A double-network wall material water-bursting bead and a microflow control preparation method thereof

Abstract

The application provides a double-network wall material water explosion bead and a microflow control preparation method thereof, and the water explosion bead comprises a wall material and a core material; the wall material comprises the following raw materials in parts by mass: 5-25 parts of ethanol, 30-70 parts of a multifunctional vinyl monomer, 20-60 parts of a modified natural polymer and 1-5 parts of a photoinitiator 1173; the wall material of the water explosion bead is composed of an interpenetrating network polymer; on one hand, the modified natural polymer is used as a base, and based on the internal hydrogen bond interaction, the water explosion bead wall material is endowed with high mechanical properties; on the other hand, the interpenetrating network polymer structure is constructed through free radical polymerization of the multifunctional vinyl monomer, the crosslinking density of the water explosion bead wall material is improved, and then the water retention rate is improved; the water explosion bead is prepared through a three-phase microflow control droplet technology, a coaxial co-flow focusing microflow control chip is adopted, the interfacial tension among the core material, the wall material and the silicone oil of the water explosion bead is adjusted through a surfactant, and the construction and regulation of the water explosion bead with a stable structure are realized.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a double-network wall material water-bursting beads and its microfluidic control preparation method. Background Technology

[0002] Water-soluble flavoring capsules are important for increasing the moisture content of cigarette smoke, improving its smoothness, reducing irritation, and enhancing sensory comfort. However, currently, most cigarette flavoring capsules are of the W / O type, which limits the application of water-soluble flavorings in cigarette flavoring capsules. Furthermore, oil-soluble additives participate in combustion, introducing other impurities into the smoke and affecting the sensory quality of cigarettes.

[0003] my country's technology for preparing tobacco water-based flavor capsules started relatively late and is still in the research and development stage. The selection of wall materials and the improvement of process conditions remain key issues that urgently need to be addressed, significantly impacting the industrial production and market development of tobacco water-based flavor capsules. Therefore, in-depth research on O / W type tobacco water-based flavor capsules is of great significance for improving cigarette smoking quality and further expanding the application of flavor capsules in cigarette aroma enhancement and moisture retention.

[0004] Microfluidics is a technology for processing complex fluids at the microscale. It features high specific surface area, high heat and mass transfer efficiency, high controllability, low energy consumption, and continuous production, making it important for applications in fluid manipulation, chemical synthesis, analytical testing, and materials preparation. In microchannels, the fluid is in a laminar flow state, thus interfacial tension plays a dominant role. Shandong General Tobacco New Material Technology Co., Ltd. disclosed a patent (publication number CN114158768A) on March 11, 2022, which describes a method for preparing and applying water-soluble burst beads using microchannels. The method uses a water / ethanol mixed solution as the inner phase (core material) and a system of photocurable resin, reactive diluent, and additives as the intermediate phase (wall material) to prepare the water burst beads. Guangxi China Tobacco Industry Co., Ltd. disclosed a method for preparing water-soluble core material burst beads based on millifluidic technology in its publication No. CN108378417A published on August 10, 2018. The method uses a water / ethanol mixed solution as the inner phase (core material) and a photocurable coating containing a photoinitiator that is insoluble in the water phase, such as epoxy acrylate, polyurethane acrylate, polyester acrylate, etc., as the intermediate phase (wall material) to prepare water burst beads.

[0005] Although the above invention has enabled the continuous preparation of water-bursting beads, the raw material system used is complex, the production process is cumbersome, the production cost is high, the mechanical strength of the wall material is poor, it is easy to break and cause leakage, and the core material is a water / ethanol mixed solution, which affects the quality of cigarettes. Summary of the Invention

[0006] The present invention aims to provide a dual-network wall material water-bursting beads and its microfluidic preparation method. The method utilizes an interpenetrating network polymer as the wall material and a water core material, employing microfluidic droplet technology and ultraviolet light curing to prepare water-bursting beads. The prepared water-bursting bead wall material is composed of an interpenetrating network gel. On one hand, modified natural polymers serve as the base, and the water-bursting bead wall material possesses high mechanical properties based on intramolecular hydrogen bonding interactions. On the other hand, the interpenetrating network polymer structure is constructed through free radical polymerization of multifunctional vinyl monomers, increasing the crosslinking density of the water-bursting bead wall material and thus improving its water retention rate. Furthermore, the preparation method is simple and easily industrialized.

[0007] The specific technical solution of this invention is as follows:

[0008] A type of dual-network wall material water-bursting beads, the raw materials of which include wall material and core material;

[0009] The wall material comprises the following parts by weight of raw materials:

[0010] 5-25 parts of ethanol

[0011] 30-70 parts of multifunctional vinyl monomer

[0012] 20-60 parts of modified natural polymer

[0013] Photoinitiator 1173, 1-5 parts.

[0014] The multifunctional vinyl monomer is one or more of a difunctional vinyl monomer, a trifunctional vinyl monomer, or a tetrafunctional vinyl monomer.

[0015] The difunctional vinyl monomer is selected from one or more of tripropylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, or neopentyl glycol diacrylate;

[0016] The trifunctional vinyl monomer is selected from one or more of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, glycerol propoxy acid (1PO / OH) triacrylate, trimethanol propane ethoxy ester triacrylate, and propoxylated trimethylolpropane triacrylate.

[0017] The tetrafunctional vinyl monomer is selected from one or more of pentaerythritol tetraacrylate and bis(trimethylolpropane)tetraacrylate.

[0018] The modified natural polymer is a carbon-carbon double bond modified natural polymer or a carbon-carbon double bond and epoxy group modified natural polymer.

[0019] The carbon-carbon double bond modified natural polymer is selected from one or more of the following: methacrylic anhydride modified gelatin, methacrylic acid modified silk fibroin, methacryloyl carboxymethyl chitosan, or maleic anhydride modified β-cyclodextrin.

[0020] The carbon-carbon double bond and epoxy-modified natural polymers are selected from one or more of glycidyl methacrylate-modified gelatin and glycidyl methacrylate-modified silk fibroin.

[0021] The core material includes deionized water and a surfactant;

[0022] The surfactant is one or more of OP-10, Span-20, Tween-80, Tween-81, Tween-85, Myrij-45, Myrij-49, polyoxyethylene 400 monolaurate, polyoxyethylene 400 monostearate, and polyoxyethylene 400 monooleate.

[0023] The surfactant is 1-2% by weight of the total mass of the water-bursting bead core material.

[0024] This invention provides a microfluidic preparation method for water-bursting beads of a dual-network wall material, comprising the following steps:

[0025] a) Using water-containing popping bead core material, wall material precursor and silicone oil as the inner phase, middle phase and outer phase respectively, the flow rate of the three-phase fluid is adjusted by a peristaltic pump to generate O / W type microdroplets;

[0026] b) The water droplets are cured by ultraviolet light at the outlet to form water droplets;

[0027] c) The water-bursting beads of the double-network wall material are obtained by washing with anhydrous ethanol and drying.

[0028] The viscosity of the silicone oil mentioned in step a) is 1-1000 cs.

[0029] In step a), the inner diameter of the channel of the inner phase is 300-600 μm, the inner diameter of the channel of the intermediate phase is 500-2000 μm, and the inner diameter of the channel of the outer phase is 4.0-5.0 mm.

[0030] The internal phase flow rate in step a) is 0.5-2 mL / min, the intermediate phase flow rate is 0.5-2 mL / min, and the external phase flow rate is 10-15 mL / min.

[0031] The UV curing power mentioned in step b) is 1000-3000W, and the curing time is 1-5s.

[0032] In step c), anhydrous ethanol is used to clean the silicone oil, unreacted monomers, photoinitiators, and surfactants from the surface of the water-bursting beads.

[0033] This invention discloses a method for preparing water-bursting beads using interpenetrating network polymers as the wall material and a water-core material, through microfluidic droplet technology and ultraviolet light curing. The water-bursting bead wall material is composed of an interpenetrating network gel. On one hand, modified natural polymers serve as the base, and the water-bursting bead wall material possesses high mechanical properties based on intramolecular hydrogen bonding interactions. On the other hand, the interpenetrating network polymer structure is constructed through free radical polymerization of multifunctional vinyl monomers, increasing the crosslinking density of the water-bursting bead wall material and thus improving its water retention rate.

[0034] Compared with existing technologies, the water-bursting bead wall material provided by this invention allows for the formation of an interpenetrating polymer network by multifunctional vinyl monomers and modified natural polymers. On one hand, the carbon-carbon double bonds and epoxy groups in the modified natural polymers can form chemically cross-linked polymer networks. Furthermore, the natural polymer surface contains a large number of hydroxyl, carboxyl, and amino groups, which can generate multiple intermolecular hydrogen bonds, exhibiting dynamic / reversible cross-linking characteristics. Under external stimuli, these bonds can spontaneously break and recombine, providing an energy dissipation mechanism for the polymer network and improving the mechanical properties of the water-bursting bead wall material. On the other hand, the carbon-carbon double bonds in the multifunctional vinyl monomers can undergo free radical polymerization, thereby forming a highly cross-linked molecular network.

[0035] Compared with traditional methods, the interpenetrating network polymer structure of the water-bursting bead wall material in this invention can effectively improve the crosslinking density of the water-bursting bead wall material, thereby improving its mechanical properties and water retention rate. The water-bursting beads are prepared using three-phase microfluidic droplet technology, employing a coaxial co-current focusing microfluidic chip. The interfacial tension between the core material, wall material, and silicone oil of the water-bursting bead is controlled by surfactants, achieving the construction and control of structurally stable water-bursting beads. This invention overcomes the shortcomings of traditional water-bursting bead wall materials, such as poor strength, poor water retention, and insufficient encapsulation rate, and has the advantages of simple operation, low cost, mild conditions, and ease of large-scale preparation. The water-bursting beads prepared by this invention have stable structures, high wall material strength, strong water retention, and high encapsulation rate. This invention has the advantages of simple operation, low cost, mild conditions, and ease of large-scale preparation. Attached Figure Description

[0036] Figure 1 A schematic diagram of the microfluidic control process for preparing water-blown beads for tobacco;

[0037] Figure 2 This is a microscope image of the water-based explosive beads used in Embodiment 1 of the present invention;

[0038] Figure 3 The molecular structure of maleic anhydride-modified β-cyclodextrin is shown.

[0039] Figure 4 The diagram shows the free radical polymerization reaction of difunctional, trifunctional, and tetrafunctional vinyl monomers. Detailed Implementation

[0040] The present invention is illustrated below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0041] The methacrylic anhydride-modified gelatin used in this invention was purchased from Suzhou Yongqinquan Intelligent Equipment Co., Ltd., EFL-GM-60, a methacrylamide gelatin; the methacrylic acid-modified silk fibroin was purchased from Suzhou Yongqinquan Intelligent Equipment Co., Ltd., EFL-SilMA-001, a methacrylamide silk fibroin; the methacryloylcarboxymethyl chitosan was purchased from Suzhou Yongqinquan Intelligent Equipment Co., Ltd., EFL-CMCSMA-200K, a methacrylamide carboxymethyl chitosan; and the maleic anhydride-modified β-cyclodextrin was prepared according to the method disclosed in Biomaterials, 2010, 31, 21:5536-5544.

[0042] The carbon-carbon double bond and epoxy group modified natural polymers are selected from glycidyl methacrylate modified gelatin and prepared according to the method disclosed in Biofabrication, 2021, 13, 03410; glycidyl methacrylate modified silk fibroin is prepared according to the method disclosed in Biofabrication, 2021, 13, 034102.

[0043] Example 1

[0044] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0045] Using a coaxial co-current focusing microfluidic chip ( Figure 1 The microfluidic chip uses deionized water containing 1 wt% Tween-80 as the core material (inner phase), a mixture containing 5 wt% ethanol, 70 wt% tripropylene glycol diacrylate, 20 wt% commercially available methacrylic anhydride-modified gelatin, and 5 wt% photoinitiator 1173 as the wall material precursor (intermediate phase), and silicone oil with a viscosity of 1 cs as the outer phase. The flow rates of the three phases are adjusted using a peristaltic pump to generate O / W type microdroplets. The inner diameter of the inner phase channel is 410 μm, the inner diameter of the intermediate phase channel is 650 μm, and the inner diameter of the outer phase channel is 4.0 mm. The flow rates of the inner phase are 1.0 mL / min, the intermediate phase is 0.8 mL / min, and the outer phase is 10 mL / min. UV curing at the microfluidic chip outlet with a curing power of 1000 W and a curing time of 5 s initiates the curing of the intermediate phase resin, forming water droplets. The surface of the water-bursting beads was cleaned with anhydrous ethanol to remove silicone oil, unreacted monomers, photoinitiator, and surfactants, and then dried in a forced-air drying oven at 30°C for 1 hour. The resulting water-bursting beads are as follows: Figure 2 As shown, the diameter is approximately 1.85 mm and the wall thickness is approximately 153 μm.

[0046] Example 2

[0047] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0048] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 1 wt% Tween-80 as the inner phase core material, ethanol containing 5 wt%, polyethylene glycol diacrylate, 20 wt% self-made glycidyl methacrylate modified gelatin, and photoinitiator 1173 as the wall material precursor as the meso phase, and silicone oil with a viscosity of 1 cs as the outer phase. The flow rates of the three phases were adjusted by a peristaltic pump to generate O / W type microdroplets. The inner phase channel had an inner diameter of 600 μm, the meso phase channel had an inner diameter of 1000 μm, and the outer phase channel had an inner diameter of 4.5 mm. The flow rates were 1.2 mL / min for the inner phase, 1.0 mL / min for the meso phase, and 12 mL / min for the outer phase. UV curing at the microfluidic chip outlet (2000 W, 3 s) initiated the curing of the meso phase resin, forming water droplets. The surface of the water-bursting beads was cleaned with anhydrous ethanol to remove silicone oil, unreacted monomers, photoinitiator, and surfactant, and then dried in a forced-air drying oven at 30°C for 1 hour. The resulting water-bursting beads had a diameter of approximately 2.53 mm and a wall thickness of approximately 201 μm.

[0049] Example 3

[0050] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0051] A coaxial co-current focusing microfluidic chip was used, with 2 wt% Span-20 deionized material as the inner phase core, 5 wt% ethanol, 70 wt% trimethylolpropane triacrylate, 20 wt% self-made maleic anhydride modified β-cyclodextrin, and 5 wt% photoinitiator 1173 as the wall material precursor as the intermediate phase, and silicone oil with a viscosity of 500 cs as the outer phase. The flow rates of the three phases were adjusted by a peristaltic pump to generate O / W type microdroplets. The inner diameter of the inner phase channel was 600 μm, the inner diameter of the intermediate phase channel was 1000 μm, and the inner diameter of the outer phase channel was 4.5 mm. The flow rates of the inner phase were 1.2 mL / min, the intermediate phase flow rates were 1.0 mL / min, and the outer phase flow rates were 12 mL / min. UV curing at the microfluidic chip outlet with a curing power of 3000W and a curing time of 1 second initiates the curing of the mesophase resin. Anhydrous ethanol is used to clean the surface of the water-bursting beads of silicone oil, unreacted monomers, photoinitiator, and surfactant, followed by drying in a forced-air drying oven at 30°C for 1 hour. This forms water-bursting beads with a diameter of approximately 2.48 mm and a wall thickness of approximately 230 μm.

[0052] Example 4

[0053] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0054] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 2 wt% Span-20 as the inner phase core material, 25 wt% ethanol, 30 wt% propoxylated trimethylolpropane triacrylate, 44 wt% self-made glycidyl methacrylate modified silk fibroin, and 1 wt% photoinitiator 1173 as the wall material precursor, and silicone oil with a viscosity of 500 cs as the outer phase. The flow rates of the three phases were adjusted by a peristaltic pump to generate O / W type microdroplets. The inner diameter of the inner phase channel was 600 μm, the inner diameter of the intermediate phase channel was 1000 μm, and the inner diameter of the outer phase channel was 4.5 mm. The flow rates of the inner phase were 1.2 mL / min, the intermediate phase flow rates were 1.0 mL / min, and the outer phase flow rates were 12 mL / min. The mesophase resin was cured at the microfluidic chip outlet using ultraviolet light at a power of 3000W for 3 seconds. Anhydrous ethanol was used to clean the surface of the water-bursting beads, removing silicone oil, unreacted monomers, photoinitiator, and surfactants. The beads were then dried in a forced-air drying oven at 30°C for 1 hour to form water-bursting beads. The resulting water-bursting beads had a diameter of approximately 2.32 mm and a wall thickness of approximately 175 μm.

[0055] Example 5

[0056] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0057] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 1 wt% OP-10 as the inner phase core material, ethanol containing 5 wt%, pentaerythritol tetraacrylate containing 70 wt%, commercially available methacryloyl carboxymethyl chitosan containing 20 wt%, and photoinitiator 1173 containing 5 wt% as the wall material precursor intermediate phase, and silicone oil with a viscosity of 1000 cs as the outer phase. The flow rates of the three phases were adjusted by a peristaltic pump to generate O / W type microdroplets. The inner diameter of the inner phase channel was 600 μm, the inner diameter of the intermediate phase channel was 2000 μm, and the inner diameter of the outer phase channel was 5.0 mm. The flow rates of the inner phase were 2.0 mL / min, the intermediate phase flow rates were 1.8 mL / min, and the outer phase flow rates were 15 mL / min. The mesophase resin was cured at the microfluidic chip outlet using ultraviolet light at a power of 1000W for 1 second. Anhydrous ethanol was used to clean the surface of the water-bursting beads, removing silicone oil, unreacted monomers, photoinitiator, and surfactants. The beads were then dried in a forced-air drying oven at 30°C for 1 hour to form water-bursting beads. The resulting water-bursting beads had a diameter of approximately 3.19 mm and a wall thickness of approximately 223 μm.

[0058] Example 6

[0059] A microfluidic preparation method for water-bursting beads of a dual-network wall material includes the following steps:

[0060] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 1 wt% OP-10 as the inner phase core material, ethanol containing 15 wt%, di(trimethylolpropane)tetraacrylic acid containing 50 wt%, self-made glycidyl methacrylate modified gelatin containing 32 wt%, and photoinitiator 1173 as the intermediate phase precursor, and silicone oil with a viscosity of 1000 cs as the outer phase. The flow rates of the three phases were adjusted by a peristaltic pump to generate O / W type microdroplets. The inner diameter of the inner phase channel was 600 μm, the inner diameter of the intermediate phase channel was 2000 μm, and the inner diameter of the outer phase channel was 5.0 mm. The flow rates of the inner phase were 2.0 mL / min, the intermediate phase flow rates were 1.8 mL / min, and the outer phase flow rates were 15 mL / min. The mesophase resin was cured at the microfluidic chip outlet using ultraviolet light at a power of 2000W for 3 seconds. Anhydrous ethanol was used to clean the surface of the water-bursting beads, removing silicone oil, unreacted monomers, photoinitiator, and surfactants. The beads were then dried in a forced-air drying oven at 30°C for 1 hour to form water-bursting beads. The resulting water-bursting beads had a diameter of approximately 2.98 mm and a wall thickness of approximately 204 μm.

[0061] Comparative Example 1

[0062] A method for preparing water-bursting beads includes the following steps:

[0063] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 1 wt% Tween-80 as the inner phase core material, and a mixture containing 5 wt% ethanol and 70 wt% tripropylene glycol diacrylate as the outer phase core material. 20wt% gelatin A 5 wt% photoinitiator 1173 was used as the intermediate phase of the wall material precursor, with silicone oil as the outer phase. The flow rates of the three-phase fluids were adjusted using a peristaltic pump to generate O / W-type microdroplets. The inner phase channel had an inner diameter of 410 μm, the intermediate phase channel had an inner diameter of 650 μm, and the outer phase channel had an inner diameter of 4.0 mm. The flow rates were 1.0 mL / min for the inner phase, 0.8 mL / min for the intermediate phase, and 10 mL / min for the outer phase. The intermediate phase resin was cured at the microfluidic chip outlet using UV light at a power of 2000 W for 3 seconds. Anhydrous ethanol was used to wash away the silicone oil, unreacted monomers, photoinitiator, and surfactant from the surface of the water-bursting beads. The beads were then dried in a forced-air drying oven at 30°C for 1 hour to form water-bursting beads. The resulting water-bursting beads had a diameter of approximately 1.93 mm and a wall thickness of approximately 178 μm.

[0064] Comparative Example 2

[0065] A method for preparing water-bursting beads includes the following steps:

[0066] A coaxial co-current focusing microfluidic chip was used, with deionized water containing 2 wt% Span-20 as the inner phase core material, and core materials containing 5 wt% ethanol and 70 wt% trimethylolpropane triacrylate. 20wt% β-cyclodextrin A three-phase mixture consisting of 5 wt% photoinitiator 1173 as the intermediate phase and 500 cs silicone oil as the outer phase was generated by regulating the flow rates of the three-phase fluids using a peristaltic pump. The inner phase channel had an inner diameter of 600 μm, the intermediate phase channel had an inner diameter of 2000 μm, and the outer phase channel had an inner diameter of 5.0 mm. The flow rates were 2.0 mL / min for the inner phase, 1.8 mL / min for the intermediate phase, and 15 mL / min for the outer phase. UV curing at the microfluidic chip outlet initiated the curing of the intermediate phase resin, forming water droplets. The resulting water droplets had a diameter of approximately 2.96 mm and a wall thickness of approximately 204 μm.

[0067] Comparative Example 3

[0068] A method for preparing water-bursting beads includes the following steps: using a coaxial co-current focusing microfluidic chip, and respectively using a core material containing 1 wt% OP-10 deionized water, 5 wt% ethanol, 70 wt% pentaerythritol tetraacrylate, and 20 wt%... Carboxymethyl chitosan A 5 wt% photoinitiator 1173 was used as the intermediate phase of the wall material precursor, and silicone oil with a viscosity of 1000 cs was used as the outer phase. The flow rates of the three-phase fluids were adjusted using a peristaltic pump to generate O / W type microdroplets. The inner phase channel had an inner diameter of 600 μm, the intermediate phase channel had an inner diameter of 2000 μm, and the outer phase channel had an inner diameter of 5.0 mm. The flow rates were 2.0 mL / min for the inner phase, 1.8 mL / min for the intermediate phase, and 15 mL / min for the outer phase. The intermediate phase resin was cured at the microfluidic chip outlet using UV light at a curing power of 2000 W for 2 seconds. Anhydrous ethanol was used to wash away the silicone oil, unreacted monomers, photoinitiator, and surfactant from the surface of the water-bursting beads, and the beads were dried in a forced-air drying oven at 30°C for 1 hour to form water-bursting beads. The resulting water-bursting beads had a diameter of approximately 3.03 mm and a wall thickness of approximately 223 μm.

[0069] The products obtained from the examples and comparative examples were tested according to the standards, and the test results are shown in Table 1 below. The test methods are as follows:

[0070] Roundness was measured using a microscope. The morphology of the burst beads was observed and measured under a microscope. A circle was fitted using the least squares method to obtain the position of the center of the outer contour of the burst bead shell and the radius R1 of the circle. The maximum distance dmax and minimum distance dmin from the outer contour of the burst bead shell to the center of the circle were also obtained. The roundness can be calculated using the following formula:

[0071]

[0072] Concentricity was measured using a microscope. The morphology of the burst beads was observed and measured under a microscope. The radii R1 and R2 of the inner and outer contour circles of the burst bead shell, as well as the distance d between the centers of the two circles, were obtained by fitting circles using the least squares method. The concentricity can be calculated using the following formula:

[0073]

[0074] The bursting strength was measured using an electronic universal testing machine and calculated using the following formula:

[0075]

[0076] The water-carrying capacity was determined using the standard test method of weight difference. The total mass of the bursting beads is m, and the mass of the core liquid is m. 水 The water-carrying capacity can be calculated using the following formula:

[0077]

[0078] The 7-day water retention rate was determined using the standard test method of weight difference. The initial mass of the burst beads was measured and recorded as m0. The burst beads were placed in a constant temperature and humidity chamber at 25℃ and 35% RH for 7 days, and the mass of the burst beads after 7 days was recorded as m7. The weight of the completely dried burst bead shell was then recorded as m. 壳 The 7-day water retention rate of the popping beads can be calculated using the following formula:

[0079] Table 1. Test results of water-bursting beads for each embodiment and comparative example.

[0080]

[0081]

[0082] The data underlined above are those that do not meet the requirements of this invention.

[0083] Due to limitations in the raw materials used, the functionality of the vinyl monomer has a significant impact on its strength. Examples 1 and 2 used difunctional raw materials; Example 3 used trimethylolpropane triacrylate, which is trifunctional. Higher functionality results in higher crosslinking density and higher strength.

[0084] Due to the properties of the raw materials themselves, the glycidyl methacrylate-modified silk fibroin content in Example 4 is relatively high, at 44 wt%. This raw material is highly hydrophilic, and its high content easily leads to water evaporation.

[0085] Comparative Example 1 was compared with Example 1, where Comparative Example 1 used unmodified gelatin, and Example 1 used commercially available methacrylic anhydride-modified gelatin. The test data shows that the bursting strength (5.12 kPa) of the water-bursting bead wall material prepared with gelatin in Comparative Example 1 is significantly lower than that of the water-bursting bead wall material prepared with methacrylic anhydride-modified gelatin in Example 1 (7.14 kPa). This is because gelatin is a linear macromolecule and does not contain a chemically cross-linked structure, thus it cannot form a chemically cross-linked double network structure with multifunctional vinyl monomers. Using methacrylic anhydride-modified gelatin introduces carbon-carbon double bond groups into the gelatin molecule, allowing for the formation of a chemically cross-linked structure through free radical polymerization. This, in turn, enables the formation of a chemically cross-linked double network structure with multifunctional vinyl monomers, increasing the cross-linking density and consequently improving the bursting strength.

[0086] Comparative Example 2 and Example 3 were compared, with Comparative Example 2 using unmodified β-cyclodextrin and Example 3 using self-made maleic anhydride-modified β-cyclodextrin. The test data showed that the bursting strength (6.89 kPa) of the water-bursting bead wall material prepared in Comparative Example 2 using β-cyclodextrin was significantly lower than that of the water-bursting bead wall material prepared in Example 3 using maleic anhydride-modified β-cyclodextrin (13.96 kPa). This is because β-cyclodextrin is a natural polysaccharide polymer with a cyclic structure, which cannot form a chemically cross-linked double network structure with multifunctional vinyl monomers. Modifying β-cyclodextrin with maleic anhydride introduces carbon-carbon double bond groups into the β-cyclodextrin molecule, allowing β-cyclodextrin to be covalently grafted into the polymer network through free radical polymerization. Furthermore, the numerous hydroxyl and carboxyl groups in the β-cyclodextrin molecule can form multiple intermolecular hydrogen bond interactions, increasing the cross-linking density and thus improving the bursting strength.

[0087] Comparative Example 3 will be compared with Example 5, wherein Comparative Example 3 uses unmodified materials. Carboxymethyl chitosan Example 5 used commercially available methacryloxycarboxymethyl chitosan. The test data shows that in Comparative Example 3... Carboxymethyl chitosan The bursting strength (7.48 kPa) of the water-bursting bead wall material prepared using methacryloyl carboxymethyl chitosan as the raw material in Example 5 is significantly lower than that (15.13 kPa). This is because carboxymethyl chitosan does not contain reactive groups capable of free radical polymerization, making it impossible to form a chemically cross-linked double network structure with multifunctional vinyl monomers through free radical polymerization. Furthermore, the introduction of the strongly hydrophilic carboxymethyl group weakens the hydrogen bonds in the chitosan molecule. Modifying carboxymethyl chitosan with methacrylic anhydride introduces carbon-carbon double bond groups into the carboxymethyl chitosan molecule, enabling it to form a chemically cross-linked double network structure with multifunctional vinyl monomers through free radical polymerization, thereby increasing the cross-linking density and thus improving the bursting strength.

[0088] As can be seen from the specific test data of the examples and comparative examples, the water-bursting beads of the double-network wall material of the present invention have the characteristics of high mechanical properties, high water content, and high water retention. Among these, the bursting strength of the water-bursting beads is related to the type and active groups of the modified natural polymer, the functionality of the ethylene monomer, and the content of both. On the one hand, by introducing vinyl groups (such as maleic acid-modified β-cyclodextrin, with a structure like...) into the natural polymer... Figure 3 As shown), it can undergo free radical polymerization, forming a double network structure through copolymerization with multifunctional vinyl monomers, thereby increasing the crosslinking density of the water-bursting bead wall material, and thus improving its mechanical properties and water retention rate. On the other hand, by further introducing epoxy-based active groups into the natural polymer, the bursting strength and water retention rate of the water-bursting beads can be further improved. Simultaneously, based on the abundant hydroxyl, carboxyl, and amino groups within the natural polymer, intermolecular hydrogen bonding interactions can be enhanced, further improving the mechanical properties of the water-bursting bead wall material. Furthermore, as the functionality of the vinyl monomers increases, the crosslinking degree of the water-bursting bead wall material's molecular network can be increased, thereby improving the mechanical properties and water retention rate of the water-bursting bead wall material (e.g., ...). Figure 4 Furthermore, increasing the content of modified natural polymers and multifunctional ethylene monomers can effectively improve the mechanical properties and water retention rate of water-bursting beads.

Claims

1. A type of double-network wall material water-bursting beads, characterized in that, The dual-network wall material water burst beads include a wall material and a core material; The wall material comprises the following parts by weight of raw materials: 5-25 parts of ethanol 30-70 parts of multifunctional vinyl monomer 20-60 parts of modified natural polymer Photoinitiator 1173, 1-5 parts; The multifunctional vinyl monomer is one or more of a difunctional vinyl monomer, a trifunctional vinyl monomer, or a tetrafunctional vinyl monomer; The modified natural polymer is a carbon-carbon double bond modified natural polymer or a carbon-carbon double bond and epoxy group modified natural polymer. The carbon-carbon double bond modified natural polymer is selected from one or more of the following: methacrylic anhydride modified gelatin, methacrylic acid modified silk fibroin, methacryloyl carboxymethyl chitosan, or maleic anhydride modified β-cyclodextrin. The carbon-carbon double bond and epoxy-modified natural polymers are selected from one or more of glycidyl methacrylate-modified gelatin and glycidyl methacrylate-modified silk fibroin. The core material includes deionized water and surfactant.

2. The double-network wall material water-bursting beads according to claim 1, characterized in that, The difunctional vinyl monomer is selected from one or more of tripropylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, or neopentyl glycol diacrylate.

3. The double-network wall material water-bursting beads according to claim 1, characterized in that, The trifunctional vinyl monomer is selected from one or more of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, glycerol propoxy acid (1PO / OH) triacrylate, trimethanol propane ethoxy ester triacrylate, and propoxylated trimethylolpropane triacrylate.

4. The double-network wall material water-bursting beads according to claim 1, characterized in that, The tetrafunctional vinyl monomer is selected from one or more of pentaerythritol tetraacrylate and bis(trimethylolpropane)tetraacrylate.

5. A microfluidic control method for preparing water-bursting beads of a dual-network wall material as described in any one of claims 1-4, characterized in that, The microfluidic preparation method includes the following steps: a) Using water-containing popping bead core material, wall material precursor and silicone oil as the inner phase, middle phase and outer phase respectively, the flow rate of the three-phase fluid is adjusted by a peristaltic pump to generate O / W type microdroplets; b) Water droplets are formed by UV curing at the outlet; c) The water-bursting beads of the double-network wall material are obtained by washing with anhydrous ethanol and drying.

6. The microfluidic preparation method according to claim 5, characterized in that, In step a), the inner diameter of the channel of the inner phase is 300-600 μm, the inner diameter of the channel of the intermediate phase is 500-2000 μm, and the inner diameter of the channel of the outer phase is 4.0-5.0 mm.

7. The microfluidic preparation method according to claim 5 or 6, characterized in that, The internal phase flow rate in step a) is 0.5-2 mL / min, the intermediate phase flow rate is 0.5-2 mL / min, and the external phase flow rate is 10-15 mL / min.

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