CN115598895A

CN115598895A - Low-voltage driven liquid light valve and preparation method thereof

Info

Publication number: CN115598895A
Application number: CN202211201745.5A
Authority: CN
Inventors: 王志浩; 曾西平
Original assignee: Shenzhen Huake Tek Co Ltd
Current assignee: Shenzhen Huake Tek Co Ltd
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2023-01-13

Abstract

The invention relates to the technical field of liquid light valves, in particular to a low-voltage driven liquid light valve and a preparation method thereof. The low-voltage driven liquid light valve comprises a first transparent electrode, a dimming liquid and a second transparent electrode which are sequentially arranged; the dimming solution comprises dimming particles, a suspension, a dispersant and an organic solvent; the dispersant is PVP. The invention also discloses a preparation method of the liquid light valve driven by low voltage, which comprises the following steps: preparing dimming particles; preparing a suspension; dissolving PVP in an organic solvent at a certain temperature; mixing the dimming particles with an organic ester solution of PVP, and then mixing with the suspension to obtain dimming liquid; and filling the dimming solution between the first transparent electrode and the second transparent electrode, and sealing. The liquid light valve prepared by the invention can be driven under low voltage, has high response speed, short recovery time and good repeatability, and has good safety by adopting stable PVP (polyvinyl pyrrolidone) at normal temperature and normal pressure as a dispersing agent.

Description

Low-voltage driven liquid light valve and preparation method thereof

Technical Field

The invention relates to the technical field of liquid light valves, in particular to a low-voltage driven liquid light valve and a preparation method thereof.

Background

Light valves are devices that can achieve light flux and color adjustment under external voltage driving, and can be classified into Electrochromic (EC), polymer Dispersed Liquid Crystal (PDLC), and suspended particle (also called light-adjusting particle) devices (SPD) according to their operation principles. The EC is driven by direct current voltage, the color light is regulated and controlled by losing electrons of inorganic/organic electrochromic materials in the dimming layer, the PDLC and the SPD are driven by alternating current voltage, and the luminous flux is regulated by the conversion of Brownian motion-oriented arrangement of liquid crystal molecules and dimming particles in the PDLC and the SPD respectively. Among them, SPD is more and more popular in the market due to its advantages of good weather resistance, rich color, and rapid response.

A conventional SPD is composed of two layers of transparent electrodes and a light modulating layer sandwiched between the electrodes, and the light modulating layer is composed of light modulating droplets containing light modulating particles and a base body supporting the light modulating droplets. At present, the products are applied to the fields of intelligent vehicle windows, aircraft portholes, office partitions and the like. In the SPD, the matrix and the light-adjusting liquid are both organic polymers, which often have technical barriers such as poor repeatability, large organic gas emission, and the refractive indexes of the two need to be precisely matched. More importantly, the matrix and the dimming solution need to be uniformly separated, so that the molecular weight/viscosity of the matrix and the dimming solution is relatively high, which causes the dimming particles to be difficult to rotate in the dimming solution, and the conventional SPD needs to work normally under a relatively high driving voltage (above 110V).

Recently, the SPD gets rid of a complex process of separating a polymer phase in the traditional preparation process, and directly seals the dimming liquid mixed with dimming particles between two layers of transparent electrodes, so that the liquid SPD light valve with a simple structure is obtained. However, its apparent shortness is that the dimmer particles are no longer confined to the interior of the dimmer droplets, but rather can undergo a greater range of brownian motion, and are therefore more prone to agglomeration and deposition, causing SPD failure. In the prior art, nitrocellulose is generally adopted for dispersing dimming particles, but the prepared SPD has the defects of high driving voltage, low response speed and long recovery time, and the nitrocellulose is a flammable and explosive substance, is difficult to obtain and has large pollution in the production process.

Disclosure of Invention

In order to solve the above problems, the present invention provides a liquid light valve driven by low voltage and a method for manufacturing the same based on the existing liquid light valve.

On one hand, the invention provides a low-voltage driven liquid light valve, which comprises a first transparent electrode, a dimming liquid and a second transparent electrode which are sequentially arranged; the dimming solution comprises dimming particles, a suspension, a dispersant and an organic solvent; the dispersant is PVP.

Further, the driving voltage of the liquid light valve is 25-40V.

Further, the light-adjusting particles are quinine iodosulfate nanorods.

Further, the suspension is an acrylic polymer having a viscosity of 30 to 200cps.

Further, the molecular weight of PVP is between 8000 and 220000.

More preferably, the molecular weight of PVP is between 8000 and 58000.

Further, the organic solvent is selected from one or more of ethyl acetate, butyl acetate, isoamyl acetate, triacetin and trioctyl trimellitate, and preferably is isoamyl acetate.

Further, the first transparent electrode and the second transparent electrode are selected from one or more of an ITO conductive glass, an ITO conductive film, a nano silver wire conductive film, a nano copper wire conductive film, a PEDOT conductive film, a graphene conductive film and a carbon nanotube conductive film.

PVP is an excellent dispersant. In many nanoparticle synthesis and dispersion processes, PVP can adsorb to the surface of the nanoparticles, thereby inhibiting aggregation of the particles. In the invention, the iodine quinine sulfate particles are easy to form aggregates in the suspension, which leads to the increase of the working voltage of the product. The electrophilic reaction of pyrrole nitrogen in PVP molecule is very strong, so it is easy to combine with iodine element with electron concentration outside nucleus. When PVP is introduced into the suspension, it can adsorb to the surface of the quinine iodosulfate nanoparticles, thus promoting their dispersion; meanwhile, the PVP forms an organic molecular layer on the surface of the particles, so that a good transition effect is achieved between the particles and the suspension liquid, the particles can be effectively lubricated, and the voltage required by particle overturning can be effectively reduced by the PVP.

On the other hand, the invention also provides a preparation method of the liquid light valve driven by low voltage, which comprises the following preparation steps:

(1) Preparing dimming particles;

(2) Preparing a suspension;

(3) Dissolving PVP in an organic ester solvent to obtain an organic ester solution of the PVP;

(4) Mixing the dimming particles obtained in the step (1) with the organic ester solution of PVP obtained in the step (3) to obtain a mixed solution, and then mixing the mixed solution with the suspension obtained in the step (2) to obtain a dimming solution;

(5) And (4) filling the dimming liquid obtained in the step (4) between the first transparent electrode and the second transparent electrode, and packaging to obtain the liquid light valve.

Further, the mass fraction of PVP in the organic ester solution of PVP in the step (3) is 0.1-10%, preferably 0.5-5%.

Further, the mass ratio of the dimming particles, the organic ester solution of PVP and the suspension in the step (4) is x: y:100, wherein x is between 2 and 6 and y is between 10 and 50.

The PVP can effectively inhibit the particle agglomeration, but the excessive use amount of the PVP can cause the solution to be viscous, so that the particles are difficult to turn over under an electric field, while the organic ester selected by the invention is used as a solvent, the PVP can be dissolved, the viscosity of the suspension can be reduced, but the excessive use amount of the PVP can cause the particles to re-agglomerate. Therefore, the present invention sets the mass fraction of PVP and the mass ratio in the light control solution as described above to achieve the best effect.

Compared with the prior art, the invention has the beneficial effects that:

1. the PVP is adopted as the dispersant, the dispersion capability and the stability of the PVP are excellent, the retardation of the dimming particles in the dimming liquid during the rotation motion can be reduced, and the dimming particles can freely turn over under the action of an electric field, so that the liquid light valve prepared by the invention can be driven under low voltage, the energy consumption of a dimming device during the use is greatly saved, and the PVP has the advantages of high response speed and short recovery time.

2. The invention discloses a preparation method of a low-voltage driven liquid light valve, which is characterized in that dimming particles are uniformly dispersed in an organic ester solvent, and the organic ester solvent containing PVP and the dimming particles is fully mixed with a suspension liquid to obtain a dimming liquid suitable for SPD. On one hand, the viscosity of the dimming solution is reduced, and the agglomeration and deposition of dimming particles are prevented; on the other hand, the dispersibility of the dimming particles is further improved, so that the SPD device can be repeatedly used and keeps low performance degradation, and the repeatability is good.

3. The PVP is adopted as the dispersing agent, compared with the traditional dispersing agent, the PVP has good solubility, and can be dissolved in water and various polar organic solvents; the product is stable at normal temperature and pressure, low in toxicity and good in safety; the pollution in the production process is less, and the method conforms to the concept of environmental protection.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of a low voltage driven liquid light valve made in accordance with the present invention;

fig. 2 is a schematic diagram of the transmittance of a liquid light valve prepared in embodiment 1 of the present invention;

FIG. 3 is a schematic diagram of the transmittance of a liquid light valve prepared in example 2 of the present invention;

fig. 4 is a schematic diagram of the transmittance of a liquid light valve prepared in embodiment 3 of the present invention;

FIG. 5 is a schematic diagram of the transmittance of a liquid light valve prepared in embodiment 4 of the present invention;

FIG. 6 is a schematic diagram of the transmittance of a liquid light valve prepared in embodiment 5 of the present invention;

FIG. 7 is a schematic diagram of the transmittance of a liquid light valve prepared in comparative example 1 according to the present invention;

fig. 8 is a schematic diagram of the transmittance of a liquid light valve prepared in comparative example 2 according to the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A low voltage driven liquid light valve is prepared as follows:

(1) Preparing dimming particles:

in an ice bath environment, 5g of quinine sulfate is dissolved in a mixture of 400mL of water, 3mL of concentrated sulfuric acid and 30mL of glacial acetic acid, and 5g of FeCl is added to the mixture ₃ Obtaining light yellow solution A; similarly, under an ice bath environment, 2.5g of I ₂ And 1g of KI are dissolved in a mixed solution of 20g of alcohol and 20g of water to obtain a dark brown solution B; under the action of ultrasound, uniformly mixing the solution A and the solution B while stirring for reaction, keeping the temperature of a reaction system not more than 5 ℃, and centrifuging and drying after 1h of reaction to obtain dimming particles;

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain suspension with the viscosity of 91 cps;

(3) Dissolving 0.1g of PVP with molecular weight of 8000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

(4) Adding 2g of the dimming particles obtained in the step (1) into the organic ester solution of PVP obtained in the step (3), and performing ultrasonic dispersion to obtain a mixed solution; taking 1g of mixed solution, and stirring and mixing 5g of the suspension obtained in the step (2) to obtain dimming solution;

(5) And (4) filling the dimming liquid obtained in the step (4) between two layers of ITO glass to obtain the liquid light valve.

As shown in fig. 1, which is a schematic diagram of the operation of a low voltage-driven liquid light valve prepared by the present invention, when the liquid light valve is not powered on, the dimming particles in the liquid light valve will be in an irregular distribution state, and at this time, the liquid light valve is in a transparent and opaque appearance state; when the liquid light valve is electrified, the dimming particles in the liquid light valve are arranged in order, light can penetrate through the dimming particles freely, and the liquid light valve is in a transparent state instantly.

As shown in fig. 2 and table 1, the liquid light valve obtained in example 1 has a transmittance of about 40% in the visible light range when no voltage is applied, and changes to a transparent state when a voltage of 25V is applied, and the transmittance thereof increases to about 90%, the response time is 50ms, and the recovery time is 0.4s.

Example 2

A low voltage driven liquid light valve, which differs from the embodiment 1 mainly in that PVP with different molecular weights are used, and the preparation steps are as follows:

(1) Preparing dimming particles:

in an ice bath environment, 5g of quinine sulfate is dissolved in a mixture of 400mL of water, 3mL of concentrated sulfuric acid and 30mL of glacial acetic acid, and 5g of FeCl is added to the mixture ₃ Obtaining light yellow solution A; similarly, under an ice bath environment, 2.5g of I ₂ And 1g KI in a mixture of 20g alcohol and 20g water to obtain a dark brown solution B; under the action of ultrasound, uniformly mixing the solution A and the solution B while stirring for reaction, keeping the temperature of a reaction system not to exceed 5 ℃, and centrifuging and drying after 1-hour reaction to obtain dimming particles;

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 104 cps;

(3) Dissolving 0.1g of PVP with the molecular weight of 58000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

(5) And (5) filling the dimming solution obtained in the step (4) between two layers of ITO glass to obtain the liquid light valve.

As shown in fig. 3 and table 1, the liquid light valve obtained in example 2 has a transmittance of about 40% in the visible light range when no voltage is applied, and changes to a transparent state when a voltage of 25V is applied, and the transmittance thereof increases to about 80%, the response time is 90ms, and the recovery time is 1.2s.

Example 3

(1) Preparing dimming particles:

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 97 cps;

(3) Dissolving 0.1g of PVP with the molecular weight of 220000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

As shown in fig. 4 and table 1, the liquid light valve obtained in example 3 has a transmittance of about 40% in the visible light range when no voltage is applied, and changes to a transparent state when a voltage of 40V is applied, and the transmittance thereof increases to about 70%, the response time is 120ms, and the recovery time is 2.6s.

Example 4

A low voltage driven liquid light valve, which differs from example 1 mainly in that PVP organic ester solution with different mass fractions is used, and is prepared by the following steps:

(1) Preparing dimming particles:

5g of quinine sulfate is dissolved in a mixture of 400mL of water, 3mL of concentrated sulfuric acid and 30mL of glacial acetic acid in an ice bath environment, and 5g of FeCl is added to the mixture ₃ Obtaining light yellow solution A; similarly, 2.5g of I were added under ice bath ₂ And 1g KI in a mixture of 20g alcohol and 20g water to obtain a dark brown solution B; under the action of ultrasound, uniformly mixing the solution A and the solution B while stirring for reaction, keeping the temperature of a reaction system not more than 5 ℃, and centrifuging and drying after 1h of reaction to obtain dimming particles;

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 88 cps;

(3) Dissolving 0.01g of PVP with molecular weight of 8000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

As shown in fig. 5 and table 1, the liquid light valve obtained in example 4 has a transmittance of about 30% in the visible light range when no voltage is applied, and changes to a transparent state when a voltage of 25V is applied, and the transmittance thereof increases to about 60%, the response time is 70ms, and the recovery time is 3.5s.

Example 5

(1) Preparing dimming particles:

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 102 cps;

(3) Dissolving 1g of PVP with the molecular weight of 8000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

As shown in fig. 6 and table 1, the liquid light valve obtained in example 4 has a transmittance of about 40% in the visible light range when no voltage is applied, and changes to a transparent state when a voltage of 40V is applied, and the transmittance thereof increases to about 80%, the response time is 150ms, and the recovery time is 3.3s.

Comparative example 1

A liquid light valve, which differs from example 1 in that no dispersant is used, is prepared by the following steps:

(1) Preparing dimming particles:

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 95 cps;

(3) Directly dispersing 0.1g of dimming particles into 5g of the suspension obtained in the step (2) to obtain dimming liquid;

(4) And filling the obtained dimming liquid between two layers of ITO glass to obtain the liquid light valve.

As shown in fig. 7 and table 1, the liquid light valve obtained in comparative example 1 has a transmittance of about 40% in the visible light range when no voltage is applied, and needs to apply a voltage of about 70V when the state of the device is changed to a transparent state, i.e., the transmittance increases to about 90%, and the response time is 60ms; because the particles are agglomerated after power failure, the recovery time is over 120s, and the device can be completely recovered to the initial state only by proper ultrasonic vibration.

Comparative example 2

A liquid light valve, which differs from example 1 in that PVP of a larger molecular weight is used as a dispersing agent, and is prepared by the steps of:

(1) Preparing dimming particles:

in an ice bath environment, 5g of quinine sulfate is dissolved in a mixture of 400mL of water, 3mL of concentrated sulfuric acid and 30mL of glacial acetic acid, and 5g of FeCl is added to the mixture ₃ Obtaining light yellow solution A; similarly, 2.5g of I were added under ice bath ₂ And 1g KI in a mixture of 20g alcohol and 20g water to obtain a dark brown solution B; under the action of ultrasound, uniformly mixing the solution A and the solution B while stirring for reaction, keeping the temperature of a reaction system not to exceed 5 ℃, and centrifuging and drying after 1-hour reaction to obtain dimming particles;

(2) Preparing a suspension:

putting 0.9mmol of lauryl methacrylate and 0.1mmol of hydroxyethyl methacrylate into a three-neck flask for uniform mixing, then adding 100mL of toluene and 4mL of hexanethiol, and introducing nitrogen into the uniformly mixed liquid; heating the reaction system to 60 ℃, adding 0.3g of azodiisobutyronitrile into the reaction system, keeping the temperature for reaction for 24 hours, and finally performing rotary evaporation at 100 ℃ to obtain a suspension with the viscosity of 99 cps;

(3) Dissolving 0.01g of PVP with the molecular weight of 1300000 in 10g of isoamyl acetate to obtain an organic ester solution of the PVP;

As shown in fig. 8 and table 1, the liquid light valve obtained in comparative example 2 has a transmittance of about 35% in the visible light range when no voltage is applied, and the state changes to a transparent state when a voltage of 110V is applied, and the transmittance increases to about 70%, and the response time is 260ms, so that it is difficult to return to the original state.

Table 1 comparison of the properties of the liquid light valves prepared in the examples and comparative examples

The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.

Claims

1. A low-voltage driven liquid light valve is characterized by comprising a first transparent electrode, a dimming liquid and a second transparent electrode which are sequentially arranged;

the dimming solution comprises dimming particles, a suspension, a dispersant and an organic solvent;

the dispersant is PVP.

2. The liquid light valve as claimed in claim 1, wherein the driving voltage of the liquid light valve is 25-40V.

3. The low voltage driven liquid light valve of claim 1 wherein said light modulating particles are quinine iodosulfate nanorods.

4. The low voltage driven liquid light valve as claimed in claim 1, wherein the suspension is an acrylate polymer having a viscosity of 30 cps to 200cps.

5. A low voltage driven liquid light valve as claimed in claim 1, wherein the PVP has a molecular weight of 8000-220000.

6. The low voltage driven liquid light valve of claim 1 wherein the organic solvent is selected from one or more of ethyl acetate, butyl acetate, isoamyl acetate, triacetin, and trioctyl trimellitate.

7. The low voltage liquid light valve of claim 1, wherein the first transparent electrode and the second transparent electrode are selected from one or more of ITO conductive glass, ITO conductive film, silver nanowire conductive film, copper nanowire conductive film, PEDOT conductive film, graphene conductive film, and carbon nanotube conductive film.

8. A method of manufacturing a low voltage driven liquid light valve as claimed in any one of claims 1 to 7, comprising the steps of:

(1) Preparing dimming particles;

(2) Preparing a suspension;

(3) Dissolving PVP in an organic solvent to obtain an organic ester solution of the PVP;

(5) And (5) filling the dimming liquid obtained in the step (4) between the first transparent electrode and the second transparent electrode, and packaging to obtain the liquid light valve.

9. The method according to claim 8, wherein the PVP in the step (3) is present in an amount of 0.1-10% by weight in the organic ester solution of PVP.

10. The method according to claim 8, wherein the mass ratio of the light-adjusting particles, the organic ester solution of PVP and the suspension in step (4) is x: y:100, wherein x is between 2 and 6 and y is between 10 and 50.