CN113359360A

CN113359360A - Composite particle and light modulation device containing the same

Info

Publication number: CN113359360A
Application number: CN202010142375.7A
Authority: CN
Inventors: 王耀; 谷小虎; 邱运昌
Original assignee: Jiangsu Jitri Smart Liquid Crystal Sci and Tech Co Ltd
Current assignee: Jiangsu Jitri Smart Liquid Crystal Sci and Tech Co Ltd
Priority date: 2020-03-04
Filing date: 2020-03-04
Publication date: 2021-09-07
Also published as: WO2021175034A1

Abstract

The present invention provides a composite particle comprising an inner core having a non-spherically symmetric shape and an outer shell composed of a material different from that of the inner core, the material of the outer shell being regularly distributed along the shape of the inner core, so that the composite particle has optical dichroism and dielectric anisotropy. The invention also provides a dimming device comprising the composite particle. By controlling the size and shape of the inner core of the composite particle of the invention, the size and length-diameter ratio of the finally formed composite particle can be effectively controlled, so that the composite particle has structural anisotropy; by utilizing the optical dichroism of the shell material, the finally formed composite particles have both optical dichroism and dielectric anisotropy, can provide rich colors, and have wider application in light modulation devices.

Description

Composite particle and light modulation device containing the same

Technical Field

The present invention relates to a composite particle having a core-shell structure, and more particularly, to a composite particle having dichroism and a light modulation device including the same.

Background

With the development of science and technology, the application of the light-adjusting glass in the fields of buildings, transportation and office is more and more extensive, and especially the application in the fields of automobiles, high-speed rails, airplanes and the like is more noticed. The existing dimming glass market is mature PDLC intelligent glass and electrochromic intelligent glass, wherein the PDLC intelligent glass can only realize the switching between transparency and haze and cannot realize the effects of light shielding and heat insulation, and the electrochromic intelligent glass has the problems of complex film layer process, slow response time (8-20 s) and the like.

Another relatively mature technology is the SPD light valve technology, in which suspended particles are suspended in a dimming layer, and the suspended particles perform brownian motion in a state where no electric field is applied, so as to absorb, scatter or reflect incident light, thereby making the SPD light valve appear in a dark state; when an electric field is applied, the suspended particles are polarized and thus aligned with the direction of the electric field, allowing most of the incident light to pass through the light modulating layer, rendering the SPD light valve bright, as disclosed in U.S. patent application No. US 5650872A. In this technique, the shape and size of the suspended particles are important for later effects. However, due to the influence of materials and preparation processes, the shape and size of suspended particles cannot be precisely controlled, for example, U.S. patent application No. 5368780A discloses a method for preparing iodine nanorods, but the nanorods are large in size and are not uniform. Meanwhile, the suspended particles prepared conventionally have a single size and shape, so that the generated color is single, and various requirements cannot be met.

Therefore, it is desirable to provide particles which not only can effectively control the size and aspect ratio, but also provide rich color while ensuring structural and optoelectronic anisotropy.

Disclosure of Invention

In order to solve the above problems, an aspect of the present invention provides a composite particle including an inner core having a non-spherically symmetric shape and an outer shell composed of a material different from that of the inner core, the material of the outer shell being regularly distributed along the shape of the inner core, so that the composite particle has optical dichroism and dielectric anisotropy.

In a preferred embodiment, the shape of the inner core is rod-like, ribbon-like, sheet-like, needle-like, wire-like or disk-like. In a preferred embodiment, the shortest axis of the inner core has a dimension of 0.1 to 100 nm. In another preferred embodiment, the ratio of the longest axis to the shortest axis of the inner core is from 2:1 to 50: 1.

In a preferred embodiment, the material of the inner core is a metal and its compounds, non-metallic inorganic or organic.

In a preferred embodiment, the material of the outer shell is particles of anisotropic metal particles, semiconductor crystals, metal transition chalcogenides, carbon nanotubes, dichroic dyes or alkaloid polyhalides.

In a preferred embodiment, the alkaloid polyhalide is a polyhalide of a pyrrole, thiazole, imidazole, pyrazole, pyridine, pyrimidine, quinine, pyrazine, phenanthroline or purine compound. In another preferred embodiment, the alkaloid polyhalide is an alkaloid polyiodide.

In another preferred embodiment, the dichroic dyes include azo, oligomeric thiophene and anthraquinone dyes.

The invention also provides a dimming device comprising the composite particles, which comprises a first transparent base layer, a first transparent conductive layer, a dimming layer, a second transparent conductive layer and a second transparent base layer, wherein the dimming layer comprises the composite particles, a particle stabilizer and a dispersion medium, and the composite particles are suspended in the dispersion medium.

In a preferred embodiment, the longest axis of the composite particles is 10 to 1000 nm in size.

For the composite particle provided by the invention, the size and the length-diameter ratio of the finally formed composite particle can be effectively controlled by controlling the size and the shape of the inner core of the composite particle, so that the composite particle has structural anisotropy; by utilizing the optical dichroism of the shell material, the finally formed composite particles have both optical dichroism and dielectric anisotropy, can provide rich colors, and have wider application in light modulation devices.

Drawings

The invention may be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic structural view of a composite particle provided by the present invention;

FIG. 2 is a schematic diagram of a dimmer device according to the present invention when the dimmer device is not powered;

FIG. 3 is a schematic diagram of the structure and operation of the dimmer device of the present invention when powered;

FIG. 4 is a TEM image of (a) a core and (b) a composite particle according to an embodiment of the present invention;

fig. 5 is a T-V curve of a dimming device according to an embodiment of the present invention;

FIG. 6 is a microscope image of a composite particle according to an embodiment of the invention;

fig. 7 is a microscope image of a composite particle according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. The illustrated example embodiments have been set forth only for the purposes of example and that it is not intended to be limiting. Therefore, it is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

As shown in fig. 1, the composite particle 1 disclosed in the present invention has a core-shell structure, and includes an inner core 10 having an aspherical symmetrical shape and an outer shell 20 made of a material different from that of the inner core. The outer shell 20 may completely surround the inner core 10 (as shown in FIG. 1) or may only partially surround the inner core 10. The core 10 has a non-spherically symmetrical shape (i.e., a structure in which at least two optical axes are not equal in length), such as a rod, a ribbon, a sheet, a needle, a wire, or a disk. The invention is not limited thereto and other desired non-spherically symmetrical shapes may be used. For an inner core 10 having a non-spherically symmetric shape, its shortest axis is typically of a nanoscale size, while the ratio of its longest axis to its shortest axis is greater than 1. The size of the shortest axis of the core 10 is 0.1 to 100 nm, preferably 0.1 to 60 nm. The ratio of the longest axis to the shortest axis of the inner core 10 is 2:1 to 50:1, preferably 2:1 to 40: 1. The material of the inner core 10 may be metal and its compound, non-metal inorganic matter or organic matter. For example, the core 10 may be a gold nanowire, a silver nanosheet, a ferroferric oxide nanorod, a molybdenum disulfide nanosheet, a hydroxyapatite nanorod, a cellulose nanorod, or the like.

The outer shell 20 is composed of a material different from that of the inner core, which may exhibit optical dichroism in specific cases, such as anisotropic metal particles (e.g., gold nanorods), semiconductor crystals (e.g., GeAs crystals), metal transition chalcogenides (e.g., BaTiS crystals), and the like₃) Carbon nanotubes, dichroic dyes or particles of an alkaloid polyhalide. Preferably, the alkaloid polyhalide is a polyhalide of pyrrole, thiazole, imidazole, pyrazole, pyridine, pyrimidine, quinine, pyrazine, phenanthroline and purine compounds. However, the present invention is not limited thereto, and other alkaloids polyhalides of nitrogen-containing heterocycles and derivatives thereof can be used. The alkaloid polyhalide may also be an alkaloid polyiodide, such as quinine iodosulfate, iodophenanthroline dicarboxylic acid, iodopyrazine dicarboxylic acid, iodopyridine dicarboxylic acid, and the like. Dichroic dyes include azo, oligomeric thiophene or anthraquinone dyes, such as 1, 5-dicarboxy-4, 8-diamino-2-p-alkoxyphenylanthraquinone, 1-amino-4-hydroxy-2-benzenemercaptoanthraquinone or 5,5 '-dialdehyde-2, 3', 4 ', 2' -trithiophene. The material of the outer shell 20 is regularly distributed along the shape of the inner core such that the composite particle has optical dichroism and dielectric anisotropy. Specifically, if the shell material is anisotropic, the anisotropic shell material has its long axis direction substantially distributed along a fixed axis of the core; if the shell material is crystalline, the crystals have their growth direction substantially distributed along a fixed axis of the core, but the invention is not limited thereto and may also include other regular fractionsAnd (4) a cloth mode.

Due to the special core-shell structure, the composite particle 1 can keep the structural asymmetric characteristic of the inner core 10, and the size and the length-diameter ratio of the final composite particle 1 can be controlled by controlling the size and the length-diameter ratio of the inner core 10. Meanwhile, by controlling the thickness and growth tendency of the outer shell 20, which can be controlled in various ways (e.g., controlling the growth time, reaction method, or reaction rate of the outer shell, etc.), the aspect ratio different from that of the inner core 10 can be formed. Thus, the composite particle 1 has optical dichroism, structural anisotropy, and dielectric anisotropy at the same time as a whole, and exhibits different optical and electrical properties.

As shown in fig. 2, the present invention also provides a dimming device including a first transparent base layer 100, a first transparent conductive layer 200, a dimming layer 300, a second transparent conductive layer 400, and a second transparent base layer 500. The dimming layer 300 includes composite particles 1, a particle stabilizer (not shown), and a dispersion medium 2, wherein the composite particles 1 are suspended in the dispersion medium 2. The particle stabilizer serves to prevent agglomeration of the composite particles 1 so that they can be dispersed and suspended in the dispersion medium 2. The particle stabilizer may be dispersed in the dispersion medium 2, or may be attached to the surface of the composite particles 1. The particle stabilizer and dispersion medium may be the polymeric stabilizer and liquid suspension medium disclosed in SPD, which are not listed here.

In a state where an electric field is not applied, the composite particles undergo brownian motion in the dispersion medium and are randomly arranged in an arbitrary direction in the dimming layer 300, at which time their scattering and reflection of incident light are maximized. Meanwhile, the dichroic material has different absorption to the incident light in different directions, and the absorption of the dichroic material changes along with the included angle between the optical axis of the dichroic material and the electric vector of the incident light, and the optical axis of the composite particle at the moment is in any direction, so that the absorption to the incident light is maximum. At this time, the transmittance of the incident light is minimum, and the dimming device exhibits a dark state. Furthermore, due to the optical dichroism of the composite particles, the entire dimming device may exhibit a certain color. As shown in fig. 3, when an electric field is applied, the composite particles have their long axes aligned along a direction parallel to the electric field due to the structural anisotropy and the dielectric anisotropy of the composite particles, the angle between the optical axis of the composite particles and the electric vector of the incident light becomes smaller, the absorption of the incident light becomes correspondingly smaller, the scattering or reflection of the incident light is further reduced, and the transmittance of the incident light is increased, so that the dimming device exhibits a bright state. By adjusting the magnitude of the applied electric field, the light modulation device can realize continuous regulation and control of transmittance. In order to allow the composite particles to freely rotate in the dimming device, the size of the composite particles needs to be controlled in the nanometer scale. Preferably, the longest axis of the composite particle has a size of 10 to 1000 nm, more preferably 10 to 500 nm.

The material of the first transparent substrate 100 and the second transparent substrate 500 may be transparent glass or polymer material, such as PET, PEN, PC, PP, PMMA, PBT, PVC, PI, cellulose, etc. The first transparent conductive layer 200 and the second transparent conductive layer 400 may be carbon-based conductive films, metal nanowire conductive films, metal oxide conductive films, and the like, wherein the carbon-based conductive films mainly include two types of graphene oxide and carbon nanotubes, the commonly used metal nanowire conductive films include silver nanowires, copper nanowires, and the like, and the metal oxide films include indium tin oxide, indium oxide, tin oxide, zinc oxide, and a mixture of other metal oxides. In the following embodiments, transparent glass is used for each of the first transparent base layer 100 and the second transparent base layer 500, and ITO is used for each of the first transparent conductive layer 200 and the second transparent conductive layer 400.

In the following examples, the concentrations are by mass unless otherwise specified. The sizes of the core and the composite particles are obtained by statistics of TEM images or microscopic images.

Example 1

2.80 g of nitrocellulose, 37.20 g of dioctyl sebacate, 0.10 g of oil-soluble hydroxyapatite nanorods (average length: 32 nm, average width: 10 nm, as shown in FIG. 4 (a)), 1.13 g of iodine, 0.5 g of methanol, 0.84 g of CaI₂·4H₂O, 0.75 g of 2, 5-pyrazinedicarboxylic acid was placed in a 100ml container. Stirring and reacting for 16 hours at 42 ℃ by using a shaking table, centrifugally separating, washing, and centrifugally separating again to obtain blue nanorods (average length: about 400)Nanometer, average width: about 40 nm, as shown in fig. 4 (b).

Mixing the prepared nano-rods, the particle stabilizer and the dispersion medium according to a certain proportion, wherein the proportion is as follows: 5% of nano-rods, 2% of particle stabilizer nitrocellulose and 93% of dispersion medium dioctyl adipate. And (4) carrying out ultrasonic treatment to obtain a suspension with the composite particles. The uniformly mixed suspension was poured into a 5 x 5 cm-sized light modulating device, wherein the thickness of the light modulating layer was 12 microns. The transmittance of the light modulation device can be observed under the condition of 100Hz alternating current of 0V-30V, and the curve of the transmittance along with the voltage change is shown in figure 5. When the light transmittance is maximum, the light modulation device is light gray; when the transmittance is minimum, the light modulation device is dark blue.

Example 2

2.80 g of nitrocellulose, 37.20 g of dioctyl sebacate, 0.10 g of oil-soluble hydroxyapatite nanorods (average size: length 32 nm, width 10 nm), 1.13 g of iodine, 0.5 g of methanol, 0.84 g of CaI₂·4H₂O, 0.75 g of 2, 5-pyrazinedicarboxylic acid was placed in a 100mL container. After stirring and reacting for 3 hours at 42 ℃ by using a shaking table, carrying out centrifugal separation, washing and carrying out centrifugal separation again to obtain brown yellow nanorods (average length: about 50-100 nm, average width: about 10-20 nm, as shown in FIG. 6). A light modulation device was prepared in the same manner as in example 1, and changes in light transmittance and color were also observed with changes in applied voltage.

Example 3

8.40 g of nitrocellulose, 111.60 g of dioctyl sebacate, 0.30 g of oil-soluble hydroxyapatite nanorods (average size: length 200 nm, width 50 nm), 3.40 g of iodine, 1.50 g of methanol, 2.52 g of CaI₂·4H₂O, 2.25 g of 2, 5-pyrazinedicarboxylic acid was placed in a 500 ml stainless steel pot. After stirring and reacting for 1 hour at 42 ℃ with a dispersion plate, the deep purple nanorods (average length: about 1000 nm, average width: about 250 nm, as shown in FIG. 7) were obtained after centrifugal separation, washing and re-centrifugal separation. Due to its large size, a light modulating device could not be prepared in the manner of example 1.

Example 4

And (3) mixing 10.5 g of water, 0.56 g of 3,8- (bis-2-thienyl) -1, 10-phenanthroline, 0.07 g of concentrated sulfuric acid, and 0.5 g of water-soluble molybdenum disulfide nanosheet (average diameter: about 30 nm, average thickness: about 1-2 nm), and stirring for 12 hours to obtain a solution A. Mixing 0.37 g iodine, 0.23 g potassium iodide, 8.1 mg ZnSO₄7.50 g of water and 1.75 g of ethanol were ultrasonically mixed for 15 minutes to obtain solution B. Solution B was added to solution A and stirred for 1.5 hours to form a green solid precipitate. 0.1 g of a green solid was taken and dissolved in a mixed solution of 10 g of ethanol and 10 g of acetone. 0.1 g of nitrocellulose and 10 g of diisononyl terephthalate are added and mixed by ultrasonic. And (3) drying in an oven at 60 ℃ until black solid appears on the wall of the container, taking out the container, naturally cooling the container until the solid is separated out from the solution, and performing ultrasonic treatment for 30 minutes to obtain the black nanoparticle dispersion liquid. A light modulation device was prepared in the same manner as in example 1, and changes in light transmittance and color were also observed as a function of applied voltage.

Example 5

0.12 g of oil-soluble ferroferric oxide nano-rods (average length: 48 nm, average width: 12 nm) are added into 20ml of o-dichlorobenzene, ultrasonic dispersion is carried out, 20ml of DMF solution in which 240 mg of butanetetracarboxylic acid is dissolved is simultaneously dripped, and sealing is carried out. Stirring magnetically at a certain rotation speed, keeping the temperature of the mixture in an oil bath at 100 ℃ for 48 hours, cooling the solution to room temperature after the reaction is finished, adding a proper amount of phosphorus pentoxide, stirring for 6 hours, and washing with DMF for several times. 20mL of pyridine and 0.12 g of 1, 5-dicarboxy-4, 8-diamino-2-p-alkoxyphenylanthraquinone were added, stirred for 24 hours, centrifuged, and washed to obtain a dark brown nanoparticle dispersion. A light modulation device was prepared in the same manner as in example 1, and changes in light transmittance and color were also observed as a function of applied voltage.

As can be seen from the above examples, by controlling the size and shape of the inner core of the composite particle, the size and aspect ratio of the finally formed composite particle can be effectively controlled. Meanwhile, the formed composite particles can provide rich colors and optical anisotropy, and can realize the change of light transmittance and colors when being applied to a light modulation device.

Although several exemplary embodiments have been described above in detail, the disclosed embodiments are merely exemplary and not limiting, and those skilled in the art will readily appreciate that many other modifications, adaptations, and/or alternatives are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, adaptations, and/or alternatives are intended to be included within the scope of the present disclosure as defined by the following claims.

Claims

1. A composite particle comprising an inner core and an outer shell, wherein the inner core has a non-spherically symmetric shape and the outer shell is composed of a material different from that of the inner core, and the material of the outer shell is regularly distributed along the shape of the inner core, such that the composite particle has optical dichroism and dielectric anisotropy.

2. The composite particle as claimed in claim 1, wherein the shape of the inner core is rod-like, ribbon-like, plate-like, needle-like, wire-like or disk-like.

3. The composite particle according to claim 2, wherein the size of the shortest axis of the inner core is 0.1 to 100 nm.

4. The composite particle of claim 2, wherein the inner core has a size ratio of the longest axis to the shortest axis of 2:1 to 50: 1.

5. The composite particle as claimed in claim 1, wherein the material of the inner core is a metal and a compound thereof, a non-metallic inorganic substance or an organic substance.

6. The composite particle as claimed in claim 1, wherein the material of the outer shell is particles of anisotropic metal particles, semiconductor crystals, metal transition chalcogenides, carbon nanotubes, dichroic dyes or alkaloids polyhalides.

7. The composite particle according to claim 6, wherein the alkaloid polyhalide is a polyhalide of a pyrrole, thiazole, imidazole, pyrazole, pyridine, pyrimidine, quinine, pyrazine, phenanthroline or purine compound.

8. The composite particle as claimed in claim 6, wherein the alkaloid polyhalide is an alkaloid polyiodide.

9. The composite particle of claim 6, wherein the dichroic dye comprises azo, oligomeric thiophene, and anthraquinone based dyes.

10. A dimming device comprising the composite particle as claimed in any one of claims 1 to 9, the dimming device comprising a first transparent base layer, a first transparent conductive layer, a dimming layer, a second transparent conductive layer and a second transparent base layer, wherein the dimming layer comprises the composite particle, a particle stabilizer and a dispersion medium in which the composite particle is suspended.

11. The dimming device of claim 10, wherein the longest axis of the composite particle has a size of 10 to 1000 nm.