A 3D curved surface adaptable high-extensibility dimming film and its preparation method

Abstract

This invention discloses a highly stretchable dimming film adaptable to 3D curved surfaces and its preparation method, belonging to the field of dimming film technology. The dimming film comprises two PET substrates and a PDLC functional layer sandwiched between them. A polyrotaxane-modified PEDOT:PSS conductive layer is coated on the surface of the PET substrate. This conductive layer is prepared by blending a modified monomer containing a sulfonic acid group-cyclodextrin-polyethylene glycol-acrylate structure with PEDOT:PSS. After annealing, a polyrotaxane structure with a PEDOT main chain through the ring is formed, allowing the cyclodextrin to slide along the main chain to dissipate stress. Simultaneously, the sulfonate groups on the cyclodextrin replace part of the PSS as dopant ions. This invention utilizes the polyrotaxane slip toughening mechanism to maintain the conductivity of the conductive layer under large deformation. Furthermore, the acrylate groups at the ends of the modified monomer copolymerize with the PDLC network during UV curing, forming a sliding covalent bond interface, suitable for 3D curved surface dimming scenarios.

Description

Technical Field

[0001] This invention relates to the field of dimming film technology, and in particular to a 3D curved surface adapted high-extensibility dimming film and its preparation method. Background Technology

[0002] Polymer-dispersed liquid crystal (PDLC) dimming films are optoelectronic functional films that achieve switching between transparent and atomized states by controlling the orientation of liquid crystal microdroplets through an electric field. With advantages such as gentle dimming, fast response speed, and simple fabrication process, they have been widely used in architectural doors and windows, commercial partitions, and smart projection. In recent years, with the continuous upgrading of appearance designs in industries such as automotive smart cockpits, consumer electronics, and smart homes, curved interior panels and irregularly shaped display covers have gradually become mainstream. Traditional planar PDLC dimming films cannot meet the bonding requirements of 3D curved components, making high-ductility dimming films with 3D curved surface forming capabilities a key research and development direction for the industry.

[0003] Currently, the conductive base layer of 3D curved dimming films mostly uses indium tin oxide (ITO) coating. Although this type of material has excellent conductivity and light transmittance, the ceramic oxide coating is inherently very brittle, and the elongation at break is usually less than 5%. Under the biaxial stretching conditions of 3D hot pressing, the coating is very prone to cracking and the conductive path is broken. The sheet resistance will increase irreversibly and sharply, which cannot meet the requirements of curved surface forming with medium curvature or higher. Poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS), as a flexible organic conductive material, possesses excellent film-forming properties and bending resistance, and is gradually being applied to the preparation of conductive layers in flexible dimming films. However, the intrinsic conductive domains of PEDOT:PSS are rigid π-π stacked structures, and under biaxial tension of more than 15%, problems such as conductive domain breakage and irreversible damage to the conductive network still occur. Its ductility still cannot meet the deformation requirements of 3D curved surface hot pressing. Existing conventional toughening solutions mostly involve introducing flexible polymers and physically blending PEDOT:PSS. This type of method will additionally increase the proportion of insulating phase in the conductive layer and dilute the conductive pathway. It often sacrifices the initial conductivity in exchange for improved ductility, making it difficult to achieve a balance between the two.

[0004] In existing PDLC dimming films, the conductive layer and PDLC functional layer are generally physically bonded, with bonding between the layers relying solely on van der Waals forces, resulting in low interfacial peel strength. During 3D hot pressing, the conductive substrate and the PDLC cross-linked polymer network exhibit significant modulus differences, leading to asynchronous deformation response rates and the accumulation of substantial shear stress at the interface. This makes them highly susceptible to defects such as interfacial debonding and edge lifting. Furthermore, in long-term high-temperature and high-humidity environments, water molecules can easily penetrate the interface along the film edges, further weakening the interfacial bonding and causing failures such as film delamination and dimensional shrinkage, severely reducing product lifespan and long-term reliability. While existing coupling agent modification schemes can improve interfacial bonding to some extent, they are mostly rigid chemical bonds, which cannot effectively release interfacial stress during deformation, potentially exacerbating the risk of conductive layer cracking during stretching.

[0005] Currently, the mainstream molding processes for 3D curved PDLC dimming films in the industry are mainly divided into two routes. One is to first place the pre-made film into a curved mold for molding, and then perform ultraviolet curing and cross-linking. The drawback of this process is that the ultraviolet light field distribution inside the sealed curved mold is uneven, and the light intensity at different positions of the cavity is significantly different, resulting in inconsistent polymerization rate and phase separation degree. In the end, the size distribution of liquid crystal droplets in each area of ​​the curved surface is relatively wide, and the consistency of haze in the off state and transmittance in the on state is poor. The other is to first complete the planar ultraviolet curing to obtain the master film, and then achieve curved surface molding through hot pressing. Although this scheme can ensure the uniformity of liquid crystal droplets in the planar stage, during the hot pressing stretching process, the liquid crystal molecules at the interface between the conductive layer and PDLC are prone to permanent orientation misalignment, causing local haze fluctuations, contrast drift, and even irreversible image retention defects on the curved surface. Neither process can simultaneously achieve molding feasibility and curved surface optical uniformity.

[0006] In summary, existing PDLC dimming film technology adapted to 3D curved surfaces still suffers from multiple technical bottlenecks, such as difficulty in balancing the extensibility and conductivity of the conductive layer, insufficient reliability of interlayer bonding, and poor optical uniformity after curved surface molding. Various modification schemes can often only improve a single performance and cannot achieve synergistic improvement of multi-dimensional performance, making it difficult to meet the high-performance application requirements of medium curvature 3D dimming films in fields such as automotive and consumer electronics. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a 3D curved surface adaptable high-extensibility dimming film and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a 3D curved surface adapted high-extensibility dimming film, comprising upper and lower flexible transparent conductive substrates and a PDLC functional layer sandwiched between the two conductive substrates.

[0009] Preferably, the flexible transparent conductive substrate is composed of a thermoformed PET substrate and a polyrotaxane-modified PEDOT:PSS conductive layer coated on the surface of the substrate.

[0010] Preferably, the polyrotaxane-modified PEDOT:PSS conductive layer is prepared by mixing the modified monomer with a PEDOT:PSS aqueous dispersion to form a coating liquid, which is then coated onto the surface of a thermoformed PET substrate and subjected to segmented drying and annealing treatments.

[0011] Preferably, the modified monomer has the following chemical structural formula: .

[0012] Preferably, the thermoformed PET substrate is an IMD-grade optical thermoformed PET film with a thickness of 50-125 μm.

[0013] Preferably, the thickness of the polyrotaxane-modified PEDOT:PSS conductive layer is 180-350 nm.

[0014] Preferably, the PDLC functional layer is formed by UV curing of a dye-liquid mixture, with a thickness of 15-25 μm; wherein the dye-liquid mixture comprises, by mass parts: 60-68 parts of nematic liquid crystal, 25-32 parts of polyurethane acrylate prepolymer, 1-2 parts of photoinitiator, 0.1-0.5 parts of polymer microsphere spacers, 0.2-1 parts of chiral agent, and 0.5-2 parts of dichroic dye.

[0015] Preferably, the polymer microsphere spacers are selected from polymethyl methacrylate microspheres with an average particle size of 15-25 μm.

[0016] Preferably, the modified monomer is prepared by the following method: (1) Add sodium mono-6-sulfonate-β-cyclodextrin to deionized water and stir until completely dissolved. Cool to 0-3℃ in an ice bath and add sodium hydroxide aqueous solution dropwise to adjust the pH of the system to stabilize at 11.5-12.0. Continue stirring for 5-15 min. Add p-toluenesulfonyl chloride to the reaction system in 3-5 portions. Strictly control the system temperature at 0-3℃ throughout the process. After the addition is complete, keep the reaction at this temperature for 3-6 h. Maintain the pH of the system at ≥11.5 throughout the process. Add sodium hydroxide aqueous solution when the pH drops. After the reaction is complete, adjust the pH of the system to 6.0-6.5 with dilute hydrochloric acid. Let it stand at 0℃ for 6-12 h to crystallize. Collect the precipitated crude product by filtration, wash it 1-3 times with deionized water, and then recrystallize it twice with ethanol aqueous solution. After vacuum drying, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin is obtained. The chemical reaction equation is as follows: Under alkaline conditions, the primary hydroxyl group at the 6-position of the unsubstituted glucose unit in mono-6-sulfonate-β-cyclodextrin dissociates into an oxon, exhibiting strong nucleophilic activity. The nucleophile attacks the electron-deficient sulfonyl center of p-toluenesulfonyl chloride, forming a tetrahedral transition state. Subsequently, the chloride ion is removed as a leaving group, ultimately forming a stable sulfonate bond between the 6-carbon of the cyclodextrin and the sulfonyl group, completing the introduction of p-toluenesulfonyloxy groups (OTs). The reaction site is selective, possibly due to the synergistic effect of the sodium sulfonate group: the negatively charged sulfonate group electrostatically repels the oxon of the adjacent hydroxyl group, reducing the reactivity of the ortho- and meta-hydroxyl groups; simultaneously, the spatial volume of the sulfonate group creates steric hindrance to the adjacent reaction sites, causing the reaction to preferentially occur at the para-glucose 6-hydroxyl group, which is the furthest in spatial distance and has the weakest electrostatic repulsion and steric hindrance effect. (2) Under nitrogen protection, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin was added to anhydrous N,N-dimethylformamide and stirred until completely dissolved. Triethylamine was added and stirring was continued for 5-15 min. Then amino-polyethylene glycol-acrylate was added, and the temperature was raised to 60-80℃. The reaction was carried out for 12-16 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was poured into anhydrous diethyl ether and precipitated under rapid stirring. The crude product was collected by suction filtration, washed 3 times with anhydrous diethyl ether, and then dissolved in deionized water. The solution was placed in a dialysis bag and dialyzed with deionized water for 48-72 h, with the dialysate being replaced every 6 h. The dialyzed liquid was filtered through a 0.22 μm aqueous filter membrane and freeze-dried to obtain the modified monomer. The chemical reaction equation is as follows: p-Toluenesulfonyloxy (OTs) is a recognized strong leaving group in organic chemistry. The CO bond it connects to the primary carbon at the 6-position of cyclodextrin is highly polar and has a low bond energy, making it prone to heterolytic cleavage. The terminal primary amino group of amino-polyethylene glycol-acrylate is a strong nucleophile, which attacks the sp3 hybridized primary carbon atom at the 6-position from the back of the OTs group, forming a transient five-coordinate transition state. Subsequently, the CO bond is completely broken, and the OTs group leaves completely in the form of a p-toluenesulfonate anion. At the same time, the nitrogen atom forms a stable CN covalent bond with the carbon at the 6-position, completing the grafting of the polyethylene glycol acrylate side chain. Triethylamine acts as an acid-binding agent to prevent the amino group from being protonated and losing its nucleophilic activity, ensuring a high conversion rate of the reaction. Anhydrous N,N-dimethylformamide is used as a solvent to fully dissolve both types of reaction substrates without solvating the primary amino group, while also inhibiting the competitive hydrolysis side reaction of hydroxyl groups in the aqueous phase.

[0017] Preferably, in (1), the molar ratio of sodium mono-6-sulfonate-β-cyclodextrin and p-toluenesulfonyl chloride is 1:0.9-1.

[0018] Preferably, the concentration of the sodium hydroxide aqueous solution in (1) is 10-30 wt%.

[0019] Preferably, the concentration of dilute hydrochloric acid in (1) is 0.1-5 mol / L.

[0020] Preferably, the volume ratio of ethanol to water in the ethanol-water solution in (1) is 1:4-6.

[0021] Preferably, in (2), the molar ratio of sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin, triethylamine and amino-polyethylene glycol-acrylate is 1:1.5-2.5:1.2-1.6.

[0022] Preferably, the number-average molecular weight of polyethylene glycol in the amino-polyethylene glycol-acrylate in (2) is 150-300.

[0023] Preferably, the molecular weight cutoff of the dialysis bag in (2) is 1000 Da.

[0024] Furthermore, the present invention also provides a method for preparing a highly stretchable dimming film for 3D curved surface adaptation, comprising the following steps: S1. Add the modified monomer to the PEDOT:PSS aqueous dispersion, stir and mix evenly, filter through a 0.45μm aqueous filter membrane and degas under vacuum to obtain the coating solution; S2. The coating liquid is applied to the surface of a thermoformed PET substrate, and after drying and annealing, a flexible transparent conductive base layer with a polyrotaxane-modified PEDOT:PSS conductive layer is obtained. S3. Nematic liquid crystal, polyurethane acrylate prepolymer, photoinitiator, polymer microsphere spacer particles, chiral agent and dichroic dye are stirred evenly under room temperature and light-protected conditions. After vacuum degassing, a dye liquid crystal mixture is obtained. The dye liquid crystal mixture is uniformly filled between two flexible transparent conductive substrates using a roll pressing and lamination process, with one side of the conductive layer facing the dye liquid crystal mixture. After removing air bubbles, a PDLC functional layer is obtained. Under a nitrogen protective atmosphere, the entire surface is cured with ultraviolet light. After sealing the edges, a highly ductile planar dimming master film is obtained. S4. The high-stretchability planar dimming master film is placed into the cavity of a 3D curved mold, heated and kept warm, molded and bonded, and then demolded after holding pressure and cooling to obtain a 3D curved surface adapted high-stretchability dimming film finished product.

[0025] Preferably, the mass ratio of the modified monomer to PEDOT:PSS in S1 is 0.06-0.1:1.

[0026] Preferably, the solid content of the PEDOT:PSS aqueous dispersion in S1 is 1.0-1.5 wt%, wherein the mass ratio of PEDOT to PSS is 1:2.2-2.8.

[0027] Preferably, the coating in S2 is a slot coating.

[0028] Preferably, in step S2, after coating, the material is sequentially dried in three stages: 60°C for 2 minutes, 100°C for 1 minute, and 130°C for 1 minute, and then annealed at 140°C for 3 minutes.

[0029] Preferably, the wavelength of the ultraviolet light in S3 is 365 nm, and the energy density is 1000-1200 mJ / cm³. 2 .

[0030] Preferably, the heating temperature in step S4 is 105-115℃, and the holding time is 1-2 minutes.

[0031] Preferably, the molding pressure in S4 is 0.3-0.5 MPa.

[0032] Preferably, the pressure holding time in S4 is 20-40 seconds.

[0033] Preferably, the specific cooling operation in S4 is to slowly cool down to 60°C at 1-2°C / min under pressure to complete the structural shaping, and then naturally cool down to room temperature before demolding.

[0034] Preferably, the 3D curved surface adaptation of the present invention is for medium curvature 3D curved surfaces with a maximum biaxial stretching deformation of no more than 30%, such as conventional 3D dimming scenarios such as automotive center console curved surfaces, consumer electronics decorative curved surfaces, and irregularly shaped panels of home appliances.

[0035] Preferably, the mechanism of action of the 3D curved surface adaptable high-extensibility dimming film of the present invention is explained as follows: In this invention, the polyrotaxane-modified PEDOT:PSS conductive layer of the dimming film completes the construction of an inclusion structure during the annealing process: the PEDOT conjugated backbone is a hydrophobic rigid structure, which has a matching host-guest interaction with the hydrophobic cavity of cyclodextrin. During the drying and annealing stage, the molecular thermal motion intensifies, and the PEDOT molecular chains spontaneously enter the cyclodextrin cavity, forming a stable polyrotaxane structure with a main chain that is circumferentially interlocked, rather than a simple physical blending and dispersion. The sulfonate group covalently linked on the cyclodextrin can directly serve as the dopant pair ion of PEDOT, balancing the positive charge on the conjugated backbone and replacing part of the insulating polystyrene sulfonate long chain, reducing the total volume ratio of the insulating phase in the conductive layer; unlike... Conventional blended toughening agents introduce an additional insulating phase and dilute the conductive pathways. This structure does not disrupt the continuity of PEDOT conductive domains; on the contrary, it optimizes doping uniformity and maintains or even improves the intrinsic conductivity of the conductive layer. When the conductive layer is subjected to tensile stress, the cyclodextrins bonded to the PEDOT backbone can reversibly slide along the axis of the conjugated backbone, directly dissipating the stress on the backbone at the molecular level and avoiding stress concentration that could lead to backbone breakage and conductive domain fragmentation. The π-π stacking between PEDOT conductive domains only undergoes a reversible change in effective overlap area and does not produce irreversible structural damage. Therefore, it can maintain stable conductivity even under large deformation.

[0036] A sliding covalent interface is formed between the conductive layer and the PDLC functional layer through modified monomers. During UV curing, the acrylate double bonds at the ends of the modified monomers participate in the free radical polymerization reaction of the polyurethane acrylate prepolymer, covalently integrating into the cross-linked polymer network of the PDLC, achieving chemical bonding between the two layers. The interfacial peel strength is much higher than that of conventional physical bonding schemes, avoiding interlayer delamination problems during thermal cycling and long-term use. The cyclodextrin matrix and the PDLC polymer network are connected by flexible polyethylene glycol spacers, rather than a rigid anchoring structure: the glass transition temperature of polyethylene glycol segments is much lower than room temperature, possessing extremely high conformational freedom. When the two layers undergo relative deformation due to modulus differences, the displacement difference can be compensated by the stretching and curling of the segments, while reserving sufficient space for the cyclodextrin to slide along the PEDOT main chain. This structure retains the high interfacial strength of covalent bonding without generating severe stress concentration during deformation like a rigid covalent interface, mitigating the risk of interfacial shear failure during 3D molding.

[0037] The hydrophobic cavities of cyclodextrin can dynamically anchor nematic liquid crystal molecules at the interface. The cyclodextrin cavity, being a hydrophobic microenvironment, can engage in weak host-guest interactions with the rigid aromatic ring structure of the nematic liquid crystal molecules, partially encapsulating the interface liquid crystal molecules and forming a dynamic liquid crystal anchoring layer at the interface between the conductive layer and the PDLC functional layer. In conventional 3D dimming film molding processes, the liquid crystal molecules at the interface undergo permanent orientation misalignment as the film is stretched, which is the main cause of localized haze fluctuations, contrast drift, and even image retention on curved surfaces. In this solution, during stretching deformation, the cyclodextrin slides synchronously with the PEDOT main chain, and the interface liquid crystal molecules that encapsulate it also adjust their orientation accordingly, preventing permanent orientation disorder. After molding and cooling, the anchoring state of the interface liquid crystal can be restored to uniformity. Combined with the uniformly sized bulk liquid crystal microdroplets formed during the planar curing stage, this ensures consistent haze in the off-state and contrast in the on-state across the entire curved surface, solving the problem of poor optical uniformity commonly found in existing 3D dimming films.

[0038] During the 3D hot pressing process, all components of the system work together to achieve surface adaptation. This solution employs a planar UV curing followed by hot pressing process, which avoids the problems of uneven light field distribution within a closed curved mold, leading to differences in polymerization rate and wide distribution of liquid crystal droplet size. This allows for the acquisition of a PDLC structure with uniform phase separation and stable performance during the planar stage. The hot pressing temperature is controlled above the glass transition temperature of the PDLC polymer and below the liquid crystal clearing point. At this temperature, the cross-linked polymer network of the PDLC is in a highly elastic state, capable of reversible highly elastic deformation with the mold cavity. Combined with the polyrotaxane slip toughening structure of the conductive layer and the sliding covalent interface between layers, these three elements work together to achieve gradual stress dissipation. This prevents irreversible damage such as conductive path breakage, interface delamination, and liquid crystal droplet aggregation under biaxial tensile deformation corresponding to moderate curvature. Ultimately, while achieving surface adaptation, the electro-optical properties and long-term reliability of the planar dimming film are fully preserved. It should be noted that there is a reasonable boundary for the curvature of this process. When the biaxial tensile deformation exceeds 30%, the thermoformed PET substrate approaches its own yield limit, and the high elastic deformation of the PDLC crosslinking network will also exceed the reversible range. Even if the conductive layer and interface structure can continue to dissipate stress, the overall film may still experience problems such as irreversible deformation of the substrate and breakage of the bulk liquid crystal droplets. Therefore, the optimal working condition for this scheme is medium curvature surface forming.

[0039] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a polyrotaxane-modified conductive structure with a PEDOT conjugated main chain that passes through a ring. By utilizing the reversible slip of cyclodextrin along the main chain to dissipate tensile stress at the molecular level, it avoids irreversible breakage of conductive domains and significantly improves the tensile strength of the conductive layer. At the same time, the sulfonic acid groups covalently linked on the cyclodextrin can serve as dopant pairs to optimize the doping uniformity of the conductive layer without introducing an additional insulating phase. Under the premise of maintaining excellent intrinsic conductivity, it achieves a significant improvement in conductive ductility, making it suitable for deformation conditions in 3D curved surface molding.

[0040] 2. This invention constructs a sliding covalent bonding interface between the conductive layer and the PDLC functional layer. The acrylate end groups of the modified monomer participate in the free radical polymerization of PDLC to achieve chemical bonding between the two layers, improve the interfacial peel strength, and effectively avoid the interlayer delamination problem under cold and hot cycling and humid and hot environments. The cyclodextrin and the polymer network are connected by flexible polyethylene glycol spacer arms, which can release shear stress through chain segment movement during deformation, thus taking into account both high bonding strength and interfacial deformation resistance.

[0041] 3. This invention utilizes the weak host-guest interaction between the hydrophobic cavities of cyclodextrin and liquid crystal molecules to form a dynamic liquid crystal anchoring layer at the phase interface. During the stretching process of curved surface hot pressing, the cyclodextrin slides synchronously with the PEDOT conductive backbone, which can drive the liquid crystal molecules at the interface to adjust their orientation synchronously, avoiding permanent misalignment of the liquid crystal caused by stretching, eliminating defects such as local haze fluctuations and optical inhomogeneities on the curved surface, and ensuring the uniformity of the electro-optical performance of the dimming film across the entire area after 3D molding.

[0042] 4. This invention adopts a process route of planar UV curing followed by hot pressing, which can complete uniform polymerization-induced phase separation in the planar stage, avoiding the problem of wide distribution of liquid crystal microdroplets caused by uneven light field distribution in the closed curved mold. Combined with the multi-level stress dissipation mechanism of polyrotaxane conductive layer and sliding covalent interface, the integrity of film structure can be maintained during the molding process of medium curvature surface. The finished product has excellent long-term stability and can be adapted to the curved surface dimming application needs of multiple fields. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0044] Preparation Example 1: The specific preparation method of the modified monomer includes the following steps: (1) Add 1 mol of sodium mono-6-sulfonate-β-cyclodextrin to deionized water and stir until completely dissolved. Cool to 0-3℃ in an ice bath and add 10wt% sodium hydroxide aqueous solution dropwise to adjust the pH of the system to stabilize at 11.5. Continue stirring for 5 min and add 0.9 mol of p-toluenesulfonyl chloride to the reaction system in 3 portions. Strictly control the temperature of the system at 0-3℃ throughout the process. After the addition is complete, keep the reaction at the temperature for 3 h and maintain the pH of the system at ≥11.5 throughout the process. Add sodium hydroxide aqueous solution when the pH drops. After the reaction is complete, adjust the pH of the system to 6.0 with 0.1 mol / L dilute hydrochloric acid and let it stand at 0℃ for 6 h to crystallize. Collect the precipitated crude product by filtration, wash it once with deionized water, and then recrystallize it twice with ethanol aqueous solution. The volume ratio of ethanol to water in the ethanol aqueous solution is 1:4. After vacuum drying, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin is obtained. (2) Under nitrogen protection, 1 mol of sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin was added to anhydrous N,N-dimethylformamide and stirred until completely dissolved. 1.5 mol of triethylamine was added and stirring was continued for 5 min. Then 1.2 mol of amino-polyethylene glycol-acrylate (the number average molecular weight of polyethylene glycol was 150) was added. The temperature was raised to 60 °C and the reaction was carried out for 12 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was poured into anhydrous diethyl ether and precipitated under rapid stirring. The crude product was collected by suction filtration, washed 3 times with anhydrous diethyl ether, and then dissolved in deionized water. The solution was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed with deionized water for 48 h. The dialysate was changed every 6 h. The dialyzed liquid was filtered through a 0.22 μm aqueous filter membrane and freeze-dried to obtain the modified monomer.

[0045] Preparation Example 2: The specific preparation method of the modified monomer includes the following steps: (1) Add 1 mol of sodium mono-6-sulfonate-β-cyclodextrin to deionized water and stir until completely dissolved. Cool to 0-3℃ in an ice bath and add 20wt% sodium hydroxide aqueous solution dropwise to adjust the pH of the system to stabilize at 11.8. Continue stirring for 10 min and add 0.95 mol of p-toluenesulfonyl chloride to the reaction system in 4 portions. Strictly control the temperature of the system at 0-3℃ throughout the process. After the addition is completed, keep the reaction at the temperature for 4.5 h and maintain the pH of the system at ≥11.5 throughout the process. Add sodium hydroxide aqueous solution when the pH drops. After the reaction is completed, adjust the pH of the system to 6.2 with 2 mol / L dilute hydrochloric acid and let it stand at 0℃ for 9 h to crystallize. Collect the precipitated crude product by filtration, wash it twice with deionized water, and then recrystallize it twice with ethanol aqueous solution. The volume ratio of ethanol to water in the ethanol aqueous solution is 1:5. After vacuum drying, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin is obtained. (2) Under nitrogen protection, 1 mol of sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin was added to anhydrous N,N-dimethylformamide and stirred until completely dissolved. 2 mol of triethylamine was added and stirring was continued for 10 min. Then 1.4 mol of amino-polyethylene glycol-acrylate (polyethylene glycol with a number average molecular weight of 200) was added. The temperature was raised to 70 °C and the reaction was carried out for 14 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was poured into anhydrous diethyl ether and precipitated under rapid stirring. The crude product was collected by suction filtration, washed 3 times with anhydrous diethyl ether, and then dissolved in deionized water. The solution was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed with deionized water for 60 h. The dialysate was changed every 6 h. The dialyzed liquid was filtered through a 0.22 μm aqueous filter membrane and freeze-dried to obtain the modified monomer.

[0046] Preparation Example 3: The specific preparation method of the modified monomer includes the following steps: (1) Add 1 mol of sodium mono-6-sulfonate-β-cyclodextrin to deionized water and stir until completely dissolved. Cool to 0-3℃ in an ice bath and add 30wt% sodium hydroxide aqueous solution dropwise to adjust the pH of the system to stabilize at 12.0. Continue stirring for 15 min. Add 1 mol of p-toluenesulfonyl chloride to the reaction system in 5 portions. Strictly control the temperature of the system at 0-3℃ throughout the process. After the addition is complete, keep the reaction at the temperature for 6 h. Maintain the pH of the system at ≥11.5 throughout the process. Add sodium hydroxide aqueous solution when the pH drops. After the reaction is complete, adjust the pH of the system to 6.5 with 5 mol / L dilute hydrochloric acid. Let it stand at 0℃ for 12 h to crystallize. Collect the precipitated crude product by filtration. Wash it 3 times with deionized water and then recrystallize it 2 times with ethanol aqueous solution. The volume ratio of ethanol to water in the ethanol aqueous solution is 1:6. After vacuum drying, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin is obtained. (2) Under nitrogen protection, 1 mol of sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin was added to anhydrous N,N-dimethylformamide and stirred until completely dissolved. 2.5 mol of triethylamine was added and stirring was continued for 15 min. Then 1.6 mol of amino-polyethylene glycol-acrylate (polyethylene glycol with a number average molecular weight of 300) was added. The temperature was raised to 80 °C and the reaction was carried out for 16 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was poured into anhydrous diethyl ether and precipitated under rapid stirring. The crude product was collected by suction filtration, washed 3 times with anhydrous diethyl ether, and then dissolved in deionized water. The solution was placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed with deionized water for 72 h. The dialysate was changed every 6 h. The dialyzed liquid was filtered through a 0.22 μm aqueous filter membrane and freeze-dried to obtain the modified monomer.

[0047] Comparative Preparation Example 1: The difference between Comparative Preparation Example 1 and Preparation Example 2 is that mono-6-sulfonate sodium-β-cyclodextrin is replaced with β-cyclodextrin.

[0048] Example 1: A specific method for preparing a 3D curved surface adaptable high-extensibility dimming film, comprising the following steps: S1. The modified monomer obtained in Preparation Example 1 was added to a PEDOT:PSS aqueous dispersion with a solid content of 1.0 wt%, wherein the mass ratio of PEDOT to PSS was 1:2.2. The mixture was stirred and mixed evenly, and the mass ratio of modified monomer to PEDOT:PSS was 0.06:1. After filtration through a 0.45 μm aqueous filter membrane and vacuum degassing, a coating solution was obtained. S2. The coating liquid is applied to the surface of a 50μm thick IMD-grade optical thermoforming PET substrate using a slit coating method. After coating, the substrate is subjected to three stages of gradient drying: 60℃ for 2 min, 100℃ for 1 min, and 130℃ for 1 min. Then, it is annealed at 140℃ for 3 min to obtain a flexible transparent conductive base layer with a 180nm thick polyrotaxane-modified PEDOT:PSS conductive layer. S3. 60g of nematic liquid crystal, 32g of polyurethane acrylate prepolymer, 1g of photoinitiator, 0.1g of polymer microsphere spacers (polymethyl methacrylate microspheres, average particle size 15μm), 0.2g of chiral agent, and 0.5g of dichroic dye were stirred uniformly at room temperature in the dark. After vacuum degassing, a dye-liquid crystal mixture was obtained. Using a roll-pressing process, the dye-liquid crystal mixture was uniformly filled between two flexible transparent conductive substrates, with the conductive layer facing the dye-liquid crystal mixture. After removing air bubbles, a 15μm thick PDLC functional layer was obtained. Under a nitrogen protective atmosphere, the entire surface was cured using 365nm ultraviolet light with an energy density of 1000mJ / cm². 2 After edge sealing, a highly ductile planar dimming master film is obtained; S4. Place the high-extensibility planar dimming master film into the cavity of the 3D curved mold, heat it to 105℃, keep it at that temperature for 1 minute, and then press it with a pressure of 0.3MPa for 20 seconds. Under the pressure, slowly cool it down to 60℃ at a rate of 1℃ / min to complete the structural shaping. Then, let it cool naturally to room temperature and demold to obtain the finished high-extensibility dimming film that is adapted to the 3D curved surface.

[0049] Example 2: A specific method for preparing a 3D curved surface adaptable high-extensibility dimming film, comprising the following steps: S1. The modified monomer obtained in Preparation Example 2 was added to a PEDOT:PSS aqueous dispersion with a solid content of 1.2 wt%, wherein the mass ratio of PEDOT to PSS was 1:2.5. The mixture was stirred and mixed evenly, and the mass ratio of modified monomer to PEDOT:PSS was 0.08:1. After filtration through a 0.45 μm aqueous filter membrane and vacuum degassing, a coating solution was obtained. S2. The coating liquid was applied to the surface of a 75μm thick IMD-grade optical thermoforming PET substrate using a slit coating method. After coating, the substrate was subjected to three stages of gradient drying: 60℃ for 2 min, 100℃ for 1 min, and 130℃ for 1 min. Then, it was annealed at 140℃ for 3 min to obtain a flexible transparent conductive base layer with a 250nm thick polyrotaxane-modified PEDOT:PSS conductive layer. S3. 64g of nematic liquid crystal, 29g of polyurethane acrylate prepolymer, 1.5g of photoinitiator, 0.3g of polymer microsphere spacers (polymethyl methacrylate microspheres, average particle size 20μm), 0.6g of chiral agent, and 1.25g of dichroic dye were stirred uniformly at room temperature in the dark. After vacuum degassing, a dye-liquid crystal mixture was obtained. Using a roll-pressing process, the dye-liquid crystal mixture was uniformly filled between two flexible transparent conductive substrates, with the conductive layer facing the dye-liquid crystal mixture. After removing air bubbles, a 20μm thick PDLC functional layer was obtained. Under a nitrogen protective atmosphere, the entire surface was cured using ultraviolet light with a wavelength of 365nm, achieving an energy density of 1100mJ / cm². 2 After edge sealing, a highly ductile planar dimming master film is obtained; S4. Place the high-extensibility planar dimming master film into the cavity of the 3D curved mold, heat it to 110℃, keep it at that temperature for 1.5 min, and then press it with a pressure of 0.4MPa for 30 s. Under the pressure, slowly cool it down to 60℃ at a rate of 1.5℃ / min to complete the structural shaping. Then, let it cool naturally to room temperature and demold to obtain the finished high-extensibility dimming film that is adapted to the 3D curved surface.

[0050] Example 3: A specific method for preparing a 3D curved surface adaptable high-extensibility dimming film, comprising the following steps: S1. The modified monomer obtained in Preparation Example 3 was added to a PEDOT:PSS aqueous dispersion with a solid content of 1.5 wt%, wherein the mass ratio of PEDOT to PSS was 1:2.8. The mixture was stirred and mixed evenly, and the mass ratio of modified monomer to PEDOT:PSS was 0.1:1. After filtration through a 0.45 μm aqueous filter membrane and vacuum degassing, a coating solution was obtained. S2. The coating liquid was applied to the surface of a 125μm thick IMD-grade optical thermoforming PET substrate using a slit coating method. After coating, the substrate was subjected to three stages of gradient drying: 60℃ for 2 min, 100℃ for 1 min, and 130℃ for 1 min. Then, it was annealed at 140℃ for 3 min to obtain a flexible transparent conductive base layer with a 350nm thick polyrotaxane-modified PEDOT:PSS conductive layer. S3. 68g of nematic liquid crystal, 25g of polyurethane acrylate prepolymer, 2g of photoinitiator, 0.5g of polymer microsphere spacers (polymethyl methacrylate microspheres, average particle size 25μm), 1g of chiral agent, and 2g of dichroic dye were stirred uniformly at room temperature in the dark. After vacuum degassing, a dye-liquid crystal mixture was obtained. Using a roll-pressing process, the dye-liquid crystal mixture was uniformly filled between two flexible transparent conductive substrates, with the conductive layer facing the dye-liquid crystal mixture. After removing air bubbles, a 25μm thick PDLC functional layer was obtained. Under a nitrogen protective atmosphere, the entire surface was cured using ultraviolet light with a wavelength of 365nm and an energy density of 1200mJ / cm². 2 After edge sealing, a highly ductile planar dimming master film is obtained; S4. Place the high-extensibility planar dimming master film into the cavity of the 3D curved mold, heat it to 115℃, keep it at that temperature for 2 minutes, and then press it with a pressure of 0.5MPa for 40 seconds. Under the pressure, slowly cool it down to 60℃ at a rate of 2℃ / min to complete the structural shaping. Then, let it cool naturally to room temperature and demold to obtain the finished high-extensibility dimming film that is adapted to the 3D curved surface.

[0051] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that no modified monomer is added, and the other raw material ratios and preparation process parameters are the same as those in Example 2.

[0052] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the modified monomer obtained in Preparation Example 2 was replaced with an equimolar mass of sodium mono-6-sulfonate-β-cyclodextrin, while the other raw material ratios and preparation process parameters were the same as in Example 2.

[0053] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the modified monomer obtained in Preparation Example 2 was replaced with the modified monomer obtained in Comparative Preparation Example 1 by an equimolar mass, while the other raw material ratios and preparation process parameters were the same as in Example 2.

[0054] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the modified monomer obtained in Preparation Example 2 was replaced with equimolar mass of β-cyclodextrin.

[0055] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the modified monomer obtained in Example 2 was replaced with an equal mass of a physical mixture of sodium mono-6-sulfonate-β-cyclodextrin and PEG200 (the molar ratio of the two is 1:1, which is consistent with the functional group ratio of the modified monomer). The remaining raw material ratios and preparation process parameters are completely consistent with those of Example 2.

[0056] Performance testing: The dimming film samples prepared in each embodiment and comparative example were subjected to the following performance tests.

[0057] 1. Basic electro-optic performance test: Take planar dimming mother film samples from each embodiment and comparative example, and use a haze meter with an integrating sphere to test the haze in the off state when no power is applied and the visible light transmittance in the on state after applying the rated driving voltage. 2. Conductivity and ductility test: Take the flexible transparent conductive substrates corresponding to each embodiment and comparative example, cut them into square samples of the same size, and use a four-probe sheet resistance meter to select 5 evenly distributed points in the center area of ​​the sample to test the initial sheet resistance. Take the average value as the initial sheet resistance. Fix the sample on a biaxial tension fixture and stretch it synchronously at a uniform speed to 30% biaxial strain at room temperature. Let it stand for 10 minutes, and test the sheet resistance again at the same test points. Calculate the increase in sheet resistance relative to the initial sheet resistance after stretching. 3. Interlayer interface bonding performance test: The planar dimming master film of each embodiment and comparative example was cut into strips with a width of 15mm and a length of 150mm. The upper conductive substrate and PDLC functional layer of one end of the sample were peeled off by about 20mm. The two ends after peeling were fixed in the upper and lower clamps of a universal tensile testing machine. The tensile test was carried out at a constant rate of 50mm / min using the 180° peel mode. The average tensile force value of the stable section during the peeling process was recorded and converted into the interlayer peel strength per unit width. 4. Curved Surface Optical Uniformity Test: The 3D curved surface mold used in this test is a medium-curvature spherical cavity, corresponding to a maximum biaxial tensile rate of 30% for the film. This matches the actual molding conditions of mainstream curved surface dimming films such as those used in automotive central control systems. All samples were prepared under the same mold and molding parameters. A haze meter with an integrating sphere was used, selecting four typical positions: the center of the curved surface, the long edge, the short edge, and the corner of maximum curvature. The haze in the off-state and the transmittance in the on-state were measured under both unpowered and powered conditions. Each position was tested three times, and the average value was taken. The maximum fluctuation value of the haze in the off-state and the maximum fluctuation value of the transmittance in the on-state were calculated. 5. Reliability test for damp heat aging: The planar dimming master film of each embodiment and comparative example was cut into standard samples of 100mm×100mm and placed in a constant temperature and humidity test chamber at 85℃ and 85% relative humidity. After continuous aging for 1000h, the samples were taken out and left to stand for 24h under normal temperature and humidity conditions until the condition stabilized. First, the dimensional changes in the length and width of the samples were measured and the average dimensional shrinkage rate was calculated. Then, the sheet resistance increase and the interface peel strength retention rate after aging were tested. The experimental results are shown in Table 1.

[0058] Table 1 Performance Test Results Data Analysis: As can be seen from the performance test data in Table 1, the performance of the dimming film prepared by the technical solution of the present invention in the embodiments is significantly better than that of all the comparative examples. Among them, Example 2 achieves the best balance between optical performance, conductivity stability, interface bonding strength, curved surface optical uniformity and aging resistance reliability, and has the best overall performance.

[0059] Regarding basic electro-optical performance, the off-state haze fluctuation of all samples was less than 1.5%. This is because the off-state haze is determined by the scattering ability of the liquid crystal droplets in the PDLC body. The PDLC formulation and curing process of all samples were completely consistent, and the modification of the conductive layer did not affect the scattering characteristics of the PDLC body, which is in line with the basic laws of optoelectronic materials. The on-state transmittance of the embodiments was generally higher than that of the comparative examples. This may be because the sulfonic acid groups of the modified monomers optimized the doping state of PEDOT, reduced the sheet resistance of the conductive layer, made the electric field distribution on the film surface more uniform, and made the liquid crystal molecules more fully oriented under the driving voltage, reducing residual scattering in the on-state, thus improving the transmittance.

[0060] In terms of conductivity and stretchability, the initial sheet resistance of the embodiment was lower than that of the comparative example, and the increase in sheet resistance after 30% biaxial stretching was much smaller than that of each comparative example. The reduction in initial sheet resistance is because the sulfonate group on the modified monomer can be directly used as the dopant pair ion of PEDOT, replacing part of the insulating polystyrene sulfonate long chain, reducing the proportion of insulating phase in the conductive layer, while optimizing the uniformity of doping distribution and improving the continuity of conductive pathways. The improvement in conductivity stability after stretching is due to the polyrotaxane structure formed by cyclodextrin and PEDOT main chain. When subjected to tensile stress, the cyclodextrin wrapped on the main chain can undergo reversible slip along the axial direction, dissipating stress at the molecular level and avoiding stress concentration that causes the conjugated main chain to break and the conductive domain to break. This allows the conductive network to maintain structural integrity under large deformation, adapting to the stretching conditions in the 3D curved surface forming process.

[0061] Regarding interlayer bonding performance, the interfacial peel strength of the embodiment is significantly higher than that of the comparative example with pure physical bonding. During UV curing, the acrylate double bonds at the ends of the modified monomers can participate in the free radical polymerization reaction of the PDLC prepolymer and covalently integrate into the cross-linked polymer network of the PDLC, forming chemical bonds between the conductive layer and the functional layer. This replaces the pure van der Waals force bonding in the conventional solution, thus greatly improving the interfacial bonding strength and effectively avoiding interlayer delamination problems during thermal cycling and molding. At the same time, the flexible polyethylene glycol spacer arms connecting the cyclodextrin and the acrylate ends ensure that the interface is not a rigid anchored structure. When deformation occurs, the expansion and curling of the chain segments can compensate for the displacement difference between the two layers, releasing the interfacial shear stress and further improving the interface's resistance to deformation damage.

[0062] Regarding the optical uniformity of the curved surface, the off-state haze and on-state transmittance fluctuations of the embodiment are significantly lower than those of the comparative example. On one hand, the high ductility and strong interfacial bonding of the conductive layer prevent relative slippage between the conductive layer and the PDLC layer during 3D hot pressing, avoiding the extrusion deformation and orientation disorder of liquid crystal droplets caused by interfacial shear forces. On the other hand, the hydrophobic cavities of cyclodextrin can form a weak host-guest inclusion interaction with the liquid crystal molecules at the interface. During stretching deformation, the cyclodextrin slides synchronously with the PEDOT main chain, causing the interfacial liquid crystal molecules to adjust their orientation synchronously, preventing permanent orientation misalignment. Therefore, after cooling, the liquid crystal state of each region of the curved surface is uniform and consistent, without any abnormal fluctuations in local haze or transmittance.

[0063] In terms of reliability under humid heat aging, the dimensional shrinkage rate and sheet resistance increase of the embodiment after aging were significantly lower than those of the comparative example, and the interfacial peel strength retention rate was also higher. The covalently bonded interfacial structure can prevent external water molecules from penetrating into the interlayer, avoiding the weakening of bonding force caused by interfacial hydrolysis; at the same time, the slip structure of polyrotaxane can buffer the release of internal stress in the PDLC polymer network during aging, reducing the overall film dimensional shrinkage. In terms of conductivity, the stabilizing doping effect of sulfonic acid groups and PEDOT backbone reduces the probability of dopant ion removal and conductive domain aggregation under humid heat, enabling the conductive network to maintain high integrity after aging, thus resulting in better long-term performance stability.

[0064] Comparative Example 1 is a blank sample without any added modified monomers, representing the current technical level of conventional PEDOT:PSS-based PDLC dimming films. Its conductive layer lacks a polyrotaxane toughening structure, resulting in severe damage to the conductive pathways after stretching and the highest increase in sheet resistance. The conductive layer and PDLC layer are purely physically bonded, with weak interfacial adhesion, leading to significant performance degradation after damp heat aging. Furthermore, the interface lacks dynamic liquid crystal anchoring, resulting in disordered liquid crystal orientation and the worst optical uniformity after 3D molding.

[0065] Comparative Example 2 uses sodium mono-6-sulfonate-β-cyclodextrin to replace the modified monomer, retaining the sulfonic acid doping group and the cyclodextrin core. Therefore, it can reduce the initial sheet resistance and improve the tensile conductivity stability to a certain extent. However, due to the lack of polyethylene glycol acrylate side chains, it cannot form covalent bonds with the PDLC network. The interface is still physically bonded, and the improvement in peel strength and aging performance is limited. During the molding process, the two layers are prone to relative shear displacement, which aggravates the liquid crystal orientation disorder. The improvement in the optical uniformity of the curved surface is not significant. This verifies the necessity of the covalent interface structure for interlayer bonding and curved surface optical performance.

[0066] Comparative Example 3 uses a monofunctional modified monomer without sodium sulfonate substitution, retaining the polyethylene glycol acrylate side chain, which can form a covalent bonding interface with PDLC. Therefore, the interface peel strength and interface retention rate after aging are close to the level of the example, far superior to the sample with pure physical bonding. However, due to the lack of sulfonic acid doping groups, the doping state of PEDOT cannot be optimized. Instead, an additional cyclodextrin insulating phase is introduced, resulting in an initial sheet resistance higher than the blank comparative example. The improvement in conductivity and ductility is also limited, proving that the sulfonic acid self-doping structure is the core element for achieving excellent conductivity.

[0067] Comparative Example 4 uses pure β-cyclodextrin to replace the modified monomer without any functionalization. It has neither sulfonic acid doping groups nor reactive acrylate side chains. It can only form a very weak host-guest inclusion interaction with the PEDOT backbone, and can hardly play a toughening role. The interface is still purely physical adhesion. Therefore, its overall performance is only slightly better than the blank Comparative Example 1, with no substantial improvement. This proves that unfunctionalized cyclodextrin cannot meet the modification requirements of 3D curved surface dimming film. The para-bifunctional substitution structure of the present invention is necessary.

[0068] Comparative Example 5 used a physical mixture of sodium mono-6-sulfonate-β-cyclodextrin and PEG200. The types and molar proportions of functional groups were consistent with the modified monomers of this invention, but the two substances did not form an integrated molecular structure through covalent bonds. Free polyethylene glycol could not anchor cyclodextrin to provide a slip buffer space, and the toughening effect of polyrotaxane was greatly reduced. At the same time, free polyethylene glycol did not have reactive acrylate end groups and could not connect to the PDLC network to form a covalent interface. It might even migrate to the interface to form a weak interface layer, resulting in limited improvement in interfacial bonding and aging performance. The liquid crystal anchoring effect could not be stably exerted. Therefore, the overall performance was far lower than that of the examples, directly proving that the performance improvement of this invention was not a simple superposition of the functional components, but rather a synergistic effect achieved by the integrated bifunctional molecular structure.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A highly elongated dimming film adaptable to 3D curved surfaces, characterized in that, It includes two flexible transparent conductive substrates and a PDLC functional layer sandwiched between the two conductive substrates; The flexible transparent conductive substrate is composed of a thermoformed PET substrate and a polyrotaxane-modified PEDOT:PSS conductive layer coated on the surface of the substrate. The polyrotaxane-modified PEDOT:PSS conductive layer is prepared by mixing the modified monomer with a PEDOT:PSS aqueous dispersion to form a coating liquid, which is then coated on the surface of a thermoformed PET substrate and subjected to segmented drying and annealing treatments. The modified monomer has the following chemical structural formula: 。 2. The 3D curved surface adaptable high-extensibility dimming film according to claim 1, characterized in that, The thermoformed PET substrate is an IMD-grade optical thermoformed PET film with a thickness of 50-125 μm; the polyrotaxane-modified PEDOT:PSS conductive layer has a thickness of 180-350 nm; the PDLC functional layer is formed by UV curing of a dye liquid crystal mixture with a thickness of 15-25 μm. The dye-liquid crystal mixture comprises, by mass parts: 60-68 parts nematic liquid crystal, 25-32 parts polyurethane acrylate prepolymer, 1-2 parts photoinitiator, 0.1-0.5 parts polymer microsphere spacers, 0.2-1 parts chiral agent, and 0.5-2 parts dichroic dye.

3. The 3D curved surface adaptable high-extensibility dimming film according to claim 1, characterized in that, The modified monomer is prepared as follows: (1) Add sodium mono-6-sulfonate-β-cyclodextrin to deionized water and stir until completely dissolved. Cool to 0-3℃ in an ice bath and add sodium hydroxide aqueous solution dropwise to adjust the pH of the system to be stable at 11.5-12.

0. Continue stirring for 5-15 minutes. Add p-toluenesulfonyl chloride to the reaction system in 3-5 portions. Strictly control the system temperature at 0-3℃ throughout the process. After the addition is complete, keep the reaction at the temperature for 3-6 hours. Maintain the pH of the system at ≥11.5 throughout the process. Add sodium hydroxide aqueous solution when the pH drops. After the reaction is complete, adjust the pH of the system to 6.0-6.5 with dilute hydrochloric acid. Let it stand at 0℃ for 6-12 hours to crystallize. Collect the precipitated crude product by filtration. Wash with deionized water 1-3 times and recrystallize twice with ethanol aqueous solution. After vacuum drying, obtain sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin. (2) Under nitrogen protection, sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin was added to anhydrous N,N-dimethylformamide and stirred until completely dissolved. Triethylamine was added and stirring was continued for 5-15 min. Then amino-polyethylene glycol-acrylate was added and the temperature was raised to 60-80℃. The reaction was carried out for 12-16 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was poured into anhydrous diethyl ether and precipitated under rapid stirring. The crude product was collected by suction filtration, washed 3 times with anhydrous diethyl ether, and then dissolved in deionized water. The solution was placed in a dialysis bag and dialyzed with deionized water for 48-72 h. The dialysate was changed every 6 h. The dialyzed liquid was filtered through a 0.22 μm aqueous filter membrane and freeze-dried to obtain the modified monomer.

4. The 3D curved surface adaptable high-extensibility dimming film according to claim 3, characterized in that, In (1), the molar ratio of sodium mono-6-sulfonate-β-cyclodextrin and p-toluenesulfonyl chloride is 1:0.9-1; the concentration of sodium hydroxide aqueous solution is 10-30wt%; the concentration of dilute hydrochloric acid is 0.1-5mol / L; and the volume ratio of ethanol to water in the ethanol aqueous solution is 1:4-6.

5. The 3D curved surface adaptable high-extensibility dimming film according to claim 3, characterized in that, In (2), the molar ratio of sodium mono-6-sulfonate-mono-6'-p-toluenesulfonyl-β-cyclodextrin, triethylamine, and amino-polyethylene glycol-acrylate is 1:1.5-2.5:1.2-1.6; the number average molecular weight of polyethylene glycol in amino-polyethylene glycol-acrylate is 150-300; and the molecular weight cutoff of the dialysis bag is 1000 Da.

6. The method for preparing a 3D curved surface adaptable high-extensibility dimming film according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Add the modified monomer to the PEDOT:PSS aqueous dispersion, stir and mix evenly, filter through a 0.45μm aqueous filter membrane and degas under vacuum to obtain the coating solution; S2. The coating liquid is applied to the surface of a thermoformed PET substrate, and after drying and annealing, a flexible transparent conductive base layer with a polyrotaxane-modified PEDOT:PSS conductive layer is obtained. S3. Nematic liquid crystal, polyurethane acrylate prepolymer, photoinitiator, polymer microsphere spacer particles, chiral agent and dichroic dye are stirred evenly under room temperature and light-protected conditions. After vacuum degassing, a dye liquid crystal mixture is obtained. The dye liquid crystal mixture is uniformly filled between two flexible transparent conductive substrates using a roll pressing and lamination process, with one side of the conductive layer facing the dye liquid crystal mixture. After removing air bubbles, a PDLC functional layer is obtained. Under a nitrogen protective atmosphere, the entire surface is cured with ultraviolet light. After sealing the edges, a highly ductile planar dimming master film is obtained. S4. The high-stretchability planar dimming master film is placed into the cavity of a 3D curved mold, heated and kept warm, molded and bonded, and then demolded after holding pressure and cooling to obtain a 3D curved surface adapted high-stretchability dimming film finished product.

7. The method for preparing a 3D curved surface adaptable high-extensibility dimming film according to claim 6, characterized in that, The mass ratio of the modified monomer to PEDOT:PSS in S1 is 0.06-0.1:1; the solid content of the PEDOT:PSS aqueous dispersion is 1.0-1.5 wt%, wherein the mass ratio of PEDOT to PSS is 1:2.2-2.

8.

8. The method for preparing a 3D curved surface adaptable high-extensibility dimming film according to claim 6, characterized in that, The coating in S2 is a slot coating; after coating, it is dried in three stages of gradient drying: 60℃ for 2 min, 100℃ for 1 min, and 130℃ for 1 min, and then annealed at 140℃ for 3 min.

9. The method for preparing a 3D curved surface adaptable high-extensibility dimming film according to claim 6, characterized in that, The ultraviolet light in S3 has a wavelength of 365 nm and an energy density of 1000-1200 mJ / cm³. 2 .

10. The method for preparing a 3D curved surface adaptable high-extensibility dimming film according to claim 6, characterized in that, The heating temperature in S4 is 105-115℃, the holding time is 1-2 min; the molding pressure is 0.3-0.5 MPa; the holding time is 20-40 s; the specific cooling operation is to slowly cool down to 60℃ at 1-2℃ / min under the holding pressure to complete the structural shaping, and then naturally cool down to room temperature before demolding.

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