CN100431956C - Process for preparing mesoporous silicon dioxide spiral coil - Google Patents

Abstract

A method for preparing a mesoporous silica spiral tube, the feature of the present invention is: placing 100g·L ^- 1 glucose aqueous solution at 160-190°C for 3-6 hours to obtain an aqueous polysaccharide solution; Sugar aqueous solution, polyoxyethylene ether-polyoxypropylene ether-polyoxyethylene ether triblock polymer surfactant (average molecular weight 5800) and 2mol L ^-1 hydrochloric acid solution are mixed, and orthosilicic acid is added Ethyl ester; 100g L ^- 1 glucose aqueous solution, polyoxyethylene ether-polyoxypropylene ether-polyoxyethylene ether triblock polymer surfactant (average molecular weight 5800), 2mol L ^-1 The optimal weight ratio between the hydrochloric acid solution and the tetraethyl orthosilicate reactants is 50:1:40:2; after the tetraethyl orthosilicate is fully hydrolyzed, place it in a closed container and heat it to 160~190°C. Keep warm for 24 hours; after the product is separated, washed and dried, it is calcined at 550-650°C for 6-8 hours in an air atmosphere, and then lowered to room temperature to obtain a three-stage self-assembled mesoporous silica spiral tube.

Description

A kind of preparation method of mesoporous silica spiral tube

1. Technical field

The invention relates to a new type of silicon dioxide spiral tube and its preparation method, which belongs to the technical field of nanomaterial preparation

2. Background technology

Artificially synthesizing helical structure materials at the mesoscopic level has broad significance, not only because the helical structure and life phenomena are so close, but also the helical structure materials also provide superior performance than ordinary materials. As far as helical carbon nanotubes are concerned, in the early 1990s, Japan's Motojima produced helical carbon fibers with good reproducibility. In addition to the excellent properties of ordinary carbon fibers such as heat resistance, chemical stability, electrical and thermal conductivity, thermal expansion and low density, helical carbon fibers also have typical chiral characteristics and good elasticity due to their special helical structure. It can be used as a new type of electromagnetic wave absorber, micro-sensitive energy absorber and micro-spring.

In recent years, micron-scale mesoporous _SiO2 helical tubes formed with mesoporous structures as basic constituent units have been reported one after another. In summary, the currently synthesized mesoporous SiO ₂ helical tubes can be divided into two types: one is that the larger product particles present a helical tubular structure, that is, the macroscopic morphology (micron scale) of the product exhibits a helical tubular shape, while the other The basic unit (mesoporous) does not necessarily show an ordered helical structure, and the synthesis of Ozin and other research groups is representative; the other is that the mesoporous itself (nanoscale) that constitutes the macroscopic morphology also shows an ordered structure. For example, the work of Che et al. reported by Nature in 2004, the mesoporous pipelines in their products show a consistent direction of rotation, and macroscopically appear as chiral micron helical rods; Stucky et al. have similar reports on NatureMaterials.

From the perspective of the synthesis route, the synthesis methods of these typical mesoporous spiral tubes are different, and can be roughly divided into: (1) single template method; (2) template plus physical action; (3) composite template (4) soft and hard template method. Among them, the work of Che's research group used the mechanism of composite templates [Che, S. et al. Nature 2004, 429, 281].

In Che's work, helical compound templates are formed mainly by adjusting the charge interaction between the templates. The specific process is as follows: 0.32g (1mmol) of amino acid salt N-miristoyl-L-alanine sodium (C ₁₄ -L-AlaS) was dissolved in 32g of water at room temperature, and then 1.4g (0.14mmol) of 0.1mol·L ^-1 hydrochloric acid solution was added to acidify part of the amino acid salt to produce a certain amount of free amino acid (C ₁₄ -L-AlaA ). After the above mixed solution was stirred for 1 hour, 1.4 g of tetraethyl orthosilicate (TEOS) and 0.20 g of N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride (TMAPS) were added to the mixed solution. In the above mixed system, the ammonium group of TMAPS is positively charged, while the hydrophilic headgroups of C ₁₄ -L-Alas and C ₁₄ -L-AlaA are negatively charged, and the two templates assemble into a helical structure through the interaction of positive and negative charges The composite template agent, and then by controlling the hydrolysis of TEOS, the silica is uniformly coated on the template agent, and after calcination at 650°C for 6 hours in an air atmosphere, microrods with a helical channel structure are finally obtained. Although relatively uniform helical microrods can be produced through this route, there are still several shortcomings: (1) the synthetic raw materials (such as amino acid salts) are expensive, and the general laboratory synthesis is acceptable, but it is not conducive to large-scale preparation; (2) The pore size of the obtained sample is small (2~3nm), which is not conducive to the later modification of the pore; (3) The helical pore structure in the sample is single, and only the first-order pore (2~3nm mesopore) limits its application range.

We have successfully synthesized micron helical tubes with cheap raw materials such as glucose and tri-block copolymers. The structure is complex and the raw materials are easy to synthesize, so it has a good application prospect.

3. The content of the invention

The purpose of the present invention; provide a new preparation method, use it to prepare three-level self-assembled mesoporous silica spiral tube. Primary hole: mesoporous (10nm); secondary hole: solenoid (70nm) composed of mesopore as the wall; tertiary hole: micron spiral tube composed of secondary hole-solenoid. It is expected to be applied in the processing of complex nanometer and micrometer devices.

The principle of the present invention is as follows: first control the degree of polymerization of glucose to obtain the primary template of polydextrose, and then under strong acidic conditions, interact with the polymer neutral surfactant and polydextrose through hydrogen bonds to form an advanced template , add a silicon source therein, make it hydrolyze under specific conditions, uniformly cover the surface of the template, and obtain a tertiary mesoporous silica spiral tube after calcination.

The object of the present invention is achieved in this way: 100g·L ^-1 aqueous glucose solution is placed at 160-190°C for 3-6 hours to obtain an aqueous solution of polysaccharide; Epoxypropylene ether-polyoxyethylene ether triblock polymer surfactant (average molecular weight 5800) (abbreviated as P123) and 2mol L ^-1 hydrochloric acid solution are mixed, and tetraethyl orthosilicate is added; 100g L ^-1 glucose aqueous solution, polyoxyethylene ether-polyoxypropylene ether-polyoxyethylene ether triblock polymer surfactant (average molecular weight 5800), 2mol L ^-1 hydrochloric acid solution and orthosilicic acid The weight ratio between several ethyl ester reactants is 40~60:1:30~50:2~3; after the ethyl orthosilicate is fully hydrolyzed, place it in a closed container, heat it to 160~190°C, and keep it warm for 24 Hours; After the product is separated, washed and dried, it is calcined at 550-650°C for 6-8 hours in an air atmosphere, and then lowered to room temperature to obtain a three-stage self-assembled mesoporous silica spiral tube.

Taking the situation in Example 1 as an example, for ease of understanding, the formation process of the composite template is shown in Figure 1; the characterization and structure simulation diagram of the obtained product is shown in Figure 2.

The advantage of the preparation method that the present invention adopts is:

1. Using glucose as the precursor for the preparation of polydextrose, the raw material is easy to obtain, the preparation process is simple, and it has a good interaction with the block copolymer under the preparation conditions, and can form a special composite template. Moreover, the hydrothermal glucose solution can also obtain micro-carbon spheres as a by-product, which can also be used for the preparation of nanomaterials;

2. Through the preparation process of the present invention, a higher-level and more complex pore structure can be prepared, which provides the possibility for the processing of complex nano-devices.

4. Description of drawings

Figure 1: Schematic diagram of composite template formation.

Figure 2: Characterization results and structural simulation diagrams of products prepared by the method of the present invention. (A) Transmission electron microscope (TEM) results of the obtained sample, scale bar: 500 nm. Among them, the inserted figure is a partially enlarged TEM image and a fast Fourier transform image of the corner of the helical tube, the scale in the figure: 20nm; (B) the secondary hole-the transmission electron microscope result of the solenoid, the scale: 100nm; (C ) Scanning electron microscope (SEM) results of the obtained sample, scale bar: 300nm; (D) Simulation diagram of the spiral tube. Wherein, the inserted figure is a schematic cross-sectional structure diagram of the secondary hole.

5. Specific implementation

The preparation process is divided into two main stages:

1. Preparation of polycondensate

Dissolve 5.0 g of glucose in 50 ml of water, then transfer it into an 80 ml airtight container, heat to 190°C, keep for 4 hours, cool down to room temperature, and filter to obtain an orange-red polycondensate solution.

2. Preparation of Spiral Tubes

1.0g polyoxyethylene ether-polyoxypropylene ether-polyoxyethylene ether triblock polymer surfactant (average molecular weight 5800) is dissolved in the hydrochloric acid solution that 40g concentration is 2mol L ^-1 , at 40 Add all the obtained polycondensate solution at ℃ (the pH value of the solution is about 1 at this time), stir for 1 hour, add 2.0 g of tetraethyl orthosilicate (TEOS), stir and react at 40 ℃ for 24 hours, then move it into an airtight container. Heated to 190°C for 24 hours, filtered and washed, air-dried, calcined at 550°C in an air atmosphere for 6 hours, and lowered to room temperature to obtain a three-stage self-assembled mesoporous silica spiral tube.

After the determination sample was ground, it was ultrasonically dispersed by ethanol solution and then placed on a copper grid for observation.

The application of the present invention is: a three-stage self-assembled mesoporous silicon dioxide helical tube is prepared in a simple way, which can be used for the processing of complex nanometer devices, such as; microcoils, nanometer springs and the like. It can also be used as a catalyst carrier to load different active components in different pore structures, and it is expected to prepare novel catalytic materials.

Claims (2)

1. the preparation method of a mesoporous silicon dioxide spiral coil is characterized in that: with 100gL ^-1D/W place 160-190 ℃ to keep 3-6 hour down, obtain the bunching sugar aqueous solution; With bunching sugar aqueous solution and poly-oxyethylene ether-poly-propylene oxide ether-poly-oxyethylene ether three block macromolecular polymeric surfactant molecular-weight average 5800 and 2molL ^-1Hydrochloric acid soln mixes mutually, adds tetraethoxy; 100gL ^-1D/W, poly-oxyethylene ether-poly-propylene oxide ether-poly-oxyethylene ether three block macromolecular polymeric surfactant molecular-weight average 5800,2molL ^-1Weight ratio between several reactants of hydrochloric acid soln and tetraethoxy is 40-60: 1: 30-50: 2-3; Treat that the abundant hydrolysis of tetraethoxy is placed in the encloses container, be heated to 160-190 ℃, be incubated 24 hours; Product after separation, washing, drying, under air atmosphere 550-650 ℃ roasting 6-8 hour, after reduce to room temperature and obtain three grades of self-assembly mesoporous silicon dioxide spiral coils.

2. according to the preparation method of the described mesoporous silicon dioxide spiral coil of claim 1, it is characterized in that 100gL ^-1D/W, poly-oxyethylene ether-poly-propylene oxide ether-poly-oxyethylene ether three block macromolecular polymeric surfactant molecular-weight average 5800,2molL ^-1Weight ratio is 50: 1: 40 between several reactants of hydrochloric acid soln and tetraethoxy: 2.

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