CN104746160A - Infrared transmittance/reflectivity variable nano composite fiber and preparation method thereof - Google Patents

Abstract

The invention relates to a nanocomposite fiber with variable infrared transmittance/reflectivity and a preparation method, wherein the nanocomposite fiber includes an organic polymer and rutile phase vanadium dioxide nanoparticles compounded in the organic polymer , wherein the mass fraction of the rutile phase vanadium dioxide nanoparticles is 0.5% to 50%, and the diameter of the nanocomposite fibers is 100nm to 2μm.

Description

Nanocomposite fiber with variable infrared transmittance/reflectance and preparation method

technical field

The invention relates to the technical field of nanofibers, in particular to a nanocomposite fiber containing vanadium dioxide nanoparticles with variable infrared transmittance/reflectance, a preparation method thereof and a fiber mat made thereof.

Background technique

Vanadium dioxide is a material with a variety of crystal structures. At 68°C, there is a reversible phase transition from a low-temperature monoclinic phase (M phase) semiconductor state to a high-temperature tetragonal phase (R phase) metallic state. With this phase transition, the material The optical and electrical properties change suddenly. Based on the change of optical transmittance before and after the phase transition of vanadium dioxide, it is applied to smart window materials (G.Xu, P.Jin, M.Tazawa, K.Yoshimura, Optimization of antireflection coating for VO ₂ -basedenergy efficient window, Solar Energy Materials and Solar Cells, 83(2004) 29-37), the smart window has a high transmittance of infrared light below the phase transition temperature, which is conducive to maintaining indoor heat preservation, and blocks most of the infrared radiation outside the phase transition temperature , for practical application, the phase transition temperature of the vanadium dioxide smart window will be adjusted to about 30°C by doping tungsten. Vanadium dioxide smart window materials are currently prepared by two methods, one is coated by magnetron sputtering as in the previous article; the other is formed by chemical methods, first preparing a precursor solution or two Dispersion of vanadium oxide nanopowder, and then spin coating, spray coating and other methods to make film. For the preparation of vanadium dioxide M-phase nano-powder, it can be directly obtained by hydrothermal reaction (Chinese patent CN102120615A), or the vanadium dioxide nano-powder of phase B or A is hydrothermally synthesized, and then transformed into M phase by heat treatment (Chinese patent CN101863511A). The morphology of the vanadium dioxide nanopowder can be spherical, rod-like, linear, and ribbon-like.

In terms of infrared reflective coatings, transparent conductive oxides (TCO) prepared by nano-powder coatings or magnetron sputtering coatings are used to improve the infrared reflectivity of architectural glass, and coatings containing metal or semiconductor nanoparticles use their infrared The absorption capacity is used to achieve low reflection of infrared light. But there is no related report on fabrics with variable infrared transmittance and reflectivity.

In terms of fabrics containing functional nanomaterials, the most common report is the use of antibacterial fabrics containing nanosilver (Xu Xiongli; Cao Yurong; Zhou Meihua, used for medical dressings containing nanosilver gelatin/chitosan composite nanofiber felt and its preparation, Chinese Patent CN101187111A), other fabrics containing metal or semiconductor nanoparticles are used in catalysis and sensor materials (Formo, E., Lee, E., Campbell, D., Xia, Y.N. Functionalization of electrospun TiO2 nanofibers with Pt nanoparticles and nanowires for catalytic applications. Nano Lett8,668-672(2008)), the textile method used is generally electrospinning, and there are also reports of using melt spinning (Jiemo Tian; bioactive nanofibers and their products, Chinese patent CN1635201A). There are currently no reports of fiber mats containing vanadium dioxide, and no reports of textiles used for infrared radiation regulation.

Contents of the invention

Aiming at the problems existing in the prior art, we have designed a nanocomposite fiber and a composite fiber mat containing vanadium dioxide nanoparticles with variable infrared transmittance/reflectivity.

Herein, the present invention provides a nanocomposite fiber with variable infrared transmittance or reflectance, wherein the nanocomposite fiber includes an organic polymer and rutile phase vanadium dioxide nanoparticles compounded in the organic polymer , wherein the mass fraction of the rutile phase vanadium dioxide nanoparticles is 0.5% to 50%, and the diameter of the nanocomposite fibers is 100nm to 2μm.

The advantage of the present invention is that a kind of nanocomposite fiber with variable infrared transmittance and reflectivity that has not been reported has been obtained, and the goods (fiber felt) prepared by this composite fiber are in low transmission and low reflection state at high temperature, and Low temperature is in a state of high transmission and high reflection. When using undoped pure rutile phase vanadium dioxide nanoparticles, the transition temperature is 68°C. The transition temperature can be lowered by adjusting the element doping within a certain range as needed. or elevated.

In the present invention, the rutile phase vanadium dioxide nanoparticles include pure rutile phase vanadium dioxide nanoparticles and/or element-doped rutile phase vanadium dioxide nanoparticles.

In the present invention, the particle size of the rutile phase vanadium dioxide nanoparticles is less than 100 nm.

In the present invention, the organic polymer may be at least one of polyvinylpyrrolidone, polyvinyl alcohol, polymethylmethacrylate, polyethylene-vinyl acetate, and polyacrylonitrile.

In the present invention, the mass fraction of the rutile phase vanadium dioxide nanoparticles preferably ranges from 5% to 40%.

The present invention also provides a method for preparing the above-mentioned nanocomposite fiber, wherein the nanocomposite fiber is prepared by a spinning method, wherein the spinning solution is mixed with the organic polymer, rutile phase vanadium dioxide nanoparticles and an organic solvent forming, wherein the mass fraction of rutile phase vanadium dioxide nanoparticles in the spinning solution is 0.1%-10%.

In the present invention, the spinning method may include electrospinning, melt spinning, wet spinning, and dry spinning.

Preferably, the spinning method is electrospinning, and the spinning voltage may be 8kV-30kV.

The spinning can be carried out continuously or discontinuously, and in this case, the spinning time is preferably 5 to 60 minutes.

Description of drawings

Fig. 1 is the scanning electron micrograph of the monoclinic phase vanadium dioxide nanoparticle that is used for electrospinning;

Fig. 2 is the scanning electron micrograph of the composite fiber containing vanadium dioxide nanoparticles with a diameter of 500nm in backscattering mode, and the organic matter used in this spinning is PVP;

Fig. 3 is the infrared transmission spectrum of fiber mats containing vanadium dioxide nanoparticles with different mass fractions at high temperature and low temperature, and the organic substance used in this spinning is PVP;

Fig. 4 is the infrared diffuse reflectance spectrum of the fiber mat containing vanadium dioxide nanoparticles of different mass fractions under high temperature state and low temperature state, and the organic matter used in this spinning is PVP;

Figure 5 is a scanning electron micrograph of a composite fiber mat containing vanadium dioxide nanoparticles with a diameter of 1 μm in secondary electron mode, and the organic substance used for spinning is PMMA.

Detailed ways

The present invention will be further described below in conjunction with the drawings and the following embodiments. It should be understood that the drawings and the following embodiments are only used to illustrate the present invention rather than limit the present invention.

The invention designs and prepares a nanocomposite fiber mat containing vanadium dioxide nanoparticles with variable infrared transmittance and reflectivity.

The technical scheme adopted in the present invention is: mix monoclinic phase (rutile phase) vanadium dioxide nanoparticles with an organic solution that can be used for electrospinning and ultrasonically disperse them evenly before performing electrospinning. The mass fraction of vanadium dioxide in the solution It is 0.5% to 8%, and the spinning diameter can be adjusted between 150nm and 1μm by adjusting the content of organic matter in the solution. Spinning is received by aluminum foil, and after reaching a certain thickness, it can be completely peeled off and the infrared optical performance can be tested.

Vanadium dioxide nanoparticles are monoclinic phase (M-phase) vanadium dioxide or doped M-phase vanadium dioxide nanoparticles, and the doping elements are any existing elements that can change the phase transition temperature of vanadium dioxide, such as tungsten and molybdenum , niobium, tantalum, titanium, chromium, fluorine, etc.

The advantage of the present invention is that a kind of nanocomposite fiber mat with variable infrared transmission and reflection that has not been reported has been obtained. The temperature is 68°C during doping, and it can be adjusted to decrease or increase within a certain range through element doping as required.

In the present invention, the discontinuous spinning method is adopted, and the spinning time of the fiber mat with variable transmittance is 5 to 15 minutes, preferably 10 minutes. At this time, the difference between high and low temperature infrared transmittance can reach more than 10%. , and as the spinning time increases, the fiber mat becomes thicker, and the ability to adjust the light transmittance decreases until it loses its transparency. Fiber mats with variable reflectivity generally need to be spun for more than 20 minutes to achieve a certain thickness and strength. The difference in infrared reflectivity between high and low temperatures increases with the increase in vanadium dioxide content within a certain range, up to more than 30%. After the fiber mat reaches a certain thickness, the imitation time does not affect its reflectivity.

The nanocomposite fiber structure designed by the present invention can be used to manufacture various energy-saving products such as curtains, tents, clothing, parasols and the like. Its preparation may not be limited to the electrospinning method but includes various spinning methods such as melt spinning, wet spinning, dry spinning, etc. that can be used in industrial mass production.

Examples are given below to describe the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above contents of the present invention all belong to the present invention scope of protection. The specific process parameters such as time and temperature in the following example are only an example of a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values exemplified below.

Example 1

VO ₂ -PVP composite nanofiber mat (VO ₂ mass fraction about 26%)

Mix and stir 0.7g PVP (molecular weight: 1.3 million) and 9.3g alcohol to dissolve PVP, then add 0.25g monoclinic phase vanadium dioxide nanoparticles (phase transition temperature is 40°C, the same below), ultrasonically disperse after 5 hours Electrospinning. The spinning voltage is 15kV, the advancing speed of the syringe is 2.5ml/h, and the distance from the needle to the receiving screen is 15cm. Spinning for 10 minutes (test transmission spectrum) or 30 minutes (test diffuse reflectance spectrum) to obtain a composite nanofiber mat with a fiber diameter of 500 nm. Please see attached drawing 2 for scanning electron microscope photos, attached attached drawing 3 for transmission spectra at high temperature (60°C) and low temperature (20°C), and attached attached drawing 4 for infrared diffuse reflectance spectra at high temperature (60°C) and low temperature (20°C) The dotted line in .

Example 2

VO ₂ -PVP composite nanofiber mat (VO ₂ mass fraction about 38%)

0.7g of PVP and 9.3g of alcohol were mixed and stirred to dissolve the PVP, then 0.5g of monoclinic phase vanadium dioxide nanoparticles were added, ultrasonically dispersed for 5 hours before electrospinning. The spinning voltage is 15kV, the advancing speed of the syringe is 2.5ml/h, and the distance from the needle to the receiving screen is 15cm. Spinning for 30 minutes to obtain a composite nanofiber mat with a fiber diameter of 500 nm. The transmission spectrum at high temperature (60°C) and low temperature (20°C) is shown in Figure 3, and the infrared diffuse reflectance spectrum at high temperature (60°C) and low temperature (20°C) is shown in the dotted line in Figure 4.

Example 3

VO ₂ -PMMA composite nanofiber mat (VO ₂ mass fraction about 21%)

2.25g PMMA and 7.75g DMF (dimethylformamide) were mixed and stirred to dissolve PMMA, then 0.6g monoclinic phase vanadium dioxide nanoparticles were added, and electrospinning was performed after ultrasonic dispersion for 5 hours. The spinning voltage is 10kV, the advancing speed of the syringe is 1.5ml/h, and the distance from the needle to the receiving screen is 15cm. A composite nanofiber mat with a fiber diameter of 1 μm was obtained by spinning for 30 minutes. The scanning electron microscope photos are shown in Figure 5.

Example 4

VO ₂ -PAN composite nanofiber mat (VO ₂ mass fraction about 17%)

0.5g PAN and 9.5g DMF were mixed and stirred to dissolve PAN, then 0.1g monoclinic vanadium dioxide nanoparticles were added, and electrospinning was performed after ultrasonic dispersion for 5 hours. The spinning voltage is 12kV, the advancing speed of the syringe is 2.5ml/h, and the distance from the needle to the receiving screen is 15cm. Spin for 30 minutes to obtain a composite nanofiber mat with a fiber diameter of 250 nm.

Example 4

VO ₂ -PEVA composite nanofiber mat (VO ₂ mass fraction about 29%)

1.6g of PEVA and 8.4g of chloroform were mixed and stirred to dissolve PEVA, then 0.25g of monoclinic phase vanadium dioxide nanoparticles were added, and electrospinning was performed after ultrasonic dispersion for 5 hours. The spinning voltage is 18kV, the advancing speed of the syringe is 2.5ml/h, and the distance from the needle to the receiving screen is 15cm. Spinning for 30 minutes to obtain a composite nanofiber mat with a fiber diameter of 500 nm.

Industrial Applicability: The present invention provides nanocomposite fibers with variable infrared transmittance/reflectance, which can be used to manufacture various energy-saving products such as curtains, tents, clothing, parasols, etc.

Claims (8)

1. the nano-composite fiber of infrared transmittivity/varying reflectivity, it is characterized in that, described nano-composite fiber includes organic polymer and is compounded in the rutile phase hypovanadic oxide nano particle of described organic polymer, the mass fraction of wherein said rutile phase hypovanadic oxide nano particle is 0.5% ~ 50%, and the diameter of described nano-composite fiber is 100nm ~ 2 μm.

2. nano-composite fiber according to claim 1, is characterized in that, described rutile phase hypovanadic oxide nano particle comprises the rutile phase hypovanadic oxide nano particle of pure rutile phase hypovanadic oxide nano particle and/or element doping.

3. nano-composite fiber according to claim 1 and 2, is characterized in that, the particle diameter of described rutile phase hypovanadic oxide nano particle is below 100nm.

4. nano-composite fiber according to any one of claim 1 to 3, is characterized in that, described organic polymer is at least one in polyvinylpyrrolidone, polyvinyl alcohol, polymethyl methacrylate, EVA and polyacrylonitrile.

5. the preparation method of a nano-composite fiber according to any one of claim 1 to 4, it is characterized in that, described nano-composite fiber is prepared by spin processes, wherein spinning solution is mixed to form by described organic polymer, rutile phase hypovanadic oxide nano particle and organic solvent, wherein, in described spinning solution, the mass fraction of rutile phase hypovanadic oxide nano particle is 0.1% ~ 10%.

6. preparation method according to claim 5, is characterized in that, described spin processes comprises electrostatic spinning, melt spinning, wet spinning and dry spinning.

7. the preparation method according to claim 5 or 6, is characterized in that, described spin processes is electrostatic spinning, and spinning voltage is 8kV ~ 30kV.

8. the fibrofelt made of a nano-composite fiber according to any one of claim 1 to 4, it is characterized in that, the infrared transmittivity of described fibrofelt when the phase transition temperature lower than described rutile phase hypovanadic oxide nano particle or reflectivity are higher than the infrared transmittivity of described fibrofelt when the phase transition temperature higher than described rutile phase hypovanadic oxide nano particle or reflectivity.