An organic-inorganic hybrid chiral film and a method for preparing the same

Abstract

The application aims to provide an organic-inorganic hybrid chiral film and a preparation method thereof. The organic-inorganic hybrid chiral film comprises at least two hybrid orientation films, the hybrid orientation film comprises a flexible polymer film and one-dimensional metal nanomaterials distributed on the surface of the flexible polymer film and arranged in an orientation manner, and the flexible polymer film is an achiral polymer film; and each layer of the hybrid orientation film is arranged in a preset deflection angle along the orientation axis direction of the one-dimensional metal nanomaterials. The obtained chiral film is not dependent on a chiral template, has high CD intensity, high g-factor and covers ultraviolet-visible-near infrared super wide wave bands, and the preparation method has low cost and strong universality.

Description

Technical Field

[0001] This invention belongs to the field of chiral thin film material preparation technology, and relates to an organic-inorganic hybrid chiral thin film and its preparation method. Background Technology

[0002] Chirality is ubiquitous in various microscopic and macroscopic structures in nature, ranging from the basic building blocks of life, such as proteins, nucleic acids, enzymes, and alkaloids, to the shells of beetles and even the vast universe. These chiral structures originate from the asymmetric state of their internal molecular and assembly structures, which gives these materials unique optical properties such as circular dichroism (CD) and brings great application potential. Therefore, constructing artificial chiral optically active materials using strategies such as molecular self-assembly and metasurface technology has become a research hotspot (Chem. Sci., 2022, 13, 633-656), and is constantly developing towards better comprehensive performance and higher application value. In recent years, macroscopic-scale artificial chiral thin film materials have attracted great attention due to their higher application value. Their unique optical properties and stronger optical activity compared to chiral solution systems make them extremely valuable in fields such as polarization imaging, encrypted information transmission, chiral sensing, and chiral microwave absorption stealth.

[0003] Currently, some typical methods for constructing chiral thin film materials include chiral template methods (Science, 2020, 368, 1472-1477) and laser processing technology (Nat. Mater., 2021, 20, 1024-1028). Chiral template methods utilize macromolecules or helical polymers with chiral structures to assemble with non-chiral materials, obtaining thin film materials that possess both chiral optical activity and other properties. This method has the advantages of well-defined chiral structures and controllable optical activity; however, the optical activity of the final film is overly dependent on the chosen chiral template, and the material properties of the chiral template are relatively limited and have poor compatibility with other components, resulting in a relatively weak CD signal. Laser processing technology is a newly emerging method for constructing chiral metasurface materials in recent years. This technology can process the microstructure of materials on substrates such as metals and polymers to obtain chiral microstructures that can interact with circularly polarized light. This method has the advantages of strong CD signal and wide selectivity for substrate materials, but its complex processing and expensive machining costs greatly limit its use as a universal chiral material preparation method. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the present invention aims to provide an organic-inorganic hybrid chiral thin film and its preparation method. The resulting chiral thin film does not depend on a chiral template and has high CD strength. The preparation method is low in cost and has strong universality.

[0005] This invention is achieved through the following technical solution:

[0006] An organic-inorganic hybrid chiral thin film includes at least two hybrid orientation films, wherein the hybrid orientation films include a flexible polymer film and a one-dimensional metal nanomaterial distributed on the surface of the flexible polymer film and arranged in an orientation, wherein the flexible polymer film is a non-chiral polymer film; each layer of hybrid orientation film is stacked and arranged at a preset deflection angle along the orientation axis direction of the one-dimensional metal nanomaterial.

[0007] Preferably, the flexible polymer film is a PVA film.

[0008] Preferably, the one-dimensional metal nanomaterial is gold or silver.

[0009] Preferably, the morphology of the one-dimensional metal nanomaterial is nanorods or nanowires.

[0010] Preferably, adjacent hybrid orientation films are stacked at a preset deflection angle, and each hybrid orientation film is deflected either clockwise or counterclockwise.

[0011] Furthermore, the deflection angle between the uppermost hybrid orientation film and the lowermost hybrid orientation film is in the range of 0° to ±360°, and is not 0°±A90°, where A is a constant.

[0012] Furthermore, the preset deflection angle is ±45°, or the deflection angle between the uppermost hybrid orientation film and the lowermost hybrid orientation film is ±45°.

[0013] The method for preparing the organic-inorganic hybrid chiral thin film includes the following steps:

[0014] S1, A solution of one-dimensional metal nanomaterials is coated onto the surface of a flexible polymer film, and after drying, a hybrid film loaded with one-dimensional metal nanomaterials is obtained.

[0015] S2, the hybrid film is axially stretched in one direction at a preset stretching ratio to obtain a hybrid orientation film;

[0016] S3. Take two or more hybrid orientation films obtained in S2 and stack them along the orientation axis with a preset deflection angle to obtain an organic-inorganic hybrid chiral film.

[0017] Preferably, in S2, the preset draw ratio is 200% to 500%.

[0018] Preferably, in S2, the hybrid membrane is wetted with water before axial stretching.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention is based on the understanding of the fundamental definition of chiral materials (the phenomenon that an object cannot be superimposed on its mirror image). It employs a macroscopic multilayer helical stacking similar to a cholesteric liquid crystal structure to obtain an artificial chiral material with strong chiral optical properties. Each layer of hybrid oriented film is stacked along the orientation axis of a one-dimensional metallic nanomaterial at a predetermined deflection angle to obtain a macroscopic helical structure. This macroscopic helical structure gives it significant chiral optical activity. The optical activity of the chiral film is independent of the chiral template and exhibits high CD intensity. The CD signal of the chiral film of this invention spans the ultraviolet-visible-near-infrared ultrawide band (200–2500 nm), with a maximum intensity reaching 12.5 degrees and a corresponding absorption asymmetry factor (g-factor) of 0.99, demonstrating extremely high optical activity. Furthermore, the excellent mechanical properties of this chiral film (tensile strength: 230 MPa, elongation at break: 23%) greatly enhance the material's application range and durability.

[0021] The present invention describes a method for preparing an anisotropic hybrid oriented film. First, a flexible polymer film is used to align rigid one-dimensional metal nanomaterials under axial external force, resulting in an anisotropic hybrid oriented film with excellent orientation and tunable flexibility. Then, two or more layers of this anisotropic hybrid oriented film are rotated and stacked along the orientation axis to obtain a macroscopic helical structure. This macroscopic helical structure gives the film significant chiral optical activity. Precise control of parameters such as interlayer angle, single-layer orientation, and thickness at the macroscopic scale allows for the preparation of artificial chiral films with tunable structure and optical properties. This preparation process is simple, efficient, low-cost, and allows for precise control of the chiral structure of the material at the macroscopic scale. Most importantly, this construction strategy enables the large-scale preparation of flexible chiral film materials.

[0022] Furthermore, prior to axial stretching, the hybrid membrane is wetted with water. Using water as a medium allows the hydrogen bond network in the polymer to open, enabling more efficient and uniform stretching and orientation. It also allows the one-dimensional metal nanomaterials to form a free state, which, under axial stress, forms an oriented structure. In addition, water as a wetting agent ensures the material's environmental friendliness and sustainability, greatly expanding its application range. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The gold nanorod distribution on the surface of the PVA-AuNRs hybrid film before and after axial stretching as described in Embodiment 1 of the present invention; a) before axial stretching; b) after axial stretching.

[0025] Figure 2 This is a cross-sectional SEM image of the PVA-AuNRs hybrid orientation film after axial stretching in Embodiment 1 of the present invention.

[0026] Figure 3 These are the CD and g-factor spectra of PVA-AuNRs chiral films with different deflection angles (0°, ±15°, ±30°, ±45°) prepared in Example 1 of this invention.

[0027] Figure 4 The CD intensity at different wavelengths corresponds to the chiral thin films with different deflection angles (0°, ±15°, ±30°, ±45°, ±60°, ±75°, ±90°) prepared in Example 1 of this invention.

[0028] Figure 5 This is a comparison of CD spectra of PVA-AuNRs hybrid chiral films with different monolayer orientations prepared in Example 2 of the present invention.

[0029] Figure 6 This is a comparison of CD spectra of PVA chiral films and PVA-AuNRs hybrid chiral films with different gold nanorod concentrations prepared in Example 3 of this invention.

[0030] Figure 7 This is a comparison of CD spectra of multilayer PVA-AuNRs hybrid chiral films with different stacking numbers (two, three, and four layers) prepared in Example 4 of the present invention, with the interlayer deflection angle fixed at +45°.

[0031] Figure 8 The CD spectra of multilayer stacked PVA-AuNRs hybrid chiral films prepared in Example 5 of the present invention are compared, with a total deflection angle of +45° and interlayer deflection angles of +45° (two layers), +22.5° (three layers), and +15° (four layers).

[0032] Figure 9The images show the stress-strain curves of a single-layer PVA-AuNRs hybrid chiral film with a 450% stretch ratio, as well as physical images demonstrating its bendability and flexibility. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0035] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0036] The organic-inorganic hybrid chiral thin film of the present invention comprises at least two hybrid orientation films, wherein the hybrid orientation films comprise a flexible polymer film and a one-dimensional metal nanomaterial distributed on the surface of the flexible polymer film and arranged in an orientation, wherein the flexible polymer film is a non-chiral polymer film; each layer of hybrid orientation film is stacked and arranged at a preset deflection angle along the orientation axis direction of the one-dimensional metal nanomaterial.

[0037] The method for preparing the organic-inorganic hybrid chiral thin film involves coating a solution of one-dimensional metal nanomaterials onto the surface of a prepared flexible polymer film, and then stretching it at different ratios after drying to obtain a monolayer anisotropic hybrid orientation film with adjustable orientation. The monolayer anisotropic hybrid orientation film is then stacked in double or multiple layers along its orientation axis with a certain deflection angle to obtain a chiral thin film with a helical structure similar to cholesteric liquid crystal.

[0038] The method for preparing organic-inorganic hybrid chiral thin films according to the present invention specifically includes the following steps:

[0039] S1, A solution of one-dimensional metal nanomaterials is coated onto the surface of a flexible polymer film, and after drying, a hybrid film loaded with one-dimensional metal nanomaterials is obtained.

[0040] S2, the hybrid film is axially stretched in one direction at a preset stretching ratio to obtain a hybrid orientation film;

[0041] S3. Take two or more hybrid orientation films obtained in S2 and stack them along the orientation axis with a preset deflection angle to obtain an organic-inorganic hybrid chiral film.

[0042] In some specific embodiments of the present invention, the preparation method of the flexible polymer film in S1 is as follows: dissolving polymer particles in water to obtain a polymer solution, drying the polymer solution to form a film, and obtaining a flexible polymer film.

[0043] In some specific embodiments of the present invention, in S1, the flexible polymer film is a PVA film. The thickness of the flexible polymer film is generally controlled to be ≥50μm, specifically 50, 100, or 150μm.

[0044] In some specific embodiments of the present invention, in S1, the one-dimensional metal nanomaterial is a metal nanomaterial with plasmon properties, such as gold or silver, and its morphology is nanorods or nanowires; the aspect ratio of the one-dimensional metal nanomaterial is variable, ranging from 1.5 to 10, specifically 4 (size 20nm*80nm), and the solution concentration range of the one-dimensional metal nanomaterial is 0.1 to 1mg / ml.

[0045] In some specific embodiments of the present invention, in S1, the coating amount of the one-dimensional metal nanomaterial on the surface of the flexible polymer film ranges from 1×10⁻⁶. -4 mg / mm 2 ~2×10 -3 mg / mm 2 .

[0046] In some specific embodiments of the present invention, in S2, the stretching rate is 50-500 mm / min, specifically 100 mm / min; the preset stretching ratio is 200%-500%, specifically 200%, 300%, 450%, or 500%; before axial stretching, the hybrid membrane can be wetted with water.

[0047] In some specific embodiments of the present invention, in S3, adjacent hybrid alignment films are stacked at a preset deflection angle, and the deflection direction of each layer of hybrid alignment film is the same (i.e., each layer of hybrid alignment film deflects clockwise or counterclockwise), forming a helical chiral film. The total deflection angle of the chiral film, that is, the deflection angle of the uppermost hybrid alignment film relative to the lowermost hybrid alignment film, is in the range of 0° to ±360°, and is not 0°±A90°, where A is a constant; that is, the total deflection angle of the chiral film can be adjusted within a 360-degree range, thereby displaying different circular dichroism spectral characteristics. As long as the total deflection angle is not 0°±A90°, there will be a CD signal, only with different intensities. For chiral films formed by two hybrid alignment layers, the strongest signal is observed at a deflection angle of 45°±A90°. For chiral films formed by multiple hybrid alignment layers, the CD signal intensity decreases with increasing the number of layers (>2) when the total deflection angle is 45°±A90°. When the deflection angle between adjacent hybrid alignment layers is 45°±A90°, the CD signal strengthens with increasing layer count. Preferably, the deflection angle between adjacent hybrid alignment layers is ±45°, or the deflection angle between the uppermost and lowermost hybrid alignment layers is ±45°. Interlayer spacing within the range of 0–35 mm has almost no impact on the optical activity of the material.

[0048] In this embodiment of the invention, the basic circular dichroism (including CD intensity, g-factor, coverage wavelength width, etc.) of the obtained chiral thin film is characterized using commercially available CD spectroscopy.

[0049] Example 1: Chiral thin films with different deflection angles

[0050] 5g of PVA particles were weighed and poured into 95g of pure water. The mixture was heated to 90℃ and magnetically stirred at 1500r / min for 3 hours until the particles were completely dissolved, yielding a PVA solution with a solid content of 5%. 20g of the prepared PVA solution was weighed and poured into a 10cm×10cm petri dish, then dried in a 45℃ oven. After drying and film formation, a PVA film with a thickness of approximately 100μm was obtained. A 0.1ml solution of 0.5mg / ml gold nanorods (AuNRs) was drop-coated onto a 1cm diameter circular area on the surface of the PVA film. After the solvent had fully evaporated, the film was peeled off to obtain a PVA-AuNRs hybrid film.

[0051] The PVA-AuNRs hybrid film was cut into rectangular strips of 4×1.5cm, and held at both ends by a stretching device. The middle 1.5cm width of the rectangular strip was fully wetted with pure water and then axially stretched at a ratio of 450%. Finally, the strip was dried and shaped by water evaporation to obtain anisotropic PVA-AuNRs hybrid oriented films with a certain degree of orientation. Two PVA-AuNRs hybrid oriented films were stacked along the axial direction with deflection angles of 0°, ±15°, ±30°, and ±45° respectively (clockwise rotation of the orientation direction of the upper film relative to the lower film is defined as positive (+), and counterclockwise rotation as negative (-)). Finally, double-layer stacked PVA-AuNRs hybrid chiral films with different deflection angles were obtained.

[0052] Example 2: Chiral films with different monolayer orientation degrees (drawing ratios)

[0053] 5g of PVA particles were weighed and poured into 95g of pure water. The mixture was heated to 90℃ and magnetically stirred at 1500r / min for 3 hours until the particles were completely dissolved, yielding a PVA solution with a solid content of 5%. 20g of the prepared PVA solution was weighed and poured into a 10cm×10cm petri dish, then dried in a 45℃ oven. After drying and film formation, a PVA film with a thickness of approximately 100μm was obtained. A 0.1ml solution of 0.5mg / ml gold nanorods (AuNRs) was drop-coated onto a 1cm diameter circular area on the surface of the PVA film. After the solvent had fully evaporated, the film was peeled off to obtain a PVA-AuNRs hybrid film.

[0054] The PVA-AuNRs hybrid film was cut into rectangular strips of 4×1.5cm. Two PVA-AuNRs strips were taken and attached to both ends of a stretching device. The middle 1.5cm width of the rectangular strips was thoroughly wetted with pure water, and then axially stretched at 300% and 450% ratios, respectively. Finally, after water evaporation and drying, anisotropic PVA-AuNRs hybrid oriented films with different orientations were obtained. Finally, two PVA-AuNRs hybrid oriented films with different orientations (100%, 300%, and 450% without stretching) were stacked along the axial direction with a deflection angle of +45°, respectively, to obtain a double-layer stacked PVA-AuNRs hybrid chiral film with different orientations and an interlayer deflection angle of +45°.

[0055] Example 3: Chiral films obtained with different gold nanorod concentrations

[0056] 5g of PVA particles were weighed and poured into 95g of pure water. The mixture was heated to 90℃ and magnetically stirred at 1500r / min for 3 hours until the particles were completely dissolved, yielding a PVA solution with a solid content of 5%. 20g of the prepared PVA solution was weighed and poured into a 10cm×10cm petri dish, then dried in a 45℃ oven. After drying and film formation, a PVA film with a thickness of approximately 100μm was obtained. 0.1ml of 0.5mg / ml and 0.2ml of gold nanorod (AuNRs) solutions were respectively drop-coated onto circular areas with a diameter of 1cm on the surface of the PVA film. After the solvent had fully evaporated, the PVA-AuNRs hybrid films with gold nanorod concentrations of C1 = 0.00065mg / ml and C2 = 0.0013mg / ml were peeled off. The performance of these films after subsequent processing was compared with that of a pure PVA film without gold nanorods (C0 = 0mg / ml).

[0057] The PVA films and PVA-AuNRs hybrid films of the above three concentrations were cut into rectangular strips of 4×1.5cm. Each strip was held at both ends in a stretching device. The middle 1.5cm width of the rectangular strips was thoroughly wetted with pure water, followed by axial stretching at a 450% ratio. After drying and setting by water evaporation, anisotropic PVA-oriented films and PVA-AuNRs hybrid oriented films with different gold concentrations and a certain degree of orientation were obtained. The two oriented films were stacked along the axial direction with a deflection angle of ±45° to finally obtain bilayer stacked PVA-AuNRs hybrid chiral films with different gold nanorod concentrations.

[0058] Example 4: The effect of layer number variation on signal when the interlayer deflection angle is 45°

[0059] 5g of PVA particles were weighed and poured into 95g of pure water. The mixture was heated to 90℃ and magnetically stirred at 1500r / min for 3 hours until the particles were completely dissolved, yielding a PVA solution with a solid content of 5%. 20g of the prepared PVA solution was weighed and poured into a 10cm×10cm petri dish, then dried in a 45℃ oven. After drying and film formation, a PVA film with a thickness of approximately 100μm was obtained. A 0.1ml solution of 0.5mg / ml gold nanorods (AuNRs) was drop-coated onto a 1cm diameter circular area on the surface of the PVA film. After the solvent had fully evaporated, the film was peeled off to obtain a PVA-AuNRs hybrid film.

[0060] The PVA-AuNRs hybrid film was cut into rectangular strips of 4×1.5cm, and held at both ends by a stretching device. The middle 1.5cm width of the rectangular strip was thoroughly wetted with pure water, and then axially stretched at a ratio of 450%. Finally, the strip was dried and shaped by water evaporation to obtain anisotropic PVA-AuNRs hybrid oriented films with a certain degree of orientation. Multiple PVA-AuNRs hybrid oriented films were stacked along the axial direction with an interlayer deflection angle of +45° to obtain multilayer stacked PVA-AuNRs hybrid chiral films with different numbers of stacked layers (two, three, and four layers).

[0061] Example 5: Effect of Layer Number Variation on Signal When Total Deflection Angle is 45°

[0062] 5g of PVA particles were weighed and poured into 95g of pure water. The mixture was heated to 90℃ and magnetically stirred at 1500r / min for 3 hours until the particles were completely dissolved, yielding a PVA solution with a solid content of 5%. 20g of the prepared PVA solution was weighed and poured into a 10cm×10cm petri dish, then dried in a 45℃ oven. After drying and film formation, a PVA film with a thickness of approximately 100μm was obtained. A 0.1ml solution of 0.5mg / ml gold nanorods (AuNRs) was drop-coated onto a 1cm diameter circular area on the surface of the PVA film. After the solvent had fully evaporated, the film was peeled off to obtain a PVA-AuNRs hybrid film.

[0063] The PVA-AuNRs hybrid film was cut into rectangular strips of 4×1.5cm, and held at both ends by a stretching device. The middle 1.5cm width of the rectangular strip was thoroughly wetted with pure water, and then axially stretched at a 450% ratio. Finally, after water evaporation and drying, an anisotropic PVA-AuNRs hybrid oriented film with a certain degree of orientation was obtained. Two, three, and four PVA-AuNRs hybrid oriented films were stacked axially with a total deflection angle of +45°, respectively, resulting in multilayer stacked PVA-AuNRs hybrid chiral films with a total deflection angle of +45° for all layers and interlayer deflection angles of +45° (two layers), +22.5° (three layers), and +15° (four layers), respectively.

[0064] Figure 1 The figure shows the distribution of gold nanorods on the surface of the PVA-AuNRs hybrid film before and after axial stretching as described in Example 1 of this invention. As can be seen from the figure, before axial stretching, the gold nanorods are randomly distributed along their axial direction, while after axial stretching, the gold nanorods exhibit a certain degree of orientation. This indicates that the method of this invention can utilize the flexible polymer film to drive the rigid gold nanorods to align under the action of axial external force, thereby obtaining an anisotropic hybrid oriented film with excellent orientation and adjustable flexibility.

[0065] Figure 2This is a cross-sectional SEM image of the PVA-AuNRs hybrid orientation film after axial stretching in Embodiment 1 of the present invention. As can be seen from the image, the PVA polymer network exhibits typical orientation stripe characteristics along the stress direction after axial stress stretching, confirming its excellent orientation properties.

[0066] Figure 3 These are the CD spectra and g-factor spectra (obtained by standardized conversion of CD intensity) of bilayer PVA-AuNRs chiral films prepared in Example 1 with different deflection angles (0°, ±15°, ±30°, ±45°). Figure 3 As can be seen from a and b, as the interlayer deflection angle increases within the range of 0° to 45°, the CD intensity and g-factor intensity continuously increase, the peak shape of the signal curve remains unchanged, and the signal coverage wavelength reaches 200 to 2500 nm. The signals obtained at the corresponding positive and negative angles have good symmetry, corresponding to different chiral structures, which also proves that the chiral structure (right-handed, left-handed) of the material designed in this invention can be effectively controlled by changing the deflection angle.

[0067] Figure 4 The deflection angles of two PVA-AuNRs chiral films were adjusted from -90° to +90°, and the intensity changes of their CD characteristic peaks were statistically analyzed. As can be seen from the figure, when the interlayer deflection angle is 0°±A90°, A is a constant. Since the orientation directions of the two stacked films are consistent or perpendicular to each other, they belong to the racemic state and therefore have almost no circular dichroism. The effect of the deflection angle on the CD signal shows a periodicity of 180°, which also shows that this angle control strategy can effectively control the chiral structure of the material.

[0068] Figure 5 The figure shows a comparison of CD spectra of PVA-AuNRs hybrid chiral films with different monolayer orientations prepared in Example 2. As can be seen from the figure, the CD intensity of bilayer PVA-AuNRs hybrid chiral films at the same angle is significantly improved with the increase of monolayer orientation.

[0069] Figure 6 The image shows a comparison of CD spectra of PVA chiral films with different gold nanorod concentrations and PVA-AuNRs hybrid chiral films prepared in Example 3. As can be seen from the image, the PVA chiral film without gold nanorods has no CD signal, while the composite material with gold nanorods shows a CD signal after 400 nm. Furthermore, the CD intensity of the chiral film increases significantly with the increase of gold concentration.

[0070] Figure 7The CD spectra of multilayer PVA-AuNRs hybrid chiral films with different stacking numbers (two, three, and four layers) prepared in Example 4 are compared with the interlayer deflection angle fixed at +45°. It can be seen from the figure that the CD intensity of the chiral film increases slightly with the increase of the number of layers.

[0071] Figure 8 The CD spectra of multilayer stacked PVA-AuNRs hybrid chiral films prepared in Example 5 are compared. The total deflection angle is fixed at +45°, and the interlayer deflection angles are +45° (two layers), +22.5° (three layers), and +15° (four layers). It can be seen from the figure that the CD intensity of the chiral film decreases slightly with the increase of the number of layers.

[0072] Figure 9 The figures show the stress-strain curves of a single-layer PVA-AuNRs hybrid chiral film at a 450% stretch ratio, along with a photograph demonstrating its bendability and flexibility. As can be seen from the figures, the PVA-AuNRs hybrid chiral film possesses good mechanical strength and flexibility, which provides a foundation for its application in various environments.

[0073] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An organic-inorganic hybrid chiral thin film, characterized in that, The device comprises at least two hybrid orientation films, each comprising a flexible polymer film and a one-dimensional metal nanomaterial distributed on the surface of the flexible polymer film in an oriented manner. The flexible polymer film is a non-chiral polymer film, and the one-dimensional metal nanomaterial has the morphology of nanorods or nanowires. Each layer of the hybrid orientation film is stacked along the orientation axis of the one-dimensional metal nanomaterial at a predetermined deflection angle. The deflection angle between the uppermost and lowermost hybrid orientation films is in the range of 0° to ±360°, and is not 0° ± A90°, where A is a constant. The method for preparing the organic-inorganic hybrid chiral thin film includes the following steps: S1, A solution of one-dimensional metal nanomaterials is coated onto the surface of a flexible polymer film, and after drying, a hybrid film loaded with one-dimensional metal nanomaterials is obtained. S2, the hybrid membrane is wetted with water, and then the hybrid membrane is axially stretched in one direction at a preset stretching ratio to obtain a hybrid orientation membrane; S3. Take multiple hybrid orientation films obtained in S2 and stack them along the orientation axis with a preset deflection angle to obtain an organic-inorganic hybrid chiral film.

2. The organic-inorganic hybrid chiral thin film according to claim 1, characterized in that, The flexible polymer film is a PVA film.

3. The organic-inorganic hybrid chiral thin film according to claim 1, characterized in that, The one-dimensional metallic nanomaterial is gold or silver.

4. The organic-inorganic hybrid chiral thin film according to claim 1, characterized in that, The two adjacent hybrid orientation films are stacked at a preset deflection angle, and each hybrid orientation film is deflected either clockwise or counterclockwise.

5. The organic-inorganic hybrid chiral thin film according to claim 4, characterized in that, The preset deflection angle is ±45°, or the deflection angle between the uppermost hybrid orientation film and the lowermost hybrid orientation film is ±45°.

6. The method for preparing the organic-inorganic hybrid chiral thin film according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1, A solution of one-dimensional metal nanomaterials is coated onto the surface of a flexible polymer film, and after drying, a hybrid film loaded with one-dimensional metal nanomaterials is obtained. S2, the hybrid membrane is wetted with water, and then the hybrid membrane is axially stretched in one direction at a preset stretching ratio to obtain a hybrid orientation membrane; S3. Take multiple hybrid orientation films obtained in S2 and stack them along the orientation axis with a preset deflection angle to obtain an organic-inorganic hybrid chiral film.

7. The method for preparing an organic-inorganic hybrid chiral thin film according to claim 6, characterized in that, In S2, the preset draw ratio is 200%~500%.

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