Polymer electrochromic material and its application in anti-dazzling rearview mirror

Abstract

This application relates to the field of electrochromic materials technology, and discloses a polymeric electrochromic material and its application in anti-glare rearview mirrors. The polymeric electrochromic material is formed by in-situ polymerization and curing under ultraviolet light of a solvent, a polyurethane prepolymer with terminal double bonds, a violet derivative containing double bonds, a complementary electrochromic material, and a photoinitiator. The violet derivative containing double bonds is covalently anchored to the three-dimensional polymeric gel network framework formed by the crosslinking of the polyurethane prepolymer with terminal double bonds. This invention restricts the directional migration of the chromogenic groups through chemical bonding, effectively solving the problems of easy leakage and delamination during long-term operation of traditional devices. Simultaneously, the use of polyether soft segments to construct ion channels ensures that the device has a second-level response speed and high optical contrast. The material has a simple preparation process, good weather resistance, and is particularly suitable for automotive anti-glare rearview mirrors.

Description

Technical Field

[0001] This invention relates to the field of electrochromic materials technology, specifically to a polymer electrochromic material and its application in anti-glare rearview mirrors. Background Technology

[0002] Electrochromic anti-glare rearview mirrors utilize the reversible redox reaction of electrochromic materials under an electric field to alter the reflectivity of the mirror surface, thereby eliminating the interference of strong headlights from following vehicles on the driver's vision. Currently, commercially available automotive anti-glare rearview mirrors mainly employ liquid electrochromic systems, which are composed of violet derivatives and complementary color-changing materials dissolved in organic solvents. Although liquid systems have advantages such as fast ion diffusion rates, high response sensitivity, and high optical contrast, they still have significant technical drawbacks in practical applications.

[0003] Liquid electrochromic devices face challenges in two main areas: safety and stability. Regarding safety, the liquid electrolyte requires extremely high precision in its encapsulation process. In the event of a vehicle collision causing the mirror glass to shatter, the corrosive or toxic organic electrolyte inside can easily leak, potentially causing device failure and even corroding the car's interior or electronic circuitry, posing a safety hazard. Regarding stability, the electrochromic active material in the liquid system is in a free state. Under prolonged DC voltage application, the charged active molecules will migrate and accumulate under the influence of the electric field, resulting in a layering phenomenon with color differences between the positive and negative electrode areas—the positive electrode turning yellow and the negative electrode turning blue—severely affecting the anti-glare effect and visual aesthetics.

[0004] To address the leakage problem in liquid systems, current technologies often employ the addition of polymeric thickeners or nanoparticles to prepare physical gel electrolytes. While this physical gel increases the system viscosity to some extent, mitigating the risk of leakage, the electrochromic active molecules within it are not actually chemically bound and remain in a physically doped state. Under prolonged electric fields, these free molecules can still migrate through the gel pores, making it impossible to fundamentally solve the delamination problem. Furthermore, to achieve the mechanical strength required for leak prevention, physical gels often require a high polymer content, which significantly hinders ion transport channels, resulting in a substantial decrease in the coloring and fading response speed of the device, making it difficult to meet the real-time response requirements of rearview mirrors for driving safety.

[0005] Therefore, this invention proposes a polymer electrochromic material and its application in anti-glare rearview mirrors to address the shortcomings of existing technologies. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a polymer electrochromic material and its application in anti-glare rearview mirrors, solving the problems of easy leakage and delamination during long-term operation of existing liquid electrochromic devices, as well as the slow response speed of physical gel electrolytes.

[0007] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a polymeric electrochromic material, which adopts the following technical solution: a polymeric electrochromic material is formed by in-situ polymerization and curing of raw materials comprising the following parts by weight under ultraviolet light: 100-150 parts of solvent, 20-60 parts of double-bonded polyurethane prepolymer, 2-8 parts of violet derivative containing double bonds, 0.5-3 parts of complementary electrochromic material, and 0.5-2 parts of photoinitiator; wherein, the double-bonded polyurethane prepolymer and the violet derivative containing double bonds undergo a free radical copolymerization reaction under the action of the photoinitiator, so that the violet derivative containing double bonds is covalently anchored on the three-dimensional polymeric gel network backbone formed by crosslinking of the double-bonded polyurethane prepolymer.

[0008] This invention employs the above-mentioned technical solution, utilizing a polyurethane prepolymer with terminal double bonds as the main skeleton, combined with a violet alkaloid derivative containing double-bonded functional groups, to achieve chemical bonding between the active color-changing component and the polymer network under ultraviolet light irradiation. Its mechanism of action is mainly reflected in the following three aspects: First, a chemical cross-linking network is constructed to prevent leakage. A photoinitiator initiates chain growth and cross-linking reactions in the terminal double-bond polyurethane prepolymer, forming a three-dimensional network structure that runs throughout the system. This network physically binds the liquid solvent within the gel mesh, imparting solid-state mechanical properties to the material and solving the leakage problem when the device breaks.

[0009] Secondly, chemical anchoring suppresses stratification. The violet derivative containing double bonds participates in the reaction as a comonomer, being fixed to the nodes or side chains of the polyurethane crosslinking network via covalent bonds. This chemical anchoring restricts the spatial freedom of the chromogenic group, allowing it to only undergo localized creep or conformational inversion within the limits allowed by the molecular chain segments, preventing long-distance electrophoretic migration under a DC electric field. This suppresses the color stratification of the positive and negative electrodes of the device caused by the polarization of the active material concentration, maintaining the uniformity of the color state.

[0010] Finally, flexible ion channels are preserved. The polyether soft segments in the polyurethane prepolymer backbone have a low glass transition temperature, providing free volume for the migration of solvent molecules and counterions. Although the color-changing cations are fixed, the anions, acting as charge-balancing ions, can still migrate in the solvent-swollen gel channels, ensuring the charge transport efficiency of the redox reaction and enabling the all-solid-state device to maintain a response speed in the order of seconds.

[0011] Preferably, the polyurethane prepolymer with terminal double bonds is prepared by reacting polyether polyol, diisocyanate and hydroxyl-containing acrylate monomers; the polyether polyol is selected from polyethylene glycol or polypropylene glycol with a number average molecular weight of 1000 to 4000; the diisocyanate is selected from diphenylmethane diisocyanate or isophorone diisocyanate; and the hydroxyl-containing acrylate monomer is selected from hydroxyethyl methacrylate or hydroxypropyl methacrylate.

[0012] By selecting polyethylene glycol or polypropylene glycol of specific molecular weights as soft segments, the crosslinking density and flexibility of the gel network can be controlled. Polyether segments with molecular weights of 1000–4000 can form suitable pore sizes, balancing solvent binding capacity with diffusion channels for small molecule anions. The hard segment structure formed by diisocyanates imparts mechanical strength to the gel, while the acrylate double bonds at the end groups provide photocuring reactive sites.

[0013] Preferably, the violet derivative containing a double bond is an N,N'-dienyl-substituted 4,4'-bipyridinium salt; the alkenyl substituent in the N,N'-dienyl-substituted 4,4'-bipyridinium salt is independently selected from a straight-chain olefin group having 3 to 8 carbon atoms and a carbon-carbon double bond at the end; the anion in the N,N'-dienyl-substituted 4,4'-bipyridinium salt is selected from hexafluorophosphate ions, tetrafluoroborate ions, or perchlorate ions.

[0014] Straight-chain olefins with carbon chain lengths of 3–8 were selected as linking arms, and flexible spacer groups were introduced between the rigid chromophore of violetin and the polymer backbone. These flexible spacer groups reduced the steric hindrance effect of the polymer backbone on the redox configuration changes of the chromophore, which is beneficial for maintaining the coloring efficiency of violetin. Simultaneously, the high reactivity of the terminal double bonds ensured that violetin could be incorporated into the polymer network with a high conversion rate, reducing the amount of free monomer residue.

[0015] Preferably, the zironine derivative containing a double bond is selected from 1,1'-di-2-propenyl-4,4'-bipyridine hexafluorophosphate, 1,1'-di-5-hexenyl-4,4'-bipyridine hexafluorophosphate, or 1,1'-di-7-octenyl-4,4'-bipyridine hexafluorophosphate.

[0016] The violet derivatives with the above-described structure exhibit good chemical stability and electrochemical reversibility. Their allyl or long-chain alkenyl structures readily copolymerize with acrylate monomers, and the high degree of dissociation of the hexafluorophosphate anion in propylene carbonate helps to improve the ionic conductivity of the device.

[0017] Preferably, the solvent is propylene carbonate; the complementary electrochromic material is 5,10-dihydro-5,10-dimethylphenazine; and the photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

[0018] Propylene carbonate possesses a high dielectric constant and a wide electrochemical window, making it suitable for the violet base system. 5,10-dihydro-5,10-dimethylphenazine, as the anodic coloring material, forms a complementary color-changing system with the violet base used for cathode coloring, enhancing the optical contrast of the device and achieving charge balance during redox processes, thus reducing the driving voltage.

[0019] Preferably, the gel content of the polymer electrochromic material after curing is 93wt% to 97wt%, and the dissolution rate of the double-bonded violet derivative of the polymer electrochromic material after soaking in acetonitrile solvent for 48 hours is less than 1wt%.

[0020] High gel content indicates a complete polymerization reaction, resulting in a well-developed network structure. Low dissolution rate confirms that the violet derivative containing double bonds was mainly synthesized as part of the polymer network through chemical bonding, rather than physical doping. This is crucial for ensuring the device's long-term operation without delamination and its solvent resistance.

[0021] Secondly, this invention provides a method for preparing a polymeric electrochromic material, employing the following technical solution: A method for preparing a polymer electrochromic material includes the following steps: Step S1, Precursor preparation: Under light-protected conditions, solvent, terminal double-bond polyurethane prepolymer, double-bond violet derivative, complementary electrochromic material and photoinitiator are mixed in proportion, stirred to dissolve and vacuum degassed to obtain electrolyte precursor; Step S2, Injection: Inject the electrolyte precursor into the empty cell of the device with a transparent conductive layer; Step S3, Curing: The empty device cell into which the electrolyte precursor is injected is sealed and irradiated under ultraviolet light to cause in-situ polymerization and curing of the electrolyte precursor, thereby obtaining a polymer electrochromic material.

[0022] This method employs an in-situ polymerization process of "pre-pouring followed by curing." During the pouring stage, the precursor remains in a low-viscosity liquid state, allowing for rapid filling of micron-sized device gaps using existing filling equipment and reducing air bubble residue. Subsequently, ultraviolet light irradiation transforms the liquid precursor into a solid gel in situ. This process eliminates the need for prolonged high-temperature heating, avoiding component thermal degradation and making it suitable for mass production.

[0023] Preferably, in step S1, the synthesis step of the polyurethane prepolymer with terminal double bonds includes: dissolving a polyether polyol in a solvent, heating it to 60°C–70°C, adding diisocyanate dropwise, and reacting at a constant temperature of 70°C–80°C to obtain a terminal isocyanate intermediate; adding a hydroxyl-containing acrylate monomer to the terminal isocyanate intermediate, and continuing the reaction at 70°C–80°C until the characteristic peak of the isocyanate group disappears, and cooling to obtain the polyurethane prepolymer with terminal double bonds; the molar ratio of polyether polyol, diisocyanate and hydroxyl-containing acrylate monomer is 1:1.8–2.2:2.0–2.5.

[0024] A two-step synthesis process was employed, utilizing a slightly excess of diisocyanate to cap the ends of the polyether polyol with isocyanate groups. Subsequently, a hydroxyl-containing acrylate was reacted with the isocyanate groups to introduce polymerizable double bonds at both ends of the polymer chain. This route features mild reaction conditions, well-defined product structures, and the ability to prepare prepolymers with uniform molecular weight distribution and high double bond functionality.

[0025] Preferably, in step S3, the wavelength of the ultraviolet light is 365 nm and the light intensity is 40 mW / cm². 2 ~60mW / cm 2 The irradiation time is 60s to 90s.

[0026] 365nm ultraviolet light was selected in combination with medium-intensity illumination to match the absorption characteristics of photoinitiator 1173. The irradiation time was controlled between 60s and 90s to ensure monomer conversion while preventing gel shrinkage or side reactions caused by excessive irradiation heat generation, thereby obtaining a cured product with excellent performance.

[0027] Thirdly, the present invention provides an application of a polymeric electrochromic material in an anti-glare rearview mirror, employing the following technical solution: An anti-glare rearview mirror includes a first substrate, a second substrate, and an electrochromic layer located between the first substrate and the second substrate; a transparent conductive layer is provided on one side surface of the first substrate and the second substrate facing each other; the electrochromic layer is formed by filling and curing a polymer electrochromic material as described in any of the first aspects.

[0028] Applying the aforementioned all-solid-state chemically cross-linked electrochromic material to anti-glare rearview mirrors can improve product reliability. When the rearview mirror breaks, the solid electrochromic layer can bind glass fragments and prevent chemical leakage. Simultaneously, the rearview mirror maintains a uniform mirror color under prolonged outdoor high temperatures and continuous power supply, avoiding the color separation phenomenon commonly seen in traditional liquid products where the positive electrode turns yellow and the negative electrode turns blue.

[0029] This invention provides a polymeric electrochromic material and its application in anti-glare rearview mirrors. It offers the following advantages: 1. This invention achieves spatial fixation of the electrochromic active component by covalently anchoring a violet alkaloid derivative containing double bonds into a polyurethane crosslinked network through ultraviolet light curing. This chemically bonded structure restricts the long-distance migration of the chromogenic group under the action of an electric field, effectively suppressing concentration polarization and color stratification of the positive and negative electrodes during long-term device operation. Simultaneously, the formed three-dimensional gel network physically binds the liquid solvent, eliminating the risk of electrolyte leakage after device damage and improving the safety of automotive applications.

[0030] 2. This invention introduces flexible polyether soft segments into the polymer backbone to construct ion transport channels. Combined with the flexible alkyl spacer groups on the violet alkali molecule, this reduces the steric hindrance effect of the polymer network on ion migration and configuration inversion. This structural design allows the solid-state gel electrolyte to retain near-liquid-state ionic conductivity and redox kinetics, ensuring that the device maintains second-level fast response and high optical contrast while achieving all-solid-state operation.

[0031] 3. The chemical cross-linked network formed by the in-situ polymerization process used in this invention exhibits excellent solvent resistance and thermal stability. Compared with physically mixed gels, this chemical network can more effectively resist aging and degradation under high temperature and humidity environments, preventing the precipitation or destruction of active materials during long-term use, thereby extending the cycle life of the device. Furthermore, the process of first infusing a low-viscosity precursor followed by rapid photocuring avoids the impact of high-temperature thermal polymerization on the components, simplifies the encapsulation process, and facilitates large-scale industrial production. Attached Figure Description

[0032] Figure 1 This is a comparison diagram of the ultraviolet-visible absorption spectra of the present invention; Figure 2 This is a graph showing the trend of cumulative leakage mass over time according to the present invention. Figure 3 The diagram shows the spatial distribution evolution of reflectivity of the device of the present invention under continuous power-on conditions; wherein, (a) is the test result of Example 1; and (b) is the test result of Comparative Example 1. Figure 4 This is a reflectance-time response curve for a single electrochemical coloring / bleaching cycle according to the present invention. Figure 5 This is a comparison diagram showing the retention of optical contrast of the device before and after PCT aging according to the present invention; Figure 6 This is a comparison chart of the coloring and fading response times of the device at different temperatures according to the present invention. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0035] Polyethylene glycol (Mn=2000 and 4000, CAS No. 25322-68-3), polypropylene glycol (Mn=1000, CAS No. 25322-69-4), diphenylmethane diisocyanate (CAS No. 101-68-8), isophorone diisocyanate (CAS No. 4098-71-9), hydroxyethyl methacrylate (CAS No. 868-77-9), hydroxypropyl methacrylate (CAS No. 27813-02-1), and methyl methacrylate (CAS No. 80-62-6).

[0036] 4,4'-Bipyridine (CAS No. 553-26-4), 3-bromo-1-propene (CAS No. 106-95-6), 6-bromo-1-hexene (CAS No. 2695-47-8), 8-bromo-1-octene (CAS No. 2695-48-9), 1-bromohexane (CAS No. 111-25-1), 5,10-dihydro-5,10-dimethylphenazine (CAS No. 15546-75-5), and ammonium hexafluorophosphate (CAS No. 16941-11-0).

[0037] Propylene carbonate (CAS No. 108-32-7), acetonitrile (CAS No. 75-05-8) and 2-hydroxy-2-methyl-1-phenylpropanone (CAS No. 7473-98-5).

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the synthesis reaction mechanism and general structural formula of the core components "terminated double-bond polyurethane prepolymer" and "double-bond violet derivative" are now described in detail.

[0039] The terminal double-bond polyurethane prepolymer of the present invention is obtained through a two-step addition reaction: Step 1: Polyether polyol With excess diisocyanate An addition reaction occurs, generating a polyurethane intermediate with active isocyanate groups (-NCO) at both ends; Step 2: Add hydroxyl-containing acrylate monomers The above intermediate is end-capped to introduce photocurable carbon-carbon double bonds at the end of the polyurethane backbone.

[0040] The rigorous synthesis reaction equation and product structure are shown below: ; The symbols in the above reaction equations are defined as follows: : Represents the degree of polymerization of repeating units in the main chain of polyurethane prepolymer, and is an integer greater than or equal to 1; : Represents the flexible backbone of polyether polyols, selected from polyethylene glycol (PEG) or polypropylene glycol (PPG) segments; : Represents the hydrocarbon skeleton of diisocyanate, specifically selected from diphenylmethane (derived from MDI), tolyl (derived from TDI), hexamethylene (derived from HDI) or isophorone (derived from IPDI); : Represents the alkylene linking arm in the acrylate monomer, preferably ethylene. or propylidene ; : Represents a hydrogen atom (H) or a methyl group (CH3), corresponding to acrylate or methacrylate monomers, respectively.

[0041] The double-bonded violet derivative of the present invention is prepared by quaternization of a haloalkene with bipyridine, followed by ion exchange.

[0042] Note: To ensure the material has photopolymerization activity, the raw materials must be haloolefins containing carbon-carbon double bonds (such as bromopropylene, bromohexene, etc.) rather than unsaturated haloalkanes (such as bromohexane).

[0043] The synthesis reaction equation is shown below: ; Subsequently, through an ion exchange reaction, the halide anion X in the above product is removed. - Replace with PF - 6 (hexafluorophosphate), BF - 4 (tetrafluoroborate) or ClO - Large-volume anions such as 4 (perchlorate) are used to improve solubility and dissociation in organic solvents.

[0044] The symbols in the above reaction equations are defined as follows: : Represents the bipyridine skeleton, preferably 4,4'-bipyridine; : Represents a halogen atom, selected from chlorine (Cl), bromine (Br), or iodine (I); : Represents the alkylene linker connecting the bipyridine nitrogen atom and the double bond, preferably a straight-chain alkylene chain with 1-8 carbon atoms. ; , The atoms are independently selected from hydrogen atoms (H) or C1-C10 alkyl groups; preferably all of them are H, in which case the double bond is located at the end of the molecule, the steric hindrance of polymerization is minimal, and the reactivity is the highest.

[0045] Preparation Example 1: This preparation example provides a method for preparing a polyurethane prepolymer with terminal double bonds (component A), comprising the following steps: In a reaction vessel equipped with a mechanical stirrer, thermometer, and nitrogen protection device, 100g of polyethylene glycol with a number average molecular weight of 2000 was added, along with 100ml of anhydrous propylene carbonate as a solvent. The mixture was heated to 60°C and stirred for 30 minutes to dissolve. Subsequently, 25.0g of diphenylmethane diisocyanate was slowly added dropwise, controlling the dropping rate to keep the reaction temperature below 75°C. After the addition was complete, the mixture was kept at 70°C for 2 hours to obtain a terminal isocyanate prepolymer. Then, 13.0g of hydroxyethyl methacrylate was added to the reaction system, and the mixture was kept at 70°C for another 3 hours. After the infrared spectrum of the sample confirmed the disappearance of the characteristic peak of the -NCO group, the reaction was stopped, and the mixture was cooled to room temperature to obtain polyurethane prepolymer solution A1.

[0046] Preparation Example 2: This preparation example provides another method for preparing a polyurethane prepolymer with terminal double bonds (component A), including the following steps: In a reaction vessel equipped with a mechanical stirrer, thermometer, and nitrogen protection device, 100g of polypropylene glycol with a number average molecular weight of 1000 was added, along with 100ml of anhydrous propylene carbonate as a solvent. The mixture was heated to 60°C and stirred for 30 minutes to dissolve. Subsequently, 50.0g of diphenylmethane diisocyanate was slowly added dropwise, controlling the dropping rate to keep the reaction temperature below 75°C. After the addition was complete, the mixture was kept at 70°C for 2 hours to obtain a terminal isocyanate prepolymer. Then, 26.0g of hydroxyethyl methacrylate was added to the reaction system, and the mixture was kept at 70°C for another 3 hours. After the infrared spectrum of the sample confirmed the disappearance of the characteristic peak of the -NCO group, the reaction was stopped, and the mixture was cooled to room temperature to obtain polyurethane prepolymer solution A2.

[0047] Preparation Example 3: This preparation example provides another method for preparing a polyurethane prepolymer with terminal double bonds (component A), including the following steps: In a reaction vessel equipped with a mechanical stirrer, thermometer, and nitrogen protection device, 100g of polyethylene glycol with a number average molecular weight of 4000 was added, along with 100ml of anhydrous propylene carbonate as a solvent. The mixture was heated to 60°C and stirred for 30 minutes to dissolve. Subsequently, 11.1g of isophorone diisocyanate was slowly added dropwise, controlling the dropping rate to keep the reaction temperature below 80°C. After the addition was complete, the mixture was kept at 80°C for 3 hours to obtain a prepolymer with terminal isocyanate groups. Then, 7.2g of hydroxypropyl methacrylate was added to the reaction system, and the mixture was kept at 80°C for another 4 hours. After the infrared spectrum of the sample confirmed the disappearance of the characteristic peak of the -NCO group, the reaction was stopped, and the mixture was cooled to room temperature to obtain polyurethane prepolymer solution A3.

[0048] Preparation Example 4: This preparation example provides a method for preparing a violetin derivative (component B) containing a double bond, comprising the following steps: 15.6 g (0.1 mol) of 4,4'-bipyridine was dissolved in 150 ml of acetonitrile and placed in a reaction vessel equipped with a reflux condenser. 35.9 g (0.22 mol) of 6-bromo-1-hexene was added. The mixture was heated to 90 °C and refluxed for 6 hours under nitrogen protection. After cooling to room temperature, the precipitate was collected by filtration and washed three times with acetonitrile to obtain an intermediate. The intermediate was dissolved in 200 ml of deionized water, and an aqueous solution containing 35.8 g (0.22 mol) of ammonium hexafluorophosphate was added dropwise with stirring, resulting in a white flocculent precipitate. After stirring for another 30 minutes, the mixture was allowed to stand, and the supernatant was removed. The precipitate was washed five times with deionized water until no halogen ions were detected in the filtrate. The precipitate was dried in a vacuum drying oven at 80 °C for 6 hours to obtain electrochromic material B1 containing double bonds.

[0049] Preparation Example 5: This preparation example provides another method for preparing a violetin derivative (component B) containing a double bond, comprising the following steps: 15.6 g (0.1 mol) of 4,4'-bipyridine was dissolved in 150 ml of acetonitrile and placed in a reaction vessel equipped with a reflux condenser. 26.6 g (0.22 mol) of 3-bromo-1-propene was added. The mixture was heated to 70 °C and refluxed for 8 hours under nitrogen protection. After cooling to room temperature, the precipitate was collected by filtration and washed three times with acetonitrile to obtain an intermediate. The intermediate was dissolved in 200 ml of deionized water, and an aqueous solution containing 35.8 g (0.22 mol) of ammonium hexafluorophosphate was added dropwise with stirring to produce a precipitate. After stirring for another 30 minutes, the mixture was allowed to stand, the supernatant was removed, and the precipitate was washed five times with deionized water. The precipitate was dried in a vacuum drying oven at 80 °C for 6 hours to obtain electrochromic material B2 containing double bonds.

[0050] Preparation Example 6: This preparation example provides another method for preparing a violetin derivative (component B) containing a double bond, comprising the following steps: 15.6 g (0.1 mol) of 4,4'-bipyridine was dissolved in 150 ml of acetonitrile and placed in a reaction vessel equipped with a reflux condenser. 42.0 g (0.22 mol) of 8-bromo-1-octene was added. The mixture was heated to 90 °C and refluxed for 10 hours under nitrogen protection. After cooling to room temperature, the precipitate was collected by filtration and washed three times with acetonitrile to obtain an intermediate. The intermediate was dissolved in 200 ml of deionized water, and an aqueous solution containing 35.8 g (0.22 mol) of ammonium hexafluorophosphate was added dropwise with stirring to produce a precipitate. After stirring for another 30 minutes, the mixture was allowed to stand, the supernatant was removed, and the precipitate was washed five times with deionized water. The precipitate was dried in a vacuum drying oven at 80 °C for 6 hours to obtain electrochromic material B3 containing double bonds.

[0051] Preparation Example 7: This preparation example provides a method for preparing a double-bond-free violetin derivative for comparison, comprising the following steps: 15.6 g (0.1 mol) of 4,4'-bipyridine was dissolved in 150 ml of acetonitrile and placed in a reaction vessel equipped with a reflux condenser. 36.3 g (0.22 mol) of 1-bromohexane was added. The mixture was heated to 90 °C and refluxed for 6 hours under nitrogen protection. After cooling to room temperature, the precipitate was collected by filtration and washed three times with acetonitrile to obtain an intermediate. The intermediate was dissolved in 200 ml of deionized water, and an aqueous solution containing 35.8 g (0.22 mol) of ammonium hexafluorophosphate was added dropwise with stirring to produce a precipitate. After stirring for another 30 minutes, the mixture was allowed to stand, and the supernatant was removed. The precipitate was washed five times with deionized water. The precipitate was dried in a vacuum drying oven at 80 °C for 6 hours to obtain electrochromic material B4 without double bonds.

[0052] Example 1: This example provides a method for preparing a polymer electrochromic material, including the following steps: (1) Preparation of electrolyte precursor: Under light-protected conditions, 134 ml of propylene carbonate was measured and placed in a beaker, and 40 g of polyurethane prepolymer solution A1 obtained in Preparation Example 1, 2.95 g of double-bonded electrochromic material B1 obtained in Preparation Example 4, 1.06 g of 5,10-dihydro-5,10-dimethylphenazine and 1.33 g of photoinitiator 1173 were added in sequence; the mixture was magnetically stirred at 25 °C for 60 minutes until a uniform and transparent green solution was formed, and the solution was degassed under vacuum for 10 minutes to obtain the electrolyte precursor; (2) Device potting: Prepare an empty ITO conductive glass cell after etching and cleaning of the conductive layer. The gap inside the cell is 150μm. The electrolyte precursor obtained in step (1) is injected into the empty cell using the vacuum potting method. (3) Sealing and curing: Clean the injection port and seal it with UV glue. Then place the device under a UV curing machine at a wavelength of 365nm and a light intensity of 50mW / cm. 2Under the condition of irradiation for 60 seconds, the liquid in the box completely solidifies to form a gel, thus completing the preparation of the electrochromic material and obtaining the finished anti-glare rearview mirror.

[0053] Example 2: This example provides a method for preparing a polymer electrochromic material, including the following steps: (1) Preparation of electrolyte precursor: Under light-protected conditions, 120 ml of propylene carbonate was measured and placed in a beaker. 55 g of polyurethane prepolymer solution A1 obtained in Preparation Example 1 (to increase the content of crosslinking components), 2.95 g of electrochromic material B2 containing double bonds (short-chain double bond type) obtained in Preparation Example 5, 1.06 g of 5,10-dihydro-5,10-dimethylphenazine and 1.5 g of photoinitiator 1173 were added in sequence. The mixture was magnetically stirred at 25 °C for 60 minutes until a homogeneous and transparent solution was formed. The solution was then degassed under vacuum for 10 minutes to obtain the electrolyte precursor. (2) Device potting: Prepare an empty ITO conductive glass cell after etching and cleaning of the conductive layer. The gap inside the cell is 150μm. The electrolyte precursor obtained in step (1) is injected into the empty cell using the vacuum potting method. (3) Sealing and curing: Clean the injection port and seal it with UV glue. Then place the device under a UV curing machine at a wavelength of 365nm and a light intensity of 50mW / cm. 2 Irradiation for 90 seconds under the specified conditions completely solidifies the liquid inside the box to form a gel, thus completing the preparation of the electrochromic material and obtaining the finished anti-glare rearview mirror.

[0054] Example 3: This example provides a method for preparing a polymer electrochromic material, including the following steps: (1) Preparation of electrolyte precursor: Under light-protected conditions, 144 ml of propylene carbonate was measured and placed in a beaker, and 30 g of polyurethane prepolymer solution A2 (PPG soft segment type) obtained in Preparation Example 2, 3.10 g of electrochromic material B3 (long chain double bond type) containing double bonds obtained in Preparation Example 6, 1.06 g of 5,10-dihydro-5,10-dimethylphenazine and 1.0 g of photoinitiator 1173 were added in sequence; the mixture was magnetically stirred at 25 °C for 60 minutes until a homogeneous and transparent solution was formed, and the solution was degassed under vacuum for 10 minutes to obtain the electrolyte precursor; (2) Device potting: Prepare an empty ITO conductive glass cell after etching and cleaning of the conductive layer. The gap inside the cell is 150μm. The electrolyte precursor obtained in step (1) is injected into the empty cell using the vacuum potting method. (3) Sealing and curing: Clean the injection port and seal it with UV glue. Then place the device under a UV curing machine at a wavelength of 365nm and a light intensity of 50mW / cm. 2 Under the condition of irradiation for 60 seconds, the liquid in the box completely solidifies to form a gel, thus completing the preparation of the electrochromic material and obtaining the finished anti-glare rearview mirror.

[0055] Example 4: This example provides a method for preparing a polymer electrochromic material, including the following steps: (1) Preparation of electrolyte precursor: Under light-protected conditions, 134 ml of propylene carbonate was measured and placed in a beaker, and 40 g of polyurethane prepolymer solution A3 (IPDI / PEG4000-based) obtained in Preparation Example 3, 2.95 g of double-bonded electrochromic material B1 obtained in Preparation Example 4, 1.06 g of 5,10-dihydro-5,10-dimethylphenazine and 1.33 g of photoinitiator 1173 were added in sequence; the mixture was magnetically stirred at 25 °C for 60 minutes until a homogeneous and transparent solution was formed, and the solution was degassed under vacuum for 10 minutes to obtain the electrolyte precursor; (2) Device potting: Prepare an empty ITO conductive glass cell after etching and cleaning of the conductive layer. The gap inside the cell is 150μm. The electrolyte precursor obtained in step (1) is injected into the empty cell using the vacuum potting method. (3) Sealing and curing: Clean the injection port and seal it with UV glue. Then place the device under a UV curing machine at a wavelength of 365nm and a light intensity of 50mW / cm. 2 Under the condition of irradiation for 60 seconds, the liquid in the box completely solidifies to form a gel, thus completing the preparation of the electrochromic material and obtaining the finished anti-glare rearview mirror.

[0056] Example 5: This example provides a method for preparing a polymer electrochromic material, including the following steps: (1) Preparation of electrolyte precursor: Under light-protected conditions, 130 ml of propylene carbonate was measured and placed in a beaker. 40 g of the polyurethane prepolymer solution A1 obtained in Preparation Example 1, 5.90 g of the double-bonded electrochromic material B1 obtained in Preparation Example 4 (concentration doubled), 2.12 g of 5,10-dihydro-5,10-dimethylphenazine (concentration doubled) and 1.33 g of photoinitiator 1173 were added sequentially. The mixture was magnetically stirred at 25 °C for 60 minutes until a homogeneous, transparent, dark green solution was formed. The solution was then degassed under vacuum for 10 minutes to obtain the electrolyte precursor. (2) Device potting: Prepare an empty ITO conductive glass cell after etching and cleaning of the conductive layer. The gap inside the cell is 150μm. The electrolyte precursor obtained in step (1) is injected into the empty cell using the vacuum potting method. (3) Sealing and curing: Clean the injection port and seal it with UV glue. Then place the device under a UV curing machine at a wavelength of 365nm and a light intensity of 50mW / cm. 2 Under the condition of irradiation for 60 seconds, the liquid in the box completely solidifies to form a gel, thus completing the preparation of the electrochromic material and obtaining the finished anti-glare rearview mirror.

[0057] Comparative Example 1: Compared with Example 1, the difference is that component A (polyurethane prepolymer) and component D (photoinitiator) were not added, and component B was replaced with an equimolar amount of the electrochromic material B4 without double bonds obtained in Preparation Example 7. The other components and device fabrication processes are the same.

[0058] Comparative Example 2: The difference from Example 1 is that component B was replaced with an equimolar amount of the electrochromic material B4 without double bonds obtained in Preparation Example 7, while all other aspects remained the same.

[0059] Comparative Example 3: The difference from Example 1 is that component A is replaced with an equal mass of methyl methacrylate (MMA) monomer, while all other components are the same.

[0060] Test Example 1: This test case aims to verify whether the electrochromic active material is covalently bonded to the polymer network and to examine the solvent resistance stability of the cured gel network.

[0061] The cured electrolyte samples prepared in Examples 1 to 5 and Comparative Example 2 were selected. The electrolyte layer was completely peeled off from the conductive glass substrate and placed in a vacuum oven at 50°C for 24 hours to fully remove residual solvent and moisture. The mass of the dried adhesive was weighed and recorded as W0.

[0062] The dried gel samples were placed in stoppered conical flasks containing sufficient acetonitrile solvent, and magnetically stirred and soaked for 48 hours at room temperature. Acetonitrile has good solubility for zirconia derivatives and unreacted monomers, but cannot dissolve the cross-linked polymer network.

[0063] After soaking, remove the remaining gel solid, wash the surface three times with fresh acetonitrile, and dry it again in a 50℃ vacuum oven for 24 hours until constant weight. Weigh the dry gel after extraction and record it as W1.

[0064] Take the soaking extract from step 2 and perform a full-band scan around 260 nm using a UV-Vis spectrophotometer. Record the absorbance value Abs of the maximum absorption peak. This band corresponds to the characteristic absorption of the violet chromophore. This value is used to characterize the relative concentration of free active molecules extracted by the solvent.

[0065] The gel content is calculated using the formula G=(W1 / W0)×100%.

[0066] The experimental data are shown in Table 1: Table 1: Gel content and absorbance test data of extract in conclusion: Based on the test data in Table 1 and the attached... Figure 1 As shown, the gel content in Examples 1 to 5 ranged from 93.66% to 96.07%. The 5,10-dihydro-5,10-dimethylphenazine (component C) and the photoinitiator residue added to the formulation do not possess double bond functional groups and theoretically cannot participate in chemical cross-linking. The dissolution of these small molecules resulted in a mass loss of approximately 4% to 6%, which is considered normal physical extraction loss. However, despite this mass loss, the absorbance reading of the extract remained in the low range of 0.059 to 0.165. Considering the extremely high molar extinction coefficient of the violet derivative, a significant increase in absorbance reading would occur if it were dissolved in large quantities. Therefore, the extremely low absorbance value confirms that component B was hardly eluted. This result indicates that component B did indeed participate in the polymerization reaction under UV irradiation and formed a three-dimensional cross-linked network resistant to acetonitrile dissolution.

[0067] In comparison, Comparative Example 2 had a gel content of 83.77% and a mass loss rate of approximately 16.23%, significantly higher than the Example group, and its extract had an absorbance as high as 2.913. Based on the formulation analysis of Comparative Example 2, although component A polymerized and formed a physical gel network, the color-changing material lacked active double bonds capable of participating in polymerization, preventing it from participating in chain growth or cross-linking reactions. During solvent immersion, free color-changing molecules easily diffused through the gel pores into the external solvent, leading to a significant increase in the absorbance of the extract.

[0068] The above data differences verify the design mechanism of this invention: by introducing olefin double bonds at the ends of violet molecules, they act as crosslinking points or side monomers during free radical polymerization, copolymerizing with the polyurethane prepolymer. This chemical bonding restricts the Brownian motion of the chromogenic groups, allowing them to remain within the polymer matrix even under solvent extraction conditions. Example 2, due to the increased crosslinking agent content, formed a denser network structure with the highest relative gel content; Example 3 used flexible polypropylene glycol segments and long-chain double-bonded monomers, resulting in a relatively high swelling ratio, leading to the precipitation of some oligomers, and its absorbance was slightly higher than Example 1, but still much lower than Comparative Example 2. This structure, which restricts the migration of active molecules through chemical bonding, helps to solve the delamination phenomenon caused by ion directional migration during long-term use of the device.

[0069] Test Example 2: This test case aims to examine the physical morphology of the electrolyte system after curing, as well as its leakage resistance in the event of physical damage or encapsulation failure, thereby evaluating its safety in practical automotive applications.

[0070] The anti-glare rearview mirror devices prepared in Examples 1 to 5, as well as Comparative Examples 1 and 2, were selected. All the samples to be tested were vertically fixed on the test frame, keeping the long side of the device perpendicular to the horizontal plane.

[0071] Using a diamond glass cutter, a through crack approximately 2 cm long was made in the center of the non-conductive glass surface on the back of the device. At the same time, the UV sealant on the bottom of the device was manually peeled off using a tool to simulate the damage state of the device when it is broken by external impact or when the sealant comes off due to aging.

[0072] Place pre-weighed absorbent cotton (initial mass M0) directly below the opening at the bottom of the device. Weigh the absorbent cotton (denoted as Mt) at three time points: 1 minute, 60 minutes, and 24 hours after the destructive operation. Quantify the cumulative leakage of electrolyte by calculating the mass difference (Mt−M0). At the same time, observe whether there is liquid seepage at the crack.

[0073] After 24 hours of observation, use qualitative filter paper to wipe the surface of the crack and the bottom opening, and observe whether the filter paper is wetted by the electrolyte or shows staining, so as to determine whether there is a trace leakage that is difficult to observe with the naked eye.

[0074] The experimental data are shown in Table 2: Table 2: Physical state of electrolytes and leakage observation records under destructive conditions in conclusion: Based on the observation data and weighing results in Table 2, and the attached... Figure 2 As shown, in Examples 1 to 5, after physical damage and seal peeling, the internal electrolytes maintained a stable gel morphology, with a cumulative leakage of 0.000g within 60 minutes, and no visible liquid flow was observed. In the filter paper wiping test after 24 hours, the cracked surface only showed a dry or slightly sticky state, with no obvious solvent precipitation.

[0075] The results indicate that the polyurethane prepolymer and the monomers containing double bonds in the system underwent a cross-linking reaction under photoinitiation conditions, forming a three-dimensional polymer network that runs through the entire system. This network structure effectively binds the liquid propylene carbonate solvent and the conductive ions dissolved within it within the microstructure, giving the macroscopic material the mechanical characteristics of a solid. Specifically, Example 2, due to the increased proportion of cross-linking components, exhibited higher hardness and drier crack areas; Example 3, due to the use of flexible polypropylene glycol segments, exhibited a certain degree of pressure-sensitive adhesion. This adhesion is helpful in practical applications to bind glass fragments together and prevent them from scattering when the glass breaks.

[0076] Comparative Example 1, lacking any polymerizing components, maintained a consistently low-viscosity liquid state. Upon encapsulation failure or glass breakage, the liquid rapidly leaked out under gravity, causing device malfunction. More seriously, the leaked electrolyte contained organic solvents and active chemical components, which could easily corrode automotive interiors, electronic circuit boards, and surrounding sensors, posing a greater safety hazard. While Comparative Example 2 also formed a leak-proof gel, as demonstrated by the results of Test Example 1, its internal active color-changing molecules were only physically encapsulated and not bound by chemical bonds. This test confirms that the gelation method solves the leakage hazard of traditional liquid electrochromic devices and improves device safety under physical damage conditions.

[0077] Test Example 3: This test case aims to investigate whether the internal active color-changing components of the device migrate long distances due to the electric field and gravity under the operating conditions of applying DC voltage for a long time, thereby verifying the influence of chemical bonding on the spatial distribution stability of active materials.

[0078] The anti-glare rearview mirror devices prepared in Examples 1 to 5, as well as Comparative Examples 1 and 2, were selected. All the samples to be tested were vertically fixed on the test stand, keeping the long side of the device perpendicular to the horizontal plane, and the electrode leads were connected to a DC regulated power supply.

[0079] Within the effective viewing window area of ​​the device, a position 10 mm from the edge of the positive electrode is selected as the positive electrode side test point, and a position 10 mm from the edge of the negative electrode is selected as the negative electrode side test point.

[0080] At room temperature, a constant DC voltage of 1.2V was applied to each device to induce a low-reflectivity coloring state. The voltage was continuously applied, and the reflectivity values ​​of the upper and lower test points were measured using a reflectivity meter at three time points: 0 hours after power-on, 12 hours after power-on, and 24 hours after power-on. The units were expressed as percentages.

[0081] Record the test data and calculate the reflectance difference ΔR between the positive and negative test points at 24 hours. The calculation method is to subtract the absolute value of the reflectance of the lower test point from the reflectance of the upper test point. This difference characterizes the concentration polarization and stratification of the active material inside the device.

[0082] The experimental data are shown in Table 3: Table 3: Data on reflectivity variation in the positive and negative electrode regions of the device under long-term coloring conditions in conclusion: Based on the test data in Table 3 and the appendix Figure 3As shown, under a continuous DC electric field for 24 hours, the devices of different systems exhibited differences in stability. The reflectance difference between the positive and negative electrode test points in Examples 1 to 5 ranged from 0.37% to 2.23%. Among them, Example 2, due to the increased proportion of crosslinking components in the formulation, formed a denser crosslinking network, and its anti-delamination performance was relatively good, with a reflectance difference of only 0.37% after 24 hours. This data indicates that although free electrochromic active groups tend to undergo directional migration or sedimentation under the continuous drive of the electric field, the double bond at the end of component B molecule in this invention has been incorporated into the polymer network backbone formed by component A through a copolymerization reaction. This chemical bonding provides a spatial confinement effect. The chromotropic groups are anchored at specific nodes of the gel network, and their movement is limited to local peristalsis or conformational inversion of molecular chain segments, making long-distance electrophoretic migration difficult, thereby maintaining the uniformity of the concentration of active substances inside the electrolyte on a macroscopic level.

[0083] In contrast, the liquid device in Comparative Example 1 showed a reflectance difference of 50.31% after 24 hours. The reflectance on the positive electrode side rebounded to 52.36% and was accompanied by yellowing, while the negative electrode side appeared dark blue due to the excessively high concentration of active material, exhibiting obvious color stratification between the positive and negative electrodes, a typical phenomenon of concentration polarization. Although Comparative Example 2 formed a physical gel, its reflectance difference still reached 32.46%. This indicates that simple physical thickening or physical networks can only increase the resistance to ion migration and delay the occurrence of stratification, but cannot eliminate the directional migration of free active molecules under the action of a DC electric field.

[0084] The data for Example 3 are slightly higher than those for Example 1. This is presumably because the polypropylene glycol segments used in Example 3 are relatively flexible and have a wider molecular weight distribution. Some of the chromogenic groups grafted onto the long chain segments underwent a certain degree of microscopic displacement under the influence of an electric field. However, compared to the comparative example, its stability is still within the range required for automotive applications. This test confirms the effectiveness of the chemical anchoring mechanism in solving the delamination problem of electrochromic devices during long-term operation.

[0085] Test Example 4: This test case aims to investigate the influence of the polymer network structure after the electrolyte system is cured on the internal ion transport dynamics, as well as the difference in optical performance between the colored and faded states of the device, and to verify the contribution of flexible chain segment design to the response speed.

[0086] Anti-glare rearview mirror devices prepared in Examples 1 to 5, as well as Comparative Examples 1 and 3, were selected as test samples.

[0087] A photoelectric combined testing platform was constructed, and a reflectivity meter was used to monitor the reflectivity change in the central region of the device. The incident angle of the light source was set to a standard angle commonly used in the industry. At the same time, the ITO conductive layer of the device was connected to the electrochemical workstation through wires.

[0088] The electrochemical workstation program was set to the chronoamperometry method, and a square wave pulse voltage was applied: first, the voltage was maintained at 0V for 30 seconds to put the device in a high reflectivity fading state; then, the voltage was switched to 1.2V and maintained for 30 seconds to put the device into a low reflectivity coloring state. The test was repeated 5 times, and the reflectivity change curve over time was recorded in real time.

[0089] Extract the following key parameters from the recorded curves: High reflectivity Steady-state reflectance in the faded state.

[0090] low reflectivity Steady-state reflectance under tinted conditions.

[0091] Coloring response time Reflectivity from The time point required for the price to drop to 90% of the total change.

[0092] Fading response time Reflectivity from The time required to rise to 90% of the total change.

[0093] The experimental data are shown in Table 4: Table 4: Summary of Device Optoelectronic Performance and Response Time Test Data in conclusion: Based on the test data in Table 4 and the appendix Figure 4 As shown, the coloring response times of Examples 1 to 4 range from 3.25 s to 4.36 s, and the fading response times range from 4.67 s to 5.88 s. Compared with the pure liquid device of Comparative Example 1 (coloring 2.62 s, fading 3.85 s), the all-solid-state device of the present invention has a slight delay in response speed, but it is still within the second-level response range, meeting the real-time requirements of anti-glare rearview mirrors (typically requiring coloring less than 6 seconds and fading less than 8 seconds).

[0094] This result validates the effectiveness of the molecular structure design of component A. The long-chain polyether soft segments (PEG / PPG) contained in the polyurethane prepolymer have a low glass transition temperature at the microscopic level and are in a highly elastic state at room temperature. These flexible molecular segments provide sufficient free volume for the migration of solvent molecules and counterions, forming ion transport channels similar to a liquid environment. Therefore, although the electrolyte has been completely solidified into a gel at the macroscopic level, the ionic conductivity at the microscopic level has not decreased significantly.

[0095] Example 3, using polyethylene glycol with a larger molecular weight or more flexible polypropylene glycol segments, exhibits stronger segment mobility and minimizes hindrance to ion migration, thus achieving a response time (2.45 s) closest to the liquid-state comparative example. In contrast, Example 2, due to the increased crosslinking agent content and higher mesh density, experienced steric hindrance to ion migration, resulting in a slightly longer response time. Data from Example 5 indicates that while increasing the concentration of the active component can reduce low reflectivity (deeper coloration), it also slightly slows down the response speed due to increased system viscosity.

[0096] Comparative Example 3 shows that when a rigid PMMA matrix formed by the polymerization of methyl methacrylate is used to replace the flexible polyurethane network of this invention, the device exhibits extremely low optical contrast and a response time exceeding 60 seconds, failing to meet practical application requirements. This is because the rigid polymer segments are in a glassy state at room temperature, effectively freezing the molecular chains and severely blocking ion diffusion paths, thus limiting redox reactions. This comparative data directly supports the necessity of the mechanism of "introducing flexible polyether segments to construct ion transport channels" in this invention, demonstrating that this solution achieves solid-state processing while maintaining excellent photoelectric response performance.

[0097] Test Example 5: This test case aims to examine the sealing reliability of the device under extreme environments of high temperature, high humidity, and high pressure, especially the chemical compatibility of the electrolyte system with the encapsulating sealant, and the retention rate of electrochromic properties after aging treatment.

[0098] The anti-glare rearview mirror devices prepared in Examples 1 to 5 and Comparative Example 1 were selected as test samples. Before the test, the reflectance of each sample in the initial state was measured by a reflectance meter, and the difference between the two was recorded as the initial optical contrast ΔR0.

[0099] The samples were placed in a high-pressure accelerated aging test chamber for PCT aging testing. The ambient temperature was set at 121 degrees Celsius and the relative humidity at 100%, utilizing the pressure naturally generated by water vapor at high temperatures. This condition was used to accelerate the simulation of the chemical interaction and interfacial stability between the electrolyte and the sealing sealant under extreme conditions. The test adopted a cyclic mode, with one cycle consisting of 20 hours of operation followed by 4 hours of shutdown. To fully highlight the advantages of the polymer gel material in terms of leakage resistance, the test intensity was increased beyond the industry standard (7 cycles), with a total of 15 consecutive cycles.

[0100] After aging, the sample was removed and left to stand at room temperature for 4 hours to restore thermal equilibrium. The sealing area of ​​the device was visually inspected for leakage, peeling of the sealant, or the formation of bubbles. The sample was then connected to an electrochemical workstation and subjected to 1,000 consecutive coloring and fading cycles within a voltage range of 0V to 1.2V to further examine the operational stability of the aged device.

[0101] After the cycle is completed, the optical contrast of each sample is measured again and recorded as ΔR1. The contrast retention rate after aging is calculated according to the formula K=(ΔR1 / ΔR0)×100%.

[0102] The experimental data are shown in Table 5: Table 5: Summary of PCT Aging and Electrochemical Cycling Test Data in conclusion: Based on the data in Table 5 and the appendix Figure 5 As shown, after 15 cycles of high-temperature, high-humidity, and high-pressure aging, followed by 1000 electrochemical cycles, the effects of different electrolyte systems on device lifetime exhibited significant differences. The contrast retention rates of Examples 1 to 5 ranged from 93.68% to 97.84%, with Example 2, due to its higher cross-linking density, exhibiting stronger binding ability of its polymer backbone to solvents and active molecules, achieving a retention rate of 97.84%. Visual inspection revealed that most of the example samples maintained the integrity of their encapsulation structure, with no obvious sealing failures.

[0103] In contrast, the pure liquid device in Comparative Example 1 exhibited a contrast retention rate of only 54.61% after testing, and traces of liquid seepage were observed at the seal. In-depth analysis of the failure mechanism reveals that this difference arises because the relatively slow chemical swelling and corrosion of the sealing sealant by the electrolyte at room temperature is significantly amplified under the high temperature and pressure of the PCT environment. The increased thermal motion of solvent molecules and significantly enhanced penetration lead to rapid breakage of the sealant polymer chains or a decrease in interfacial adhesion, ultimately resulting in physical leakage. Once the seal fails, external oxygen and moisture penetrate the device, quenching the reduced free radicals of violet alkali, leading to a significant reduction in coloring efficiency.

[0104] Data from the examples demonstrate that the gel network formed through in-situ polymerization effectively curbs this amplified corrosion effect. On one hand, it creates kinetic constraint: gelation binds the liquid solvent within a three-dimensional network, significantly increasing the rheological resistance to solvent molecule diffusion to the sealing interface, thus physically slowing down the corrosion process. On the other hand, it achieves interface stability: the active chromogenic component B is anchored to the polymer chains through chemical bonds, reducing its local free concentration at the interface and minimizing direct chemical erosion of the sealant by active organic molecules. This dual effect of physical barrier and chemical fixation enables the all-solid-state device to maintain the stability of the sealing system even under harsh environments, extending the device's lifespan.

[0105] Test Example 6: The invention aims to verify the antifreeze properties and electrochemical response rate of the polymer electrochromic material under low temperature (-30℃ and -40℃) conditions, and to evaluate the role of the polyether soft segment in the polyurethane network in maintaining the low-temperature ionic conductivity.

[0106] Anti-glare rearview mirror devices prepared according to Examples 1 to 5, as well as Comparative Examples 1 and 3, were selected.

[0107] The above samples were placed in a high and low temperature alternating damp heat test chamber, and the temperature was set to -30℃. The temperature was maintained for 4 hours to allow the electrolyte inside the device to reach thermal equilibrium.

[0108] At low temperature, the device was connected to an electrochemical workstation via leads. A 1.2V DC voltage was applied to drive the device to be colored, and the time required for the reflectivity to decrease from a high reflectivity state to 90% of the total change was recorded as the low-temperature coloring time.

[0109] Cut off the voltage and short-circuit, and record the time required for the reflectivity to recover to 90% of the total change range. This time is recorded as the low-temperature fading time.

[0110] The test chamber temperature was further reduced to -40℃, and the test steps were repeated after 2 hours of constant temperature.

[0111] Visually inspect the device to see if it exhibits turbidity, phase separation, or crystal precipitation at low temperatures.

[0112] The experimental data are shown in Table 6: Table 6: Summary of Device Response Performance Data under Low Temperature Conditions Conclusion: Based on the data in Table 6 and the appendix... Figure 6As shown, at -30℃, the coloring response time of Examples 1 to 5 remained between 10.2s and 14.8s, and the fading time was between 15.4s and 21.0s. Although the response speed of the gel sample was slightly slower than that of the pure liquid system of Comparative Example 1 (coloring time 8.6s) due to the increased solvent viscosity and hindered polymer chain movement at low temperatures, no freezing failure occurred, and it still possessed practical anti-glare function.

[0113] Example 3 exhibited the best low-temperature performance (coloring at -30°C for 10.2 s), with a response speed close to that of a liquid system. This is attributed to the use of polypropylene glycol (PPG) with a moderate molecular weight and methyl side chains as the soft segment in the formulation. This structure disrupts the regularity of the molecular chain, effectively reducing the glass transition temperature (Tg) and ensuring unobstructed ion transport channels under extremely cold conditions.

[0114] In contrast, Comparative Example 3, which uses a rigid PMMA matrix, essentially lost its responsiveness at -30°C (time > 120 s), indicating that the rigid polymer chains freeze at low temperatures, severely blocking the ion diffusion path. The flexible polyurethane network design of this invention effectively solves this problem, ensuring the reliability of the device under extreme conditions of -40°C.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high molecular electrochromic material, characterized by, It is made by in-situ polymerization and curing of raw materials containing the following parts by weight under ultraviolet light: Solvent: 100-150 parts; 20 to 60 parts of end-double-bond polyurethane prepolymer; Contains 2 to 8 parts of a double-bonded violetine derivative; 0.5 to 3 parts of complementary electrochromic material; Photoinitiator 0.5 to 2 parts; In this process, the polyurethane prepolymer with terminal double bonds and the violet derivative containing double bonds undergo a free radical copolymerization reaction under the action of the photoinitiator, so that the violet derivative containing double bonds is covalently anchored to the three-dimensional polymeric gel network backbone formed by the crosslinking of the polyurethane prepolymer with terminal double bonds.

2. The polymer electrochromic material according to claim 1, wherein The polyurethane prepolymer with terminal double bonds is prepared by reacting polyether polyol, diisocyanate and hydroxyl-containing acrylate monomers. The polyether polyol is selected from polyethylene glycol or polypropylene glycol with a number average molecular weight of 1000 to 4000; the diisocyanate is selected from diphenylmethane diisocyanate or isophorone diisocyanate. The hydroxyl-containing acrylate monomers are selected from hydroxyethyl methacrylate or hydroxypropyl methacrylate.

3. The polymer electrochromic material according to claim 1, wherein The violet derivative containing double bonds is an N,N'-dienyl-substituted 4,4'-bipyridine salt; The alkenyl substituents in the N,N'-dienyl-substituted 4,4'-bipyridine salt are independently selected from straight-chain olefin groups having 3 to 8 carbon atoms and a carbon-carbon double bond at the end. The anion in the N,N'-dienyl-substituted 4,4'-bipyridine salt is selected from hexafluorophosphate ions, tetrafluoroborate ions, or perchlorate ions.

4. The polymer electrochromic material according to claim 3, characterized in that, The zironine derivative containing double bonds is selected from 1,1'-di-2-propenyl-4,4'-bipyridine hexafluorophosphate, 1,1'-di-5-hexenyl-4,4'-bipyridine hexafluorophosphate, or 1,1'-di-7-octenyl-4,4'-bipyridine hexafluorophosphate.

5. The polymer electrochromic material according to claim 1, wherein The solvent is propylene carbonate; The complementary electrochromic material is 5,10-dihydro-5,10-dimethylphenazine. The photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

6. The polymer electrochromic material according to claim 1, wherein The gel content of the polymer electrochromic material after curing is 93wt% to 97wt%, and the dissolution rate of the double-bonded violet derivative of the polymer electrochromic material after soaking in acetonitrile solvent for 48 hours is less than 1wt%.

7. A method for producing the polymer electrochromic material according to any one of claims 1 to 6, characterized by, Includes the following steps: S1. Under light-protected conditions, the solvent, the polyurethane prepolymer with terminal double bonds, the violet derivative containing double bonds, the complementary electrochromic material and the photoinitiator are mixed in proportion, stirred to dissolve and vacuum degassed to obtain the electrolyte precursor. S2. Inject the electrolyte precursor into a device empty box with a transparent conductive layer; S3. Seal the empty device box into which the electrolyte precursor is injected, and irradiate it under ultraviolet light to cause the electrolyte precursor to undergo in-situ polymerization and solidification, thereby obtaining the polymer electrochromic material.

8. The method of claim 7, wherein the polymer electrochromic material is prepared by the steps of: (a) dissolving the polymer electrochromic material in a solvent; (b) applying the solution to a substrate; and (c) drying the solution. In step S1, the synthesis step of the end-double-bond polyurethane prepolymer includes: The polyether polyol was dissolved in the solvent, heated to 60℃~70℃, and diisocyanate was added dropwise. The reaction was carried out at a constant temperature of 70℃~80℃ to obtain the terminal isocyanate intermediate. A hydroxyl-containing acrylate monomer is added to the terminal isocyanate intermediate, and the reaction is continued at 70°C to 80°C until the characteristic peak of the isocyanate group disappears. The mixture is then cooled to obtain the terminal double bond polyurethane prepolymer. The molar ratio of the polyether polyol, the diisocyanate, and the hydroxyl-containing acrylate monomer is 1:1.8-2.2:2.0-2.

5.

9. The method of claim 7, wherein the polymer electrochromic material is prepared by the steps of: (a) dissolving the polymer electrochromic material in a solvent; (b) applying the solution to a substrate; and (c) drying the solution. In step S3, the wavelength of the ultraviolet light is 365 nm, the light intensity is 40 mW / cm 2 ~ 60 mW / cm 2 and the irradiation time is 60 s ~ 90 s.

10. The application of a polymeric electrochromic material according to any one of claims 1 to 6 in an anti-glare rearview mirror.

Images