Giant electrorheological fluid capsule, preparation method and application of giant electrorheological fluid capsule in rigid-flexible matrix digital controllable intelligent material

Abstract

The invention discloses a giant electrorheological fluid capsule, a preparation method and application of the giant electrorheological fluid capsule in a rigid-flexible matrix digital controllable intelligent material, and belongs to the technical field of novel intelligent materials. The giant electrorheological fluid capsule comprises an inner core and an outer core, wherein the inner core is formed by giant electrorheological fluid; the organic shell layer wraps the inner core; the surface modification layer is positioned outside the organic shell layer; wherein the surface modification layer is a siloxane layer which is formed through silanization reaction and is terminated by a low-surface-energy substance. The invention also provides a preparation method of the composition. Compared with the prior art, the preparation method has the advantages that the surface energy of a shell layer is reduced, the wetting and compatibility with non-polar external phases such as silicone oil are improved, secondary coagulation and electrostatic agglomeration are inhibited, the dielectric loss is reduced, and more stable long-term rheological property is obtained while the response speed and yield stress are ensured.

Description

Technical Field

[0001] This invention relates to the field of novel smart materials technology, and in particular to a giant electrorheological fluid capsule, its preparation method, and its application in rigid-flexible matrix digitally controllable smart materials. Background Technology

[0002] Electrorheological fluids are a general term for a class of liquids whose viscosity increases significantly with increasing electric field strength. When the electric field increases to a certain threshold, the rheological properties of the fluid change. As a novel type of smart material, electrorheological fluids have distinct characteristics and advantages, and their rheological properties that change with electric field strength indicate a broad market prospect.

[0003] Giant electrorheological fluids are widely used in applications such as damping regulation, haptic feedback, and programmable structural components. The core advantage lies in the rapid and reversible increase of the system's yield stress under an applied electric field, while maintaining low loss and low viscosity background after the field is removed. Existing systems are mostly dispersed as solid particles or microcapsules in non-polar media such as silicone oil, and their performance is significantly affected by the coupling of particle-oil interfacial energy, interparticle interactions, and electrical losses.

[0004] However, traditional technologies mainly rely on surfactants to maintain the stable dispersion of solid particles in silicone oil. But surfactants are prone to migration and rearrangement under strong electric fields and temperature rise conditions, leading to bridging, secondary coagulation, and increased dielectric loss, as well as drift of yield stress and response window over time. In existing technologies, if the shell solvent is miscible with the giant current rheostat base fluid (such as silicone oil), it can cause problems such as difficulty in capsule formation and core leakage.

[0005] CN104774675A discloses an improved giant electrorheological fluid (GER) and its preparation method. The GER comprises: a metal salt nanocomposite coated with urea; a polar molecular additive; and a highly wettable insulating liquid; wherein the metal salt nanocomposite is suspended in the highly wettable insulating liquid. By adding the polar molecular additive, the yield stress of the GER under an electric field is increased by more than 50%, while the current density is reduced to less than one-quarter of the original GER. The reversible response time remains the same, while the sedimentation stability is significantly improved. The zero-field viscosity of the improved GER is the same as that of the GER without the additive. The improved GER properties enhance electrical and mechanical properties and can be applied to vehicle clutches, hydraulic brakes, and vehicle shock absorbers. However, its performance needs further improvement. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a giant electrorheological fluid capsule that, in a silicone oil system, simultaneously inhibits secondary coagulation and electrostatic agglomeration, reduces dielectric loss, without sacrificing yield stress and response speed, and improves cycle and storage stability.

[0007] To achieve the above objectives, the present invention provides a giant electrorheological fluid capsule and a method for preparing the same.

[0008] The giant electrorheological fluid capsule can be prepared by methods known in the art, such as microfluidics, membrane emulsification, or high-pressure homogenization emulsification.

[0009] A method for preparing a giant electrorheological fluid capsule, characterized by comprising the following steps:

[0010] (1) Provide a giant electrorheological fluid as the core phase;

[0011] (2) An organic shell is formed outside the core phase by interfacial polymerization reaction to obtain a preliminary microcapsule;

[0012] (3) The initial microcapsules are subjected to surface silanization treatment to form a siloxane layer;

[0013] (4) The siloxane layer is capped with a capping agent to obtain the giant electrorheological fluid capsule.

[0014] A further preferred method for preparing giant electrorheological fluid capsules includes the following steps:

[0015] 1) Solution preparation:

[0016] Toluene-2,4-diisocyanate was added to a solvent and stirred until homogeneous to obtain an organic shell solution.

[0017] Weigh out polyvinyl alcohol and add it to water. Heat the mixture and cool it to room temperature. Then add ethylenediamine and stir until homogeneous to obtain an outer aqueous phase solution.

[0018] 2) Microfluidic controlled droplet and collection:

[0019] Three syringes were filled with giant electrorheological fluid, organic shell solution, and outer aqueous phase solution, respectively, and connected to the three inlets of the flow-focusing microfluidic chip.

[0020] A double emulsion droplet is formed in the chip channel, consisting of a core of giant electrorheological fluid, a middle organic layer containing diisocyanate, and an outer aqueous phase. The droplets are continuously produced and collected, and magnetically stirred to prevent aggregation, resulting in an emulsion droplet suspension.

[0021] 3) Interface aggregation and solidification:

[0022] The collected emulsion droplet suspension was placed in a constant temperature water bath for treatment to obtain pre-formed microcapsules.

[0023] 4) Cleaning and drying:

[0024] Store under the following conditions: filtration, washing, drying, sealing, protection from light, and dryness.

[0025] A further preferred method for preparing giant electrorheological fluid capsules includes the following steps:

[0026] 1) Solution preparation:

[0027] Weigh 9-11g of toluene-2,4-diisocyanate and add it to 90-100g of solvent and stir until homogeneous to obtain an organic shell solution;

[0028] Weigh 1-2g of polyvinyl alcohol and add it to 90-110mL of water. Heat and stir at 80-100℃ until completely dissolved. After cooling to room temperature, add 4-6g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0029] 2) Microfluidic controlled droplet and collection:

[0030] Three syringes were respectively filled with giant electrorheological fluid, organic shell solution, and outer aqueous phase solution, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0031] Giant electrorheological fluid: 1-6 mL per hour;

[0032] Organic shell solution: 1-5 mL per hour;

[0033] Outer aqueous phase solution: 10-20 mL per hour;

[0034] A double emulsion droplet is formed in the chip channel, consisting of a core of giant electrorheological fluid, a middle organic layer containing diisocyanate, and an outer aqueous phase. The droplets are continuously produced and collected, and magnetically stirred to obtain an emulsion droplet suspension.

[0035] 3) Interface aggregation and solidification:

[0036] The collected emulsion droplet suspension was placed in a constant temperature water bath at 40-50℃ and shaken at 100-200 times per minute for 1-3 hours to obtain the initial microcapsules.

[0037] 4) Cleaning and drying:

[0038] The microcapsules were filtered through a 0.45-micron microporous membrane; they were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40-50℃ for 12-24 hours to obtain dried giant electrorheological fluid capsules; they were stored under sealed, light-proof and dry conditions.

[0039] The solvent may be selected from organic solvents that are immiscible or poorly miscible with the giant current rheological fluid base, including but not limited to cyclohexane, dibutyl sebacate, dibutyl phthalate and their mixtures.

[0040] Capsules with toluene-2,4-diisocyanate and ethylenediamine shells are used in giant electrorheological fluids. Current technologies primarily rely on surfactants to maintain their stability in silicone oil, resulting in generally poor compatibility and a tendency for secondary aggregation, which negatively impacts performance. Therefore, a silanized shell is introduced outside the toluene-2,4-diisocyanate and ethylenediamine shells. The active functional group -NH2 interacts with the external phase, improving the compatibility between the capsule and silicone oil. However, this process is prone to embrittlement and slows the response. Further modification with hexamethyldisilazane significantly reduces interfacial polarity and surface free energy, changing the wetting of the shell from restricted to spontaneous, and the expansion coefficient from negative to positive, thus weakening short-range attraction and bridging channels. Simultaneously, the methylsiloxane outer layer slightly swells in the silicone oil, forming a nanoscale soft brush-like layer that provides charge-free steric hindrance stability and improves yield stress and response time. It also significantly reduces static adhesion and slows the migration of polar molecules from the core to the external phase, delaying the drift of performance parameters over time.

[0041] In silicone oil systems, it simultaneously suppresses secondary solidification and electrostatic agglomeration, reduces dielectric loss, without sacrificing yield stress and response speed, and improves cycle and storage stability.

[0042] A further preferred method for preparing giant electrorheological fluid capsules includes the following steps:

[0043] 1) Solution preparation:

[0044] Weigh 9-11g of toluene-2,4-diisocyanate and add it to 90-100g of anhydrous cyclohexane solvent and stir until homogeneous to obtain an organic shell solution.

[0045] Weigh 1-2g of polyvinyl alcohol and add it to 90-110mL of water. Heat and stir at 80-100℃ until completely dissolved. After cooling to room temperature, add 4-6g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0046] 2) Microfluidic controlled droplet and collection:

[0047] Three syringes were respectively filled with giant electrorheological fluid, organic shell solution, and outer aqueous phase solution, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0048] Giant electrorheological fluid: 1-6 mL per hour;

[0049] Organic shell solution: 1-5 mL per hour;

[0050] Outer aqueous phase solution: 10-20 mL per hour;

[0051] A double emulsion droplet is formed in the chip channel, consisting of a core of giant electrorheological fluid, a middle organic layer containing diisocyanate, and an outer aqueous phase. The droplets are continuously produced and collected, and magnetically stirred to obtain an emulsion droplet suspension.

[0052] 3) Interface aggregation and solidification:

[0053] The collected emulsion droplet suspension was placed in a constant temperature water bath at 40-50℃ and shaken at 100-200 times per minute for 1-3 hours to obtain the initial microcapsules.

[0054] 4) Cleaning and drying:

[0055] Filter using a 0.45-micron microporous membrane; rinse alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; place the pre-formed microcapsules under vacuum drying at 40-50℃ for 12-24 hours to obtain dried giant electrorheological fluid capsules; store under sealed, light-proof, and dry conditions.

[0056] 5) Mix 70-80 mL of anhydrous ethanol and 5-10 mL of water evenly, then add glacial acetic acid to adjust the pH to 4-4.5. Under an ice-water bath, add silane compound and stir at 300-500 rpm for 30-60 min to obtain silica sol. Add the dried capsules obtained in step 4) to the silica sol and mix evenly. The solid content should be 5-10 wt%. Stir at 300-500 rpm for 20-40 min at 20-30℃. Raise the temperature to 40-50℃, adjust the pH to 4-5, and treat for 60-120 min. After the reaction is complete, centrifuge, wash, and dry to obtain the treated capsules. 6) Add the capsules treated in step 5) to 10-12 mL of end-capping agent and treat at 40-50℃ under a nitrogen atmosphere for 6-10 h. Remove, wash, and dry to obtain giant electrorheological fluid capsules.

[0057] The silane compound is at least one selected from tetrakis(2-ethylhexyloxy)silane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, ethyl silicate, and 3-aminopropyltriethoxysilane. More preferably, the silane compound is a mixture of tetrakis(2-ethylhexyloxy)silane and N-(2-aminoethyl)-3-aminopropyltriethoxysilane in a volume ratio of (7-9):(0.5-2).

[0058] The capping agent is hexamethyldisilazane.

[0059] The method for preparing the giant electrorheological fluid includes the following steps:

[0060] 1) Heat dimethyl silicone oil in an ice-water bath at 0-5℃ with stirring, then add 4A molecular sieve and mix, then separate and remove the 4A molecular sieve; then add Span 80 and stir evenly.

[0061] 2) Add urea to coat titanium-based inorganic materials, shear and disperse them, then increase the rotation speed to continue shearing treatment;

[0062] 3) Insert an ultrasonic probe into the mixture for treatment;

[0063] 4) Transfer to a vacuum planetary mixer, degas, release the vacuum, discharge, and obtain a giant electrorheological fluid.

[0064] The method for preparing urea-coated titanium-based inorganic materials includes the following steps:

[0065] S1 is prepared by adding 9-11g of titanium-based inorganic material to 800-1000mL of saturated urea solution at 60-70℃ and ultrasonically dispersing for 30-60min.

[0066] S2 is heated to 80-90℃, stirred at 100-300rpm, connected to a vertical condenser for atmospheric distillation and collection of the distillate, and kept at a constant temperature for 1-6 hours to obtain a concentrated slurry;

[0067] S3 cools the above concentrated slurry to 0-5°C and lets it stand for 12-24 hours to promote the recrystallization of urea on the surface of nanowires to form a coating layer.

[0068] S4 filtration, ethanol washing, vacuum drying at 60-70℃ and -0.095MPa for 12-24h, and passing through a 100-200 mesh sieve to obtain urea-coated titanium-based inorganic material.

[0069] The titanium-based inorganic material mentioned therein is at least one of titanium dioxide and barium titanate.

[0070] The present invention also provides a giant electrorheological fluid capsule, which is prepared by the above method.

[0071] This invention also provides an application of a giant electrorheological fluid capsule in a rigid-flexible matrix digitally controllable smart material.

[0072] The beneficial effects of this invention are:

[0073] 1. Compared with the prior art, the present invention introduces a silanized layer outside the organic shell and performs end passivation with low polar groups (such as methyl groups), which significantly reduces the surface energy of the shell, improves the wetting and compatibility with non-polar external phases such as silicone oil, inhibits secondary condensation and electrostatic agglomeration, and reduces dielectric loss. While ensuring response speed and yield stress, it obtains more stable long-term rheological properties.

[0074] 2. Compared with existing technologies, the shell layer is prepared by the synergistic effect of tetra(2-ethylhexyloxy)silane and amino-containing silane to create an organic-inorganic interpenetrating network, which improves toughness while maintaining the integrity of the shell layer and reduces the risk of embrittlement caused by microcracks and local excessive cross-linking. Detailed Implementation

[0075] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0076] Flow-focused microfluidic chip (Suzhou Wenhao Microfluidics Technology Co., Ltd., Model: 3.2.002.00.036) - Focused PDMS chip with a channel depth of 50 μm and a linewidth of 100 μm, PDMS-glass slide bonding.

[0077] Other raw materials not mentioned are all common raw materials. The above content is only for the purpose of illustrating the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase the same / similar raw materials from the market or prepare them themselves.

[0078] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0079] Example 1

[0080] A method for preparing anatase titanium dioxide nanowire powder includes the following steps:

[0081] Step (1) Add 240 mL of tetrabutyl titanate to 600 mL of 10 mol / L NaOH aqueous solution at a rate of 5 mL / min and mix well. Heat to 40 °C. After the addition is complete, continue stirring for 60 min to obtain a milky white sodium titanate precursor suspension.

[0082] Step (2) The above suspension was transferred into a polytetrafluoroethylene-lined high-pressure reactor and heated to 180°C at 2°C / min and kept at that temperature for 24 hours. The heating was stopped and the mixture was allowed to cool naturally to room temperature to obtain a white product.

[0083] Step (3) Transfer the product to a 500 mL centrifuge cup, centrifuge at 10000 rpm for 15 min, and discard the supernatant; add 400 mL of water and sonicate for 5 min, then centrifuge again, repeat until the supernatant pH=7; then disperse the precipitate in 2 L 0.1 M HCl solution, stir at 300 rpm for 2 h, and then wash with water until the supernatant pH=7 to obtain hydrogen-form titanate nanowires;

[0084] Step (4) The hydrogen-type titanate nanowires were dried at 80°C for 24 hours, ground into a fine powder, placed in an alumina crucible, heated to 500°C at 5°C / min and held for 2 hours, then cooled to 200°C at 2°C / min and cooled to room temperature with the furnace to obtain anatase titanium dioxide nanowire powder.

[0085] Example 2

[0086] A method for preparing urea-coated titanium dioxide nanowire powder includes the following steps:

[0087] S1 At 65°C, 10g of the anatase titanium dioxide nanowire powder obtained in Example 1 was added to 1000mL of saturated urea solution and ultrasonically dispersed (600W, 3s on / 2s off) for 30min.

[0088] S2 is heated to 80℃, stirred at 200rpm, connected to a vertical condenser for atmospheric distillation and collection of the distillate, and kept at a constant temperature for 5 hours to obtain a concentrated slurry.

[0089] S3 cools the above concentrated slurry to 4°C and lets it stand for 12 hours to promote the recrystallization of urea on the surface of nanowires to form a coating layer.

[0090] S4 filtration, ethanol washing, vacuum drying at 60℃ and −0.095MPa for 12h, and passing through a 200-mesh sieve to obtain urea-coated titanium dioxide nanowire powder.

[0091] Example 3

[0092] The preparation method of giant electrorheological fluid includes the following steps:

[0093] 1) Add 500g of dimethyl silicone oil with a viscosity of 100cSt to a beaker and control the temperature in an ice-water bath at 5℃; mechanically stir at 500rpm for 5min, add 10g of 4A molecular sieve, increase the stirring speed to 2000rpm for 30min, then separate and remove the 4A molecular sieve; then add 3g of Span 80 and stir evenly.

[0094] 2) Add 100g of urea-coated titanium dioxide nanowire powder prepared in Example 2, shear at 5000rpm for 10min, and then increase to 12000rpm for 30min;

[0095] 3) Transfer the mixture to a wide-mouth container, insert the ultrasonic probe, set it to 800W, turn it on for 5 seconds and turn it off for 3 seconds, for a total of 30 minutes to complete dispersion and degassing;

[0096] 4) Transfer to a vacuum planetary mixer, and degas for 60 minutes at 60℃ and −0.098MPa, with a revolution of 30 rpm and a rotation of 50 rpm. Release the vacuum, discharge the material, and obtain a uniform and fine giant electrorheological fluid.

[0097] Example 4

[0098] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0099] 1) Solution preparation:

[0100] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0101] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0102] 2) Microfluidic controlled droplet and collection:

[0103] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0104] Giant electrorheological fluid: 5 mL per hour;

[0105] Organic shell solution: 3 mL per hour;

[0106] Outer aqueous phase solution: 15 mL per hour;

[0107] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0108] 3) Interface aggregation and solidification:

[0109] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0110] 4) Cleaning and drying:

[0111] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried giant electrorheological fluid capsules; and stored under sealed, light-proof, and dry conditions.

[0112] Example 5

[0113] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0114] 1) Solution preparation:

[0115] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0116] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0117] 2) Microfluidic controlled droplet and collection:

[0118] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0119] Giant electrorheological fluid: 5 mL per hour;

[0120] Organic shell solution: 3 mL per hour;

[0121] Outer aqueous phase solution: 15 mL per hour;

[0122] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0123] 3) Interface aggregation and solidification:

[0124] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0125] 4) Cleaning and drying:

[0126] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0127] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 9 mL of ethyl silicate and 1 mL of 3-aminopropyltriethoxysilane, and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm for 20 min at 30 °C, raise the temperature to 40 °C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain the treated capsules. 6) Add the capsules treated in step 5) to 10 mL of hexamethyldisilazane and treat at 40 °C for 8 h under a nitrogen atmosphere. Take out, wash, and dry to obtain giant electrorheological fluid capsules.

[0128] Example 6

[0129] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0130] 1) Solution preparation:

[0131] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0132] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0133] 2) Microfluidic controlled droplet and collection:

[0134] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0135] Giant electrorheological fluid: 5 mL per hour;

[0136] Organic shell solution: 3 mL per hour;

[0137] Outer aqueous phase solution: 15 mL per hour;

[0138] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0139] 3) Interface aggregation and solidification:

[0140] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0141] 4) Cleaning and drying:

[0142] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0143] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 9 mL of ethyl silicate and 1 mL of 3-aminopropyltriethoxysilane, and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm at 30°C for 20 min, then raise the temperature to 40°C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain giant electrorheological fluid capsules.

[0144] Example 7: Method for preparing giant electrorheological fluid capsules, comprising the following steps:

[0145] 1) Solution preparation:

[0146] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0147] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0148] 2) Microfluidic controlled droplet and collection:

[0149] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0150] Giant electrorheological fluid: 5 mL per hour;

[0151] Organic shell solution: 3 mL per hour;

[0152] Outer aqueous phase solution: 15 mL per hour;

[0153] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0154] 3) Interface aggregation and solidification:

[0155] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0156] 4) Cleaning and drying:

[0157] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0158] 5) Add the dried capsules obtained in step 4) to 10 mL of hexamethyldisilazane, treat at 40 °C for 8 h under a nitrogen atmosphere, remove, wash and dry to obtain giant electrorheological fluid capsules.

[0159] Example 8

[0160] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0161] 1) Solution preparation:

[0162] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0163] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0164] 2) Microfluidic controlled droplet and collection:

[0165] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0166] Giant electrorheological fluid: 5 mL per hour;

[0167] Organic shell solution: 3 mL per hour;

[0168] Outer aqueous phase solution: 15 mL per hour;

[0169] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0170] 3) Interface aggregation and solidification:

[0171] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0172] 4) Cleaning and drying:

[0173] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0174] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 9 mL of tetrakis(2-ethylhexyloxy)silane and 1 mL of N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm for 20 min at 30 °C, raise the temperature to 40 °C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain the treated capsules. 6) Add the capsules treated in step 5) to 10 mL of hexamethyldisilazane and treat at 40 °C for 8 h under a nitrogen atmosphere. Take out, wash, and dry to obtain giant electrorheological fluid capsules.

[0175] Example 9

[0176] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0177] 1) Solution preparation:

[0178] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0179] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0180] 2) Microfluidic controlled droplet and collection:

[0181] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0182] Giant electrorheological fluid: 5 mL per hour;

[0183] Organic shell solution: 3 mL per hour;

[0184] Outer aqueous phase solution: 15 mL per hour;

[0185] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0186] 3) Interface aggregation and solidification:

[0187] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0188] 4) Cleaning and drying:

[0189] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0190] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 9 mL of tetrakis(2-ethylhexyloxy)silane and 1 mL of N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm at 30°C for 20 min, then raise the temperature to 40°C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain giant electrorheological fluid capsules.

[0191] Example 10

[0192] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0193] 1) Solution preparation:

[0194] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0195] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0196] 2) Microfluidic controlled droplet and collection:

[0197] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0198] Giant electrorheological fluid: 5 mL per hour;

[0199] Organic shell solution: 3 mL per hour;

[0200] Outer aqueous phase solution: 15 mL per hour;

[0201] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0202] 3) Interface aggregation and solidification:

[0203] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0204] 4) Cleaning and drying:

[0205] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0206] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 10 mL of tetrakis(2-ethylhexyloxy)silane and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm at 30°C for 20 min, then raise the temperature to 40°C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain giant electrorheological fluid capsules.

[0207] Example 11

[0208] A method for preparing giant electrorheological fluid capsules includes the following steps:

[0209] 1) Solution preparation:

[0210] Weigh 10g of toluene-2,4-diisocyanate and add it to 90g of anhydrous cyclohexane and stir until homogeneous to obtain an organic shell solution.

[0211] Weigh 1g of polyvinyl alcohol (KurarayPOVAL™205) and add it to 99mL of water. Heat and stir at 90℃ until completely dissolved. After cooling to room temperature, add 5g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution.

[0212] 2) Microfluidic controlled droplet and collection:

[0213] Three syringes were respectively filled with the giant electrorheological fluid, organic shell solution, and outer aqueous phase solution prepared in Example 3, and connected to the three inlets of the flow-focusing microfluidic chip; the flow rates were adjusted and stabilized under a microscope as follows:

[0214] Giant electrorheological fluid: 5 mL per hour;

[0215] Organic shell solution: 3 mL per hour;

[0216] Outer aqueous phase solution: 15 mL per hour;

[0217] Double emulsions are formed in the chip channel, with a core of giant electrorheological fluid, an organic layer containing diisocyanate in the middle, and an outer aqueous phase. They are continuously produced and collected in a beaker containing 50 mL of the outer aqueous phase solution. The beaker is magnetically stirred at 200 rpm to prevent aggregation, and an emulsion suspension is obtained.

[0218] 3) Interface aggregation and solidification:

[0219] The collected emulsion droplet suspension was placed in a 40°C constant temperature water bath and shaken 100 times per minute for 2 hours to obtain the initial microcapsules.

[0220] 4) Cleaning and drying:

[0221] The microcapsules were filtered through a 0.45-micron microporous membrane; the microcapsules were rinsed alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; the pre-formed microcapsules were vacuum dried at 40°C for 12 hours to obtain dried capsules; and stored under sealed, light-proof, and dry conditions.

[0222] 5) Mix 75 mL of anhydrous ethanol and 5 mL of water evenly, then add glacial acetic acid to adjust the pH to 4.3. Under an ice-water bath, add 10 mL of N-(2-aminoethyl)-3-aminopropyltriethoxysilane and stir at 500 rpm for 30 min to obtain silica sol. Add the dried capsules obtained in step 4) to the above silica sol and mix evenly. The solid content is 10 wt%. Stir at 500 rpm at 30°C for 20 min, then raise the temperature to 40°C, adjust the pH to 5.0, and treat for 60 min. After the reaction is completed, centrifuge, wash, and dry to obtain giant electrorheological fluid capsules.

[0223] Test Example 1

[0224] Long-term stability (resistance to settlement) test:

[0225] Test method:

[0226] 1. Mix 0.5g of microcapsules with 1g of dimethyl silicone oil (10cSt) to obtain a suspension.

[0227] 2. Place the sample into a graduated transparent sample tube and let it stand.

[0228] 3. Observe and photograph the settling interface height daily, and record the ratio of the settling interface height H to the initial liquid column height H0 (H / H0); whether a clear interface appears at the end of 30 days; and the redispersion time after slight shaking (manually 5 times).

[0229] Acceptable criteria: After standing for 30 days, the sedimentation volume ratio is < 5%. After inverting the sample tube and shaking it manually 10 times, it should redisperse into a homogeneous suspension within 60 seconds, with no visible stubborn precipitates. This is the most direct and successful proof of microencapsulation.

[0230] Table 1

[0231] Will the interface appear after 30 days? Shake and then disperse time / s Example 4 yes 45 Example 5 no 9 Example 6 yes 18 Example 7 yes 12 Example 8 no 5 Example 9 yes 15 Example 10 yes 11 Example 11 yes 20

[0232] Test Example 2

[0233] Test item: Performance after high temperature and high humidity storage.

[0234] Equipment: Constant temperature and humidity chamber.

[0235] Methods: The microcapsule powder was stored at 85℃ / 85%RH for 500 hours. Afterwards, it was removed, cooled to room temperature, and a DC electric field of E=3.0kV / mm was applied. After stabilization for 60 seconds, the same shear rate scan was performed. The yield stress was obtained by fitting the flow curve using the Bingham model with rheometer software. Each sample was repeated three times.

[0236] Acceptable standard: After storage, the attenuation rate of its yield stress (τ_y) is <10%.

[0237] Table 2

[0238] Attenuation rate / % Example 4 17.2 Example 5 7.6 Example 6 14.3 Example 7 8.8 Example 8 6.4 Example 9 12.0 Example 10 10.8 Example 11 16.1

[0239] As can be seen from the data in Tables 1 and 2, the capsules with toluene-2,4-diisocyanate and ethylenediamine shells used in Example 4 for giant electrorheological fluid have poor compatibility with silicone oil and are prone to moisture absorption, which means that the anti-settling and damp heat resistance need to be further improved.

[0240] Example 5 introduces a silanized shell and modifies it with hexamethyldisilazane, which significantly reduces interfacial polarity and surface free energy, making the wetting of the shell by the silicone oil change from restricted to spontaneous (the expansion coefficient changes from negative to positive), thereby weakening short-range attraction and bridging channels; at the same time, the methylsiloxane outer layer swells slightly in the silicone oil to form a nanoscale soft brush-like layer, providing charge-free steric hindrance stability and improving yield stress.

[0241] Example 6 uses silanization treatment to improve the adhesion and mechanical integrity of the inner and outer layers, but the surface still exposes hydrophilic sites such as -Si-OH and -NH2, which increases polarity and hygroscopicity, but still has a great impact on its stability and yield stress.

[0242] Example 7 uses hexamethyldisilazane to treat the hydrophilic sites on the surface to methylate, which significantly reduces the surface free energy, improves silicone oil wetting and weakens short-range attraction and bridging, and also inhibits moisture absorption, thereby improving its stability and resistance to damp heat.

[0243] The performance of Example 8 is better than that of Example 2. The possible reason is that tetra(2-ethylhexyloxy)silane has greater steric hindrance and is easier to form a more uniform outer network with fewer defects, which reduces the generation of microcracks and localized highly cross-linked hard spots. N-(2-aminoethyl)-3-aminopropyltriethoxysilane has a double amine end, which forms multiple hydrogen bonds with the shell and forms an organic-inorganic interpenetrating network at the interface, improving the continuity and toughness of the shell, while being more compatible with silicone oil.

[0244] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A giant electrorheological fluid capsule, characterized in that, include: - A core composed of giant electrorheological fluid; - An organic shell that encloses the core; -and a surface modification layer located outside the organic shell layer; The surface modification layer is a siloxane layer formed by silanization reaction and capped with a low surface energy material.

2. A method for preparing the giant electrorheological fluid capsule as described in claim 1, characterized in that, Includes the following steps: (1) Provide a giant electrorheological fluid as the core phase; (2) An organic shell is formed outside the core phase by interfacial polymerization reaction to obtain a preliminary microcapsule; (3) The initial microcapsules are subjected to surface silanization treatment to form a siloxane layer; (4) The siloxane layer is capped with a capping agent to obtain the giant electrorheological fluid capsule.

3. The method for preparing giant electrorheological fluid capsules as described in claim 2, characterized in that, Includes the following steps: 1) Solution preparation: At 0-5℃, dimethyl silicone oil is mixed with 4A molecular sieve, and then the 4A molecular sieve is separated and removed. Span 80 is then added and stirred evenly. Urea-coated titanium-based inorganic materials are added and sheared and dispersed to obtain a giant electrorheological fluid. Toluene-2,4-diisocyanate was added to a solvent to obtain an organic shell solution; Polyvinyl alcohol, water, and ethylenediamine are mixed to obtain an outer aqueous phase solution; 2) Microfluidic control of droplets and collection: A giant electrorheological fluid, an organic shell solution, and an outer aqueous solution are injected into a focusing microfluidic chip to form an emulsion suspension with a giant electrorheological fluid core, an organic shell in the middle, and an aqueous phase on the outer layer. 3) Interface aggregation and solidification: The collected emulsion droplet suspension was placed in a constant temperature water bath for treatment to obtain pre-formed microcapsules. 4) Cleaning and drying.

4. The method for preparing giant electrorheological fluid capsules as described in claim 3, characterized in that, Includes the following steps: 1) Solution preparation: Weigh 9-11g of toluene-2,4-diisocyanate and add it to 90-100g of solvent and stir until homogeneous to obtain an organic shell solution; Weigh 1-2g of polyvinyl alcohol and add it to 90-110mL of water. Heat and stir at 80-100℃ until completely dissolved. After cooling to room temperature, add 4-6g of ethylenediamine and stir evenly to obtain the outer aqueous phase solution. 2) Microfluidic control of droplets and collection: Three syringes were filled with giant electrorheological fluid, organic shell solution, and outer aqueous phase solution, respectively, and connected to the three inlets of the flow-focusing microfluidic chip. A double emulsion droplet is formed in the chip channel, consisting of a core of giant electrorheological fluid, a middle organic layer containing diisocyanate, and an outer aqueous phase. The droplets are continuously produced and collected, and magnetically stirred to obtain an emulsion droplet suspension. 3) Interface aggregation and solidification: The collected emulsion droplet suspension was placed in a constant temperature water bath at 40-50℃ and shaken at 100-200 times per minute for 1-3 hours to obtain the initial microcapsules. 4) Cleaning and drying: Filter using a 0.45-micron microporous membrane; rinse alternately with water and anhydrous ethanol to remove unreacted monomers and polyvinyl alcohol residues; The pre-formed microcapsules were vacuum dried at 40-50℃ for 12-24 hours to obtain dried giant electrorheological fluid capsules; they were then stored under sealed, light-proof, and dry conditions.

5. The method for preparing giant electrorheological fluid capsules as described in claim 4, characterized in that, It also includes step 5): forming a silanized layer on the surface of the capsule obtained in step 4).

6. The method for preparing giant electrorheological fluid capsules as described in claim 5, characterized in that, The preparation method of step 5) is as follows: mix anhydrous ethanol and water evenly, then adjust the pH, add silane compound under ice-water bath, stir and treat to obtain silica sol; add the dried capsules obtained in step 4) to the above silica sol and mix evenly, heat and treat to obtain capsules.

7. The method for preparing giant electrorheological fluid capsules as described in claim 6, characterized in that, It also includes step 6), the specific preparation method of which is: add the capsule treated in step 5) above into the capping agent, heat it under a nitrogen atmosphere, and obtain the giant electrorheological fluid capsule.

8. The method for preparing giant electrorheological fluid capsules as described in claim 6, characterized in that, The silane compound is at least one of tetra(2-ethylhexyloxy)silane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, ethyl silicate, and 3-aminopropyltriethoxysilane.

9. The method for preparing giant electrorheological fluid capsules as described in claim 6, characterized in that, The capping agent is hexamethyldisilazane.

10. The application of the giant electrorheological fluid capsule as described in claim 1 in rigid-flexible matrix digitally controllable smart materials.