Preparation method of silicone nanowire grafted clay mineral and application thereof

Abstract

The application discloses a preparation method of a silicone nanowire grafted clay mineral. First, a certain amount of dissociated clay mineral is ultrasonically dispersed in an organic solvent; second, chlorosilane is added into the solution, and silicone nanowires are in-situ grown on hydroxyl sites on the surface of the clay mineral through hydrolysis and condensation of the chlorosilane; and finally, the silicone nanowire grafted clay mineral is obtained through centrifugation, washing and drying. The silicone nanowire grafted clay mineral prepared by the method has a multi-dimensional microstructure, and can effectively improve the mechanical properties and ion transfer and other physical and chemical properties of a polymer composite material. The method is simple, efficient and low in cost, and can promote high-value utilization of the clay mineral.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanocomposite material preparation, and particularly relates to a preparation method of organosilicon nanowire grafted clay mineral. BACKGROUND

[0002] Clay minerals are widely present in nature and are an important mineral raw material. The chemical composition of clay minerals mainly includes SiO2, Al2O3, Fe2O3, MgO, and a small amount of K2O, Na2O, CaO, and water. According to the crystal structure of clay minerals, clay minerals can be divided into 1:1 type and 2:1 type. The 1:1 type refers to the combination of one silicon-oxygen tetrahedral sheet and one aluminum-oxygen octahedral sheet, and the 2:1 type refers to the combination of one aluminum-oxygen octahedral sheet sandwiched between two silicon-oxygen tetrahedral sheets. Clay minerals have a variety of micro-morphologies, such as rod-shaped attapulgite, tubular halloysite, sheet-shaped montmorillonite, and porous diatomite. Due to the advantages of abundant active sites, easy chemical modification, and abundant reserves, environmental friendliness, and low price, clay minerals have been applied in energy storage, adsorption, and other fields, and have been deeply studied in improving the ion transfer and mechanical properties of polymer composites. For example, clay minerals can effectively improve the ionic conductivity, flame retardancy, and mechanical stability of polymer composites (CN201611109450.X, CN201811346058.6, CN115954541.A).

[0003] Although clay minerals show great application prospects in the construction of polymer composites, the agglomeration of clay minerals in the polymer matrix has always plagued the commercial application of clay minerals in the field of polymer composites. Therefore, modifying clay minerals to change their surface chemical properties, enhancing the compatibility of clay minerals with polymers, and improving the dispersion of clay minerals in the polymer matrix are the keys to the commercial application of clay mineral / polymer composites. For example: patent CN201010293065.1 uses quaternary phosphonium salt ionic liquid to modify montmorillonite, and the modified montmorillonite has more stable chemical properties and greatly improved compatibility with polymers, greatly expanding the application range of montmorillonite; patent CN201810635476.0 introduces graphene between the layers of montmorillonite nanosheets to obtain graphene-modified montmorillonite that can be uniformly dispersed in polymers; patent CN202210733227.1 uses organic acid and melamine aqueous solution to modify kaolinite, and the modified kaolinite can significantly improve the mechanical properties and flame retardant efficiency of polymers; patent CN109888382.A uses clay minerals as additives to increase the porosity of polyvinylidene fluoride composites and improve the ionic conductivity of the polymer composites. In addition to the above technical development, Raluca Ianchis and Tao Tang respectively use the hydrolysis and condensation reaction of tetraethyl orthosilicate to prepare silica nanowire-modified sodium-based-montmorillonite (Appl. Clay Sci. 2014, 95, 232-242; Nanotechnology 2007, 18, 115620).

[0004] The above technologies and researches mainly focus on the change of the surface chemical properties of clay minerals to solve the compatibility problems of clay minerals in polymer composites. However, due to the limited contact interface between clay minerals and polymers, the physicochemical properties of polymer composites are still limited. Therefore, the present application develops a method for improving the mechanical properties and ion transfer performance of polymer composites by grafting organosilicon nanowires to clay minerals. Unlike conventional clay mineral materials, the organosilicon nanowire-grafted clay minerals of the present application not only effectively solve the agglomeration problem of clay minerals in polymers, but also increase the mechanical strength of polymer composites, and can form a large number of long-range continuous interfaces with polymers to improve the ion transfer and other physicochemical properties of polymer composites. SUMMARY

[0005] The present application aims to provide a preparation method of organosilicon nanowire-grafted clay minerals, which modifies the surface interface of clay minerals to prepare organosilicon nanowire-grafted clay minerals with multi-scale microstructure.

[0006] I. Preparation of organosilicon nanowire-grafted clay minerals

[0007] The preparation method of the organic silicon nanowire grafted clay mineral is that the clay mineral nanomaterial after dissociation (the purpose of dissociation is to improve the grafting rate of the organic silicon nanowire) is added into an organic solvent through ultrasonic and homogenization, and a uniform suspension is obtained through stirring and ultrasonic treatment; then the water content in the reaction system is controlled by using a nitrogen gas flow with a water content of 100-300 ppm, and chlorosilane is added, and the organic silicon nanowire is in-situ grown on the hydroxyl sites on the surface of the clay mineral through hydrolysis and condensation of the chlorosilane; finally, the organic silicon nanowire grafted clay mineral is obtained through centrifugation, washing and drying.

[0008] The clay mineral is one of kaolinite, vermiculite, hectorite, montmorillonite and attapulgite, and the concentration of the clay mineral in the reaction system is 1-60 mg / mL.

[0009] The organic solvent is at least one of n-hexane, toluene, acetonitrile, ethanol and acetone.

[0010] The water content in the reaction system is controlled to be 10-800 ppm.

[0011] The chlorosilane is at least one of diethyldichlorosilane, ethyltrichlorosilane, methylvinyl dichlorosilane, methyltrichlorosilane and vinyltrichlorosilane, and the concentration of the chlorosilane in the reaction system is 0.01-30 mg / mL.

[0012] The hydrolysis and condensation reaction condition is that the system is shaken for 3-72 h at 20-50 ℃.

[0013] The length-diameter ratio of the organic silicon nanowire is 3-50:1.

[0014] The synthesis mechanism of the application is that the organic silicon nanowire grafted clay mineral is prepared by in-situ growth of the organic silicon nanowire on the surface of the clay mineral through hydrolysis and condensation reaction of chlorosilane based on the fact that the clay mineral contains rich hydroxyl functional groups and the hydroxyl is used as an initiation point.

[0015] II. Micro-morphology of the organic silicon nanowire grafted clay mineral

[0016] Figure 1 and Figure 2 The organic silicon nanowire grafted clay mineral micro-morphology of the application in Example 3 is compared with that of the comparative example, and the experimental results show that the length of the organic silicon nanowire on the surface of the organic silicon nanowire grafted clay mineral prepared by the application can reach 200-1000 nm, and the diameter is about 20-60 nm.

[0017] III. Application of the organic silicon nanowire grafted clay mineral

[0018] To demonstrate the superior performance of the organosilicon nanowire grafted clay mineral of the present invention, the organosilicon nanowire grafted clay mineral of the present invention was used as a filler and dispersed in an N-methylpyrrolidone solution. It was then ultrasonically treated to ensure uniform dispersion. Subsequently, polyvinylidene fluoride or polyethylene oxide was added, and after ultrasonic and homogenization treatments, a uniform slurry was obtained. Finally, a polymer composite material was obtained by solution casting.

[0019] Taking polyvinylidene fluoride (PVDF) as an example, the mass ratio of organosilicon nanowires grafted with clay minerals to PVDF is 1:5, the solvent is N-methylpyrrolidone, and the solid content in the slurry is 10 wt%. Meanwhile, montmorillonite was used as a filler in the comparative example to prepare a PVDF composite material for comparison.

[0020] Mechanical strength: such as Figure 4 As shown, the polymer composite material prepared by grafting clay minerals with organosilicon nanowires as invented in Example 3 has a tensile strength of 3.7 MPa and an elongation at break of 88.5%. Compared with the polymer composite material prepared by using montmorillonite as filler in the comparative example, its tensile strength and elongation at break are increased by 1.3 and 2.3 times, respectively.

[0021] Ion transport: such as Figure 3 As shown, experimental results indicate that the polymer composite material prepared using the organosilicon nanowires grafted with clay minerals as an additive as described in Example 3 exhibits an ionic conductivity as high as 0.5 × 10⁻⁶ at 30 °C. −3 S cm −1 The ionic conductivity of the polymer composite material prepared with montmorillonite as an additive in the comparative example was increased by 3 times.

[0022] In summary, the organosilicon nanowires grafted clay minerals involved in this invention have a multi-scale microstructure, which can effectively increase the mechanical strength of polymer composites. Furthermore, they can form a large number of long-range continuous interfaces with polymers, thereby improving the physicochemical properties of polymer composites, such as ion transport. Attached Figure Description

[0023] Figure 1 The microstructure of clay minerals in the comparative example is shown.

[0024] Figure 2 The image shows the microstructure of the organosilicon nanowire grafted clay mineral in Example 3.

[0025] Figure 3 The graph shows a comparison of the ionic conductivity of clay mineral / polymer composite nanocomposites prepared using clay mineral grafts with organic silicon nanowires prepared in Comparative Example, Example 1, and Example 3 as additives at different temperatures.

[0026] Figure 4Stress-strain curves of clay mineral / polymer composites prepared by using the clay mineral grafted with the silicone nanowire of the comparative example, the inventive silicone nanowire of Example 3, respectively, as an additive. DETAILED DESCRIPTION

[0027] The application will be further explained in connection with specific embodiments.

[0028] Comparative Example

[0029] Montmorillonite nanosheet with a sheet layer thickness of about 1 nm and an average diameter of about 1 μm.

[0030] Application and performance: The montmorillonite nanosheet was used as an additive to prepare a polymer composite. The preparation method was the same as that of Example 1 (the mass ratio of the montmorillonite nanosheet to the polyvinylidene fluoride was 1:5, and the solid content in the slurry was 10 wt%). The ion conductivity at 30 °C was 0.26 x 10 −3 S cm −1 , the tensile strength was 2.9 MPa, and the elongation at break was 38.3%.

[0031] Example 1

[0032] Preparation of the silicone nanowire grafted kaolinite: 120 mL of methanol solution was taken, 0.4 g of kaolinite was added, and the solution was sealed and subjected to ultrasonic treatment. The water content in the solution was adjusted to 120 ppm, 250 μL of methyltrichlorosilane was added, and the solution was shaken in a constant-temperature shaker at 25 °C for 12 h to allow the reaction to proceed completely. The solution was then washed with a methanol solution, the precipitate was collected by centrifugation, and the precipitate was dried for use.

[0033] Preparation of the polymer composite using the silicone nanowire grafted kaolinite as an additive: The silicone nanowire grafted kaolinite was used as a filler, which was dispersed in an N-methylpyrrolidone solution and subjected to ultrasonic treatment to make the dispersion uniform. Subsequently, polyvinylidene fluoride was added, and the solution was subjected to ultrasonic treatment and homogenization to prepare a uniform slurry. Finally, the solution casting method was used to prepare a polymer composite. The mass ratio of the silicone nanowire grafted kaolinite to the polyvinylidene fluoride was 1:5, and the solid content in the slurry was 10 wt%.

[0034] Performance: The ion conductivity at 30 °C was 0.38 x 10 −3 S cm −1 , the tensile strength was 3.1 MPa, and the elongation at break was 53.8%.

[0035] Example 2

[0036] Preparation of organosilicon nanowire grafted laponite: take 60 mL of toluene solution, add 0.3 g of laponite, seal and ultrasonic, adjust the water content in the solution to 250 ppm, add 150 μL of methyl vinyl dichlorosilane, shake in a constant temperature shaker at 35 ℃ for 6 h, wash with toluene solution after sufficient reaction, collect the precipitate by centrifugation, and dry for standby.

[0037] Application and performance: the polymer composite prepared by using organosilicon nanowire grafted laponite as an additive, the method is the same as example 1 (the mass ratio of organosilicon nanowire grafted laponite and polyvinylidene fluoride is 1:5, and the solid content in the slurry is 10wt%), the ion conductivity is 0.40×10 −3 S cm −1 , the tensile strength is 3.3 MPa, and the elongation at break is 62.8%.

[0038] Example 3

[0039] Preparation of organosilicon nanowire grafted montmorillonite: take 80 mL of acetonitrile solution, add 0.2 g of montmorillonite, seal and ultrasonic, adjust the water content in the solution to 400 ppm, add 600 μL of diethyl dichlorosilane, shake in a constant temperature shaker at 40 ℃ for 48 h, wash with acetonitrile solution after sufficient reaction, collect the precipitate by centrifugation, and dry for standby.

[0040] Application and performance: the polymer composite prepared by using organosilicon nanowire grafted montmorillonite as an additive, the method is the same as example 1 (the mass ratio of organosilicon nanowire grafted montmorillonite and polyvinylidene fluoride is 1:5, and the solid content in the slurry is 10wt%), the ion conductivity is 0.50×10 −3 S cm −1 , the tensile strength is 3.7 MPa, and the elongation at break is 88.5%.

[0041] Example 4

[0042] Preparation of organosilicon nanowire grafted vermiculite: take 180 mL of acetone solution, add 0.5 g of vermiculite, seal and ultrasonic, adjust the water content in the solution to 300 ppm, add 300 μL of methyl vinyl dichlorosilane, shake in a constant temperature shaker at 45 ℃ for 24 h, wash with acetone solution after sufficient reaction, collect the precipitate by centrifugation, and dry for standby.

[0043] Application and performance: the polymer composite prepared by using organosilicon nanowire grafted vermiculite as an additive, the method is the same as example 1 (the mass ratio of organosilicon nanowire grafted vermiculite and polyvinylidene fluoride is 1:5, and the solid content in the slurry is 10wt%), the ion conductivity is 0.33×10−3 S cm −1 , the tensile strength was 3.0 MPa, and the elongation at break was 63.3%.

[0044] Example 5

[0045] Preparation of the organic silicon nanowire grafted palygorskite: 150 mL of ethanol solution was taken, 0.2 g of palygorskite was added, and after sealing, ultrasonic was performed, the moisture content in the solution was adjusted to 600 ppm, 150 μL of vinyltrichlorosilane was added, and after being shaken in a constant temperature shaker at 30 °C for 18 h, it was fully reacted, then it was washed with an ethanol solution, the precipitate was collected by centrifugation, and after drying, it was reserved.

[0046] Application and performance: the polymer composite prepared by using the organic silicon nanowire grafted palygorskite as an additive, the method was the same as in Example 1 (the mass ratio of the organic silicon nanowire grafted palygorskite and polyethylene oxide was 1:5, and the solid content in the slurry was 10 wt%), the ionic conductivity was 0.48×10 −3 S cm −1 , the tensile strength was 1.8 MPa, and the elongation at break was 53.6%.

Claims

1. A method for preparing silicone nanowire grafted clay mineral, comprising: adding dissociated clay mineral into an organic solvent, stirring and ultrasonic treating to obtain a uniform suspension; then adjusting the water content in the reaction system to 10-800 ppm and adding chlorosilane, and through hydrolysis and condensation of the chlorosilane, growing silicone nanowires in situ at the hydroxyl sites on the surface of the clay mineral; and finally centrifuging, washing and drying to obtain a silicone nanowire grafted clay mineral nanocomposite. The clay mineral is one of kaolinite, vermiculite, hectorite, montmorillonite and attapulgite, and the concentration of the clay mineral in the reaction system is 1-60 mg / mL. The chlorosilane is at least one of diethyldichlorosilane, ethyltrichlorosilane, methylvinyl dichlorosilane, methyltrichlorosilane and vinyltrichlorosilane, and the concentration of the chlorosilane in the reaction system is 0.01-30 mg / mL. The hydrolysis and condensation reaction conditions are oscillation at 20-50 ℃ for 3-72 h. The length-diameter ratio of the in-situ grown silicone nanowires is 3-50:

1.

2. The method for preparing organosilicon nanowires grafted with clay minerals according to claim 1, characterized in that: The organic solvent is at least one of n-hexane, toluene, acetonitrile, ethanol and acetone. 3.Use of the silicone nanowire grafted clay mineral prepared by the method of claim 1 in improving the mechanical properties and ion transfer performance of a polymer composite.

4. Use of the silicone nanowire grafted clay mineral nanocomposite material according to claim 3 for improving the mechanical properties and the ion transport properties of polymer composites, characterized in that: The silicone nanowire grafted clay mineral is used as a filler, dispersed in a solvent by ultrasonic treatment, and then a polymer is added, and after ultrasonic and homogenization treatment, a uniform slurry is obtained; finally, a polymer composite is prepared by solution casting.

5. Use of the silicone nanowire grafted clay mineral nanocomposite material according to claim 4 for improving the mechanical properties and the ion transport properties of polymer composites, characterized in that: The mass ratio of the silicone nanowire grafted clay mineral to the polymer is 1:5, the solvent is N-methyl pyrrolidone, and the polymer is polyvinylidene fluoride or polyethylene oxide.

Images