阅读说明：本技术 一种C3N4/TiO2纳米复合颗粒电流变液及其制备方法 (C3N4/TiO2Nano composite particle electric rheologic liquid and its preparing method ) 是由 王宝祥 张博 李昌昊 郑昊男 陈漪 郝春成 于 2021-10-12 设计创作，主要内容包括：本发明涉及一种C-(3)N-(4)/TiO-(2)纳米复合颗粒电流变液及其制备方法,该电流变液的分散相是C-(3)N-(4)/TiO-(2)纳米复合颗粒,采用两步法制备而成；所得C-(3)N-(4)具备疏松多孔的二维材料特征,负载TiO-(2)纳米颗粒后形成一种C-(3)N-(4)/TiO-(2)纳米复合颗粒；该材料与甲基硅油所配成的电流变液具有一些优异的特性,包括极强的电流变效应、很好的抗沉淀稳定性、电流密度低、化学稳定性好。附图中显示了C-(3)N-(4)/TiO-(2)纳米复合颗粒电流变液在不同电场强度下其剪切应力与剪切速率的关系。(The invention relates to a compound C 3 N 4 /TiO 2 Nano composite particle electrorheological liquid and its preparation method, the dispersed phase of said electrorheological liquid is C 3 N 4 /TiO 2 The nano composite particles are prepared by adopting a two-step method; obtained C 3 N 4 Has the characteristics of loose and porous two-dimensional material and is loaded with TiO 2 Formation of a C after nanoparticles 3 N 4 /TiO 2 A nanocomposite particle; the electrorheological fluid prepared from the material and the methyl silicone oil has some excellent characteristics, including extremely strong electrorheological effect, excellent anti-precipitation stability, low current density and good chemical stability. In the drawing, C is shown 3 N 4 /TiO 2 The nano composite particle electrorheological liquid has the relation between the shearing stress and the shearing rate under different electric field strengths.)

1. An electric rheologic liquid is characterized by that its dispersed phase is C₃N₄/TiO₂Nano composite particles, wherein the continuous phase is dimethyl silicone oil; c₃N₄/TiO₂The nano composite particles are prepared by a two-step method, and a loose porous two-dimensional material C is prepared by a calcination method₃N₄(ii) a Then with C₃N₄As a template, and preparing C by a sol-gel method₃N₄/TiO₂A nanocomposite particle; c₃N₄/TiO₂The nano composite particles have unique appearance, extremely strong electrorheological effect, good temperature effect and moderate current density.

2. An electrorheological fluid according to claim 1, characterized in that the preparation process comprises the following steps:

(1) dissolving 2g of dicyandiamide and 6g of sodium chloride in 50mL of deionized water, and fully stirring the mixture until the mixture is uniform; then quickly freezing in liquid nitrogen to a solid state, and drying in a freeze dryer for 24h to obtain white fine powder; calcining the white powder in a muffle furnace at 550 ℃ for 4h, heating at the rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, then centrifugally washing with deionized water and absolute ethyl alcohol for 3 times respectively, drying in an oven at 70 ℃ for 6h, and fully grinding to obtain light yellow carbon nitride powder;

(2) adding 1.5mL of tetrabutyl titanate into a mixed solution of 60mL of absolute ethyl alcohol and 30mL of isopropanol, stirring for 30min, washing with absolute ethyl alcohol, and centrifuging to obtain TiO₂Drying the nanoparticles in an oven at 70 deg.C for 12 hr to obtainA solid powder;

(3) dispersing 0.5g of carbon nitride powder in 50ml of absolute ethyl alcohol, stirring for 30min to uniform creamy yellow, and then adding 0.1g of TiO₂Dispersing nanoparticles with ultrasound for 2h, heating to 70 deg.C, evaporating to dryness, and collecting to obtain C₃N₄/TiO₂A nanocomposite particle;

(4) the sample and the dimethyl silicone oil are prepared into the electrorheological fluid according to the weight ratio of the solid particles to the silicone oil of 10wt percent.

Technical Field

The invention relates to an electrorheological fluid and a preparation method thereof, in particular to a C₃N₄/TiO₂Nano composite particle electric rheologic liquidAnd a method for preparing the same.

Background

The role of intelligent materials in scientific research and social development of people is more and more important, and people can respond correspondingly under the excitation of various external conditions, and the response is often special and rare. For example: pressure, temperature, electric field, magnetic field, pH, etc. Electrorheological fluids (ERF) have received increasing attention in recent years as a novel smart material, and are characterized in that under the condition of an applied electric field, a series of viscosity and rheological property changes occur in dispersed particles with high polarization capability dispersed in an insulating medium (silicone oil, mineral oil, etc.), and the process is reversible and the response speed is extremely fast (generally, several milliseconds). The effect of the electric field on the internal structure and the rheological properties of the dispersion is called electrorheological effect. Electrorheological fluids are therefore generally composed of two parts; the electro-rheological properties of the dispersed phase and the insulating medium are mainly determined by the former.

Electrorheological fluids are intelligent materials that respond rapidly to electric fields, and are typically suspensions of high dielectric constant, small particles dispersed in low dielectric constant insulating liquids. Under the action of an external electric field, the material is constructed into a chain or columnar structure between two parallel electrodes, so that the rheological properties of the material, including shear stress, elastic modulus, shear viscosity and the like, can be converted from liquid to solid-like, the viscosity and the shear strength of the material can be rapidly improved, and the material has the characteristic of rapid reversibility. The electrorheological material has great application prospect in the fields of vibration reduction, mechanical transmission, automatic control, electromechanical integration, micro-driving and the like due to low energy consumption and controlled and changed quality.

The dispersed phase material refers to solid particles of the electrorheological fluid and is generally divided into four types: an organic polymer material; an inorganic material; a composite material; a liquid material. However, any material should generally satisfy the following characteristics: (1) appropriate conductivity and large dielectric constant; (2) the working temperature range is wide and the physical and chemical properties are stable; (3) appropriate morphology and density. The organic polymer materials are mainly classified into two types: one class is materials with large pi-shaped keys due to largeDue to the conjugation of the n-bond electron cloud, the material has strong polarization capability under the action of an electric field and has a large dielectric constant; the other type is a material containing polar functional groups, and the material tends to have larger polarization capacity under the action of an electric field due to the overlarge polarizability of the polar groups. Graphite phase carbon nitride material (g-C)₃N₄) As a novel conjugated two-dimensional polymer, the conjugated two-dimensional polymer has wide application in the field of functional materials in recent years. The inorganic material mainly refers to metal oxide, wherein nano TiO₂The electrorheological dispersed phase material is considered to have a great potential, has a high dielectric constant, is simple and convenient in preparation method, has the characteristics of non-toxic and environment-friendly raw materials, and occupies a great proportion in the electrorheological material. It is well known that the microstructure and surface morphology of dispersed phase nanoparticles have a significant effect on their electrorheological properties, TiO₂The degree of closeness and interaction between particles has a large effect on the interface polarization. The composite material generally comprises a conductive layer and an insulating layer, and the core conductive layer particles ensure the rapid polarization of the particles, so the core part of experimental design and modification is often formed. The outer insulating layer is mainly used for protecting conductive layer particles, reducing the conductivity of the conductive layer particles, protecting polarized charges from agglomeration and maintaining stable electrostatic interaction among the particles. Therefore, the composite material with a special structure can greatly improve the electrorheological properties of the original composite material and the original composite material. The liquid material mainly refers to liquid crystal polymer, and the material has the greatest characteristic that the problem of coagulation which is common in solid materials does not exist, but the intrinsic viscosity of the material is often higher, and the delamination phenomenon is often generated.

The invention aims to provide g-C₃N₄/TiO₂The nano composite particle electrorheological liquid has dispersed phase of g-C₃N₄/TiO₂The nano composite particles have a continuous phase of dimethyl silicone oil. g-C₃N₄/TiO₂The nano composite particles have unique morphology, and the results of a scanning electron microscope and a transmission electron microscope show that the g-C₃N₄/TiO₂The nano composite particle is porous composite structure, TiO₂Nanoparticles in g-C₃N₄The interlayer deposition is carried out, the distribution is uniform and the grain diameter is fine. Preparation processThe modified sol-gel method is not added with any surfactant, belongs to a template-free method, and is green and environment-friendly. The electrorheological fluid prepared from the material and the methyl silicone oil has excellent suspension stability due to the anti-sedimentation property of the hollow structure particles, and solves a great problem of electrorheological fluid. The process can also regulate and control the appearance, the size, the pore degree and the like of the product by controlling the reaction time and the proportion, and has strong adjustability.

The invention also aims to provide a two-step method for preparing g-C₃N₄/TiO₂A method for preparing nanoparticles, which belongs to an improved two-step composite preparation method, C₃N₄/TiO₂The nano composite particles are prepared by a two-step method, and a loose porous two-dimensional material C is prepared by a calcination method₃N₄Then with C₃N₄As a template, and preparing C by a sol-gel method₃N₄/TiO₂A nanocomposite particle; c₃N₄/TiO₂The nano composite particles have unique appearance, extremely strong electrorheological effect, good temperature effect and moderate current density. The electrorheological fluid prepared from the material and the methyl silicone oil has excellent characteristics including extremely strong electrorheological effect, excellent anti-precipitation stability, low current density and good chemical stability.

The purpose of the invention can be realized by the following technical scheme:

the dispersed phase of the electrorheological fluid prepared by the invention is g-C₃N₄/TiO₂The nano particles and the continuous phase are dimethyl silicone oil.

The preparation process of the electrorheological fluid comprises the following steps:

(1) adding 1.5mL tetrabutyl titanate into a mixed solution of 60mL absolute ethyl alcohol, 30mL isopropyl alcohol and 1.5mL deionized water, stirring for 30min, washing with absolute ethyl alcohol, and centrifuging to obtain TiO₂Drying the nano particles in an oven at 70 ℃ for 12 hours to obtain solid powder; calcining 2g of dicyandiamide in a muffle furnace at 550 ℃ for 4h at the heating rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, and then using deionized water and anhydrous ethylAlcohol is centrifugally washed for 3 times, and the mixture is dried in an oven at 70 ℃ for 6 hours to obtain light yellow carbon nitride powder.

(2) Dispersing 0.5g of carbon nitride powder in 50ml of absolute ethyl alcohol, stirring for 30min to uniform creamy yellow, and then adding 0.1g of TiO₂Dispersing nanoparticles with ultrasound for 2h, heating to 70 deg.C, evaporating to dryness, and collecting to obtain C₃N₄/TiO₂A nanocomposite particle.

(3) The sample and the dimethyl silicone oil are prepared into the electrorheological fluid according to the weight ratio of the solid particles to the silicone oil of 10wt percent.

Drawings

FIGS. 1g-C₃N₄SEM photograph of template

FIG. 2g-C₃N₄/TiO₂SEM photograph of nanoparticles

FIGS. 3g-C₃N₄/TiO₂TEM photograph of nanoparticles

FIGS. 4g-C₃N₄/TiO₂Nanoparticle XRD profile

FIGS. 5g-C₃N₄/TiO₂Nanoparticle FTIR spectra

FIG. 6g-C₃N₄/TiO₂Nanoparticle BET Curve

FIGS. 7g-C₃N₄/TiO₂Current change performance diagram of nano particles

FIG. 8TiO₂SEM photograph of nanoparticles

FIG. 9g-C₃N₄/TiO₂Nanoparticle SEM photograph (15mL isopropanol)

FIG. 10g-C₃N₄/TiO₂Nanoparticle SEM photograph (20mL isopropanol)

Detailed Description

The first embodiment is as follows: (g-C)₃N₄Preparation of (1)

g-C₃N₄The catalyst is prepared by a calcination method, and the specific operation process is as follows: 2g of dicyandiamide and 6g of sodium chloride are dissolved in 50mL of deionized water, and the mixture is fully stirred until the mixture is uniform. Then rapidly frozen in liquid nitrogen to solid state, and dried in a freeze dryer for 24h to obtain white fine powder.Calcining the white powder in a muffle furnace at 550 ℃ for 4h, heating at the rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, then centrifugally washing with deionized water and absolute ethyl alcohol for 3 times respectively, and drying in an oven at 70 ℃ for 6h to obtain light yellow carbon nitride powder. FIG. 1 is g-C₃N₄SEM photograph of template, as can be seen, g-C₃N₄The template is of a nano lamellar structure, the thickness of the layer is about 5-7nm, the wall surface is smooth, the interlayer gap is moderate, and the pore size is uniform.

Example two:

adding 1.5mL of tetrabutyl titanate into a mixed solution of 60mL of absolute ethyl alcohol, 30mL of isopropanol and 1mL of deionized water, stirring the solution for 30min, washing with absolute ethyl alcohol, and centrifuging for three times to obtain the nano TiO₂Drying the granules in an oven to obtain solid powder; 2g of dicyandiamide and 6g of sodium chloride are dissolved in 50ml of deionized water and stirred sufficiently until uniform. Then rapidly frozen in liquid nitrogen to solid state, and dried in a freeze dryer for 24h to obtain white fine powder. Calcining the white powder in a muffle furnace at 550 ℃ for 4h, heating at the rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, then centrifugally washing with deionized water and absolute ethyl alcohol for 3 times respectively, and drying in an oven at 70 ℃ for 6h to obtain light yellow carbon nitride powder; dispersing 0.5g of carbon nitride powder in 50ml of absolute ethyl alcohol, stirring for 30min to uniform creamy yellow, and then adding 0.1g of TiO₂Dispersing nanoparticles with ultrasound for 2h, heating to 70 deg.C, evaporating to dryness, and collecting to obtain C₃N₄/TiO₂A nanocomposite particle. The sample and the dimethyl silicone oil are prepared into the electrorheological fluid according to the weight ratio of the solid particles to the silicone oil of 10wt percent.

FIG. 2 and FIG. 3 are g-C, respectively₃N₄/TiO₂SEM and TEM photographs of the nanoparticles show that the morphology of the composite particles is nano-sheet, TiO₂The nanoparticles are uniformly distributed between the layers. FIG. 4 is g-C₃N₄/TiO₂XRD pattern of nanoparticles, pristine TiO₂XRD spectrum of (1) and anatase TiO₂(JCPDS 21-1272) by matching the XRD spectra with standard anatase titanium oxide card PDF^#The comparison of 21-1272 shows that the crystal plane index corresponding to 25.37 degrees is (101),the crystal plane index corresponding to 37.03 degrees is (103), the crystal plane index corresponding to 48.12 degrees is (200), the crystal plane index corresponding to 55.10 degrees is (211), and the crystal plane index corresponding to 62.74 degrees is (204), indicating that the titanium oxide crystal form is anatase, and the peak shape is sharp, and the crystallinity is good. According to previous studies, g-C₃N₄Two characteristic information peaks are respectively disclosed at 2 theta 12.8 degrees and 27.4 degrees, which respectively correspond to two crystal face indexes of (100) and (002). The spectrum of the composite nano-particle retains the characteristic peaks of the two, and confirms that the two coexist and the crystal structure is not changed. FIG. 5 is g-C₃N₄/TiO₂FTIR profile of nanoparticles, 400-^-1Corresponding to the stretching vibration peak of the O-Ti-O bond, 1200-^-1Range corresponding to carbon nitride inside N- (C)₃Or the stretching vibration of the C-NH-C bond of 3000-3500cm^-1 range corresponds to-NH thereof₂Or the vibration of NH group, the FTIR spectrum of the compound comprises the characteristic vibration peak of the two, and the coexistence of the two and the chemical basic structure are proved not to be changed greatly. FIG. 6 is g-C₃N₄/TiO₂BET plot of the nanoparticles, from which it can be seen, g-C₃N₄/TiO₂The average pore diameter distribution of the nano particles is about 10.6nm, and the surface area of the nano particles is calculated to reach 61.7g/m according to a t-plot method²The nitrogen adsorption and desorption curve meets the characteristics of IV-type adsorption and desorption curve, which is the characteristic of a typical mesoporous material, and the pore volume is about 0.2cm³And about/g. FIG. 7 is g-C₃N₄/TiO₂The nano-particle based electrorheological fluid has the relationship between the shearing strength and the shearing rate under different field strengths. As can be seen from the figure, the voltage is added to 3kV, and the current density is smaller, which shows that the anti-breakdown performance of the electrorheological fluid of the system is better. As can be seen from the graph, in the absence of an applied electric field, the shear stress increases linearly with increasing shear rate, and the fluid exhibits Newtonian fluid behavior; after an electric field is applied, the particles are polarized in the electric field rapidly, dipoles attract each other, the particles are arranged into a chain structure, the shearing stress is increased continuously under the increase of the electric field intensity, and a platform area appears in a high-frequency areaThe electrorheological efficiency is 345, which shows the extremely strong electrorheological effect. FIG. 8 is a SEM photograph of nano-titanium dioxide, showing that the particle size is controlled in the nano range, the size is uniform, the distribution is uniform, and no obvious agglomeration phenomenon occurs.

Example three:

adding 1.5mL of tetrabutyl titanate into a mixed solution of 60mL of absolute ethyl alcohol, 15mL of isopropanol and 1mL of deionized water, stirring the solution for 30min, washing with absolute ethyl alcohol, and centrifuging for three times to obtain the nano TiO₂Drying the granules in an oven to obtain solid powder; calcining 2g of dicyandiamide in a muffle furnace at 550 ℃ for 4h at the heating rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, then centrifugally washing with deionized water and absolute ethyl alcohol for 3 times respectively, and drying in an oven at 70 ℃ for 6h to obtain light yellow carbon nitride powder; dispersing 0.5g of carbon nitride powder in 50ml of absolute ethyl alcohol, stirring for 30min to uniform creamy yellow, and then adding 0.1g of TiO₂Dispersing nanoparticles with ultrasound for 2h, heating to 70 deg.C, evaporating to dryness, and collecting to obtain C₃N₄/TiO₂A nanocomposite particle. The sample and the dimethyl silicone oil are prepared into the electrorheological fluid according to the weight ratio of the solid particles to the silicone oil of 10wt percent. FIG. 9 is g-C₃N₄/TiO₂SEM photograph of nanoparticles (15mL of isopropanol), some collapse of the pore structure of the template occurred compared to the 30mL isopropanol system, considering the formation of amorphous TiO₂So that the pores are blocked.

Example four:

adding 1.5mL of tetrabutyl titanate into a mixed solution of 60mL of absolute ethyl alcohol, 20mL of isopropanol and 1mL of deionized water, stirring the solution for 30min, washing with absolute ethyl alcohol, and centrifuging for three times to obtain the nano TiO₂Drying the granules in an oven to obtain solid powder; calcining 2g of dicyandiamide in a muffle furnace at 550 ℃ for 4h at the heating rate of 2.3 ℃/min, naturally cooling to room temperature, collecting, then centrifugally washing with deionized water and absolute ethyl alcohol for 3 times respectively, and drying in an oven at 70 ℃ for 6h to obtain light yellow carbon nitride powder; dispersing 0.5g of carbon nitride powder in 50ml of absolute ethyl alcohol, stirring for 30min to uniform creamy yellow, and then adding 0.1g of TiO₂Dispersing nanoparticles with ultrasound for 2h, heating to 70%Evaporating to dryness at deg.C and collecting to obtain C₃N₄/TiO₂A nanocomposite particle. The sample and the dimethyl silicone oil are prepared into the electrorheological fluid according to the weight ratio of the solid particles to the silicone oil of 10wt percent. FIG. 10 is g-C₃N₄/TiO₂SEM photograph of nanoparticles (20mL of isopropanol), collapse and agglomeration of the template occurred compared to 30mL of isopropanol system, resulting in a large reduction in pore structure, considering that insufficient isopropanol causes TiO₂Is not uniform.