阅读说明：本技术 一种纳米二氧化硅粉体的形貌调控及制备方法 (Shape regulation and control of nano silicon dioxide powder and preparation method ) 是由 张雪原 于 2020-06-10 设计创作，主要内容包括：本发明提供的制备方法简单,主要以水作作溶剂,方法简单绿色清洁,能够通过简单手段就能够调控得到两种形貌的二氧化硅纳米粉体,为二氧化硅的形貌调控提供了有效支撑,并首次合成了片状形貌的纳米二氧化硅,并通过调控两种阴离子的比例来精确控制纳米二氧化硅形貌实现片状和棒状的相互转变,取得了预料不到的技术效果,由于不同形貌的纳米二氧化硅孔道长度不同,可将其用于催化反应以及药物缓释等多种领域。(The preparation method provided by the invention is simple, mainly takes water as a solvent, is simple, green and clean, can be used for regulating and controlling two kinds of silicon dioxide nano powder by a simple means, provides effective support for regulating and controlling the appearance of silicon dioxide, synthesizes the nano silicon dioxide with a flaky appearance for the first time, accurately controls the appearance of the nano silicon dioxide by regulating and controlling the proportion of two anions to realize the mutual conversion of the flaky shape and the rodlike shape, and obtains unexpected technical effects.)

1. A method for regulating and controlling the shape of nano silicon dioxide powder and preparing the nano silicon dioxide powder comprises the following steps:

(1) adding absolute ethyl alcohol in a certain proportion into distilled water, and uniformly oscillating by ultrasonic to obtain a solution 1;

(2) under ultrasonic oscillation, adding Tetraethoxysilane (TEOS) into the solution 1, wherein the mass ratio of tetraethoxysilane to absolute ethyl alcohol is (1-2): 1, the mass ratio of distilled water to tetraethoxysilane is 20-30: 1, uniformly oscillating by ultrasonic to obtain a solution 2;

(3) adjusting the pH value of the solution 2 to 9-12 by using ammonia water, and then adding a certain amount of polyvinylpyrrolidone (PVP), NaBr and NaNO₃Stirring the obtained reaction system at a reaction temperature of 65-75 ℃ for reaction for 3-6 h to obtain a solution 3;

(4) and (3) centrifugally washing the solution 3 with absolute ethyl alcohol, then washing with water, and drying in vacuum to obtain the nano silicon dioxide powder with special morphology.

2. The method of claim 1, wherein: and 2, the mass ratio of the ethyl orthosilicate to the absolute ethyl alcohol to the distilled water is 1: 1: 25.

3. the method according to claims 1-2, characterized in that: in the step 3, the pH value is adjusted to 10 by ammonia water, the mass ratio of polyvinylpyrrolidone to ethyl orthosilicate is 11:1, the mass ratio of NaBr to ethyl orthosilicate is 1-3:1, and NaNO is added₃The mass ratio of the sodium-potassium-sodium silicate to the tetraethoxysilane is 1-3:1, and NaBr and NaNO are added₃The mass ratio of the added amount of the silicon dioxide to the tetraethoxysilane is 4: 1.

4. A method according to claims 1-3, characterized in that: the reaction temperature in step 3 was 70 ℃.

5. The method according to claims 1-4, characterized in that: the vacuum drying time in the step 4 is 12-24 h.

Technical Field

The invention relates to the technical field of inorganic nano material preparation, in particular to a shape regulation and preparation production method of nano silicon dioxide powder.

Background

The nano silicon dioxide material is a nano material prepared from inorganic silane, has low toxicity, small granularity, high purity, good biocompatibility, stable physicochemical property, nano small-size effect, surface effect and the like, and is widely applied to the fields of drug transportation, adsorption materials, catalytic conversion, cell uptake, luminous performance, sensing and the like. Nowadays, the research on the preparation and application of nano-silica powder has become a hot spot in the field of inorganic materials.

The production method of the silicon dioxide powder has been in history for decades and is mainly divided into a dry method and a wet method, wherein the dry method comprises a mechanical crushing method, a chemical gas phase method and an electric arc method, and the wet method comprises a precipitation method, a sol-gel method, a micro-emulsion method, a hydrothermal synthesis method and a super-gravity reaction method. The factors influencing the performance of the silicon dioxide powder material not only have size effect, but also have different distribution of silicon dioxide surface atoms in different shapes, thereby having important influence on the physical and chemical properties of the nano material.

Chinese patent CN108128781A adopts plasma direct current transfer arc as heating source to heat silicon raw material to form silicon vapor with uniform components, the silicon vapor is cooled by carrier gas to form silicon droplets to cool and produce spherical nano-silica, but the problems of large energy consumption and incapability of shape regulation exist, Geng et al adopt a series of shape-controllable nano-silica of rice shape, cube shape, capsule shape and the like prepared by hard template method by controlling the concentration of sodium sulfate aqueous solution, although the hard template has more advantages in shape control, the steps are fussy, the period is long, the preparation process has high requirements on the hard template, the structure is easy to collapse and unstable after the template is removed, Zhang et al use the template to prepare the nano-silica of bent double-rod shape and straight-rod shape by changing the proportion, and many scientists also study the formation of nano-shape by the change of temperature, reaction time and pH, the mechanism of topography-controlled synthesis remains unclear and systematic.

Therefore, by using the shape control synthesis technology, the synthesis mechanism of the silicon dioxide powder nano material with a specific morphology and the research on the physical and chemical properties of the silicon dioxide powder nano material can be prepared by a simple method, and the method has important application value and significance.

Disclosure of Invention

Based on the above consideration, the technical problem to be solved by the present invention is to provide a shape-adjustable silica nanopowder and a preparation method thereof.

The invention relates to a shape regulation and control and preparation method of nano silicon dioxide powder, which comprises the following steps:

(1) adding absolute ethyl alcohol in a certain proportion into distilled water, and uniformly oscillating by ultrasonic to obtain a solution 1;

(2) under ultrasonic oscillation, adding Tetraethoxysilane (TEOS) into the solution 1, wherein the mass ratio of tetraethoxysilane to absolute ethyl alcohol is (1-2): 1, the mass ratio of distilled water to tetraethoxysilane is 20-30: 1, uniformly oscillating by ultrasonic to obtain a solution 2;

(3) adjusting the pH value of the solution 2 to 9-12 by using ammonia water, and then adding a certain amount of polyvinylpyrrolidone (PVP), NaBr and NaNO₃Stirring the obtained reaction system at a reaction temperature of 65-75 ℃ for reaction for 3-6 h to obtain a solution 3;

(4) and (3) centrifugally washing the solution 3 with absolute ethyl alcohol, then washing with water, and drying in vacuum to obtain the nano silicon dioxide powder with special morphology.

Preferably, the mass ratio of the ethyl orthosilicate, the absolute ethyl alcohol and the distilled water in the step 2 is 1: 1: 25.

preferably, in the step 3, the pH value is adjusted to 10 by ammonia water, the mass ratio of the polyvinylpyrrolidone to the ethyl orthosilicate is 11:1, the mass ratio of the NaBr to the ethyl orthosilicate is 1-3:1, and the NaNO is added₃The mass ratio of the sodium-potassium-sodium silicate to the tetraethoxysilane is 1-3:1, and NaBr and NaNO are added₃The mass ratio of the added amount of the silicon dioxide to the tetraethoxysilane is 4: 1.

Preferably, the reaction temperature in step 3 is 70 ℃.

Preferably, the vacuum drying time in step 4 is 12-24 h.

According to the method, tetraethoxysilane is used as a precursor, ammonia water is used as a catalyst, PVP is used as a morphology protective agent, NaBr is added as a morphology regulating agent, the thermal and kinetic factors of the reaction are controlled hydrothermally in a dynamic nucleation crystallization mode, and finally the NaNO particles with the sheet-shaped and rod-shaped morphologies are obtained₃The growth of the crystal in other directions is inhibited to form a rod-shaped appearance, and more importantly, the added Br^-The adsorption on the crystal surface can promote the growth of crystal nucleus in the {110} crystal plane orientation, so that silicon dioxide with a flaky appearance is finally formed, and NO is₃ ^-The growth of crystal nuclei in the {100} crystal plane orientation is promoted, and finally, the silicon dioxide with a rod-like morphology is formed.

The invention has the beneficial effects that: the preparation method provided by the invention is simple, mainly takes water as a solvent, is simple, green and clean, can be used for regulating and controlling two types of silicon dioxide nano powder by a simple means, provides effective support for regulating and controlling the shape of silicon dioxide, synthesizes the nano silicon dioxide with a sheet shape for the first time, accurately controls the shape of the nano silicon dioxide by regulating and controlling the proportion of two types of anions to realize the mutual conversion of the sheet shape and the rod shape, and obtains unexpected technical effects.

Drawings

FIG. 1 is an SEM image of the nano-silica with a sheet morphology prepared in example 1, wherein a TEM pore channel map is embedded in the SEM image;

FIG. 2 is an SEM image of the nano-silica with a rod-like morphology prepared in example 2, wherein a TEM pore channel map is embedded in the SEM image;

FIG. 3 is an SEM image of mixed morphology nanosilica prepared in example 3;

FIG. 4 is an SEM image of the nano-silica with a sphere-like morphology prepared in comparative example 1.

Detailed Description

The following detailed description is made with reference to the accompanying drawings.