of acetone were ultrasonically dissolved and mixed evenly in a three-necked flask. 0.15 parts of dibutyltin dilaurate were added, and the mixture was preheated in an oil bath at 70°C. Further, 0.7 parts of 1,4-butanediol, 0.3 parts of 3-mercapto-1, 0.3 parts of 2-propanediol, and 0.8 parts of the above-mentioned mercapto-modified glycidyl methacrylate were dissolved and mixed, and added to the three-necked flask. The reaction was continued for 3 hours. The obtained product was rotary evaporated to remove acetone, yielding a polyurethane prepolymer.

[0070] (4) Dissolve 0.2 parts of sodium dodecylbenzenesulfonate in 80 parts of deionized water to form an aqueous phase; place 3 parts of prepolymer, 3 parts of polyethylene glycol, and 2 parts of peppermint oil in a beaker and ultrasonically mix until homogeneous to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask and stir until homogeneous. Then, dissolve 2 parts of modified β-cyclodextrin in 20 parts of deionized water and 0.1 parts of diphenylphosphine in 2 parts of ethanol, and add them dropwise to the preheated three-necked flask. After reacting at 60°C for 3 hours, β-cyclodextrin-polyurethane double-shell microcapsules can be obtained.

[0071] (5) Disperse 0.4 g of the prepared β-cyclodextrin-polyurethane double-shell microcapsules in 30 parts of deionized water to obtain a microcapsule dispersion. Immerse a pure cotton fabric (5 cm × 5 cm) in the dispersion for 20 min and dry it at 60 °C to obtain a cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

[0072] Comparative Example 1

[0073] The difference from Example 5 is that in step (4), 0.2 parts of sodium dodecylbenzenesulfonate are dissolved in 80 parts of deionized water to form an aqueous phase; 3 parts of prepolymer, 3 parts of polyethylene glycol, and 2 parts of peppermint oil are placed in a beaker and ultrasonically mixed evenly to form an oil phase. The mixed oil phase is added to the aqueous phase, and after ultrasonic emulsification, a stable oil-in-water emulsion is formed. The emulsion is transferred to a three-necked flask, stirred evenly, and heated to 60°C for 3 hours to obtain polyurethane microcapsules.

[0074] Comparative Example 2

[0075] Dissolve 0.1 parts of β-cyclodextrin in 30 parts of deionized water to obtain a cyclodextrin solution. Immerse a pure cotton fabric (5cm×5cm) in this solution for 20 minutes and dry it at 60℃ to obtain a cotton fabric treated with β-cyclodextrin.

[0076] Comparative Example 3

[0077] The difference from Example 5 lies in steps (4) and (5),

[0078] (4) Dissolve 0.2 parts of sodium dodecylbenzenesulfonate in 80 parts of deionized water to form an aqueous phase; place 3 parts of prepolymer, 3 parts of polyethylene glycol, and 2 parts of peppermint oil in a beaker and ultrasonically mix them evenly to form an oil phase. Add the mixed oil phase to the aqueous phase and ultrasonically emulsify to form a stable oil-in-water emulsion. Transfer the emulsion to a three-necked flask, stir evenly, and heat to 60°C for 3 hours to obtain polyurethane microcapsules.

[0079] (5) Disperse 0.4g of the prepared polyurethane microcapsules in 30 parts of deionized water to obtain a microcapsule dispersion. Immerse a pure cotton fabric (5cm×5cm) in the dispersion for 20min and dry it at 60℃ to obtain a cotton fabric treated with polyurethane microcapsules.

[0080] Figure 1 This is a characterization of the modified cyclodextrin structure prepared in Example 5. (From...) Figure 1 As can be seen from a, since β-CD itself contains multiple -OH groups, at 3420 cm⁻¹ -1 Characteristic absorption peaks of -OH appear at 1380, 1140, and 1040 cm⁻¹. -1 All of these are characteristic absorption peaks of β-CD itself. Modified β-cyclodextrin shows a peak at 1620 cm⁻¹. -1 An absorption peak for the asymmetric stretching vibration of C=C appeared nearby, while β-cyclodextrin itself did not show an absorption peak at that location.

[0081] In summary, the allyl group has been successfully bonded to the β-CD molecule, and the cavity structure of β-CD is preserved in the target molecule. Further 1H NMR analysis was performed on the purified sample. The 1H NMR spectra of β-CD and the modified β-CD are shown below. Figure 1As shown in b and c. 5.34 × 10⁻⁴ 6 It is a singlet peak representing the unsubstituted C3-OH proton peak on the β-CD glucose unit; (4.40~4.41)×10 -6 It is a multiplet obtained by splitting C6-H of the β-CD glucose unit by C5-H; (5.55~5.60)×10 -6 It is a doublet obtained by the splitting of C1-H on the β-CD glucose unit by C2-H; 3.77 × 10 -6 4.20×10 -6 3.71×10 -6 These are the proton peaks of C2-H, C5-H, and C4-H on β-CD. Secondly, 3.99 × 10⁻⁶ -6 This is the proton peak of the methylene group (-C7H2-) on the allyl group. This peak is affected by the oxygen atom and split into a doublet by the protons on the adjacent double bonds; 5.51 × 10 -6 It is the proton peak on -HC8=C-; (5.43~5.46)×10 -6 These are proton peaks on the terminal olefin =C9H2. In summary, the above two types of proton peaks can be identified in the 1H NMR spectrum of this substance, thus confirming the successful synthesis of allyl β-CD.

[0082] Figure 2 a is a SEM image of polyurethane microcapsules without 6-O-allyl-β-CD loading (Comparative Example 1). Figure 2 e represents the histogram of its particle size distribution. The polyurethane microcapsules mainly have a particle size concentrated at 1.1 μm and a smooth surface. After modification with β-CD modified with bromopropylene, the surface of the microcapsules becomes rougher and the diameter increases. Figure 2 As shown in Figure bd, the morphology and structure of the polyurethane microcapsules are consistent, with a diameter mainly around 1.9 μm. This can also be seen from... Figure 2 As shown in f, this indicates that 6-O-allyl-β-cyclodextrin was successfully grafted onto the surface of the microcapsule via a click reaction. Furthermore, the EDX spectra and corresponding elemental mappings of the microcapsules are as follows: Figure 2 As shown in g. The surface chemical composition of the microcapsules contains 69.0% carbon (C), 13.1% nitrogen (N), 14.8% oxygen (O) and 3.0% sulfur (S). The presence of sulfur confirms that thioglycerol was successfully grafted onto the polyurethane shell.

[0083] like Figure 3 As shown in figure a, the functional groups of the polyurethane prepolymer and microcapsules were analyzed using infrared spectroscopy. The main absorption peak of the polyurethane prepolymer is located at 1720 cm⁻¹. -1 2270cm -1 and 3450cm -1At specific wavelength positions, these absorption peaks represent the stretching vibration peaks of groups such as C=O, -NCO-, and -NH-. The infrared spectrum of the polyurethane microcapsules shows a peak at 2260 cm⁻¹. -1 The disappearance of the absorption peak at 3400 cm⁻¹ is attributed to the addition of a chain extender. The isocyanate group (-NCO) in the polyurethane prepolymer reacts with the hydroxyl group in the chain-extending polyol, leading to the disappearance of the -NCO- absorption peak in the microcapsule shell. These results indicate the successful synthesis of the polyurethane shell. Furthermore, compared to the prepolymer, the addition of cyclodextrin introduces hydroxyl groups, resulting in a higher absorption peak at 3400 cm⁻¹ in the microcapsules. -1 The nearby absorption peaks broadened significantly, further indicating that cyclodextrin had been successfully incorporated into the surface of the polyurethane microcapsules. Figure 3 Figures b and 3c show the TGA and DTG curves of peppermint essential oil, unencapsulated peppermint essential oil microcapsules, and β-cyclodextrin / polyurethane microcapsules. The TGA curve of peppermint essential oil shows its decomposition temperature between 110-200℃, which corresponds to the weight loss curve of the microcapsules. The slight decomposition of the microcapsules before 100℃ is attributed to the presence of a small amount of water; the decomposition between 100-200℃ mainly corresponds to the decomposition of peppermint essential oil, also indicating that the peppermint essential oil is encapsulated within the microcapsules. With increasing temperature, the microcapsules experience significant weight loss after 250℃, and stabilize after 400℃. This weight loss is primarily caused by the decomposition of the polymer shell material of the microcapsules. Based on the thermogravimetric curves of the microcapsules and the control group (unencapsulated microcapsules), the encapsulation rate of peppermint essential oil in these microcapsules can be calculated to be 30.91%.

[0084] like Figure 4 Figure a shows an untreated pure cotton fabric, which has a smooth cylindrical shape. In contrast, the surface of the cotton fabric treated with microcapsules becomes significantly rougher. Figure 4 b). Under higher magnification, a large number of polyurethane microcapsules can be clearly seen adhering to the fibers. Figure 4 c). EDX spectra and corresponding elemental mappings of cotton fabrics treated with microcapsules are as follows: Figure 4 As shown in d, it can be seen that carbon (C), nitrogen (N), and oxygen (O) are evenly distributed on the fiber surface; in addition, a small amount of sulfur (S) can be clearly seen, which is a manifestation of the presence of thioglycerol monomer introduced during the synthesis of microcapsule shell material. The above two points prove that the distribution of microcapsules on the fiber surface is uniform.

[0085] Figure 5 This study demonstrates the host-guest adsorption function of β-cyclodextrin loaded on polyurethane microcapsule shells. The odor adsorption performance of polyurethane microcapsules was investigated using citral and trans-2-nonenal as research materials. First, the standard concentration curve of citral was measured using a UV spectrophotometer, and the linear fitting results were obtained, as shown in the figure. Figure 5As shown in b. The standard equation obtained through linear fitting is shown in equation (1):

[0086] C = 1.90621A - 7.59367 Equation (1);

[0087] The adsorption of citral on cotton fabrics treated with polyurethane microcapsules at room temperature was determined using a UV spectrophotometer. Figure 5 As shown in c. Cotton fabric itself has a certain adsorption effect. After treating cotton fabric with polyurethane microcapsules modified with 10% β-CD according to the shell material ratio, its adsorption performance was significantly improved, but not to the expected extent. Therefore, the amount of cyclodextrin in the shell material was further increased to 25%, which resulted in a significant enhancement of the adsorption of citral by the treated cotton fabric for a period of time.

[0088] Secondly, the standard concentration curve of trans-2-nonenal was determined using a UV spectrophotometer, and the linear fitting results were obtained as follows: Figure 5 d, The standard equation obtained by linear fitting is shown in equation (2):

[0089] C = 7.31629A - 31.48825 Equation (2);

[0090] Polyurethane microcapsules modified with cyclodextrin (25% of the shell material) were impregnated onto the surface of cotton fabric. The adsorption performance of the cotton fabric for trans-2-nonenal before and after treatment was then investigated. The results are as follows: Figure 5 e. The cotton fabric itself has a very low adsorption rate for trans-2-nonenal, reaching only 7.87% after being placed at room temperature for 2 hours. However, the cotton fabric treated with microcapsules reaches 58.048%, indicating that the material has an effective adsorption capacity for trans-2-nonenal. The above results show that microcapsules have good odor-absorbing properties when applied to fabrics.

[0091] also, Figure 5 d and 5g show the adsorption performance of β-CD modified microcapsule-treated cotton fabrics for citral and trans-2-nonenal. Despite the same amount of β-CD added in the experiments, the adsorption performance of the resulting functional cotton fabrics differed significantly. This difference is mainly due to the increased number of reactive sites in the prepolymer that can interact with thiol groups in β-CD modified with bromopropene. In contrast, unmodified β-CD can only adhere to the surface of the polyurethane microcapsules via end-capping reactions, resulting in a limited number of β-CDs being incorporated into the shell. Therefore, its adsorption capacity is relatively low.

[0092] The adsorption performance of the regeneration cycle for citral and trans-2-nonenal was verified by adsorption-desorption experiments. Figure 6a and 6b show the desorption and re-adsorption results of citral on the functional cotton fabric that had previously adsorbed citral and trans-2-nonenal after heating. The re-adsorption results indicate that the fabric treated with β-CD / polyurethane microcapsules has cyclic adsorption capacity. A washing test was conducted to evaluate the recycling efficiency of the functional cotton fabric. Figure 6 c and Figure 6 Figure d shows the adsorption results of citral and trans-2-nonenal on the functional cotton fabric before and after the washing cycle. Although the washing process reduced the adsorption capacity of the fabric, it still exhibited excellent adsorption performance.

[0093] To evaluate the antibacterial properties of functional cotton fabrics, the antibacterial effects of functional cotton fabrics against Staphylococcus aureus and Escherichia coli were tested using the shaking method and colony counting method. Figure 7 a represents the antibacterial mechanism of β-CD-polyurethane microcapsules. The antibacterial effect of microcapsule-treated cotton fabrics mainly originates from the peppermint oil encapsulated within the microcapsules. The antibacterial properties of microcapsule-treated cotton fabrics (Example 5), β-CD solution (Comparative Example 2), untreated polyurethane microcapsule-treated cotton fabrics (Comparative Example 3), and untreated cotton fabrics were used as control groups to investigate the antibacterial properties of microcapsule-treated cotton fabrics.

[0094] The results of the observation of the antibacterial activity of the four groups of samples against the two bacteria are as follows: Figure 7 As shown in b and 7c, peppermint oil exhibited an inhibition rate of 98.82% against Staphylococcus aureus and 98.24% against Escherichia coli. Cotton fabrics treated with allyl-β-cyclodextrin solution showed inhibition rates of 27.06% and 8.26% against the two bacteria, respectively. The antibacterial rate of ungrafted microcapsule-treated cotton fabrics was lower. The antibacterial rates of microcapsule-functionalized cotton fabrics were 97.06% and 95.88%, respectively. These results indicate that both allyl-β-cyclodextrin and peppermint oil possess antibacterial activity. However, the antibacterial activity of cyclodextrin is relatively weak, and the main antibacterial effect of the polyurethane microcapsules is attributed to the release of the core material, PEO. The PEO encapsulation and sustained-release effect of the microcapsules provides the treated fabrics with sustained antibacterial properties. Figure 7 As shown in the diagram, the microcapsules maintained high antibacterial activity after 7 days of storage. In contrast, the antibacterial performance of samples treated directly with essential oils significantly decreased after 7 days. The fabric treated with microcapsules maintained its antibacterial effect even after 14 days, indicating the sustained-release effect of the microcapsules on the core material PEO.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A process for the preparation of a β-cyclodextrin-polyurethane double- shell microcapsule, characterized in that: include, Modified β-cyclodextrin is obtained by mixing β-cyclodextrin, anhydrous N,N-dimethylformamide-anhydrous dimethyl sulfoxide mixture, sodium hydroxide, and brominated olefins, centrifuging the mixture, washing the precipitate with acetone, filtering, and drying. The mercapto-modified glycidyl methacrylate is obtained by mixing 3-mercapto-1,2-propanediol, glycidyl methacrylate, acetone, and diphenylphosphine. Isophorone diisocyanate, acetone, dibutyltin dilaurate, 1,4-butanediol, 3-mercapto-1,2-propanediol, and the above-mentioned mercapto-modified glycidyl methacrylate were dissolved, mixed, and reacted. The resulting product was then removed by rotary evaporation to remove acetone, yielding a polyurethane prepolymer. The emulsifier is dissolved in deionized water to form an aqueous phase; the polyurethane prepolymer, polyethylene glycol, and plant essential oil are ultrasonically mixed to form an oil phase; the mixed oil phase is added to the aqueous phase, and ultrasonic emulsification is performed to form a stable oil-in-water emulsion. Polyurethane microcapsules can be obtained by dissolving modified β-cyclodextrin in deionized water and diphenylphosphine in ethanol, and then mixing and reacting them with the above oil-in-water emulsion.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the β-cyclodextrin, anhydrous N,N-dimethylformamide-anhydrous dimethyl sulfoxide mixture, sodium hydroxide, and brominated olefin is 1~5:20~50:3~5:5~10.

3. The production method according to claim 1, wherein The brominated olefins include one or more of brominated propylene, brominated butene, brominated pentylene, and brominated hexene; the emulsifier is one or more of sodium dodecylbenzenesulfonate, polyoxyethylene sorbitan monooleate, sodium dodecyl sulfate, polyoxyethylene-8-octylphenyl ether, polyoxyethylene sorbitan monolaurate, sorbitan fatty acid ester, and polyvinyl alcohol.

4. The production method according to claim 1, wherein: The mass ratio of 3-mercapto-1,2-propanediol, glycidyl methacrylate, acetone, and diphenylphosphine is 1~5:1~5:1.5~6:20~50:0.1~0.

5.

5. The production method according to claim 1, wherein: The mass ratio of isophorone diisocyanate, acetone, dibutyltin dilaurate, 1,4-butanediol, 3-mercapto-1,2-propanediol, and mercapto-modified glycidyl methacrylate is 10~20:20~60:0.1~0.4:0.5~2:0.1~0.7:0.5~2.

6. The production method according to claim 1, wherein: The mass ratio of sodium dodecylbenzenesulfonate to deionized water in the aqueous phase is 0.1~0.5:60~150; the mass ratio of polyurethane prepolymer, polyethylene glycol, and plant essential oil in the oil phase is 2~6:2~5:1~6.

7. The production method according to claim 1, wherein: The mass ratio of the modified β-cyclodextrin, deionized water, diphenylphosphine, and ethanol is 1.5~6:10~50:0.05~0.2:1~5.

8. The β-cyclodextrin-polyurethane double-shelled microcapsules prepared by the preparation method according to any one of claims 1-7, characterized in that: The microcapsule has a core-shell structure, wherein the core material is plant essential oil, the inner wall material is polyurethane, and the outer shell material is modified β-cyclodextrin.

9. The β-cyclodextrin-polyurethane bi-shell layer microcapsule according to claim 8, characterized in that: The plant essential oils include one or more of lemon essential oil, peppermint essential oil, jasmine essential oil, gardenia essential oil, and lavender essential oil.

10. The application of the β-cyclodextrin-polyurethane double-shell microcapsules as described in claim 8 in textiles, characterized in that: The β-cyclodextrin-polyurethane double-shell microcapsules are dispersed in deionized water to obtain a microcapsule dispersion; pure cotton fabric is immersed in the dispersion and then dried to obtain cotton fabric treated with β-cyclodextrin-polyurethane double-shell microcapsules.

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