Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to propose the technical solution of the present invention, and further explain the technical solution, the implementation process and the principle thereof, etc.
As an aspect of the technical solution of the present invention, it relates to an electrorheological fluid comprising: the dispersion medium comprises an insulating liquid, and the dispersed phase metal-organic framework-titanium oxide composite is uniformly dispersed in the insulating liquid of the dispersion medium.
In some embodiments, the content of the metal-organic framework-titanium oxide composite in the electrorheological fluid is 10 to 70wt%, preferably 20 to 60 wt%.
In some embodiments, the metal-organic framework-titanium oxide composite is formed by reacting a metal-organic framework material and an organotitanate. The metal organic framework-titanium oxide compound has a three-dimensional porous structure, is large in specific surface area, loads a large number of polar groups, and is excellent in electrorheological property and large in dynamic shear stress.
Wherein, the metal organic framework material can be any metal organic framework prepared by adopting a method known in the field.
Further, the metal organic framework material is preferably an organic-inorganic hybrid particle with intramolecular pores formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds, and the specific surface area is preferably more than 1500m2(ii) per gram of metal organic framework particles.
In some embodiments, the dielectric constant of the insulating liquid is 1 to 10(20 ℃, 10)-2Hz) and an electrical conductivity of 10-15~10-10(Ω·cm)-1Any one or a combination of two or more of silicone oil, castor oil, hydraulic oil, and the like is preferable, but not limited thereto.
The insulating liquid has good wettability to the metal organic framework-titanium oxide compound particles and can be spread on the surfaces of the metal organic framework-titanium oxide compound particles. The electric field is applied, the metal organic framework-titanium oxide composite particles are arranged into chains, polar groups on the surfaces of the particles form oriented dipole links along the direction of the electric field, and the insulating liquid film is penetrated to bridge the closed boundaries between adjacent particles, so that the metal organic framework-titanium oxide composite electrorheological fluid has excellent dynamic shear stress stability.
The thin layer of insulating liquid between two adjacent particles effectively prevents charge transfer between the particles under an applied electric field, so that the electrorheological fluid containing the metal-organic framework-titanium oxide composite exhibits a low leakage current density.
In conclusion, the electrorheological fluid has high dynamic shear stress, good stability, low leakage current density and excellent settling resistance.
As another aspect of the technical solution of the present invention, a method for preparing an electrorheological fluid is provided, which includes:
providing a first mixed system comprising a metal organic framework material, a surfactant, and a solvent;
providing a second mixed system comprising an organotitanate;
mixing the second mixed system with the first mixed system, and reacting to obtain a metal organic framework-titanium oxide compound;
and uniformly dispersing the metal organic framework-titanium oxide compound in insulating liquid to obtain the electrorheological fluid.
In some embodiments, the mass ratio of the metal organic framework material, surfactant, and organotitanate is 1: 0.1-4: 3 to 20.
Wherein, the metal organic framework material can be any metal organic framework prepared by adopting a method known in the field.
In some embodiments, the metal-organic framework material is preferably an organic-inorganic hybrid particle with intramolecular pores formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds, preferably with a specific surface area greater than 1500m2(ii) per gram of metal organic framework particles.
Further, the concentration of the metal-organic framework material in the first mixed system is 0.6-1.2 g/L.
In some embodiments, the surfactant includes any one or a combination of two or more of sodium dodecylbenzene sulfonate, stearic acid, lauric acid, and the like, but is not limited thereto. The surfactant has a surface modification effect, can prevent the aggregation of the metal organic framework material, and can improve the wettability of the insulating liquid to the metal organic framework-titanium oxide compound.
Further, the solvent comprises a mixed solvent of an organic solvent and water, wherein the volume ratio of the organic solvent to the water is 1: 0.05 to 0.2.
Further, the organic solvent is preferably, but not limited to, absolute ethanol.
In some embodiments, the organic titanate includes any one or a combination of two or more of butyl titanate, ethyl titanate, isopropyl titanate, and the like, but is not limited thereto.
Furthermore, the concentration of the organic titanate in the second mixed system is 5-15 g/L.
Further, the second mixed system includes an organic titanate and an organic solvent, wherein the organic solvent is preferably, but not limited to, absolute ethanol.
In some embodiments, the preparation method specifically comprises: and dropwise adding the second mixed system into the first mixed system, stirring, aging, centrifuging, washing and drying to obtain the metal organic framework-titanium oxide compound.
Furthermore, the stirring treatment is not strictly limited in time, and is preferably 0.5-5 h.
Furthermore, the aging treatment has no strict time limit, and is preferably 10-24 h.
In some embodiments, the dielectric constant of the insulating liquid is 1 to 10(20 ℃, 10)-2Hz) and an electrical conductivity of 10-15~10-10(Ω·cm)-1Any one or a combination of two or more of silicone oil, castor oil, hydraulic oil, and the like is preferable, but not limited thereto.
In some more specific embodiments, the method for preparing the metal organic framework-titanium oxide composite electrorheological fluid specifically comprises the following steps:
1) dispersing a metal organic framework material in an absolute ethyl alcohol/water mixed solvent, and adding a surfactant to obtain a suspension A;
2) dissolving organic titanate in absolute ethyl alcohol to obtain a solution B;
3) dropwise adding the solution B into the suspension A, stirring, aging, centrifuging, washing and drying to obtain a metal organic framework-titanium oxide compound;
4) and dispersing the obtained metal organic framework-titanium oxide compound in insulating liquid to obtain the electrorheological fluid.
Wherein, the steps are operated at room temperature.
As another aspect of the technical solution of the present invention, it relates to an electrorheological fluid prepared by the aforementioned method.
In conclusion, the electrorheological fluid has high dynamic shear stress, good stability, low leakage current density, excellent settling resistance, simple and easy preparation method and low cost.
It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.
The technical solutions of the present invention will be described in further detail below with reference to several preferred embodiments and accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. In the following examples, experimental methods without specific conditions noted are generally performed under conventional conditions or conditions recommended by the manufacturer, based on a full understanding of the present invention.
Example 1
(1) Weighing 0.055g MIL-101(Cr) (specific surface area 2483 m)2In a solvent (volume ratio 1: 0.1), then 0.0055g of sodium dodecyl benzene sulfonate is added to obtain a suspension A;
(2) measuring 0.5g of tetrabutyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required MIL-101(Cr) -titanium oxide composite particles.
(4) Dispersing the obtained composite particles in silicone oil to prepare the MIL-101(Cr) -titanium oxide composite electrorheological fluid with the mass fraction of 40 wt%. As shown in figures 1-3, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress was 40.5kPa, and the leakage current density was 4.5. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 96 percent after the electrorheological fluid is placed for 30 days.
Example 2
(1) 0.084g MIL-101(Fe) (specific surface area 2265 m) was weighed2In 105mL of an absolute ethanol/water mixed solvent (volume ratio of 1: 0.05), then 0.336g of sodium dodecyl sulfate is added to obtain suspension A;
(2) measuring 0.25g of ethyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required MIL-101(Fe) -titanium oxide composite particles.
(4) And dispersing the obtained composite particles in castor oil to prepare the MIL-101(Fe) -titanium oxide composite electrorheological fluid with the mass fraction of 20 wt%. As shown in figures 4-6, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress at that time was 39.8kPa, and the leakage current density was 4.7. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 94 percent after the electrorheological fluid is placed for 30 days.
Example 3
(1)0.05g of ZIF-8 (specific surface area 2034 m) was weighed2In 60mL of an absolute ethanol/water mixed solvent (volume ratio of 1: 0.2), then 0.1g of stearic acid is added to obtain a suspension A;
(2) measuring 0.75g of isopropyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required ZIF-8-titanium oxide compound particles.
(4) And dispersing the obtained composite particles in hydraulic oil to prepare the ZIF-8-titanium oxide composite electrorheological fluid with the mass fraction of 40 wt%. As shown in figures 7-9, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress was 37.9kPa, and the leakage current density was 4.4. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 95 percent after the electrorheological fluid is placed for 30 days.
Example 4
(1) Weighing 0.055g HKUST-1 (specific surface area 1783 m)2In a solvent (volume ratio 1: 0.1), then 0.11g of lauric acid was added to obtain suspension a;
(2) measuring 0.5g of tetrabutyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required HKUST-1-titanium oxide compound particles.
(4) The composite particles obtained above are dispersed in hydraulic oil to prepare HKUST-1-titanium oxide composite electrorheological fluid with the mass fraction of 30 wt%. As shown in figures 10-12, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress was 37.1kPa, and the leakage current density was 4.8. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 94 percent after the electrorheological fluid is placed for 30 days.
Example 5
(1) 0.064g MIL-101(Cr) (specific surface area)2483m2In 105mL of an absolute ethanol/water mixed solvent (volume ratio of 1: 0.05), then 0.064g of sodium dodecyl benzene sulfonate is added to obtain a suspension A;
(2) measuring 0.75g of ethyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required MIL-101(Cr) -titanium oxide composite particles.
(4) Dispersing the obtained composite particles in castor oil to prepare the MIL-101(Cr) -titanium oxide composite electrorheological fluid with the mass fraction of 50 wt%. As shown in FIGS. 13-15, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The time dynamic shear stress is 38.8KPa, and the leakage current density is 5.0 muA/cm2. The anti-settling rate of the electrorheological fluid is more than 95 percent after the electrorheological fluid is placed for 30 days.
Example 6
(1) 0.072g ZIF-8 (specific surface area 2034 m) was weighed2In 60mL of an absolute ethanol/water mixed solvent (volume ratio of 1: 0.2), then 0.144g of sodium dodecyl sulfate is added to obtain suspension A;
(2) measuring 0.25g of isopropyl titanate, dissolving in 50mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into the solution A, continuously stirring for four hours after the dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required ZIF-8-titanium oxide compound particles.
(4) And dispersing the obtained composite particles in hydraulic oil to prepare the ZIF-8-titanium oxide composite electrorheological fluid with the mass fraction of 40 wt%. As shown in FIGS. 16-18, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress was 39.6kPa, and the leakage current density was 4.5. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 96 percent after the electrorheological fluid is placed for 30 days.
Comparative example 1
(1) Mixing absolute ethyl alcohol with water to obtain 60mL of an absolute ethyl alcohol/water mixed solvent (volume ratio is 1: 0.2);
(2) measuring 0.6g of tetrabutyl titanate, dissolving in 60mL of absolute ethyl alcohol, and stirring for half an hour to obtain a solution B;
(3) dropwise adding the solution B into 60mL of absolute ethyl alcohol/water mixed solvent, continuously stirring for four hours after dropwise adding is completed, and then standing and aging for 10 hours; and filtering, washing and drying the precipitate to obtain the required titanium oxide particles.
(4) The titanium oxide particles obtained above are dispersed in hydraulic oil to prepare titanium oxide electrorheological fluid with the mass fraction of 20 wt%. As shown in FIGS. 19-21, the electrorheological fluid has a shear rate of 100s in an electric field of 4kV/mm-1The dynamic shear stress was 5.7kPa, and the leakage current density was 10.9. mu.A/cm2. The anti-settling rate of the electrorheological fluid is more than 83 percent after the electrorheological fluid is placed for 30 days, and the performance of the electrorheological fluid is obviously inferior to that of the electrorheological fluids obtained in examples 1 to 6.
In conclusion, by the technical scheme, the electrorheological fluid has the advantages of high dynamic shear stress, good stability, low leakage current density, excellent anti-settling property, simple and easy preparation method and low cost.
In addition, the present inventors have also made experiments with other materials and conditions, etc. listed in this specification, in the manner of examples 1 to 6, and have also succeeded in obtaining an electrorheological fluid having high dynamic shear stress, good stability, low leakage current density, and excellent settling resistance.
It should be noted that, in the present context, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in steps, processes, methods or experimental facilities including the element.
It should be understood that the above preferred embodiments are only for illustrating the present invention, and other embodiments of the present invention are also possible, but those skilled in the art will be able to adopt the technical teaching of the present invention and equivalent alternatives or modifications thereof without departing from the scope of the present invention.