CN112694579B - Preparation method of shear thickening fluid, paint, preparation method and application thereof - Google Patents
Preparation method of shear thickening fluid, paint, preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of shear thickening fluid, paint, a preparation method and application thereof, wherein the preparation method of the shear thickening fluid comprises the following steps: carrying out coupling grafting reaction on the nano oxide powder and a silane coupling agent containing double bonds to obtain double bond modified nano oxide powder; carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain ionic liquid containing double bonds and hydroxyl; and carrying out free radical polymerization reaction on the ionic liquid containing double bonds and hydroxyl groups and the double bond modified nano oxide powder under the action of an initiator to obtain the shear thickening liquid. According to the preparation method of the shear thickening fluid provided by the embodiment of the invention, the silane coupling agent is adopted to carry out surface modification on the oxide nanoparticles, so that the self-aggregation phenomenon of the nanoparticles can be effectively reduced, and the explosion-proof function of the shear thickening fluid is improved.
Description
Technical Field
The invention relates to the field of protection and coatings, in particular to a preparation method of a shear thickening fluid, a coating, a preparation method and application thereof.
Background
Nowadays, international security environments have entered a new period, and with the increasing activity of terrorist attacks, armed combat and the like, explosion attacks become a problem of national security risks. China insists on implementing national defense strategy which mainly aims at active defense and inherits the principles of defense, self-defense and post-issue. Therefore, once suffering from explosion attack, in order to ensure that military equipment has strong survivability and anti-impact capability and reduce property loss of the country and people to the maximum extent, the explosion-proof safety field is taken as the key content of national defense construction of China, which is a necessary requirement.
In order to reduce and prevent the damage of detonation products generated by explosion to a target and improve the anti-explosion performance of materials, methods such as increasing the thickness of a protective medium, adopting a composite structure, developing a new material and the like are generally adopted, wherein the increase of the thickness of the medium affects the mobility but affects the survivability, and the complexity of the composite structure limits the application of part of the technology. Therefore, the introduction of new materials to improve the impact resistance and explosion resistance of the medium becomes an effective means.
The new materials introduced in the protection field at present mainly comprise alloy compounds, textile fibers and some high polymer materials, and as Shear Thickening Fluid (STF) in the high polymer materials has the characteristics of excellent energy absorption property, good compatibility with a coating, good antibacterial and corrosion resistant effects and the like, the Shear thickening fluid can meet the requirements of modern military ground and temporary protection when added into a polyurethane coating, and can be widely applied in the protection field.
STF is mainly composed of a nano dispersed phase and a high molecular weight dispersion medium. When subjected to energy impact, STF can absorb energy by agglomeration of nanoparticles, reducing impact energy. However, the self-aggregation phenomenon of the nanoparticles can be generated when the nanoparticles are not subjected to external acting force due to the smaller particle diameter ratio of the nanoparticles in the nano dispersed phase, so that the energy absorption effect of the shear thickening liquid is reduced, and the protection effect of the coating is influenced.
Disclosure of Invention
Objects of the invention
The invention aims to provide a preparation method of a shear thickening fluid, a coating, a preparation method and application. According to the preparation method of the shear thickening fluid, the surface of the nano oxide particles is modified by adopting the silane coupling agent, so that the surface of the modified nano oxide particles is grafted with silane coupling agent groups, and the silane coupling agent groups enable the nano oxide particles to have stronger hydrophobicity. In addition, the double bonds of the silane coupling agent groups of the modified nano oxide particles and the double bonds of the ionic liquid undergo free radical polymerization reaction to obtain a new polymer, and the new polymer can be used as a shear thickening fluid. In addition, one end of the novel polymer is modified nano oxide, and the other end of the novel polymer is ionic liquid, so that the cluster effect of the modified nano particles and the relative slip electrostatic effect of anions and cations of the ionic liquid are synergistic, and the explosion-proof effect of the polymer is improved.
(II) technical scheme
In order to solve the problems, the invention carries out coupling grafting reaction on nano oxide powder and a silane coupling agent containing double bonds to obtain double bond modified nano oxide powder; carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain an ionic liquid containing double bonds and hydroxyl; and carrying out free radical polymerization reaction on the ionic liquid containing double bonds and hydroxyl groups and the double bond modified nano oxide powder under the action of an initiator to obtain the shear thickening liquid.
In some embodiments, the initiator is azobisisobutyronitrile. Preferably, the mass of the added initiator is 0.1% of the total mass of the ionic liquid containing double bonds and hydroxyl groups and the double bond modified nano oxide powder.
In some embodiments, quaternizing the double bond-containing pyridine reagent with a halohydrin to obtain an ionic liquid containing double bonds and hydroxyl groups comprises: carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain ionic liquid containing double bonds and hydroxyl; and (3) carrying out a displacement reaction on the ionic liquid containing the double bonds and the hydroxyl groups and monovalent sodium salt in an organic solvent to obtain the ionic liquid containing the double bonds and the hydroxyl groups after anion exchange.
It is understood that, in the metathesis reaction, the monovalent sodium salt is monovalent sodium salt powder, and the ionic liquid containing the double bond and the hydroxyl group is subjected to the metathesis reaction with the monovalent sodium salt powder in an organic solvent. The organic solvent is, for example, acetone.
In some embodiments, the monovalent sodium salt is NaBF 4 、NaHSO 3 Or NaSCN.
In some embodiments, the coupling grafting reaction of the nano-oxide powder and a silicon-oxygen coupling agent containing double bonds is carried out to obtain double-bond modified nano-oxide powder, and the method comprises the following steps: uniformly mixing the nano oxide powder with an ethanol water solution to obtain a second mixed solution; putting a silane coupling agent containing double bonds into distilled water, and performing ultrasonic dispersion for 30 minutes to obtain a hydrolyzed coupling agent; uniformly mixing the hydrolyzed coupling agent with the second mixed solution, adjusting the pH value of the solution to be within the pH value range corresponding to the nano oxide powder, and stirring at the temperature of 70-90 ℃ until the reaction is completed to obtain a mixture; centrifuging the mixture to obtain lower-layer turbid liquid; and washing and drying the lower layer turbid liquid to obtain the double-bond modified nano oxide powder.
Preferably, the nano oxide powder is nano TiO 2 Powder, nano SiO 2 Powder, nano ZnO powder or nano Al 2 O 3 One of the powders; the double-bond-containing silane coupling agent is gamma-methacryloxypropyl trimethoxy silane.
In some embodiments, the nano-oxide powder is nano-TiO 2 And during powder preparation, when the hydrolyzed coupling agent and the second mixed solution are uniformly mixed, the pH value of the solution is adjusted to be 6-7, and when the pH value is adjusted within the range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. Preferably, the pH of the adjusted solution is 6.5.
In some embodiments, the nano-oxide powder is nano-SiO 2 During powder preparation, when the hydrolyzed coupling agent is uniformly mixed with the second mixed solution, the pH value of the solution is adjusted to be 4-5, and when the pH value is adjusted to be in the rangeAnd when the nano oxide powder is used, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. The pH of the solution is preferably adjusted to 4.5.
In some embodiments, when the nano oxide powder is nano ZnO powder, when the hydrolyzed coupling agent is uniformly mixed with the second mixed solution, the pH of the solution is adjusted to 6 to 7, and when the pH is adjusted within this range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. Preferably, the pH of the adjusted solution is 6.5.
In some embodiments, the nano-oxide powder is nano-Al 2 O 3 And during powder preparation, when the hydrolyzed coupling agent and the second mixed solution are uniformly mixed, the pH value of the solution is adjusted to be 2-4, and when the pH value is adjusted within the range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. Preferably, the pH of the solution is adjusted to 3.
It is understood that, through the research of the present invention, the element of different oxide powders is different, which results in a great influence of the pH value on the grafting rate of the oxide powders, so that the above pH value range with the highest grafting rate is obtained through experimental screening.
Preferably, the quaternization reaction of the double bond-containing pyridine reagent and halohydrin to obtain the double bond-and hydroxyl-containing ionic liquid comprises the following steps: mixing a pyridine reagent containing double bonds with halohydrin, and magnetically stirring at 50-80 ℃ until the reaction is complete to obtain a liquid crude product; adding ethyl acetate into the liquid crude product and uniformly dispersing by ultrasonic; sequentially carrying out suction filtration and drying on the dispersed liquid crude product; and adding the dried liquid crude product into acetonitrile, and performing rotary evaporation to obtain the ionic liquid containing double bonds and hydroxyl groups.
Preferably, the ionic liquid containing double bonds and hydroxyl groups and the double bond modified oxide nano powder are reacted completely under the action of an initiator to obtain the shear thickening fluid, which comprises: mixing the ionic liquid containing double bonds and hydroxyl groups with absolute ethyl alcohol; adding the double-bond modified oxide nano powder into a mixed solution of an ionic liquid containing double bonds and hydroxyl groups and absolute ethyl alcohol for multiple times, and adding the double-bond modified oxide nano powder into the mixed solution of the ionic liquid containing double bonds and hydroxyl groups and absolute ethyl alcohol for ultrasonic dispersion every time to uniformly disperse the double-bond modified oxide nano powder to obtain a shear thickening solution; the shear thickening fluid was dried under vacuum until the absolute ethanol and water were removed.
Preferably, the double bond-containing pyridine reagent is 4-vinylpyridine; the halogenated alcohol is 2-bromoethanol, bromopropanol or bromobutanol.
According to a second aspect of the present invention there is provided a coating comprising a polyether polyol, an adjuvant and an isocyanate and the shear thickening fluid prepared by the method provided in the first aspect.
Preferably, the mass ratio of the shear thickening fluid to the polyether polyol is as follows: 1:3.
Preferably, the mass ratio of isocyanate to the polyether polyol is 5: 2.
According to a third aspect of the present invention, there is provided a method of preparing a coating material, comprising: preparing a shear thickening fluid according to the method of the first aspect; mixing the shear thickening liquid with polyether polyol and an auxiliary agent to obtain a mixed material; the mass ratio of the shear thickening fluid to the polyether polyol is as follows: 1: 3; mixing the mixed material with isocyanate to obtain a coating; wherein the mass ratio of the isocyanate to the polyether polyol is 5: 2.
According to a fourth aspect of the present invention there is provided the use of a coating for application to clothing, buildings, shields or protective gear.
(III) advantageous effects
The technical scheme of the invention has the following beneficial technical effects:
according to the preparation method of the shear thickening fluid, the surface of the nano oxide particles is modified by adopting the silane coupling agent, so that silane coupling agent groups are grafted on the surfaces of the modified nano oxide particles, the silane coupling agent groups enable the nano oxide particles to have strong hydrophobicity, and the double bonds of the silane coupling agent groups of the nano oxide particles and the double bonds of the ionic liquid in the obtained shear thickening fluid can be subjected to free radical polymerization reaction to obtain a new polymer, and the new polymer can be used as the shear thickening fluid. In addition, one end of the novel polymer is modified nano oxide, and the other end of the novel polymer is ionic liquid, so that the cluster effect of the modified nano particles and the relative slip electrostatic effect of anions and cations of the ionic liquid are synergistic, and the explosion-proof effect of the polymer is improved.
Drawings
FIG. 1 is a schematic flow diagram of a method for preparing a shear thickening fluid according to a first embodiment of the present invention;
FIG. 2 is an infrared spectrum of double bond modified nano-silica and nano-silica provided in example 1 of the present invention;
fig. 3 is a schematic structural view of KH570 provided in embodiment 1 of the present invention;
FIG. 4 is a schematic structural diagram of silica grafted with KH570 provided in example 1 of the present invention;
FIG. 5(a) is a transmission electron micrograph of nano-silica provided in example 1 of the present invention;
FIG. 5(b) is a transmission electron microscope image of the double bond-modified nano-silica provided in example 1 of the present invention;
FIG. 6 is a schematic structural diagram of an ionic liquid containing double bonds and hydroxyl groups provided in example 4;
FIG. 8 is a schematic flow chart of a method for preparing a coating according to a second embodiment of the present invention;
FIG. 9 is a graph comparing the performance of coatings provided in example 11 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It is to be understood that these descriptions are only illustrative and are not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a schematic flow chart of a method for preparing a shear thickening fluid according to a first embodiment of the present invention.
As shown in fig. 1, the method includes:
and step S11, carrying out coupling grafting reaction on the nano oxide powder and a silane coupling agent containing double bonds to obtain double bond modified oxide nano powder. It is understood that the double bond-modified oxide nanopowder is an oxide nanopowder grafted with a silane coupling agent group containing a double bond.
Alternatively, the nano-oxide powder may be nano-TiO 2 Powder, nano SiO 2 Powder, nano ZnO powder or nano Al 2 O 3 One of the powders; the silane coupling agent containing double bonds is gamma-methacryloxypropyltrimethoxysilane (gamma-MPS for short), and the optional type of the gamma-methacryloxypropyltrimethoxysilane is KH 570.
In the step, double bond-modified nano oxide powder is obtained by utilizing the grafting reaction between double bonds on the surface of the silane coupling agent and the nano oxide powder, compared with common nano oxide powder, the size of the nano particles is reduced, the original hydrophilic property is changed into hydrophobic nano oxide powder, and the phenomenon of self-agglomeration of the nano oxide powder in water can be reduced.
In some embodiments, when the nano-oxide powder is nano-silica, the mass of the double bond-containing silane coupling agent is 20% of the weight of the nano-silica powder.
In some embodiments, when the nano-oxide powder is nano-zinc oxide, the mass ratio of the double bond-containing silane coupling agent to the nano-zinc oxide powder is 50: 3.
In some embodiments, when the nano-oxide powder is nano-alumina, the double bond-containing silane coupling agent comprises 4.5% by mass of the nano-alumina.
In some embodiments, when the nano-oxide powder is nano-titania, the double bond-containing silane coupling agent accounts for 10% by mass of the nano-titania.
Specifically, step S11, coupling and grafting the nano-oxide powder with a double-bond-containing silica coupling agent to obtain a double-bond-modified nano-oxide powder, including:
and step S111, uniformly mixing the nano oxide powder and an ethanol aqueous solution to obtain a second mixed solution.
It is understood that, since the nanoparticles easily absorb water in the air to cause agglomeration, it is preferable that the nano-oxide powder is pre-dried to remove moisture from the nano-oxide powder before step S111. Preferably, the drying time is 3 to 5 hours, preferably 4 hours.
And step S112, putting the silane coupling agent containing the double bonds into purified water, and performing ultrasonic dispersion for 30 minutes to obtain the hydrolyzed coupling agent.
And step S113, mixing the hydrolyzed coupling agent with the second mixed solution, adjusting the pH value of the solution to be within the pH value range corresponding to the nano oxide powder, and stirring at the temperature of 70-90 ℃ until the reaction is completed to obtain a mixture.
On one hand, hydroxyl macromolecules in the gamma-methacryloxypropyltrimethoxysilane hydrolysate can be chemically bonded with hydroxyl on the surface of silicon dioxide and are linked to the surface of nano silicon dioxide molecules, so that the number of hydroxyl on the surface of the silicon dioxide is reduced to a certain extent, and agglomeration is reduced; on the other hand, the introduction of the hydrophobic long chain of the gamma-methacryloxypropyltrimethoxysilane changes the silicon dioxide from a hydrophilic type to a hydrophobic type, the polarity of molecules is weakened, the surface energy is reduced, the long chain plays a certain role in blocking, the agglomeration of the silicon dioxide is further reduced, and the double-bond modified nano oxide has stronger hydrophobicity.
In some embodiments, the hydrolyzed coupling agent is mixed with the second mixed solution, the pH value of the solution is adjusted to 4-8 to obtain a mixture, and the mixture is heated and stirred uniformly in a 70-90 ℃ water bath environment. In some embodiments, the mixture may be allowed to condense under nitrogen atmosphere at reflux during stirring in an 80 ℃ water bath.
It is understood that the water bath may be replaced by an oil bath as long as the temperature is adjusted to be the same.
It is understood that, through the research of the present invention, the elements of different oxide powders are different, which results in a great influence of the pH value on the grafting ratio of the oxide powders, so that the following pH value range with the highest grafting ratio is obtained through experimental screening.
In some embodiments, the nano-oxide powder is nano-TiO 2 And during powder preparation, when the hydrolyzed coupling agent and the second mixed solution are uniformly mixed, the pH value of the solution is adjusted to be 6-7, and when the pH value is adjusted within the range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. Preferably, the pH of the adjusted solution is 6.5.
In some embodiments, the nano-oxide powder is nano-SiO 2 And during powder preparation, when the hydrolyzed coupling agent and the second mixed solution are uniformly mixed, the pH value of the solution is adjusted to be 4-5, and when the pH value is adjusted within the range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. The pH of the solution is preferably adjusted to 4.5.
In some embodiments, when the nano oxide powder is nano ZnO powder, when the hydrolyzed coupling agent is uniformly mixed with the second mixed solution, the pH of the solution is adjusted to 6 to 7, and when the pH is adjusted within this range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. The pH of the solution is preferably adjusted to 6.5.
In some embodiments, the nano-oxide powder is nano-Al 2 O 3 And during powder preparation, when the hydrolyzed coupling agent and the second mixed solution are uniformly mixed, the pH value of the solution is adjusted to be 2-4, and when the pH value is adjusted within the range, the grafting rate of the coupling agent grafted on the nano oxide powder is highest. Preferably, the pH of the solution is adjusted to 3.
And step S114, carrying out centrifugal separation on the mixture to obtain lower-layer turbid liquid.
And step S115, washing and drying the lower layer turbid liquid to obtain the double-bond modified nano oxide powder.
In step S11, the silane coupling agent is used to modify the surface of the nanoparticles, so that the silane coupling agent group is grafted on the surface of the nano oxide, and the silane coupling agent group has double bonds, so that the nano oxide also has double bonds, the hydrophobic property of the nanoparticles can be improved, the self-agglomeration of the nanoparticles can be effectively reduced, and the dispersibility of the nanoparticles is improved compared with unmodified nano oxide powder.
And step S12, carrying out quaternization reaction on the double-bond-containing pyridine reagent and halohydrin to obtain the double-bond-and-hydroxyl-containing ionic liquid.
It is understood that the pyridine-based ionic liquid containing a double bond means, for example, a salt completely composed of anions and cations in a liquid state at room temperature or at around room temperature, and is also a low-temperature molten salt.
In addition, in the ionic liquid containing a double bond and a hydroxyl group obtained in the present step, the ionic liquid belongs to a salt, wherein the cation is an ion of a pyridine containing a double bond and a hydroxyl group, and the anion is, for example, a halogen ion.
Preferably, the pyridine ionic liquid containing double bonds is 4-vinylpyridine; the halogenated alcohol is 2-bromoethanol, bromopropanol or bromobutanol.
In some embodiments, the molar ratio of the double bond-containing pyridine reagent to the halohydrin is 1: 1.
Specifically, in step S12, the quaternization reaction of the double bond-containing pyridine reagent and halohydrin to obtain the double bond-and hydroxyl-containing ionic liquid includes:
step S121, mixing a double-bond pyridine reagent with halohydrin, and magnetically stirring at 60-80 ℃ until the reaction is complete to obtain a liquid crude product.
And step S122, adding ethyl acetate into the liquid crude product and uniformly dispersing by ultrasonic.
And step S123, sequentially carrying out suction filtration and drying on the dispersed liquid crude product.
And step S124, adding the dried liquid crude product into acetonitrile, and performing rotary evaporation to obtain the ionic liquid containing double bonds and hydroxyl groups.
And step S13, carrying out free radical polymerization reaction on the ionic liquid containing the double bonds and the hydroxyl groups and the double bond modified nano oxide powder under the action of an initiator to obtain the shear thickening liquid.
In some embodiments, the initiator is azobisisobutyronitrile. Preferably, the mass of the added initiator is 0.1% of the total mass of the ionic liquid containing double bonds and hydroxyl groups and the double bond modified nano oxide powder. When the mass of the initiator exceeds 0.1%, the ionic liquid containing double bonds and hydroxyl groups and the double bond-modified nano oxide tend to aggregate, so that the desired substance cannot be obtained, and when the mass of the initiator is less than 0.1%, the ionic liquid containing double bonds and hydroxyl groups and the double bond-modified nano oxide powder cannot be polymerized.
In some embodiments, step S13, includes: completely reacting ionic liquid containing double bonds and hydroxyl groups with the double bond modified oxide nano powder under the action of an initiator to obtain shear thickening liquid, wherein the shear thickening liquid comprises the following components:
and step S131, mixing the ionic liquid containing double bonds and hydroxyl groups with absolute ethyl alcohol.
And S132, adding the double-bond modified oxide nano powder into a mixed solution of the ionic liquid containing the double bonds and the hydroxyl and the absolute ethyl alcohol for multiple times, and performing ultrasonic dispersion on the mixture each time to uniformly disperse the double-bond modified oxide nano powder to obtain the shear thickening solution.
Step S133, the shear thickening fluid is vacuum dried until the absolute ethanol and water are removed.
It can be understood that, in the embodiment of the present invention, the silane coupling agent containing double bonds is grafted to the surface of the nano-oxide powder, so that the hydrophobicity of the double bond modified nano-oxide powder is improved, and the self-aggregation of the nano-oxide powder can be avoided, and then the double bond modified nano-oxide powder and the ionic liquid containing double bonds and hydroxyl groups undergo a radical polymerization to form a new polymer, where the new polymer is a shear thickening fluid, that is, when the double bond modified nano-oxide powder and the ionic liquid containing hydroxyl groups of double bonds undergo a radical polymerization reaction, the double bonds of the double bond modified nano-oxide powder and the ionic liquid containing hydroxyl groups of double bonds are opened, and a covalent bond is reformed to obtain the shear thickening fluid.
The principle that the shear thickening fluid provided by this embodiment has an explosion-proof performance is that when external impact is received, a cluster structure is formed at one end of the modified nano oxide particles in the shear thickening fluid, and external energy is absorbed in the process of forming the cluster structure, so that a part of energy of the impact force can be absorbed. In addition, the other end of the shear thickening liquid is ionic liquid, and positive ions and negative ions in the ionic liquid can relatively slide after being subjected to external impact force, so that the positive ions and the negative ions can be separated, and a part of energy in the external impact force is absorbed, thereby achieving the explosion-proof effect. In summary, in the shear thickening fluid provided by this embodiment, the anti-explosion effect of the shear thickening fluid can be better due to the double-effect synergistic effect of the modified oxide nanoparticles and the ionic liquid.
In some embodiments, step S12, quaternizing the double bond-containing pyridine reagent with a halohydrin to obtain an ionic liquid containing a double bond and a hydroxyl group, comprising:
step S121, carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain the ionic liquid containing the double bonds and hydroxyl.
Step S122, the salt containing double bond and hydroxyl and monovalent sodium salt are subjected to displacement reaction in an organic solvent to obtain a first mixed solution containing sodium halide. Wherein the monovalent sodium salt is one or more of NaBF4, NaHSO3 or NaSCN.
And S123, filtering the first mixed solution to obtain a filtrate, and removing the organic solvent in the filtrate to obtain the ionic liquid containing double bonds and hydroxyl groups after anion exchange. After anion exchange obtained in this stepIn the ionic liquid containing double bond and hydroxyl, the cation is the ion of pyridine containing double bond and hydroxyl, and the anion is BF4 - 、HSO3 - Or SCN - 。
In this embodiment, step S13 is to completely react the anion-exchanged ionic liquid containing double bonds and hydroxyl groups with the double bond-modified oxide nanopowder under the action of an initiator to obtain a shear thickening fluid.
Specifically, in step S13, the ionic liquid containing double bonds and hydroxyl groups after anion exchange and the double bond-modified oxide nanopowder are reacted completely under the action of an initiator to obtain a shear thickening fluid, including:
step S131, mixing the ion liquid containing double bonds and hydroxyl groups after anion exchange with absolute ethyl alcohol.
And S132, adding the double-bond modified oxide nano powder into the mixed solution of the ionic liquid containing the double bonds and the hydroxyl groups and the absolute ethyl alcohol after anion exchange for multiple times, and performing ultrasonic dispersion on the mixture each time so as to uniformly disperse the double-bond modified oxide nano powder to obtain the shear thickening liquid.
And step S133, drying the shear thickening fluid in vacuum until the absolute ethyl alcohol and the water in the shear thickening fluid are removed.
According to the preparation method of the shear thickening fluid provided by the embodiment of the invention, when the shear thickening fluid is impacted by external force, the modified nano oxide particles in the shear thickening fluid form a cluster structure at one end, and the cluster structure can absorb external energy in the process of forming the cluster structure, so that a part of energy of the impact force can be absorbed. In addition, the other end of the shear thickening liquid is ionic liquid, and positive ions and negative ions in the ionic liquid can relatively slide after being subjected to external impact force, so that the positive ions and the negative ions can be separated, and a part of energy in the external impact force is absorbed, thereby achieving the explosion-proof effect. In summary, in the shear thickening fluid provided by this embodiment, the anti-explosion effect of the shear thickening fluid can be better due to the double-effect synergistic effect of the modified oxide nanoparticles and the ionic liquid.
It can be understood that the double bonds of the double bond modified nano oxide powder and the double bonds of the ionic liquid containing the double bonds and hydroxyl groups are subjected to free radical polymerization reaction under the action of the initiator to form a new polymer, and the polymer can be uniformly dispersed in the polyurethane coating, so that the polyurethane coating also has an explosion-proof function, and compared with the coating in the prior art, the explosion-proof function is added.
The following will describe in detail the preparation of the shear thickening fluids according to the above embodiments of the present invention in different embodiments.
The following examples 1 to 3 are examples of preparing double bond-modified oxide nanopowder in step S1.
Example 1
In example 1, the oxide nanopowder was Nano-SiO 2 The double bond-containing silicone coupling agent is gamma-methacryloxypropyltrimethoxysilane (abbreviated as KH-570).
The preparation method comprises the following specific steps:
in the first step, 2.5g of Nano-SiO 2 Uniformly dispersing the mixture in 62.5ml of H prepared according to the volume ratio of water to ethanol of 1:3 under the ultrasonic condition (80Hz, 30min) 2 O+CH 3 CH 2 To an OH mixed solution (water 15.625 ml; ethanol 46.875ml in this example) was added to obtain hydrolyzed Nano-SiO 2 。
Secondly, 0.625g of KH-570 and hydrolyzed Nano-SiO are weighed 2 And (3) mixing, slowly adding acetic acid dropwise to adjust the pH value of the solution to be between 4 and 5 after uniform mixing, and stirring in a constant-temperature water bath at 75 ℃ for 4 hours to obtain a mixture containing precipitates. During stirring in a constant temperature water bath, the mixture was condensed to reflux at 80 ℃ under a nitrogen atmosphere.
And thirdly, putting the obtained mixture into a centrifugal machine for centrifugation at the rotating speed of 1600r/min, and pouring out the supernatant after centrifugation to obtain the lower turbid liquid. And then adding ethanol into the lower layer turbid solution, stirring and washing, and repeating the centrifugal washing process for 3 times to finally obtain white precipitate. In this example, ethanol was added as the lower layer of the turbid liquid during the washing processTwice the volume. Finally, taking out the white precipitate, and drying the white precipitate for 12 hours at the temperature of 80 ℃ in a vacuum environment to obtain KH-570 modified Nano-SiO 2 。
Table 1 shows KH-570-modified Nano-SiO obtained in this example 2 Table of performance parameters
| Parameter(s) | Particle size (nm) | Specific surface area (m2/g) | BJH pore size (nm) |
| Nano-SiO2 | 31.9519 | 187.7823 | 13.9769 |
| KH570-NanoSiO2 | 42.9723 | 139.6248 | 30.4572 |
As shown in Table 1, this example is performed by using silane coupling agent KH-570 to nano SiO 2 The surface modification is carried out, the nano silicon oxide and the double-bond modified nano silicon oxide are detected by a laser particle size analyzer, and the particle size is increased, but the specific surface is obviously reduced, so that the hydrophobic property is improved.
In this embodiment, on one hand, hydroxyl-bearing macromolecules in the KH-570 hydrolysate can chemically bond with hydroxyl groups on the surface of silica and link to the surface of nano silica molecules, thereby reducing the number of hydroxyl groups on the surface of silica to some extent and reducing agglomeration; on the other hand, the KH-570 hydrophobic long chain is introduced to change the hydrophilic type of the silicon dioxide into the hydrophobic type, so that the molecular polarity is weakened, the surface energy is reduced, the long chain plays a certain role in blocking, and the agglomeration of the silicon dioxide is further reduced.
In addition, the silanol product after the hydrolysis of the silane coupling agent KH-570 has two competitive reactions, one is self-polycondensation reaction, and the other is dehydration condensation with the hydroxyl on the surface of Nano-SiO 2; when the dispersion is too acidic, namely the pH is less than 4, the hydrolysis rate is too high, so that the concentration of silanol is too high, self-condensation reaction occurs when the silanol is not dispersed on the surface of silicon dioxide in time, and the grafting rate is not high; when the solution is alkaline, i.e., pH > 5, the hydrolysis rate is relatively slow but the self-condensation rate is very fast, and the self-condensation reaction to form oligomers occurs upon hydrolysis to form silanols, while the reaction with silicon hydroxyl groups on the silica surface is very low, so the grafting rate is also low. Through research, the pH value is controlled to be 4-5, so that the grafting efficiency is relatively good, and more preferably, when the hydrolysis rate and the condensation rate of a hydrolysis product are both relatively moderate when the pH value is 5, the generated silanol can be timely dispersed to the surface of silicon dioxide and is mainly reacted with silicon hydroxyl, so that the grafting efficiency is highest.
FIG. 2 is the KH-570 modified Nano-SiO provided in this example 2 Infrared spectrum of (1).
As shown in FIG. 2, the upper line corresponds to double bond-modified SiO modified with KH-570 2 Using gamma-MPS-SIO 2 Indicating that the line near the abscissa is Nano-SIO 2 As can be seen from FIG. 2, in the case of gamma-MPS-SIO 2 Upper, 2948cm -1 At a distance of 2850cm -1 The peaks are respectively carbon-hydrogen bond stretching vibration absorption peaks at 1718cm on methyl and methylene -1 The position is a carbon-oxygen double bond stretching vibration absorption peak on carbonyl, which indicates that gamma-MPS (KH570) has been successfully grafted on the nano-silica.
Fig. 3 is a schematic structural view of KH570 provided in example 1, and fig. 4 is a schematic structural view of silica grafted with KH570 provided in example 1.
As shown in fig. 3 and 4, the silane coupling agent is grafted on the silica so that the nano-oxide grafted with the silane coupling agent contains hydroxyl groups and double bonds, thereby increasing hydrophobicity all over compared to nano-silica.
In this example, unmodified nano SiO 2 And KH-570 modified nano SiO 2 Respectively dispersing in ethanol, and observing by transmission electron microscope.
As shown in FIG. 5(a), the nano SiO without modification 2 At normal temperature, water is easy to absorb, and because water molecules are absorbed, the surface of the shear thickening liquid contains a large amount of hydroxyl groups, and the particles are easy to agglomerate with an ethanol solvent under the action of hydrogen bonds, so that the water molecules are difficult to uniformly disperse in the shear thickening liquid, and the obtained shear thickening liquid has poor impact resistance.
As shown in FIG. 5(b), KH-570 modified nano SiO 2 Compared with the aggregate before modification, the aggregate is obviously reduced. After KH-570 is modified, partial hydroxyl groups are condensed with the hydrolysate of the coupling agent to make SiO 2 Surface hydroxyl radical reduction, SiO 2 Hydrogen bonding between the particles becomes weaker, thereby reducing agglomeration. Furthermore, after hydrolytic condensation of KH-570, SiO 2 The surface tension of the particles is reduced by the hydrophobic macromolecules of the surface-bonded coupling agent, and the nano SiO is enlarged by the molecules of the coupling agent 2 Steric hindrance between particles to a certain extent obstructs SiO 2 Agglomeration among particles, thereby leading the modified nano SiO 2 Can be well dispersed, so that the nano particles can be uniformly dispersed in the shear thickening fluid, and the obtained shear thickening fluid has strong impact resistance.
Example 2
In example 2, the oxide nanopowder was Nano-ZnO, and the double bond-containing silica coupling agent was γ -methacryloxypropyltrimethoxysilane (abbreviated as KH-570).
The Nano-ZnO is pre-dried for 4 hours in a vacuum drying oven at 80 ℃, the Nano-ZnO and KH570 are weighed according to the mass ratio of KH570 to the Nano-ZnO of 50:3 and added into a beaker filled with absolute ethyl alcohol and water in the volume ratio of 3:1, the mixture is subjected to ultrasonic treatment for 30 minutes, wherein the volume of the absolute ethyl alcohol is 30ml, the volume of the water is 10ml, then the mixture is transferred into a three-neck flask, and the three-neck flask containing the Nano-ZnO, the absolute ethyl alcohol and the water is placed into a constant temperature water bath at 85 ℃ to be magnetically stirred for 2 hours. And then NaOH and HCl are used for adjusting the pH value to 6.5, after the mixture is uniformly stirred, a coupling agent accounting for 6 percent of the total mass fraction is added from the bottle mouth through a dropper (the coupling agent is dissolved in certain absolute ethyl alcohol), then the mixture is magnetically stirred for 4 hours in a constant-temperature water bath at the temperature of 75 ℃, and in the stirring process of the constant-temperature water bath of the mixture, the mixture is condensed and refluxed at the temperature of 80 ℃ in a nitrogen environment to obtain a mixture containing precipitates.
And taking out the mixture, filtering and washing, purifying the obtained product by using rotary evaporation to obtain solid powder, and then drying the solid powder in a vacuum drying oven at the temperature of 80 ℃ for 12 hours to obtain double-bond modified nano zinc oxide (also called nano zinc oxide grafted with KH570 or modified nano zinc oxide).
It is understood that since ZnO is Zn in the strongly acidic condition 2+ The state of (2) exists, so that the influence of pH value on the activation index of ZnO can be examined only under weak acid or alkaline condition. Studies have shown that the oleophilic degree of modified ZnO increases gradually with increasing pH, and decreases with increasing pH when pH is greater than 6.5. This is because the nano ZnO surface atoms have unsaturated chemical bonds and tend to be ion coordinated in water, and surface hydroxylation occurs, that is, ZnO and H + Combined with Zn - OH + And the ZnO particle surface is provided with positive charges, and the combination mode is more obvious under the weak acid condition.
Example 3
In example 3, the oxide nanopowder was Nano-Al 2 O 3 The double bond-containing silica coupling agent is KH-570.
Weighing KH-570 4.5% of nano-alumina, vacuum drying at 120 deg.C for 24 hr, and adding purified water (to make nano-Al powder) 2 O 3 Dispersing for 0.5h, adding silane coupling agent KH570 4.5% of the total mass fraction, adding 95% ethanol (the weight ratio of nano-alumina, water and ethanol is 2: 5: 100), and dispersing with ultrasonic instrumentDispersing for 0.5 h.
The mixture was then condensed to reflux at 80 ℃ under nitrogen and magnetically stirred for 6 h. And after the reaction is finished, carrying out suction filtration and air drying on the product, washing the product with absolute ethyl alcohol, carrying out rotary evaporation to remove impurities, and carrying out vacuum drying at 60 ℃ for 12h to obtain the silane coupling agent modified nanoparticles.
The following examples 4-6 are examples of preparing salts containing double bonds and hydroxyl groups.
Example 4
In example 4, the halohydrin was 2-bromoethanol, and the double bond-containing pyridine reagent was 4-vinylpyridine.
The preparation method comprises the following steps:
2-bromoethanol (1.24g) and vinyl pyridine (1.05g) are weighed according to the molar ratio of 1:1, placed in a 150mL round-bottomed bottle, and subjected to condensation reflux and magnetic stirring for 24 hours under the condition of N2 in a water bath environment at 70 ℃ to generate a crude product, namely 1-hydroxyethyl-4-vinyl pyridine bromide salt. Then, the product was washed with 5mL of acetonitrile and 25mL of ethyl acetate, and the ethyl acetate-washed product was dried under vacuum at 70 ℃ to obtain a pale yellow liquid of 1-hydroxyethyl-4-vinylpyridine bromide salt.
FIG. 6 is a schematic structural diagram of an ionic liquid containing double bonds and hydroxyl groups provided in example 4.
As shown in fig. 6, after the quaternization reaction of the halohydrin and the double-bond-containing pyridine reagent, the obtained double-bond-and-hydroxyl-containing ionic liquid includes a pyridine ring, wherein the N atom of the pyridine ring is connected with a C atom, the C atom is connected with a hydroxyl group, the N atom of the pyridine ring is connected with an anion X through a cationic bond, the X is bromide, tetrafluoroborate, sulfite and thiocyanate, in this example, the anion is bromide, and the C atom para to the N atom is connected with a vinyl group.
Example 5
In example 5, the halohydrin is 2-bromoethanol, and the pyridine ionic liquid containing double bonds is 4-vinylpyridine.
4mL of 4-vinylpyridine was poured into a three-necked flask with a reflux condenser, and 3.8mL of 2-bromoethanol was then measured and slowly dropped into the three-necked flask. And magnetically stirring the mixture in an oil bath for at least 24 hours at the temperature of 50-55 ℃ until the reaction is finished to generate a liquid crude product, wherein the liquid crude product is 1-hydroxyethyl-4-vinylpyridine bromide. Washing and drying the liquid crude product by 15mL of ethyl acetate each time, adding acetonitrile, performing ultrasonic dispersion uniformly, performing rotary evaporation on the uniformly dispersed liquid for 20min under the conditions of the temperature of 40 ℃, the pressure of-0.08 MPa and the rotating speed of 10r/min to remove the ethyl acetate and the acetonitrile, wherein in the embodiment, the temperature of the rotary evaporation is 40 ℃, the pressure of-0.08 MPa and the rotating speed of 10 r/min. Obtaining dark brown liquid, namely 1-ethoxyl-4-vinylpyridine bromide, and finally drying for 24 hours at the temperature of 50 ℃ under vacuum condition to obtain light yellow 1-ethoxyl-4-vinylpyridine bromide.
Example 6
Example 6 is an example of anion exchange of the 1-hydroxyethyl-4-vinylpyridine bromide salt obtained in example 5.
Taking NaBF with a molar ratio of 1:1 4 And 1-hydroxyethyl-4-vinylpyridine bromide from example 5, were added to a 250 ml ground Erlenmeyer flask with a drying tube. After adding 100mL of acetone, stirring, reacting for 36 hours at room temperature to obtain an anion-exchanged salt containing sodium bromide (1-hydroxyethyl-4-vinylpyridine tetrafluoroborate), filtering out the sodium bromide, and performing rotary evaporation on the obtained filtrate at 50 ℃ to obtain yellow viscous liquid. Then dried under vacuum at 60 ℃ to give 1-hydroxyethyl-4-vinylpyridine tetrafluoroborate in the form of a yellow, transparent liquid.
Example 7
Weighing 6.1g of 1-hydroxyethyl-4-vinylpyridine bromide (salt containing double bonds and hydroxyl) obtained in example 5 and 30mL of absolute ethanol according to a molar ratio of 1:1, adding the mixture into a three-necked flask with reflux condensation, after the solid is completely dissolved, respectively adding 5.5g of NaBF4 in batches in equal amount, carrying out condensation reflux oil bath at 50-55 ℃ and carrying out magnetic stirring for 24 hours to generate a liquid crude product, wherein the liquid crude product is 1-hydroxyethyl-4-vinylpyridine tetrafluoroborate ionic liquid containing sodium bromide; the crude liquid product was decanted from the supernatant solution and filtered. And (3) carrying out rotary evaporation on the filtered clear liquid at the temperature of 50 ℃, the pressure of-0.08 MPa and the rotating speed of 10r/min to remove the absolute ethyl alcohol. And finally, drying the obtained liquid at 50 ℃ for 24 hours in vacuum to obtain the ionic liquid containing double bonds and hydroxyl after anion exchange, namely the 1-hydroxyethyl-4-vinylpyridine tetrafluoroborate.
Examples 8-9 are examples of preparing shear thickening fluids
Example 8
The double bond-modified Nano-SiO2-KH570(0.74g) obtained in example 1, which accounts for 27% of the mass fraction, was weighed out and added twice to 2g of the mixed solution of brominated 1-hydroxyethyl-4-vinylpyridine obtained in example 4 and a certain amount of absolute ethanol diluent, and subjected to ultrasonic dispersion until the Nano-SiO2-KH570 particles were uniformly dispersed, and then the Nano-SiO2-KH570 was repeatedly added and subjected to ultrasonic dispersion until 0.74g of Nano-SiO2-KH570 was completely added to obtain a mixture. The mixture just obtained is first dried under vacuum at room temperature and then at high temperature (100 ℃) until the addition of absolute ethanol and possible incorporation of small amounts of air bubbles and water are removed to give a shear-thickening fluid. The resulting shear-thickening fluid may be designated as Nano- -SiO 2 -KH570+ 1-hydroxyethyl-4-vinylpyridine bromide salt.
It will be appreciated that the resulting mixture is first dried at room temperature to remove the added anhydrous ethanol and then dried at elevated temperature to remove the water, if direct drying at elevated temperature would cause the ethanol and water to affect the boiling point of the product, thereby resulting in a loss of product quality.
The left side of the shear thickening fluid is provided with nano-silica particles, the surface of the silica is grafted with a silane coupling agent group, the right side of the silane coupling agent group is connected with a pyridine ring, the N atom of the pyridine ring is connected with an anion X through an ionic bond, the anion X is bromide, tetrafluoroborate, sulfite and thiocyanate, and in the embodiment, the anion is bromide.
Example 9
Weighing 27 mass percent of Nano-TiO 2 (0.74g) add 2g of a mixture of a double bond and hydroxyl containing salt and absolute ethanol diluent in two portions and disperse by ultrasound until TiO 2 The particles are uniformly dispersed, and then the addition and ultrasonic dispersion are repeated until the required TiO is calculated 2 And (5) finishing the addition. Vacuum drying is carried out at room temperature and then at high temperature (100 ℃) until the added absolute ethanol and possible minor bubbles and moisture are removed.
In the present embodiment, the salt having a double bond and a hydroxyl group may be one of 1-hydroxyethyl-4-vinylpyridine bromide, 1-hydroxyethyl-4-vinylpyridine tetrafluoroborate, 1-hydroxyethyl-4-vinylpyridine bisulfite, and 1-hydroxyethyl-4-vinylpyridine thiocyanate.
The second embodiment of the invention provides a coating, which comprises the shear thickening fluid provided by the first embodiment, polyether polyol, an auxiliary agent and isocyanate. The polyether polyol is, for example, a polyether polyol having a hydroxyl number of 210.
Preferably, the mass ratio of the shear thickening fluid to the polyether polyol is as follows: 1:3.
The mass ratio of the shear thickening fluid to the polyether polyol is as follows: the ratio of 1:3 is optimal, and if the shear thickening fluid is less, the explosion-proof effect of a coating formed by the coating is poor. If the shear thickening fluid is added too much, on one hand, the cost is high, on the other hand, the hardness of the coating is low, the explosion-proof film layer is likely to crack due to the low hardness, the toughness is poor, and the explosion-proof effect is reduced on the contrary. If the polyether polyol is too much, the hardness of a coating layer formed by the coating material may be too high, and the brittleness may be high, resulting in low explosion-proof performance.
Further preferably, the mass ratio of isocyanate to polyether polyol is 5: 2.
Optionally, the auxiliary agent is, for example, a defoaming agent, and accounts for 0.1% of the total mass of the coating. The defoamer can reduce the formation of bubbles when the coating is formed, thereby reducing the defects of the coating.
It should be noted that, isocyanate included in the coating material and hydroxyl groups of the polyether polyol may react to form polyurethane, so that the obtained coating material is a polyurethane coating material, and in this embodiment, the coating material further includes the shear thickening fluid obtained in the first embodiment, on one hand, the shear thickening fluid may improve the explosion-proof performance of the coating material, and on the other hand, the shear thickening fluid includes hydroxyl groups, and the hydroxyl groups in the shear thickening fluid may also replace the polyether polyol to react with the isocyanate, so that the usage amount of the polyether polyol may be reduced.
In addition, in this embodiment, the shear thickening fluid may be based on a coating material and stably dispersed in the coating material, and since the shear thickening fluid is grafted with a silane coupling agent and a pyridine ring on the basis of the nano metal oxide, the coating material may have a high hydrophobicity, and the shear thickening fluid may be uniformly and stably dispersed in the coating material.
Fig. 8 is a schematic flow chart of a method for preparing the coating according to the second embodiment of the present invention.
As shown in fig. 8, the method includes:
step S21, preparing a shear thickening fluid according to the method of the first embodiment;
step S22, mixing the shear thickening fluid with polyether polyol and an auxiliary agent to obtain a mixed material; the mass ratio of the shear thickening fluid to the polyether polyol is as follows: 1:3.
Step S23, mixing the mixed material with isocyanate to obtain a coating; wherein the mass ratio of the isocyanate to the polyether polyol is 5: 2.
In some embodiments, the adjuvant is a defoamer to eliminate air bubbles in the coating. Wherein the mass of the auxiliary agent is 0.1 percent of the total mass of the isocyanate and the polyether polyol.
The method for preparing the coating material according to the second embodiment of the present invention will be described in detail with reference to various examples.
The polyurethane coating obtained by the method provided by the second embodiment of the invention has the characteristics of convenience in construction, good impact resistance, high chemical stability, high dispersibility and good flame retardance.
Example 10
The shear thickening fluid prepared in example 8 is weighed and mixed with polyether polyol and an auxiliary agent to form a mixed material, wherein the mass ratio of the weighed shear thickening fluid to the polyether polyol is 1: 3. The mass of the auxiliary agent is 0.1% of the total mass of the isocyanate and the polyether polyol.
And then mixing the mixed material with isocyanate, wherein the mass ratio of the isocyanate to the polyether polyol is 5:2, uniformly stirring the mixture in a stirrer to obtain a polyurethane coating, and coating the polyurethane coating on a standard sample plate.
Example 11
0.66g of the shear thickening fluid prepared in example 8 was weighed, mixed with 2g of polyether polyol and 0.007g of auxiliary agent to form a mixed material, and then the mixed material was mixed with 5g of isocyanate to obtain a coating.
Comparative example 1
2g of polyether polyol, 5g of isocyanate and 0.007g of auxiliary were mixed to obtain a coating (abbreviated as PU coating).
Comparative example 2
2g of polyether polyol, 0.28g of nano silicon dioxide powder, 5g of isocyanate and 0.007g of auxiliary agent are mixed to obtain a coating (abbreviated as PU + SIO) 2 Paint).
FIG. 9 is a graph showing the comparative explosion-proof performance of the coating material obtained in example 11.
Wherein, three columns of samples are included from left to right, and the samples from left to right respectively represent: the coating of comparative example 1, the coating of comparative example 2, the coating of example 11.
In this figure, two rows are included, the first row representing samples not subjected to pressure extrusion and the second row representing samples subjected to pressure extrusion, and as can be seen from a comparison of the first and second rows, the coating layer in the left column is significantly deformed after extrusion, one turn smaller than the carrier, and the intermediate column is also deformed after extrusion, but in a lesser amount than the first column, as compared to the first column. As can be seen from the comparison between the first row and the second row, the coating added with the shear thickening fluid is not deformed after being extruded, and the compressive property of the coating can be shown to be better.
Table 2 below is a table of the mechanical properties of the coatings provided in example 11.
TABLE 2
| Sample/mechanical parameters | Relative compression ratio (ε ck) | Relative section expansion ratio (psi ck) |
| Comparative example 1 | 0.3 | 0.440 |
| Comparative example 2 | 0.25 | 0.266 |
| Example 11 | 0 | 0.102 |
As shown in Table 2, it can be seen from Table 2 that the relative compressibility of the paint with the shear thickening fluid added thereto was 0, i.e., the paint did not shrink when receiving a pressure shock, indicating that the paint of example 11 had better anti-explosion performance after the shear thickening fluid was added thereto.
According to a further embodiment of the present invention, there is provided the use of the coating of the above embodiment for application to clothing, buildings, shields or protective gear.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (9)
1. A method for preparing a shear thickening fluid is characterized by comprising the following steps:
carrying out coupling grafting reaction on the nano oxide powder and a silane coupling agent containing double bonds to obtain double bond modified nano oxide powder;
carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain an ionic liquid containing double bonds and hydroxyl;
carrying out free radical polymerization reaction on the ionic liquid containing double bonds and hydroxyl groups and the double bond modified nano oxide powder under the action of an initiator to obtain shear thickening liquid;
the nano oxide powder is nano TiO 2 Powder, nano SiO 2 Powder, nano ZnO powder or nano Al 2 O 3 One of the powders;
the silane coupling agent containing double bonds is gamma-methacryloxypropyltrimethoxysilane;
the double-bond-containing pyridine reagent is 4-vinylpyridine;
the halogenated alcohol is 2-bromoethanol, bromopropanol or bromobutanol;
completely reacting ionic liquid containing double bonds and hydroxyl groups with the double bond modified oxide nano powder under the action of an initiator to obtain shear thickening liquid, wherein the shear thickening liquid comprises the following components:
mixing the ionic liquid containing double bonds and hydroxyl groups with absolute ethyl alcohol;
adding the double-bond modified oxide nano powder into a mixed solution of an ionic liquid containing double bonds and hydroxyl groups and absolute ethyl alcohol for multiple times, and adding the double-bond modified oxide nano powder into the mixed solution of the ionic liquid containing double bonds and hydroxyl groups and absolute ethyl alcohol for ultrasonic dispersion every time to uniformly disperse the double-bond modified oxide nano powder to obtain a shear thickening solution;
the shear thickening fluid was dried under vacuum until the absolute ethanol and water were removed.
2. The method for preparing the shear thickening fluid according to claim 1, wherein the quaternization reaction of a double bond-containing pyridine reagent and a halohydrin is carried out to obtain an ionic liquid containing double bonds and hydroxyl groups, and the method comprises the following steps:
carrying out quaternization reaction on a pyridine reagent containing double bonds and halohydrin to obtain an ionic liquid containing double bonds and hydroxyl;
and (3) carrying out a displacement reaction on the ionic liquid containing the double bonds and the hydroxyl groups and monovalent sodium salt in an organic solvent to obtain the ionic liquid containing the double bonds and the hydroxyl groups after anion exchange.
3. The method according to claim 1, wherein the step of subjecting the nano-oxide powder and a silicon-oxygen coupling agent containing double bonds to a coupling grafting reaction to obtain double-bond modified nano-oxide powder comprises:
uniformly mixing the nano oxide powder with an ethanol water solution to obtain a second mixed solution;
putting a silane coupling agent containing double bonds into distilled water, and performing ultrasonic dispersion for 30 minutes to obtain a hydrolyzed coupling agent;
uniformly mixing the hydrolyzed coupling agent with the second mixed solution, adjusting the pH value of the solution to be within the pH value range corresponding to the nano oxide powder, and stirring at the temperature of 70-90 ℃ until the reaction is completed to obtain a mixture;
centrifuging the mixture to obtain a lower layer turbid liquid;
and washing and drying the lower layer turbid liquid to obtain the double-bond modified nano oxide powder.
4. The method according to any one of claims 1 to 3, wherein the quaternization of the double bond-containing pyridine reagent with the halohydrin to obtain the double bond-and hydroxyl-containing ionic liquid comprises:
mixing a pyridine reagent containing double bonds with halogenated alcohol, and magnetically stirring at 50-80 ℃ until the reaction is complete to obtain a liquid crude product;
adding ethyl acetate into the liquid crude product and uniformly dispersing by ultrasonic;
sequentially carrying out suction filtration and drying on the dispersed liquid crude product;
and adding the dried liquid crude product into acetonitrile, and performing rotary evaporation to obtain the ionic liquid containing double bonds and hydroxyl groups.
5. A coating comprising a polyether polyol, an adjuvant and an isocyanate and a shear thickening fluid prepared according to the method of any one of claims 1 to 4.
6. The coating of claim 5, wherein the mass ratio of the shear thickening fluid to the polyether polyol is: 1:3.
7. The coating according to claim 5 or 6, characterized in that the mass ratio of the isocyanate to the polyether polyol is 5: 2.
8. Use of a coating according to any of claims 5-7 for application to clothing, buildings or protective gear.
9. A method of preparing a coating, comprising:
preparing a shear thickening fluid according to the method of any one of claims 1 to 4;
mixing the shear thickening liquid with polyether polyol and an auxiliary agent to obtain a mixed material; the mass ratio of the shear thickening fluid to the polyether polyol is as follows: 1: 3;
mixing the mixed material with isocyanate to obtain a coating; wherein the mass ratio of the isocyanate to the polyether polyol is 5: 2.
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| CN103359740A (en) * | 2012-03-27 | 2013-10-23 | 浩华科技实业有限公司 | Preparation method of silica shear thickening liquid |
| CN107502288A (en) * | 2017-08-28 | 2017-12-22 | 湖南沃美新材料科技有限公司 | A kind of preparation method of nano silicon STF |
| CN111118902A (en) * | 2019-12-26 | 2020-05-08 | 东华大学 | Shear thickening fluid based on ionic liquid and preparation method thereof |
| CN111574992A (en) * | 2020-05-27 | 2020-08-25 | 中国石油大学(华东) | Nano-phase permeability improver for acidizing and fracturing as well as preparation method and application of nano-phase permeability improver |
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| CN103359740A (en) * | 2012-03-27 | 2013-10-23 | 浩华科技实业有限公司 | Preparation method of silica shear thickening liquid |
| CN107502288A (en) * | 2017-08-28 | 2017-12-22 | 湖南沃美新材料科技有限公司 | A kind of preparation method of nano silicon STF |
| CN111118902A (en) * | 2019-12-26 | 2020-05-08 | 东华大学 | Shear thickening fluid based on ionic liquid and preparation method thereof |
| CN111574992A (en) * | 2020-05-27 | 2020-08-25 | 中国石油大学(华东) | Nano-phase permeability improver for acidizing and fracturing as well as preparation method and application of nano-phase permeability improver |
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