CN101538066B - Method for realizing mono-disperse modification and optimal orientation array of hypovanadic oxide nano wire - Google Patents

Abstract

A method for realizing monodisperse modification and preferred orientation arrangement of vanadium dioxide nanowires. The method is that the VO ₂ nanowires can be monodispersed in chloroform after two-step surface functionalization treatment of stearic acid and cetyltrimethylammonium bromide, and no precipitation occurs after being placed for 1 month. The obtained VO ₂ nanowire LB film realized (00l) crystal plane orientation and local area alignment, and had quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties. The process of the method is very simple, low in equipment requirements, good in reproducibility, high in controllability, and in compliance with environmental requirements. This technology is suitable for assembly, integration and application of new nano-devices such as sensing, optoelectronics, and biology.

Description

A method to achieve monodisperse modification and preferred orientation arrangement of vanadium dioxide nanowires

technical field

The invention relates to a method for realizing _VO2 nanowire monodispersity and preferred orientation arrangement by using a common surfactant and a simple and feasible surface modification method, and belongs to the field of nanomaterials and nanotechnology.

Background technique

In recent years, nanotechnology has developed vigorously, and the application of nanomaterials has attracted widespread attention in various fields. However, the particle size of nanoparticles is very small, and its high surface energy makes it easy to agglomerate, poor dispersion, and the formation of secondary particles, which cannot show its favored surface area effect, volume effect and quantum size effect, which seriously affects its use. Effect. Therefore, in practical applications, how to functionalize the surface of nanoparticles, avoid the agglomeration of nanoparticles, improve their dispersion, and arrange their preferred orientation and orderly assembly is a very important research in the field of nanomaterials science. This topic is of great significance for the deviceization and practical application of nanomaterials.

Contents of the invention

Aiming at the agglomeration phenomenon existing in the nanometer field, the present invention provides a simple and feasible surface modification method to eliminate the common agglomeration of nanoparticles to obtain better monodispersity, so that _VO2 nanowires can obtain good monodispersity, and The assembly was carried out to realize the preferred orientation arrangement and local ordered assembly of VO ₂ nanowires. The obtained VO ₂ nanowire LB film has good quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

The technical scheme adopted in the present invention is as follows:

A method for realizing VO _nanowire monodisperse modification and preferred orientation arrangement, the method steps are as follows:

1. Measure 40-60 ml of toluene into a 100-ml beaker, add 0.8-1.2 mmol of stearic acid into it and stir vigorously, heat the beaker in a water bath at a temperature of 70°C, 80°C or 90°C, and keep stirring until Stearic acid dissolves or melts; Add VO _nanowire wherein, the mol ratio of VO _nanowire and stearic acid is 1: 2, centrifuge after stirring for 0.5～1.5 hours, wash with toluene to remove excess stearic acid, Obtain stearic acid-modified VO _nanowires ;

2. Weigh 8-12 grams of surfactant cetyltrimethylammonium bromide and transfer it into an 80-ml beaker, add 40 ml of cyclohexane and 10 ml of deionized water; take 0.08-0.12 mmol of stearic acid to modify Add the processed _VO2 nanowires into 8-12 ml of n-butanol, ultrasonically disperse for 5 minutes, then transfer all of them into the above-mentioned cyclohexane solution, and stir vigorously to obtain a clear and translucent microemulsion; after continuous stirring for 1.5-2.5 hours, Centrifuged, washed 8 to 12 times with a mixed solvent of isooctane/chloroform with a volume ratio of 1:1;

3. Treat the solid substrate to be hydrophilic;

4, with Langumir (Langmuir) flume, control the surface pressure-surface area isotherm of the VO _nanowire monolayer film that is processed through step 2 on the water surface, to form _VO Nanowire monolayer film;

5, the _VO2nanowire monolayer film that step 4 forms is transferred to the solid substrate surface processed in step 3 to form _VO2nanowire Langumir-Blodget (Langmuir-Blodget) i.e. LB film, to obtain The VO ₂ nanowire LB film realized the (00 l ) crystal plane orientation.

The present invention selects organic acid as the surface modifier and has two starting points: one is that the carboxyl group can generate hydrogen bonds with the hydroxyl groups on the surface of the _VO2 nanowires, so that the number of hydroxyl groups on the surface of the _VO2 nanowires is reduced, thereby reducing agglomeration; the other is that As an anionic surfactant, its carboxyl group will be hydrolyzed, which provides convenience for further modification in an aqueous environment. The secondary modification by microemulsion method is because the monodispersity of VO ₂ nanowires modified by microemulsion will be further improved. The VO ₂ nanowires could be monodispersed in chloroform after two-step surface functionalization treatment, and they were left for 1 month without precipitation. The obtained VO ₂ nanowire LB film realized (00 l ) crystal plane orientation and local area alignment, and had quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

The invention can make the _VO2 nanowires obtain better monodispersity and preferred orientation, is beneficial to assemble nanometer devices and improve the performance of nanometer devices, and provides a feasible way for the practical application of nanometer materials.

Description of drawings:

Fig. 1 is the surface functionalization schematic diagram of embodiment 1VO ₂ nanowires

Fig. 2 is the π-A isotherm graph of embodiment 1VO ₂ nanowire LB film

Fig. 3 is the SEM image of LB film under 40mN/m surface pressure of VO _nanowire 40mN/m surface after the surface modification of embodiment 1 (insert is a partially enlarged view)

Fig. 4 is the XRD spectrum of embodiment _1VO2nanowire LB film (a) and _VO2nanowire powder (b)

Its Figure 3 shows that the _VO2 nanowire LB film has a certain local order. Figure 4 shows that the (00 l ) crystal plane preferred orientation of VO ₂ nanowires is achieved after surface modification and LB assembly.

Detailed ways

The method of the present invention will be further described below by way of examples.

Example 1:

1. Measure 50 ml of toluene and transfer it into a 100 ml beaker, add 1 mmol of stearic acid into it and stir vigorously, heat the beaker in a water bath at 90°C, and keep stirring until the stearic acid dissolves or melts; add 0.5 mmol of stearic acid to it. Mole of _VO2nanowires , centrifuged after stirring for 1 hour, washed with toluene to remove excess stearic acid, to obtain stearic acid-modified _VO2nanowires ;

2. Weigh 10 grams of surfactant CTAB and transfer to 80 ml of 1 beaker, add 40 ml of cyclohexane and 10 ml of deionized water; take 0.1 mmol of stearic acid-modified _VO2 nanowires and add 10 ml of n-butanol Ultrasonic dispersion for 5 minutes, then all transferred to the above cyclohexane solution, stirred vigorously to obtain a black clear translucent microemulsion, centrifuged after continuous stirring for 2 hours, mixed with isooctane/chloroform at a volume ratio of 1:1 Solvent washing 10 times;

3. Treat the solid substrate to be hydrophilic;

4. With a Langumir tank, control the surface pressure _- surface area isotherm of the VO _nanowire monolayer film processed in step 2 on the water surface to form VO nanowire monolayer film;

5. Transfer the VO ₂ nanowire monolayer film formed in step 4 to the surface of the solid substrate treated in step 3 to form a VO ₂ nanowire LB film, realizing the (00 l ) crystal plane orientation and local The regions are aligned and have quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

The π-A isotherm curves of VO _nanowire LB films are shown in Fig. 2. The SEM image of the LB film under the 40mN/m surface pressure of _VO2 nanowires after surface modification is shown in Figure 3, where the inset is a partial enlarged view. The XRD pattern of VO ₂ nanowire LB film is shown in Figure 4(a), and the XRD pattern of VO ₂ nanowire powder is shown in Figure 4(b).

Example 2:

1. Measure 40 ml of toluene and transfer it into a 100 ml beaker, add 0.8 mmol of stearic acid into it and stir vigorously, heat the beaker in a water bath at 70°C, and keep stirring until the stearic acid dissolves or melts; add 0.4 mmol of stearic acid to it. Mole of _VO2nanowires , centrifuged after stirring for 0.5 hours, washed with toluene to remove excess stearic acid, to obtain stearic acid modified _VO2nanowires ;

2. Weigh 8 grams of surfactant CTAB and transfer it to an 80-ml beaker, add 40 ml of cyclohexane and 10 ml of deionized water; take 0.08 mmol of stearic acid-modified _VO2 nanowires and add them to 8 ml of n-butanol Ultrasonic dispersion for 5 minutes and then all transferred to the above cyclohexane solution, vigorously stirred to obtain a black clear translucent microemulsion, centrifuged after continuous stirring for 1.5h, washed with a mixed solvent of isooctane/chloroform with a volume ratio of 1:1 8 times;

3. Treat the solid substrate to be hydrophilic;

4. With a Langumir tank, control the surface pressure _- surface area isotherm of the VO _nanowire monolayer film processed in step 2 on the water surface to form VO nanowire monolayer film;

5. Transfer the VO ₂ nanowire monolayer film formed in step 4 to the surface of the solid substrate treated in step 3 to form a VO ₂ nanowire LB film, realizing the (00 l ) crystal plane orientation and local The regions are aligned and have quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

Example 3:

1. Measure 60 ml of toluene and transfer it into a 100 ml beaker, add 1.2 mmol of stearic acid into it and stir vigorously, heat the beaker in a water bath at 80°C, and keep stirring until the stearic acid dissolves or melts; add 0.6 mmol of stearic acid to it. mole _of VO nanowires, centrifuged after stirring for 1.5 hours, washed with toluene to remove excess stearic acid, and obtained stearic acid-modified VO _nanowires ;

2. Weigh 12 grams of surfactant CTAB and transfer it to an 80-ml beaker, add 40 ml of cyclohexane and 10 ml of deionized water; take 0.12 mmol of stearic acid-modified _VO2 nanowires and add it to 12 ml of n-butanol Ultrasonic dispersion for 5 minutes, then all transferred to the above cyclohexane solution, stirred vigorously to obtain a clear translucent microemulsion, centrifuged after continuous stirring for 2.5 hours, washed with a mixed solvent of isooctane/chloroform with a volume ratio of 1:1 12 times;

3. Treat the solid substrate to be hydrophilic;

4. With a Langumir tank, control the surface pressure _- surface area isotherm of the VO _nanowire monolayer film processed in step 2 on the water surface to form VO nanowire monolayer film;

5. Transfer the formed _VO2 nanowire monolayer film to the surface of the solid substrate treated in step 3 to form a _VO2 nanowire LB film, realizing the crystal plane orientation and local area orientation of vanadium dioxide nanowires (00 l ) arrangement, and has quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

Claims (1)

1. A method for realizing VO _nanowire monodisperse modification and preferred orientation arrangement, is characterized in that, method steps are as follows: 1) Measure 40-60 ml of toluene into a 100-ml beaker, add 0.8-1.2 mmol of stearic acid and stir vigorously, heat the beaker in a water bath at a temperature of 70°C, 80°C or 90°C, and continue stirring until Stearic acid dissolves or melts; Add VO nanowire wherein, the mol ratio of VO _nanowire and stearic acid is 1: 2, centrifuge after stirring for 0.5 _～ 1.5 hours, wash with toluene to remove excess stearic acid, Obtain stearic acid-modified VO _nanowires ; 2) Weigh 8-12 grams of surfactant cetyltrimethylammonium bromide and transfer it to an 80-ml beaker, add 40 ml of cyclohexane and 10 ml of deionized water; take 0.08-0.12 mmol of stearic acid to modify The processed _VO2 nanowires were ultrasonically dispersed in 8-12 ml of n-butanol for 5 minutes, then all were transferred into the above-mentioned cyclohexane solution, and stirred vigorously to obtain a clear and translucent microemulsion, which was centrifuged after 1.5-2.5 hours of continuous stirring. Separated, washed 8 to 12 times with a mixed solvent of isooctane/chloroform with a volume ratio of 1:1; 3) Treat the solid substrate to be hydrophilic; 4) using a Langmuir tank to control the surface pressure-surface area isotherm of the VO _nanowire monolayer film treated in step 2) on the water surface to form a VO _nanowire monolayer film; 5) the VO _nanowire monolayer film formed in step 4) is transferred to the solid substrate surface treated in step 3) to form a VO _nanowire Langmuir-Brodget film, i.e. LB film, to obtain VO ₂ nanowire LB films have achieved (00l) crystal plane orientation, and have good quasi-sustained photoconductivity and typical magnetic phase transition and paramagnetic properties.

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