CN113641015A - Infrared reflector and preparation method and application thereof - Google Patents
Infrared reflector and preparation method and application thereof Download PDFInfo
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- CN113641015A CN113641015A CN202110869576.1A CN202110869576A CN113641015A CN 113641015 A CN113641015 A CN 113641015A CN 202110869576 A CN202110869576 A CN 202110869576A CN 113641015 A CN113641015 A CN 113641015A
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/132—Thermal activation of liquid crystals exhibiting a thermo-optic effect
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/13718—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
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Abstract
The invention discloses an infrared reflector and a preparation method and application thereof. The adjusting layer of the infrared reflector disclosed by the invention comprises cholesteric liquid crystal microcapsules with different reflection wave bands, so that the reflection wave bands of the infrared reflector are widened, more infrared light can be reflected, the application range of the infrared reflector is enlarged, and the infrared reflector can be applied to the fields of buildings, houses or liquid crystal display and the like.
Description
Technical Field
The invention relates to the technical field of liquid crystal reflection, in particular to an infrared reflector and a preparation method and application thereof.
Background
The cholesteric liquid crystal material has the characteristic of selective Bragg reflection due to a special spiral structure, and the cholesteric liquid crystal material has special optical properties, so that the cholesteric liquid crystal is widely applied to the fields of optical coating technology, liquid crystal displays, infrared reflection film materials and the like.
In a single domain, cholesteric liquid crystal molecules are arranged perpendicular to a spiral axis, and in a plane perpendicular to the spiral axis, the cholesteric liquid crystal molecules can be regarded as nematic liquid crystal; the director of the cholesteric liquid crystal molecules changes in a direction along the helical axis, and the length of the helical axis through which they rotate 360 ° is called the pitch (P). The reflection wavelength λ of the cholesteric liquid crystal with a single pitch is P n (n is the average optical refractive index of the liquid crystal); reflection spectral bandwidth Δ λ (ne-no) P ═ Δ n P (Δ n ═ ne-no is birefringence); it can be seen from the above formula that when the p value is constant, the Δ n of the cholesteric liquid crystal material is increased under the premise that the Δ λ value is constant, which is beneficial to improving the liquid crystal reflection effect. When the cholesteric liquid crystal material has a constant delta n, the reflection waveband delta lambda can be changed by changing the pitch p value through temperature. The cholesteric liquid crystal material can show various specific optical characteristics under external stimulation due to a specific spiral structure, the spiral structure can be wound or uncoiled along with temperature change, selective reflection is generated on circularly polarized light, and the liquid crystal material containing the smectic phase-cholesteric (Sm-N) phase conversion effect can make large reflection band gap change in a tiny temperature range.
At present, a liquid crystal polymer film or a liquid crystal polymer network method is often adopted by a liquid crystal infrared reflector to enable near infrared light to be reflected or transmitted, but the reflection waveband of the liquid crystal infrared reflector is generally narrow, and the application range of the liquid crystal infrared reflector is limited to a certain extent.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides an infrared reflector which has the characteristic of wider reflection wave band.
The invention also provides a preparation method of the infrared reflector.
The invention also provides an application of the infrared reflector.
The invention provides an infrared reflector, which comprises a first transparent substrate, a second transparent substrate and an adjusting layer arranged between the first transparent substrate and the second transparent substrate, wherein the adjusting layer comprises a carrier and cholesteric liquid crystal microcapsules with different reflection wave bands.
The infrared reflector provided by the embodiment of the invention has at least the following beneficial effects: based on that the cholesteric liquid crystal microcapsules are used as main bodies of response materials, the cholesteric liquid crystal microcapsules with different reflection wave bands are included in the adjusting layer, so that the reflection wave bands of the infrared reflector are widened (the reflection bandwidth can reach more than 150nm, more preferably more than 250 nm), more infrared light can be reflected, and the application range of the infrared reflector is enlarged; meanwhile, the cholesteric liquid crystal microcapsule has a temperature response characteristic, and the temperature response is specifically as follows: increasing the temperature to reduce the pitch of the liquid crystal molecules and reduce the blue shift of the reflection wave band; the temperature is reduced to increase the pitch of liquid crystal molecules and the red shift of the reflection wave band, so that the application range of the infrared reflector is enlarged by changing the temperature to adjust the reflection wave band, the infrared reflector can be applied to the fields of buildings, houses or liquid crystal display and the like,
in some embodiments of the present invention, the difference between the maximum wavelength and the minimum wavelength of the reflection bands of the cholesteric liquid crystal microcapsules with different reflection bands is more than 150 nm.
In some preferred embodiments of the present invention, the cholesteric liquid crystal microcapsules of different reflection bands at least comprise a cholesteric liquid crystal microcapsule I of a reflection band I, a cholesteric liquid crystal microcapsule II of a reflection band II and a cholesteric liquid crystal microcapsule III of a reflection band III at a temperature of 25 ℃, wherein the wavelength of the reflection band I is 710-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-1000 nm.
In some more preferred embodiments of the present invention, the wavelength of the reflection band I is 730-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-990 nm.
In some more preferred embodiments of the present invention, the wavelength of the reflection band I is 750-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-980 nm.
In some preferred embodiments of the present invention, the ratio of the parts by mass of the cholesteric liquid crystal microcapsule I, the cholesteric liquid crystal microcapsule II and the cholesteric liquid crystal microcapsule III is (1-3) to (1-3).
In some more preferred embodiments of the present invention, the ratio of the parts by mass of the cholesteric liquid crystal microcapsule I, the cholesteric liquid crystal microcapsule II and the cholesteric liquid crystal microcapsule III is 1:1: 1.
Through the implementation mode, the reflection uniformity of the infrared reflector for each wavelength in a reflection waveband is adjusted by controlling the mass part ratio of the cholesteric liquid crystal microcapsules I-III, and the performance of the infrared reflector is improved.
In some more preferred embodiments of the present invention, the cholesteric liquid crystal microcapsule iv further comprises a reflection waveband iv at a temperature of 25 ℃, wherein the wavelength of the reflection waveband iv is 950-.
In some preferred embodiments of the invention, the ratio of the parts by weight of the cholesteric liquid crystal microcapsule I, the cholesteric liquid crystal microcapsule II, the cholesteric liquid crystal microcapsule III and the cholesteric liquid crystal microcapsule IV is (1-3): 1-3.
In some more preferred embodiments of the present invention, the ratio of the parts by weight of the cholesteric liquid crystal microcapsule I, the cholesteric liquid crystal microcapsule II, the cholesteric liquid crystal microcapsule III and the cholesteric liquid crystal microcapsule iv is 1:1:1: 1.
In some preferred embodiments of the present invention, the reflection band of the cholesteric liquid crystal microcapsules with different reflection bands is between 700-1200nm at a temperature of 25 ℃.
In some more preferred embodiments of the present invention, the reflection band of the cholesteric liquid crystal microcapsules of different reflection bands is 750-1100nm at a temperature of 25 ℃.
In some more preferred embodiments of the present invention, the reflection band of the cholesteric liquid crystal microcapsules of different reflection bands is 750-1000nm at a temperature of 25 ℃.
In some more preferred embodiments of the present invention, the reflection wavelength band of the cholesteric liquid crystal microcapsules with different reflection wavelength bands is 750-950nm at a temperature of 25 ℃.
In some embodiments of the present invention, the cholesteric liquid crystal microcapsule comprises a core material and a shell material coated on the surface of the core material.
In some preferred embodiments of the present invention, the shell material comprises at least one of silica, polyurea resin, rubber, or polyurethane resin.
In some preferred embodiments of the present invention, the core material is a liquid crystal microdroplet formed by cholesteric liquid crystal and a surfactant.
In some more preferred embodiments of the present invention, the surfactant comprises an emulsifier.
In some more preferred embodiments of the present invention, the emulsifier comprises at least one of polyvinyl alcohol and cellulose nanocrystals.
According to the embodiment, the polyvinyl alcohol and the cellulose nanocrystals not only have the emulsification effect, but also are used as the orientation agent, so that the liquid crystal molecules can be oriented, an orientation layer is not needed, the operation is simple and convenient, and the cost is low.
In some more preferred embodiments of the invention, the emulsifier is polyvinyl alcohol.
According to the embodiment, the liquid crystal in the cholesteric liquid crystal microcapsule is oriented by the polyvinyl alcohol, an orientation layer is not needed, and a complex procedure that an orientation layer is coated on a substrate to assist the orientation of liquid crystal molecules, which is common in the prior art, is omitted.
In some more preferred embodiments of the present invention, the cholesteric liquid crystal is a positive cholesteric liquid crystal.
In some more preferred embodiments of the invention, the cholesteric liquid crystal comprises nematic liquid crystal small molecules.
According to the embodiment, the nematic liquid crystal micromolecules are non-polymerizable and have strong liquidity, and the nematic liquid crystal micromolecules are wrapped by the microcapsule shell material and cannot leak, so that the liquidity of the liquid crystal micromolecules is well kept, the temperature response characteristic is not influenced and weakened, the response speed can be obviously improved in the temperature response process, and the temperature response effect is good.
In some more preferred embodiments of the present invention, the cholesteric liquid crystal is formed by self-assembly of a mixture of preparation raw materials comprising nematic liquid crystal small molecules and chiral dopants.
700-800nm is the portion with the highest infrared energy, and the reflection band lower than 700nm can affect the visible light. In order to improve the practical performance of the infrared reflector, the temperature response performance and the wide reflection band performance (the reflection bandwidth can reach more than 150nm, and more preferably more than 250 nm) of the infrared reflector are combined, and the reflection band of the infrared reflector can be moved from 750-charge 950nm (at higher temperature, usually more than 35 ℃) to 950-charge 1150nm (at lower temperature, usually less than 25 ℃) by adjusting the types of cholesteric liquid crystal microcapsules in the adjusting layer of the infrared reflector according to actual needs, so that the practicability of the infrared reflector is enhanced.
In some more preferred embodiments of the invention, the ratio of the mass fraction of the nematic liquid crystal small molecules to the chiral dopant is (60-90) to (10-40).
According to the following steps:
formula P is 1/(HTP × c); p is pitch HTP is the helical twisting force constant, c is the chiral dopant concentration
The formula λ is Δ n × P; λ is the reflection wavelength Δ n is the average refractive index, and P is the pitch.
From the above, when the chiral dopant content is high, the pitch becomes small, and the reflection band is blue-shifted; when the content of the chiral dopant is low, the pitch becomes large, and the reflection band is red-shifted.
In some more preferred embodiments of the invention, the ratio of the mass fraction of the nematic liquid crystal small molecules to the chiral dopant is (75-90): (10-25).
In some more preferred embodiments of the invention, the ratio of the mass fraction of the nematic liquid crystal small molecules to the chiral dopant is (78.5-86) to (14-21.5).
In some more preferred embodiments of the invention, the ratio of the mass fraction of the nematic liquid crystal small molecules to the chiral dopant is (81-84): (16-19).
In some more preferred embodiments of the invention, the chiral dopant comprises a small molecule chiral dopant having a temperature response.
In some more preferred embodiments of the present invention, the chiral dopant comprises at least one of S811 and R811.
In some embodiments of the present invention, the cholesteric liquid crystal microcapsule has a spherical structure.
In some preferred embodiments of the present invention, the cholesteric liquid crystal microcapsule has a three-dimensional spherical structure.
In some preferred embodiments of the present invention, the diameter of the cholesteric liquid crystal microcapsule is in the range of 10 to 100 μm.
According to the above embodiments, the infrared reflector can have an angle-independent effect using a three-dimensional cholesteric liquid crystal microcapsule spherical structure.
In some preferred embodiments of the present invention, the liquid crystal in the cholesteric liquid crystal microcapsule has a helical structure with a center diverging to the periphery.
Specifically, a cross phenomenon and a central bright spot can be seen under a polarization microscope.
In some embodiments of the present invention, the first light-transmissive substrate has a light transmittance ranging from 95 to 100%.
In some embodiments of the present invention, the second light-transmitting substrate has a light transmittance ranging from 95% to 100%.
In some preferred embodiments of the present invention, the first light-transmitting substrate includes at least one of a PET film and glass.
In some preferred embodiments of the present invention, the second light-transmitting substrate includes at least one of a PET film and glass.
In some embodiments of the present invention, the power module further includes a first electrode disposed on the first transparent substrate, a second electrode disposed on the second transparent substrate, and the first electrode and the second electrode are electrically connected to the power module respectively.
According to the embodiment, the infrared reflector disclosed by the invention has the dual properties of temperature response and electric response, the aim of wide waveband can be achieved by mixing cholesteric liquid crystal microcapsules with different reflection wavebands (the reflection bandwidth can reach more than 150nm, and more preferably more than 250 nm), liquid crystal molecules can be deflected by increasing access voltage, and the transition from fuzzy to transparent is achieved; after the voltage is removed, the liquid crystal molecules are restored to the initial state and become fuzzy from transparent, and the pitch of the liquid crystal molecules can be reduced by increasing the temperature so as to reduce the blue shift of the reflection wave band; the temperature is reduced to increase the pitch of the liquid crystal molecules and the red shift of the reflection waveband. The broadband infrared reflector with temperature response and electric response can achieve the purposes of privacy protection, energy conservation and emission reduction, can be made into a flexible device for irregular building surfaces, and can be applied to the fields of buildings, houses or liquid crystal display and the like.
In some preferred embodiments of the present invention, the core material is a liquid crystal microdrop formed by cholesteric liquid crystal and a surfactant, the cholesteric liquid crystal comprises nematic liquid crystal small molecules, and the cholesteric liquid crystal is positive cholesteric liquid crystal.
According to the embodiment, the nematic phase micromolecule liquid crystal is adopted, the liquid crystal is non-polymerizable and strong in fluidity, and the positive liquid crystal is selected, and the nematic phase micromolecule liquid crystal is wrapped by the microcapsule shell layer and cannot leak, so that the fluidity of the micromolecule liquid crystal is well kept, the temperature response characteristic is not affected and weakened, and the response speed can be obviously improved in the temperature response process; in the electric response process, the cholesteric phase can be directly changed into vertical molecular arrangement without the transition of focal conic state, and the response speed can be improved.
In some more preferred embodiments of the invention, the surfactant is polyvinyl alcohol.
According to the above embodiments, in general, in the electrical response, a positive liquid crystal requires an alignment layer of parallel alignment, and liquid crystal molecules can be changed from parallel alignment to vertical alignment after application of a voltage, while a negative liquid crystal requires an alignment layer of vertical alignment, and liquid crystal molecules can be changed from vertical alignment to parallel alignment after application of a voltage, which greatly increases the difficulty of practical operation regardless of the preparation process of the parallel alignment layer or the vertical alignment layer. The invention selects the positive liquid crystal, the polyvinyl alcohol is not only the emulsifier but also the orientation agent, the parallel orientation of the liquid crystal can be helped, the design is reasonable, and the operation is simple and convenient.
In some preferred embodiments of the present invention, the core material is a liquid crystal microdrop formed by cholesteric liquid crystal and a surfactant, the cholesteric liquid crystal comprises nematic liquid crystal small molecules, the cholesteric liquid crystal is positive cholesteric liquid crystal, and the surfactant comprises polyvinyl alcohol.
In some embodiments of the invention, the shell material comprises at least one of silica, polyurea resin, rubber, or polyurethane resin.
According to the above embodiment, the infrared reflector is internally provided with a passage due to the existence of ions, so that the instrument is short-circuited and cannot realize electric response. The silicon dioxide, the polyurea resin, the rubber and the polyurethane resin are not easy to introduce ions into the adjusting layer, so that the infrared reflector can realize electric response.
In some preferred embodiments of the present invention, the first electrode is disposed on a side of the first transparent substrate close to the adjustment layer, and the second electrode is disposed on a side of the second transparent substrate close to the adjustment layer.
In some preferred embodiments of the present invention, the first electrode is provided with a plurality of electrodes.
In some more preferred embodiments of the present invention, the first transparent substrate is uniformly distributed with a plurality of first electrodes.
In some preferred embodiments of the present invention, the second electrode is provided with a plurality of electrodes.
In some more preferred embodiments of the present invention, the second light-transmitting substrate is uniformly distributed with a plurality of second electrodes.
In some preferred embodiments of the present invention, the first electrode is an ITO electrode.
In some preferred embodiments of the present invention, the second electrode is an ITO electrode.
In some preferred embodiments of the invention, the power supply assembly is provided with a switch and a voltage regulating device.
In some further preferred embodiments of the invention, the power supply assembly comprises a power supply, the voltage regulating device being integrated in the power supply.
In some more preferred embodiments of the present invention, the voltage regulating device is in the form of a sliding varistor connected in series with the power supply to regulate the voltage.
In some embodiments of the present invention, a frame is disposed between the first transparent substrate and the second transparent substrate, and the frame encloses the cholesteric liquid crystal microcapsules and the carrier to form the adjustment layer.
In some preferred embodiments of the invention, the carrier is an insulating carrier.
In some more preferred embodiments of the invention, the insulating carrier is an insulating fluid.
In some more preferred embodiments of the present invention, the insulating carrier comprises at least one of silicone oil, natural mineral oil, or glycerin.
In a second aspect of the present invention, a method for manufacturing an infrared reflector is provided, which includes the following steps:
and S1, adding a mixture of the carrier and the cholesteric liquid crystal microcapsules with different reflection wave bands between the first transparent substrate and the second transparent substrate.
The preparation method of the infrared reflector provided by the embodiment of the invention at least has the following beneficial effects: the adjusting layer of the infrared reflector disclosed by the invention comprises cholesteric liquid crystal microcapsules with different reflection wave bands, so that the reflection wave bands of the infrared reflector are widened (the reflection bandwidth can reach more than 150nm, and more preferably more than 250 nm), more infrared light can be reflected, the application range of the infrared reflector is enlarged, and the infrared reflector can be applied to the fields of buildings, houses or liquid crystal display and the like.
In some embodiments of the invention, the method further includes step S2, where the first transparent substrate is provided with a first electrode, the second transparent substrate is provided with a second electrode, and the first electrode and the second electrode are respectively connected to the power module.
Through the above embodiment, the present invention has at least the following advantageous effects: the infrared reflector disclosed by the invention has the dual properties of temperature response and electric response, can achieve the purpose of wide wave band by mixing cholesteric liquid crystal microcapsules with different reflection wave bands, and can not only increase the access voltage to deflect liquid crystal molecules and change from fuzzy to transparent; after the voltage is removed, the liquid crystal molecules are restored to the initial state and become fuzzy from transparent, and the pitch of the liquid crystal molecules can be reduced by increasing the temperature so as to reduce the blue shift of the reflection wave band; the temperature is reduced to increase the pitch of the liquid crystal molecules and the red shift of the reflection waveband. The purposes of privacy protection, energy conservation and emission reduction can be achieved through the wide-waveband infrared reflector with temperature response and electric response, and the device can be made into a flexible device for irregular building surfaces and can be applied to the fields of buildings, houses or liquid crystal display and the like.
In some embodiments of the present invention, the method further comprises preparing cholesteric liquid crystal microcapsules, comprising the following steps:
s0-1, respectively mixing the chiral dopant and cholesteric liquid crystal according to different proportions, dissolving in a solvent, heating and stirring until the solvent is completely volatilized, and cooling to obtain cholesteric liquid crystals with different reflection wave bands;
s0-2, respectively mixing and emulsifying cholesteric liquid crystals with different reflection wave bands with a surfactant to respectively prepare Pickering emulsion with liquid crystal microdroplets;
s0-3, dropwise adding the sol solution into the Pickering emulsion prepared in the step S0-2, and wrapping the surface of the Pickering emulsion by a sol-gel method to form a shell layer to prepare cholesteric liquid crystal microcapsules with different reflection wave bands;
wherein the sol solution is ethanol and water solution of tetraethyl orthosilicate and has a pH value of 2-3.
In some preferred embodiments of the present invention, in step S0-1, under yellow light conditions, the chiral dopant is mixed with different cholesteric liquid crystals and dissolved in the solvent, and stirred at 50 ℃ until the solvent is completely volatilized, and slowly cooled to room temperature to obtain different cholesteric liquid crystals.
In some more preferred embodiments of the present invention, in step S0-1, the solvent comprises dichloromethane.
In some preferred embodiments of the present invention, in step S0-3, the stirring speed is 500 rpm.
In some preferred embodiments of the present invention, in step S0-3, the stirring time is 4 hours.
In some preferred embodiments of the present invention, in step S0-3, the sol solution is added dropwise to the Pickering emulsion prepared in step S0-2, and stirred at 500rpm for 4 hours while controlling the temperature of the sol solution at 70 ℃. And finally, slowly cooling to room temperature, and wrapping the surface of the Pickering emulsion by a sol-gel method to form a silicon dioxide shell layer.
In some preferred embodiments of the present invention, the preparation of the sol solution further comprises: adding an acidic solution into a mixed solution of tetraethyl orthosilicate, ethanol and water to adjust the pH value to 2-3, heating and stirring to prepare a sol solution.
In some more preferred embodiments of the present invention, in the step of preparing the sol solution, the acidic solution is hydrochloric acid.
In some more preferred embodiments of the present invention, the heating temperature in the preparation step of the sol solution is 60 ℃.
According to the above embodiment, after the pH of the mixture of tetraethyl orthosilicate, ethanol and water is adjusted by adding hydrochloric acid, the mixture is heated and stirred to undergo hydrolysis reaction, thereby forming a sol solution.
In some more preferred embodiments of the present invention, in the preparing step of the sol solution, the stirring time is 30 min.
In some more preferred embodiments of the present invention, in the step of preparing the sol solution, the ratio of parts by mass of tetraethyl orthosilicate to parts by mass of ethanol to parts by mass of water is 1:1: 2.
In a third aspect of the invention, the application of the infrared reflector in the fields of buildings, houses or liquid crystal displays is provided.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a schematic diagram of an infrared reflector according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a cholesteric liquid crystal microcapsule in an embodiment of the present invention;
FIG. 3 is a scanning electron microscope image of cholesteric liquid crystal microcapsules in an embodiment of the invention;
FIG. 4 is a polarization microscope photograph of cholesteric liquid crystal microcapsules in an embodiment of the invention;
FIG. 5 is a schematic diagram of the variation of the infrared reflector when no driving voltage is applied and when a driving voltage is applied in the embodiment of the present invention;
FIG. 6 is a schematic diagram of the change of an IR reflector with changing temperature in an embodiment of the invention;
FIG. 7 is a graph showing the transmittance test results of an IR reflector with no driving voltage applied and with driving voltage applied in an embodiment of the present invention;
FIG. 8 is a graph of the results of reflected wave width measurements of infrared reflectors containing different cholesteric liquid crystal microcapsules in an embodiment of the invention;
FIG. 9 is a graph illustrating the results of reflectivity measurements of IR reflectors at different temperatures according to one embodiment of the present invention;
fig. 10 is a graph showing the transmittance test results of cholesteric liquid crystal microcapsules containing different amounts of chiral dopants in examples and comparative examples according to the present invention.
Reference numerals: 1. a light-transmitting substrate; 1-1, a first light-transmitting substrate; 1-2, a second light-transmitting substrate; 2. an insulating carrier; 3. cholesteric liquid crystal microcapsules; 4. a power source; 5. a switch; 6. and (5) a frame.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the meaning of more, less, more, etc. is understood as excluding the number, and the meaning of more, less, more, etc. is understood as including the number. If there is a description of the first and second for the purpose of distinguishing technical features, it is not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Details of the chemical reagents used in the examples of the present invention are as follows:
nematic liquid crystal: 5CB, Beijing, eight billion space-time liquid crystal technology, Inc., lot number CTP 001620061801;
chiral dopant: s811, batch No. D19090303, by Beijing eight billion space-time liquid Crystal technology, Inc.;
insulating carrier: the silicone oil is dimethyl silicone oil, and has refractive index of 1.4013-1.4053(25 deg.C) and density of 0.966-0.974g/cm3(25℃)；
Polyvinyl alcohol, Shanghai Aladdin Biotechnology, Inc., batch MKCL 1109;
tetraethyl orthosilicate, Shanghai Allantin Biotechnology Ltd;
absolute ethanol, shanghai alatin Biotech, inc;
hydrochloric acid, Shanghai Aladdin Biotechnology Ltd.
Example 1
An infrared reflector is structurally shown in figure 1 and comprises two light-transmitting substrates 1 (a light-transmitting substrate I1-1 and a light-transmitting substrate II 1-2) and an adjusting layer arranged between the light-transmitting substrate I1-1 and the light-transmitting substrate II 1-2, wherein the adjusting layer comprises an insulating carrier 2 and cholesteric liquid crystal microcapsules with different reflection wave bands, the cholesteric liquid crystal microcapsules are cholesteric liquid crystal microcapsules 3 (the insulating carrier 2 and the cholesteric liquid crystal microcapsules 3 with different reflection wave bands are filled between the light-transmitting substrate I1-1 and the light-transmitting substrate II 1-2), the cholesteric liquid crystal microcapsules 3 are of a spherical structure, the diameter range of the cholesteric liquid crystal microcapsules is 10-100 mu m, and the cholesteric liquid crystal microcapsules comprise a core material and a shell material coated on the surface of the core material. The liquid crystal in the cholesteric liquid crystal microcapsule 3 is in a spiral structure with the center diverging to the periphery. The infrared reflector further comprises a power supply assembly, the power supply assembly comprises a power supply 4 and a switch 5, one side, close to the adjusting layer, of the first transparent substrate 1-1 is provided with a first electrode (not shown in the figure), one side, close to the adjusting layer, of the second transparent substrate 1-2 is provided with a second electrode (not shown in the figure), and the first electrode and the second electrode are respectively and electrically connected with the power supply assembly; a frame 6 is arranged between the first transparent substrate 1-1 and the second transparent substrate 1-2, and the insulating carrier 2 and the cholesteric liquid crystal microcapsules 3 are enclosed and sealed by the frame 6 to form an adjusting layer.
The first electrode and the second electrode are both ITO electrodes, the first transparent substrate 1-1 and the second transparent substrate 1-2 are arranged oppositely, the first transparent substrate 1-1 and the second transparent substrate 1-2 are both PET films, and the ITO electrodes are coated on the surfaces of the PET films. The ITO electrodes of the first transparent substrate 1-1 and the second transparent substrate 1-2 are oppositely arranged and are respectively connected with the power supply 4 and the two poles of the switch 5, so that when the two ITO electrodes are electrified, an electric field is formed between the first transparent substrate 1-1 and the second transparent substrate 1-2, and the size of the electric field is related to the access voltage of the ITO electrodes.
The preparation method of the infrared reflector comprises the following steps:
preparing cholesteric liquid crystals with three different reflection wave bands:
three cholesteric liquid crystals with different reflection wave bands are prepared according to the following mixture ratio:
first cholesteric liquid crystal: 83 wt% (0.83g) nematic liquid crystal 5CB and 17 wt% (0.17g) chiral dopant (S811);
second cholesteric liquid crystal: 80 wt% (0.80g) nematic liquid crystal 5CB and 20 wt% (0.2g) chiral dopant (S811);
third cholesteric liquid crystal: 77 wt% (0.77g) nematic liquid crystal 5CB and 23 wt% (0.23g) chiral dopant (S811).
Under the condition of yellow light (white light or other light), the three cholesteric liquid crystal raw materials are respectively dissolved in solvent dichloromethane to obtain three dichloromethane solutions, the three dichloromethane solutions are respectively stirred at 50 ℃ until the solvent is completely volatilized, and the temperature is slowly reduced to room temperature to obtain three different cholesteric liquid crystals.
(II) preparing a Pickering emulsion:
three pickering emulsions were prepared according to the following ratios:
a first liquid crystal pickering emulsion: weighing 0.5g of the first cholesteric liquid crystal prepared in the step (I) and 2.5g of 0.005 wt% polyvinyl alcohol solution (the mass ratio of the cholesteric liquid crystal to the 0.005 wt% polyvinyl alcohol solution is 1:5), mixing, and performing ultrasonic emulsification by using a cell crusher to prepare a first liquid crystal Pickering emulsion;
a second liquid crystal pickering emulsion: weighing 0.5g of the second cholesteric liquid crystal prepared in the step (I) and 2.5g of 0.005 wt% polyvinyl alcohol solution (the mass ratio of the cholesteric liquid crystal to the 0.005 wt% polyvinyl alcohol solution is 1:5), mixing, and performing ultrasonic emulsification by using a cell crusher to prepare second liquid crystal Pickering emulsion;
a third liquid crystalline pickering emulsion: weighing 0.5g of the third cholesteric liquid crystal prepared in the step (I) and 2.5g of 0.005 wt% polyvinyl alcohol solution (the mass ratio of the cholesteric liquid crystal to the 0.005 wt% polyvinyl alcohol solution is 1:5), mixing, and performing ultrasonic emulsification by using a cell crusher to prepare a third liquid crystal Pickering emulsion.
(III) preparation of the Sol solution
0.3g of tetraethyl orthosilicate, 0.3g of absolute ethyl alcohol and 0.6g of deionized water (the mass ratio of the tetraethyl orthosilicate, the absolute ethyl alcohol and the deionized water is 1:1:2) are mixed, a small amount of hydrochloric acid solution with the mass fraction of 4% is added to adjust the pH value to 2.8, the mixture is heated and stirred at 60 ℃ for 30min, and a sol solution is formed through hydrolysis reaction.
Three sets of sol solutions were prepared in parallel.
(IV) preparation of cholesteric liquid Crystal microcapsules
And (3) respectively dropwise adding the three sol solutions prepared in the step (III) into the three liquid crystal pickering emulsions prepared in the step (II), respectively stirring for 4 hours at the speed of 500rpm by using a magnetic stirrer, and simultaneously controlling the temperature of the sol solution at 70 ℃ by using a constant temperature bath. And finally, slowly cooling to room temperature, and wrapping a silicon dioxide shell layer on the surface of the Pickering emulsion by a sol-gel method to respectively obtain three cholesteric liquid crystal microcapsule solutions. And (3) putting the prepared three cholesteric liquid crystal microcapsule solutions into a 50 ℃ oven for drying, and finally forming three cholesteric liquid crystal microcapsules. The cholesteric liquid crystal microcapsule is shown in figure 2: the cholesteric liquid crystal microcapsule comprises a core material and shell material silicon dioxide coated on the surface of the core material, wherein the core material comprises cholesteric liquid crystal and polyvinyl alcohol coated on the cholesteric liquid crystal.
The cholesteric liquid crystal microcapsule prepared from the first cholesteric liquid crystal is a cholesteric liquid crystal microcapsule H (the content of a chiral dopant (S811) is 17 wt%, and the content of nematic liquid crystal 5CB is 83 wt%);
the cholesteric liquid crystal microcapsule prepared from the second cholesteric liquid crystal is cholesteric liquid crystal microcapsule I (the content of chiral dopant (S811) is 20 wt%, and the content of nematic liquid crystal 5CB is 80 wt%).
(V) preparation of Infrared Reflector
And (3) uniformly mixing 0.5g of the cholesteric liquid crystal microcapsules prepared in the step (IV) (the mass ratio of the three cholesteric liquid crystal microcapsules is 1:1:1) with 2.5g of insulating carrier silicone oil (the mass ratio of the cholesteric liquid crystal microcapsules to the silicone oil is 1:5), filling the mixture between a first transparent substrate and a second transparent substrate which are opposite, arranging a first electrode on one side of the first transparent substrate close to the adjusting layer, arranging a second electrode on one side of the second transparent substrate close to the adjusting layer, and electrically connecting the first electrode and the second electrode with a power supply component respectively to obtain the infrared reflector. Wherein, the power supply assembly is provided with a voltage regulating device and a switch in a matching way.
Specifically, the power supply assembly comprises a power supply, a voltage regulating device is integrated in the power supply to enable the voltage of the power supply to be controllable, two ITO electrodes are connected to two poles of the power supply, and a switch is connected to the power supply in series. Different voltages can be applied between the first light-transmitting substrate and the second light-transmitting substrate through the on-off of the switch and the control of the power voltage to form an electric field, liquid crystal molecules in the cholesteric liquid crystal microcapsule deflect under the action of the electric field, and the conversion between fuzzy and transparent can be realized. Wherein, voltage regulation apparatus's form is: the voltage regulation is realized by connecting a sliding rheostat in series with a power supply.
Example 2
(I) cholesteric liquid crystal microcapsules with different chiral dopant contents are prepared, the experimental process is the same as that of example 1, and the differences with the example 1 are respectively as follows:
cholesteric liquid crystal microcapsule a: the content of the chiral dopant (S811) was 16 wt%, and the content of the nematic liquid crystal 5CB was 84 wt%;
cholesteric liquid crystal microcapsule B: the content of the chiral dopant (S811) was 17.5% by weight, and the content of the nematic liquid crystal 5CB was 82.5% by weight;
cholesteric liquid crystal microcapsule C: the content of the chiral dopant (S811) was 19 wt%, and the content of the nematic liquid crystal 5CB was 81 wt%.
(II) preparing a plurality of infrared reflectors containing different cholesteric liquid crystal microcapsules, wherein the experimental process is the same as that of the example 1, and the differences from the example 1 are respectively as follows:
the first infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: a cholesteric liquid crystal microcapsule A, a cholesteric liquid crystal microcapsule B and a cholesteric liquid crystal microcapsule C; the mass ratio of the cholesteric liquid crystal microcapsule A to the cholesteric liquid crystal microcapsule B to the cholesteric liquid crystal microcapsule C is 1:1: 1.
And a second infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: cholesteric liquid crystal microcapsules B and cholesteric liquid crystal microcapsules C; the mass ratio of the cholesteric liquid crystal microcapsule B to the cholesteric liquid crystal microcapsule C is 1: 1;
and a third infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: a cholesteric liquid crystal microcapsule A and a cholesteric liquid crystal microcapsule C; the mass ratio of the cholesteric liquid crystal microcapsule A to the cholesteric liquid crystal microcapsule C is 1: 1;
and IV, an infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: a cholesteric liquid crystal microcapsule A and a cholesteric liquid crystal microcapsule B; the mass ratio of the cholesteric liquid crystal microcapsule A to the cholesteric liquid crystal microcapsule B is 1: 1.
Comparative example 1
The experimental process of preparing cholesteric liquid crystal microcapsules with different chiral dopant contents is the same as that of example 1, and the difference with example 1 is that:
cholesteric liquid crystal microcapsule D: the content of the chiral dopant (S811) was 14 wt%, and the content of the nematic liquid crystal 5CB was 86 wt%;
cholesteric liquid crystal microcapsule E: the content of the chiral dopant (S811) was 15 wt%, and the content of the nematic liquid crystal 5CB was 85 wt%;
cholesteric liquid crystal microcapsule F: the content of the chiral dopant (S811) was 18 wt%, and the content of the nematic liquid crystal 5CB was 82 wt%;
cholesteric liquid crystal microcapsule G: the content of the chiral dopant (S811) was 21.5% by weight, and the content of the nematic liquid crystal 5CB was 78.5% by weight.
Comparative example 2
A plurality of infrared reflectors containing different cholesteric liquid crystal microcapsules are prepared, the experimental process is the same as that of the example 1, and the differences from the example 1 are respectively that:
and (5) an infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: a cholesteric liquid crystal microcapsule A;
and six infrared reflectors: the added types of the cholesteric liquid crystal microcapsules are as follows: a cholesteric liquid crystal microcapsule B;
and a seventh infrared reflector: the added types of the cholesteric liquid crystal microcapsules are as follows: and (4) cholesteric liquid crystal microcapsules C.
Test examples
This test example tests the infrared reflector, cholesteric liquid crystal microcapsules prepared in examples 1-2 and comparative example. Wherein:
the microstructure of the mixed cholesteric liquid crystal microcapsule obtained by mixing the three cholesteric liquid crystal microcapsules prepared in example 1 in the mass ratio of 1:1:1 was tested, and the scanning electron microscope image is shown in fig. 3. Wherein, the scanning electron microscope test conditions are as follows: the test voltage was 5 kv.
The optical properties of the mixed cholesteric liquid crystal microcapsules obtained after mixing the three cholesteric liquid crystal microcapsules prepared in example 1 in a mass ratio of 1:1:1 were tested, and a polarization microscope picture is shown in fig. 4. Wherein, the test conditions of the polarizing microscope are as follows: the two polaroids are in an orthogonal state; the polarizing microscope model was Leica DM 2700P.
Test example 1 infrared reflectors were prepared with no driving voltage and with driving voltage applied, and the results of the test are shown in fig. 7. Testing the used instrument: a marine spectrometer was an Ocean Optics Maya 2000PRO spectrophotometer.
Test example 2 and comparative example 2 the infrared reflectors prepared were tested for reflection bandwidth and the results are shown in fig. 8. The test uses an instrument: a marine spectrometer was an Ocean Optics Maya 2000PRO spectrophotometer.
The infrared reflector six prepared in comparative example 2 was tested for reflection characteristics at different temperatures, and the test results are shown in fig. 9. Testing the used instrument: an ultraviolet visible near infrared spectrometer with the model of Lambda 950UV-vis spectrometer.
The cholesteric liquid crystal microcapsules I prepared in example 1, the cholesteric liquid crystal microcapsules a to C prepared in example 2, and the cholesteric liquid crystal microcapsules D to G prepared in comparative example were tested for reflection wave widths, and the test results are shown in fig. 10. Testing the used instrument: ocean spectrometer, model Ocean Optics Maya 2000PRO spectrophotometer.
As can be seen from fig. 3 and fig. 4, the spherical structure of the cholesteric liquid crystal microcapsule is complete when the cholesteric liquid crystal microcapsule is observed under a scanning electron microscope; the cholesteric liquid crystal microcapsule is observed in a transmission mode through a polarizing microscope, and the observed result shows that the orientation of liquid crystal in the cholesteric liquid crystal microcapsule presents a maltese crossing phenomenon, and the cholesteric liquid crystal microcapsule is of a spherical structure and can generate an angle independent effect.
Referring to fig. 5, when no driving voltage and no driving voltage are applied between the first transparent substrate and the second transparent substrate, the schematic diagram of the change of the ir reflector shows that the liquid crystal molecules in the cholesteric liquid crystal microcapsule divergently deflect from the center to the periphery to be aligned perpendicular to the two transparent substrates, and change from a blurred state to a state transmitting light of almost all wavelength bands.
Referring to fig. 6, when the ambient temperature is changed, the schematic diagram of the change of the infrared reflector shows that when the temperature is increased, the pitch between the liquid crystal molecules in the cholesteric liquid crystal microcapsule is reduced, so that the reflection waveband is blue-shifted; when the temperature is reduced, the pitch between the liquid crystal molecules in the cholesteric liquid crystal microcapsule is increased, so that the reflection waveband is red-shifted.
As can be seen from fig. 7, when no driving voltage is applied, the infrared reflector has a lower transmittance and reflects a near infrared band; the infrared reflector has a high transmittance when the driving voltage is applied, thereby achieving a transition between the hazy and transparent.
As can be seen from fig. 8, the reflection wave width of the infrared reflector is related to the type of cholesteric liquid crystal microcapsules contained in the infrared reflector, the reflection wave width of the infrared reflector prepared from a single cholesteric liquid crystal microcapsule is relatively narrow, and the reflection wave width of the infrared reflector after mixing cholesteric liquid crystal microcapsules of different reflection bands is increased (the reflection wave width can reach more than 150nm, and more preferably, more than 250 nm). Wherein, the first infrared reflector prepared in the embodiment 2 has a reflection wavelength of 750-1000nm (25 ℃); the reflection wavelength of the infrared reflector II is 810-995nm (25 ℃); the reflection wavelength of the infrared reflector III is divided into two sections, namely 758 and 854nm, 893 and 995nm (25 ℃); the reflection wavelength of the infrared reflector IV is 752-919nm (25 ℃).
As can be seen from fig. 9, when the temperature is changed, the reflectivity of the infrared reflector changes, and as the temperature increases, the reflection band shifts to the blue, the temperature decreases, and the reflection band shifts to the red. Specifically, when the temperature is increased from 20 ℃ to 45 ℃, the central reflection band of the infrared reflector is shifted from 950nm to 800nm, and the reflection band is shifted by 150 nm.
Fig. 10 shows the reflection band of cholesteric liquid crystal microcapsules for different contents of chiral dopants:
p is pitch HTP is the helical twisting force constant, c is the chiral dopant concentration according to the formula P ═ 1/(HTP × c);
the formula λ is Δ n × P, λ is the reflection wavelength, Δ n is the average refractive index, and P is the pitch;
when the chiral dopant content is high, the pitch becomes small, and the reflection wave band is blue-shifted; when the content of the chiral dopant is low, the pitch becomes large, and the reflection band is red-shifted. Since 700-800nm is the highest part of the infrared energy and cannot be lower than 700nm, the reflection band lower than 700nm can affect the visible light. Therefore, if the reflection band of the infrared reflector is at 750-950nm at a higher temperature (usually above 35 ℃), and the reflection band is after 950nm at a lower temperature (usually below 25 ℃), the practical requirement is better met, and the practicability is stronger. According to fig. 10, it can be seen that when the chiral dopant content is 16 wt%, 17.5 wt%, and 19 wt%, the reflection band is better, and better meets the requirement of actual needs, and the reflection bands of the three are overlapped, so that the reflection band of the infrared reflector prepared after mixing is smoother. In summary, the adjusting layer of the infrared reflector provided by the present invention includes cholesteric liquid crystal microcapsules with different reflection bands, so that the reflection band of the infrared reflector is widened (the reflection bandwidth can reach more than 150nm, preferably more than 250 nm), and more infrared light can be reflected. Meanwhile, the infrared reflector provided by the invention has an angle-independent effect by utilizing a three-dimensional cholesteric liquid crystal microcapsule spherical structure, an orientation layer is not needed to help the orientation of liquid crystal molecules, the responsiveness of liquid crystal micromolecules can be well kept, and the aim of wide wave bands can be achieved by mixing cholesteric liquid crystal microcapsules with different reflection wave bands. The infrared reflector can deflect liquid crystal molecules by increasing access voltage, so that the liquid crystal molecules are converted from fuzzy to transparent; after the voltage is removed, the liquid crystal molecules are restored to the initial state and become fuzzy from transparent, and the pitch of the liquid crystal molecules can be reduced by increasing the temperature so as to reduce the blue shift of the reflection wave band; the temperature is reduced to increase the pitch of the liquid crystal molecules and the red shift of the reflection waveband. The infrared reflector can adjust transparent and fuzzy changes according to the will of people to protect privacy of people, can adjust the movement of a reflection waveband timely according to the change of the environment to achieve the effects of being warm in winter and cool in summer and saving energy and reducing emission, has the characteristics of innovation, greenness, privacy protection, environmental protection, energy conservation and self adjustment as a novel infrared reflector, can be made into a flexible device to be used on irregular building surfaces, and can be applied to the fields of buildings, houses or liquid crystal display and the like.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (10)
1. The infrared reflector is characterized by comprising a first transparent substrate, a second transparent substrate and an adjusting layer arranged between the first transparent substrate and the second transparent substrate, wherein the adjusting layer comprises a carrier and cholesteric liquid crystal microcapsules with different reflection wave bands.
2. An infrared reflector according to claim 1, characterized in that the difference between the maximum wavelength and the minimum wavelength of the reflection bands of the cholesteric liquid crystal microcapsules with different reflection bands is more than 150 nm; preferably, the cholesteric liquid crystal microcapsules with different reflection bands at least comprise a cholesteric liquid crystal microcapsule I with a reflection band I, a cholesteric liquid crystal microcapsule II with a reflection band II and a cholesteric liquid crystal microcapsule III with a reflection band III at a temperature of 25 ℃, wherein the wavelength of the reflection band I is 710-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-1000 nm; preferably, the wavelength of the reflection band I is 730-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-990 nm; preferably, the wavelength of the reflection band I is 750-850nm, the wavelength of the reflection band II is 800-910nm, and the wavelength of the reflection band III is 860-980 nm.
3. The infrared reflector of claim 1, wherein the cholesteric liquid crystal microcapsule comprises a core material and a shell material coated on the surface of the core material; preferably, the shell material comprises at least one of silica, polyurea resin, rubber or polyurethane resin; preferably, the core material is a liquid crystal droplet formed by cholesteric liquid crystal and a surfactant; preferably, the surfactant comprises an emulsifier; preferably, the emulsifier comprises at least one of polyvinyl alcohol and cellulose nanocrystals; preferably, the emulsifier is polyvinyl alcohol.
4. An infrared reflector according to claim 3, characterized in that said cholesteric liquid crystal is a positive cholesteric liquid crystal; preferably, the cholesteric liquid crystal comprises nematic liquid crystal small molecules; preferably, the cholesteric liquid crystal is formed by mixing and self-assembling preparation raw materials comprising nematic liquid crystal small molecules and chiral dopants; preferably, the chiral dopant is a small molecule chiral dopant with a temperature response; preferably, the ratio of the mass parts of the nematic liquid crystal small molecules to the chiral dopant is (60-90) to (10-40); preferably, the ratio of the mass parts of the nematic liquid crystal small molecules to the chiral dopant is (75-90): 10-25); preferably, the ratio of the mass parts of the nematic liquid crystal small molecules to the chiral dopant is (78.5-86): (14-21.5); preferably, the mass part ratio of the nematic liquid crystal small molecules to the chiral dopant is (81-84): 16-19.
5. An infrared reflector according to claim 1, characterized in that said cholesteric liquid crystal microcapsules are of a spherical structure; preferably, the cholesteric liquid crystal microcapsule is of a three-dimensional spherical structure; preferably, the diameter of the cholesteric liquid crystal microcapsule ranges from 10 to 100 μm; preferably, the liquid crystal in the cholesteric liquid crystal microcapsule is in a spiral structure with the center diverging to the periphery.
6. The infrared reflector as claimed in claim 1, further comprising a power module, wherein the first transparent substrate is provided with a first electrode, the second transparent substrate is provided with a second electrode, and the first electrode and the second electrode are electrically connected to the power module respectively; preferably, the first electrode is arranged on one side of the first light-transmitting substrate close to the adjusting layer, and the second electrode is arranged on one side of the second light-transmitting substrate close to the adjusting layer; preferably, the first electrode is provided with a plurality of electrodes; preferably, the second electrode is provided with a plurality of electrodes.
7. An infrared reflector according to claim 1, wherein a frame is disposed between said first transparent substrate and said second transparent substrate, said frame enclosing said cholesteric liquid crystal microcapsules and said carrier to form said adjustment layer; preferably, the carrier is an insulating carrier; preferably, the insulating carrier is an insulating fluid; preferably, the insulating carrier includes at least one of silicone oil, natural mineral oil, or glycerin.
8. A preparation method of an infrared reflector is characterized by comprising the following steps:
and S1, adding a mixture of the carrier and the cholesteric liquid crystal microcapsules with different reflection wave bands between the first transparent substrate and the second transparent substrate.
9. The method for preparing an infrared reflector according to claim 8, further comprising preparing cholesteric liquid crystal microcapsules, comprising the steps of:
s0-1, respectively mixing the chiral dopant and cholesteric liquid crystal according to different proportions, dissolving in a solvent, heating and stirring until the solvent is completely volatilized, and cooling to obtain cholesteric liquid crystals with different reflection wave bands;
s0-2, respectively mixing and emulsifying cholesteric liquid crystals with different reflection wave bands with a surfactant to respectively prepare Pickering emulsion with liquid crystal microdroplets;
s0-3, dropwise adding the sol solution into the Pickering emulsion prepared in the step S0-2, and wrapping the surface of the Pickering emulsion by a sol-gel method to form a shell layer to prepare cholesteric liquid crystal microcapsules with different reflection wave bands;
wherein the sol solution is ethanol and water solution of tetraethyl orthosilicate and has a pH value of 2-3.
10. Use of the infrared reflector according to any one of claims 1 to 7 or the infrared reflector prepared by the preparation method according to any one of claims 8 to 9 in the fields of construction, home furnishing or liquid crystal display.
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