Thin film assembly film and preparation method of chiral thin film

Abstract

The invention relates to the technical field of chiral thin film preparation, in particular to a method for rapidly preparing a multiband chiral thin film through mechanical force. According to the method, weak interaction among the nanoparticles can be effectively broken through mechanical force, so that controllable transformation of an internal structure is realized, ordered assembly of the nanoparticles according to a limited direction is quickly realized, and a one-dimensional ordered structure is directly constructed. The birefringence effect of a commercial transparent single-sided adhesive tape is utilized, a nanoparticle one-dimensional ordered structure is used as a functional element, and a chiral film with a high g-factor is constructed in a rotary pasting mode.

Description

Technical Field

[0001] The present invention relates to the technical field of chiral thin film preparation, and in particular to a method for rapidly preparing a multi-band chiral thin film by using mechanical force. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] The key to constructing chiral superstructures from achiral nanoparticles lies in inducing spatial asymmetry. Current mainstream strategies focus on chiral templates and external field induction. The former achieves chiral assembly by precisely controlling the intermolecular interactions between nanoparticles, while the latter uses circularly polarized light or magnetic fields to induce chiral arrangements in specific systems. However, both methods have significant limitations in terms of universality and scope of application. The chiral template method is limited by the difficulty of finely controlling intermolecular forces, while the external field induction method places stringent requirements on the physical properties of the system. To overcome these technical bottlenecks, new assembly strategies based on macroscopic mechanical forces have gradually become a research direction with great development potential.

[0004] In recent years, the application of mechanical forces in chemical synthesis has yielded significant results, particularly in drug cocrystal screening and the exploration of novel inorganic solid structures. However, in the cutting-edge field of chiral nanoparticle assembly, research on the application of mechanical forces remains relatively scarce, and its mechanism of action remains unclear. Therefore, developing a simple, efficient, and universal construction method is of great scientific significance for advancing research in the field of chirality and deepening our understanding of the mechanism of mechanical force in chirality construction. Summary of the Invention

[0005] In order to overcome the above problems, the present invention provides a thin film assembly film and a method for preparing a chiral thin film.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A first aspect of the present invention provides a method for preparing a thin film assembly membrane, comprising the following steps:

[0008] (1) dispersing the one-dimensional nanowires in an organic solvent to form a one-dimensional nanowire solution;

[0009] (2) adding a lubricant to the one-dimensional nanowire solution, depositing the mixed solution on a single surface of a quartz plate, and obtaining a precursor assembly film after drying;

[0010] (3) Two identical precursor assembly films are stacked one on top of the other, and the single-side surfaces of the quartz plates on which one-dimensional nanowires are deposited are bonded together, and the two thin film assembly films are obtained by horizontal relative reciprocating friction.

[0011] Horizontal relative reciprocating friction means that two identical precursor assembly films undergo relative reciprocating motion in the horizontal direction, thereby achieving friction.

[0012] The second aspect of the present invention provides a thin film assembly membrane prepared by the above preparation method.

[0013] A third aspect of the present invention provides a method for preparing a chiral thin film, comprising:

[0014] A chiral thin film can be obtained by sticking a transparent single-sided tape on one side of the thin film assembly film, and laminating the adhesive layer of the transparent single-sided tape to the one side of the thin film assembly film on which the nanomaterial is deposited.

[0015] The chiral film of the present invention can selectively absorb left-handed / right-handed circularly polarized light, has a high asymmetry factor (g-factor), and exhibits ultra-high optical activity.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention relates to the technical field of chiral thin film preparation, and more specifically to a method for rapidly preparing multi-band chiral thin films using mechanical force. In the present invention, mechanical force is utilized to effectively break the weak interactions between nanoparticles, thereby achieving a controllable transformation of the internal structure and rapidly achieving the orderly assembly of nanoparticles in a defined direction, thereby directly constructing a one-dimensional ordered structure. By utilizing the birefringence effect of commercial transparent single-sided tape, the one-dimensional ordered structure of the nanoparticles is used as a functional unit, and a chiral film with a high asymmetry factor (g-factor) is constructed by rotational pasting.

[0018] (2) The present invention prepares a chiral film by assembling nanomaterials arranged in an orderly manner in a defined direction through mechanical friction technology, and the obtained chiral film exhibits ultra-high optical activity and an asymmetry factor (g-factor) of up to 1.4.

[0019] (3) The method for preparing chiral films of the present invention is simple and universal. The equipment only needs an ordinary friction device that meets the requirements of horizontal relative friction, which is easy to operate and low in cost. The structure of the prepared film is controllable, and single-component or multi-component chiral films can be prepared according to actual application requirements. The rotation angle of the tape and the ordered nanoparticle functional layer can be arbitrarily adjusted, and the medium and spacing between layers can also be precisely adjusted. It has broad application prospects.

[0020] (3) The g-factor of the Ag nanoparticle-based chiral film prepared in the present invention is as high as 0.63, showing ultrahigh optical activity.

[0021] (4) The present invention provides a series of novel chiral films with excellent performance, promoting their wide application in optoelectronic devices, biosensors, electromagnetic shielding and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 A physical diagram of a horizontal relative reciprocating friction device, where a is an overall diagram of the device, b is a partial diagram of the device, and c is a structural schematic diagram of the first support platform and the second support platform, where 1 is the table, 2 is the x- and y-axis translation platform, 3 is the z-axis translation platform, 4 is the first electric linear translation platform, 5 is the first support platform, 6 is the second support platform, 7 is the second electric linear translation platform, 8 is the controller, 9 is the lifting platform, 10 is the groove, and 11 is the quartz plate;

[0024] Figure 2 This is a graph showing the relationship between the z-axis rise height and pressure;

[0025] Figure 3 TEM image of MSC nanowires;

[0026] Figure 4 is the UV-visible absorption spectrum of MSC nanowires;

[0027] Figure 5 The structural diagram of the oriented ordered thin film assembly membrane, where a is a physical image and b is a microscope image;

[0028] Figure 6 Schematic diagram of the first chiral film based on MSC nanowires and a physical picture of the second chiral film based on MSC nanowires;

[0029] Figure 7 Figure 3 is the circular dichroism spectrum and asymmetry factor (g-factor) diagram of the first chiral film based on MSC nanowires and the second chiral film based on MSC nanowires, where a is the circular dichroism spectrum; b is the asymmetry factor (g-factor);

[0030] Figure 8 The first CeMoO-based x Chiral thin films of nanowires and second CeMoO-based xCircular dichroism spectra and g-factor diagram of chiral nanowire films, where a is the circular dichroism spectrum; b is the g-factor;

[0031] Figure 9 Circular dichroism spectra and asymmetry factor (g-factor) diagrams of the first chiral film based on NiMoO4 nanowires and the second chiral film based on NiMoO4 nanowires, where a is the circular dichroism spectrum; b is the asymmetry factor (g-factor);

[0032] Figure 10 Figure 3 is the circular dichroism spectrum and asymmetry factor (g-factor) diagram of the first chiral film based on MSC nanowires / Ag nanoparticles and the second chiral film based on MSC nanowires / Ag nanoparticles, where a is the circular dichroism spectrum; b is the asymmetry factor (g-factor);

[0033] Figure 11 Circular dichroism spectra and asymmetry factor (g-factor) diagrams of the first chiral film based on MSC nanowires / Au nanoparticles and the second chiral film based on MSC nanowires / Au nanoparticles, where a is the circular dichroism spectrum and b is the asymmetry factor (g-factor).

[0034] Figure 12 Figure 3 is the circular dichroism spectrum and asymmetry factor (g-factor) diagram of the first chiral film based on MSC nanowires / Au nanorods and the second chiral film based on MSC nanowires / Au nanorods, where a is the circular dichroism spectrum and b is the asymmetry factor (g-factor). DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] A first typical embodiment of the present invention provides a method for preparing a thin film assembly membrane, comprising the following steps:

[0038] (1) dispersing the one-dimensional nanowires in an organic solvent to form a one-dimensional nanowire solution;

[0039] (2) adding a lubricant to the one-dimensional nanowire solution, depositing the mixed solution on a single surface of a quartz plate, and obtaining a precursor assembly film after drying;

[0040] (3) Two identical precursor assembly films are stacked one on top of the other, and the single-side surfaces of the quartz plates on which one-dimensional nanowires are deposited are bonded together, and the two thin film assembly films are obtained by horizontal relative reciprocating friction.

[0041] Horizontal relative reciprocating friction means that two identical precursor assembly films undergo relative reciprocating motion in the horizontal direction, thereby achieving friction.

[0042] In one or more embodiments, in step (1), the one-dimensional nanowires include cadmium sulfide nanowires, CeMoO x nanowires and NiMoO4 nanowires.

[0043] In one or more embodiments, in step (1), the aspect ratio of the one-dimensional nanowire is greater than 1000.

[0044] In one or more embodiments, in step (1), the organic solvent is selected from one of n-hexane and cyclohexane.

[0045] In one or more embodiments, in step (1), the concentration of the one-dimensional nanowires in the one-dimensional nanowire solution is 9 to 12 g / L, preferably 10 g / L.

[0046] In one or more embodiments, in step (2), the lubricant is octadecene.

[0047] In one or more embodiments, in step (2), the volume ratio of the lubricant to the one-dimensional nanowire solution is 0.05‰ to 10‰:1, preferably 0.1‰:1.

[0048] In one or more embodiments, in step (2), the pressure during the horizontal relative reciprocating friction process is 50 to 500 kPa, preferably 300 kPa.

[0049] In one or more embodiments, in step (2), the speed during the horizontal relative reciprocating friction is 1 to 6 cm / s, preferably 4 cm / s; the time of the horizontal relative reciprocating friction is 2 to 20 s, preferably 10 s.

[0050] In one or more embodiments, the method for preparing the thin film assembly membrane further comprises:

[0051] A lubricant is added to the one-dimensional nanowire solution, and the mixed solution is deposited on a single surface of a quartz plate, and dried to obtain a first precursor assembly film;

[0052] A solution containing dispersed metal nanoparticles or metal nanorods is deposited on the surface of a first precursor assembly film on which one-dimensional nanowires are deposited, and the precursor assembly film is obtained after drying.

[0053] Preferably, the metal nanoparticles include one or more of gold nanoparticles and silver nanoparticles;

[0054] Further preferably, the particle size of the gold nanoparticles and silver nanoparticles is 5 to 30 nm;

[0055] Preferably, the solvent for dispersing the metal nanoparticles or metal nanorods includes one of n-hexane, cyclohexane and chloroform.

[0056] Preferably, the metal nanorods include one or more of gold nanorods and silver nanorods;

[0057] More preferably, the diameter of the gold nanorods and the silver nanorods is 20-50 nm, and the long diameter is 50-200 nm.

[0058] A second typical embodiment of the present invention provides a thin film assembly membrane prepared by the above preparation method.

[0059] A third typical embodiment of the present invention provides a method for preparing a chiral thin film, comprising:

[0060] A chiral thin film can be obtained by sticking a transparent single-sided tape on one side of the thin film assembly film, and laminating the adhesive layer of the transparent single-sided tape to the one side of the thin film assembly film on which the nanomaterial is deposited.

[0061] In one or more embodiments, the nanomaterial includes one-dimensional nanowires and a combination of one-dimensional nanowires and metal nanoparticles or metal nanorods.

[0062] In one or more embodiments, the clockwise angle between the center line of the transparent single-sided tape and the center line of the thin film assembly film is 0 to 90 degrees, preferably 45 degrees; the counterclockwise angle is 0 to 90 degrees, preferably 45 degrees. Clockwise represents a left-handed structure; counterclockwise represents a right-handed structure.

[0063] The chiral film of the present invention can selectively absorb left-handed / right-handed circularly polarized light, has a high asymmetry factor (g-factor), and exhibits ultra-high optical activity.

[0064] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0065] The transparent single-sided adhesive tape in the present invention is a commercially available transparent single-sided adhesive tape, and brands include Deli, Chenguang and 3M. In the following embodiments, the commercially available Deli transparent single-sided adhesive tape has a width of 2 cm.

[0066] The present invention does not limit the device for horizontal relative reciprocating friction. The device for horizontal relative reciprocating friction used in the following embodiments is as follows: Figure 1 shown.

[0067] The horizontal relative reciprocating friction device includes an x-axis and y-axis translation stage 2, which is fixed to a table 1. The upper surface of the x-axis and y-axis translation stage 2 is fixed to a z-axis translation stage 3. The upper surface of the z-axis translation stage 3 is fixed to a first electric linear translation stage 4. The table surface of the first electric linear translation stage 4 is fixed to a first support platform 5. The upper surface of the first support platform 5 is provided with a first groove, which is engaged with a first quartz plate. A second electric linear translation stage 7 is arranged above the first electric linear translation stage 4. The table surface of the second electric linear translation stage 7 is fixed to a second support platform 6. The upper surface of the second support platform 6 is provided with a second groove, which is engaged with a second quartz plate. The second electric linear translation stage 7 is fixed to a lifting platform 9, which is connected to the table 1. The first electric linear translation stage 4 and the second electric linear translation stage 7 are both electrically connected to the controller.

[0068] In order to achieve precise control of the pressure during the horizontal relative reciprocating friction process, before performing the horizontal relative reciprocating friction of the precursor assembly film, an ordinary quartz plate is first clamped in the first groove and the second groove. A pressure sensor is placed on the upper surface of the quartz plate in the first groove. The position of the lifting platform is adjusted so that the quartz plate in the second groove just fits the pressure sensor. By adjusting the height of the z-axis translation stage, the relationship between the lifting height and the pressure is obtained. The results are shown in the figure. Figure 2 As shown, in the subsequent experimental process, a defined pressure is obtained by adjusting the height of the z-axis translation stage.

[0069] Example 1

[0070] Preparation of chiral thin films based on cadmium sulfide (MSC) nanowires:

[0071] (1) The synthesis method of cadmium sulfide (MSC) nanowires is as follows: 1.28 g of cadmium oxide (CdO) and 10 mL of oleic acid (OA) were added to a round-bottom flask and heated under N2 protection to prepare a cadmium oleate precursor (Cd-OA). The mixed solution was first heated to 160 ° C and maintained for 1 hour until the solution turned transparent brown. Subsequently, the solution was cooled to 100 ° C and degassed under vacuum for about 40 minutes until no bubbles were generated, and then cooled to 50 ° C. 2 mL of pre-prepared TOP-S solution (0.8 g of sulfur powder (S) dissolved in 10 mL of tri-n-octylphosphine (TOP) solution) was injected into the Cd-OA solution. The Cd-OA / TOP-S mixed solution was heated to 130 ° C. When MSC nanowires were formed, the solution became turbid. It was maintained at this temperature for 1 hour, then quenched with an equal volume of ethyl acetate and centrifuged at 7000 rpm for 3 minutes. The precipitate was dissolved with n-hexane, precipitated with an equal volume of ethyl acetate and centrifuged. Finally, MSC nanowires were dispersed in n-hexane to a concentration of 10 g L -1 of solution.

[0072] Figure 3 TEM images of MSC nanowires. Figure 3 The assembled MSC nanowires have a one-dimensional structure of tens or even hundreds of microns.

[0073] Figure 4 is the UV-visible absorption spectrum of MSC nanowires, Figure 4 It can be seen that the UV-visible absorption peak of MSC nanowires is at 324 nm, which corresponds to the peak position of the chiral signal.

[0074] (2) Octadecene was added to the MSC nanowire solution (concentration: 10 g / L) as a lubricant to enhance the friction effect. The volume ratio of lubricant to one-dimensional nanowire solution was 0.1‰:1. 500 μL of the mixed solution was deposited on a quartz plate with dimensions of 20 mm wide and 40 mm long and slowly dried at room temperature to obtain a precursor assembly film.

[0075] Place two identical precursor assembly films in the first groove and the second groove of the aforementioned horizontal relative reciprocating friction device, adjust the position of the lifting platform so that the precursor assembly film in the second groove just fits with the precursor assembly film in the first groove, adjust the height of the z-axis translation platform so that the pressure of the two precursor assembly films is 300kPa, and adjust the controller so that the speed of the two precursor assembly films during the horizontal relative reciprocating friction process is 4cm / s; the horizontal relative reciprocating friction time is 10s, and a thin film assembly film is obtained. The structure of the thin film assembly film is as follows Figure 5 As shown, from Figure 5 It can be seen that an oriented and ordered MSC nanowire film assembly film is obtained by horizontal relative reciprocating friction.

[0076] A transparent single-sided tape was applied to the surface of the MSC nanowire thin film assembly, with the adhesive layer of the tape aligned with the surface of the thin film assembly with MSC nanowires deposited thereon. The centerline of the transparent single-sided tape formed a 45° clockwise angle with the centerline of the thin film assembly, resulting in a first chiral thin film based on MSC nanowires. The centerline of the transparent single-sided tape formed a 45° counterclockwise angle with the centerline of the thin film assembly, resulting in a second chiral thin film based on MSC nanowires.

[0077] The first chiral film based on MSC nanowires and the second chiral film based on MSC nanowires are shown in the figure. Figure 6 shown.

[0078] The performance of chiral materials is evaluated by the asymmetry factor (g-factor), which is defined as: g-factor = 2(A L- A R ) / (A L +A R )

[0079] Among them A L and A R Represents the absorbance of left-circularly polarized light and right-circularly polarized light, respectively. Larger values ​​indicate stronger performance.

[0080] The circular dichroism spectra and asymmetry factors (g-factor) of the first chiral film based on MSC nanowires and the second chiral film based on MSC nanowires prepared in this embodiment are shown in FIG. Figure 7 As shown, from Figure 7 It can be seen that the g-factor value range (1.2-1.4) of the chiral film based on MSC nanowires is greater than 1, indicating that the chiral film based on MSC nanowires prepared in this example has excellent optical activity characteristics and significant circular dichroism response. The value of this g-factor fully meets the requirements of practical applications.

[0081] Example 2

[0082] Based on CeMoO x Preparation of chiral nanowire films:

[0083] (1) 0.183g PMo 12 O 40·xH2O, 0.434g Ce(NO3)3·6H2O and 16mL octadecene were added to a 100mL three-necked flask. 7.2mL oleylamine (OAm) and 0.8mL oleic acid (OA) were injected into it and stirred vigorously. Subsequently, the three-necked flask was placed on a 50°C heating platform and heated at a constant temperature for 8h. After the reaction was completed, the product was diluted with n-hexane and precipitated with ethanol. The precipitate was redispersed with n-hexane, centrifuged at 7000rpm in n-hexane for 3min, and the washing process was repeated three times to improve the purity. Finally, CeMoO x Nanowires were dispersed in n-hexane at a concentration of 10 g L -1 The solution is ready for use.

[0084] The preparation method of the precursor assembly film and the assembly method of the thin film assembly film are the same as those in Example 1.

[0085] Paste the transparent single-sided tape on the CeMoO x The surface of the nanowire film assembly film, the adhesive layer of the transparent single-sided tape and the deposited CeMoO x The surface of the thin film assembly film of nanowires is attached. The clockwise angle between the center line of the transparent single-sided tape and the center line of the thin film assembly film is 45°, and the first CeMoO-based x The counterclockwise angle between the center line of the transparent single-sided tape and the center line of the film assembly film is 45°, and the second CeMoO-based chiral film is obtained. x Chiral thin films of nanowires.

[0086] The first CeMoO-based x Chiral thin films of nanowires and second CeMoO-based x The circular dichroism spectra and asymmetry factor (g-factor) of chiral nanowire films are as follows: Figure 8 As shown, Figure 8 It can be seen that in CeMoO x The ultraviolet absorption of the nanowires shows a significant chiral signal and has a high g-factor.

[0087] Example 3

[0088] Preparation of chiral thin films based on NiMoO4 nanowires:

[0089] (1) Under magnetic stirring, 6 mL of ethanol, 2 mL of oleylamine and 1 mL of OA were added to a 25 mL polytetrafluoroethylene liner and mixed thoroughly. Subsequently, 0.3 mL of 1 M NiCl2 solution and 0.3 mL of 1 M Na2MoO4 solution were added in sequence and stirred vigorously for 10 min. The liner was sealed in a high-pressure reactor and placed in a 140 ° C oven for 4 h. After the reaction was completed, the system was naturally cooled to room temperature and the generated product was dissolved in 10 mL of cyclohexane. Then, 20 mL of ethanol was added to induce precipitation of the product and centrifuged at 8000 rpm for 5 min. Finally, the obtained nanowires were dispersed in 20 mL of cyclohexane for use (10 g L -1 ).

[0090] The preparation method of the precursor assembly film and the assembly method of the thin film assembly film are the same as those in Example 1.

[0091] A transparent single-sided tape was applied to the surface of the NiMoO4 nanowire thin film assembly, with the adhesive layer of the tape aligned with the surface of the NiMoO4 nanowire thin film assembly. The centerline of the tape formed a 45° clockwise angle with the centerline of the thin film assembly, resulting in a first NiMoO4 nanowire-based chiral thin film. The centerline of the tape formed a 45° counterclockwise angle with the centerline of the thin film assembly, resulting in a second NiMoO4 nanowire-based chiral thin film.

[0092] The circular dichroism spectra and asymmetry factors (g-factor) of the first and second NiMoO4 nanowire-based chiral films prepared in this embodiment are shown in Figure 2. Figure 9 As shown, from Figure 9 It can be seen that the ultraviolet absorption based on NiMoO4 nanowires shows a significant chiral signal and has a high g-factor.

[0093] Example 4

[0094] Preparation of chiral thin films based on CdS nanowires / Ag nanoparticles:

[0095] Synthesis of Ag nanoparticles: First, 1.78 g of AgNO3 and 30 mL of oleylamine were mixed in a 100 mL three-necked flask. Subsequently, the three-necked flask was placed on a 60 °C heating platform to completely dissolve the AgNO3 crystals. The mixture was stirred at about 10 °C min -1 The solution was rapidly heated to 180°C at a rate of 100 μg / L and maintained at this temperature for 1 hour. Finally, the reaction system was cooled to room temperature, toluene was added to dilute the product, and the product was washed with acetone. During the washing process, the particle size distribution of the nanoparticles was optimized through the size selection process, and the particle size of the Ag nanoparticles obtained was 8 to 12 nm. The Ag nanoparticles were dispersed in n-hexane for use (5 g L -1).

[0096] Octadecene was added to a 10g / L cadmium sulfide nanowire solution as a lubricant to enhance friction. The volume ratio of lubricant to one-dimensional nanowire solution was 0.1‰:1. 500μL of the mixed solution was deposited onto a 20mm wide by 40mm long quartz slide and slowly dried at room temperature to obtain the first precursor assembly film.

[0097] 50 μL of the above-mentioned Ag nanoparticle solution was further deposited on the surface of the first precursor assembly film, and the solution was evaporated at a temperature of 30° C. to obtain a precursor assembly film.

[0098] Thin Film Assembly The film assembly method is the same as in Example 1.

[0099] A transparent single-sided tape was applied to the surface of a CdS nanowire / Ag nanoparticle thin film assembly, with the adhesive layer of the tape aligned with the surface of the CdS nanowire / Ag nanoparticle thin film assembly. The centerline of the transparent single-sided tape formed a 45° clockwise angle with the centerline of the thin film assembly, resulting in a first CdS nanowire / Ag nanoparticle chiral thin film. The centerline of the transparent single-sided tape formed a 45° counterclockwise angle with the centerline of the thin film assembly, resulting in a second CdS nanowire / Ag nanoparticle chiral thin film.

[0100] The circular dichroism spectra and asymmetry factors (g-factor) of the first chiral film based on CdS nanowires / Ag nanoparticles and the second chiral film based on CdS nanowires / Ag nanoparticles prepared in this embodiment are shown in FIG. Figure 10 As shown, from Figure 10 As can be seen in the figure, the left-handed and right-handed structures each generate corresponding chiral signals, and the direction of the chiral signals is controllable. In addition, with the assistance of nanowires, the Ag nanoparticles were induced to generate a controllable chiral signal with a g-factor as high as 0.63.

[0101] Example 5

[0102] Preparation of chiral thin films based on CdS nanowires / Au nanoparticles:

[0103] Au nanoparticle synthesis: 100 mg of HAuCl4·3H2O, 10 mL of oleylamine, and 10 mL of toluene were added to a 100 mL three-necked flask. A toluene solution containing 30 mg of tert-butylamine borane was then quickly added. After stirring for 1 hour, oleylamine-modified Au nanoparticles were obtained. The Au nanoparticles were purified by ethanol precipitation and washed by centrifugation at 7000 rpm for 2 minutes. Finally, the precipitate was redispersed in 5 mL of toluene to obtain a 5 g L -1Then, a seed growth experiment was carried out to increase the particle size of Au nanoparticles. 2 mL of toluene and 2 mL of oleylamine were added to a 20 mL glass bottle, 250 μL of the above seed solution was injected, and the glass bottle was placed on a 90 ° C heating platform to react for 3 hours to promote full growth of the seeds. After the reaction was completed, the product was cooled to room temperature, and the Au nanoparticles were precipitated with ethanol, centrifuged and washed at 7000 rpm for 2 minutes, and finally redispersed in n-hexane to prepare a concentration of 5 g L -1 The Au nanoparticle solution is set aside. The particle size of the Au nanoparticles is about 8 to 12 nm.

[0104] The preparation of the precursor assembly film is the same as in Example 4, and the assembly method of the thin film assembly film is the same as in Example 1.

[0105] A transparent single-sided tape was applied to the surface of the CdS nanowire / Au nanoparticle thin film assembly, with the adhesive layer of the tape aligned with the surface of the CdS nanowire / Au nanoparticle thin film assembly. The centerline of the transparent single-sided tape formed a 45° clockwise angle with the centerline of the thin film assembly, resulting in a first CdS nanowire / Au nanoparticle chiral thin film. The centerline of the transparent single-sided tape formed a 45° counterclockwise angle with the centerline of the thin film assembly, resulting in a second CdS nanowire / Au nanoparticle chiral thin film.

[0106] The circular dichroism spectra and asymmetry factors (g-factors) of the first chiral film based on cadmium sulfide nanowires / Au nanoparticles and the second chiral film based on cadmium sulfide nanowires / Au nanoparticles prepared in this embodiment are shown in FIG. Figure 11 As shown, from Figure 11 As can be seen in the figure, the left-handed and right-handed structures can produce chiral optical responses of corresponding configurations, and the signal intensity shows good controllable characteristics. Under the auxiliary induction of the nanowires, the Au nanoparticles produce a significantly enhanced chiral response, with a g-factor as high as 0.42, achieving effective control of chiral optical activity.

[0107] Example 6

[0108] Preparation of chiral thin films based on CdS nanowires / Au nanorods:

[0109] Synthesis of Au nanorods: First, prepare the Au nanorod growth seed solution. In a 20 mL glass bottle, mix 5 mL of a 0.5 mM HAuCl4·3H2O solution and 5 mL of a 0.2 M cetyltrimethylammonium bromide (CTAB) solution (Au(III)-CTAB). Next, dilute 0.6 mL of freshly prepared 0.01 M NaBH4 solution to 1 mL with water and rapidly inject the solution into the Au(III)-CTAB solution while stirring vigorously at 1200 rpm. The solution color immediately changes from yellow to brownish-yellow. Stir for 2 minutes to obtain the seed solution. The seed solution must be aged at room temperature for 30 minutes before use.

[0110] The growth solution was prepared as follows: In a 1-liter Erlenmeyer flask, 7.0 g of CTAB and 1.5 g of sodium oleate were dissolved in 250 mL of warm water at approximately 50°C. After the solution cooled to 30°C, 18 mL of a 4 mM AgNO₃ solution was added and the mixture was allowed to stand at 30°C for 15 minutes. Subsequently, 250 mL of a 1 mM HAuCl₄·3H₂O solution was added and stirred at 700 rpm for 90 minutes until the solution became colorless. The pH was adjusted by adding 3 mL of concentrated hydrochloric acid (12.1 M). After slowly stirring at 400 rpm for 15 minutes, 1.25 mL of a 0.064 M ascorbic acid solution was added and stirred vigorously for 30 seconds. Finally, 0.2 mL of the seed solution was injected into the growth solution. After mixing and stirring for 30 seconds, the solution was allowed to stand at 30°C for 12 hours to allow for the full growth of Au nanorods. The final product was separated by centrifugation at 7000 rpm for 30 min, and the supernatant was discarded. The obtained Au nanorods were dispersed in water (10 g L -1 ). The Au nanorods have a diameter of about 40 nm and a length of about 100 nm.

[0111] Ligand exchange process of CTAB on the surface of Au nanorods to sulfonated polystyrene: First, sulfonated polystyrene was added at 30 mg mL -1 The concentration of tetrahydrofuran was prepared. Subsequently, the dispersion was added dropwise to a solution having a concentration of 10 mg mL -1 The volume ratio of the two solutions was 1:1. Finally, the mixed system was stirred at 40 ° C for 12 h to achieve the ligand exchange process.

[0112] The preparation of the precursor assembly film is the same as in Example 4, and the assembly method of the thin film assembly film is the same as in Example 1.

[0113] A transparent single-sided tape was applied to the surface of the CdS nanowire / Au nanorod thin film assembly, with the adhesive layer of the tape aligned with the surface of the CdS nanowire / Au nanorod thin film assembly. The centerline of the transparent single-sided tape formed a 45° clockwise angle with the centerline of the thin film assembly, resulting in a first CdS nanowire / Au nanorod chiral thin film. The centerline of the transparent single-sided tape formed a 45° counterclockwise angle with the centerline of the thin film assembly, resulting in a second CdS nanowire / Au nanorod chiral thin film.

[0114] The circular dichroism spectra and asymmetry factors (g-factor) of the first chiral film based on CdS nanowires / Au nanorods and the second chiral film based on CdS nanowires / Au nanorods prepared in this embodiment are shown in FIG. Figure 12 As shown, from Figure 12 It can be seen that the left-handed and right-handed structures of Au nanorods can generate controllable chiral signals, and their g-factor is as high as 0.78, proving that they have excellent optical asymmetric properties.

[0115] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a thin film assembly membrane, characterized in that: The steps include: (1) dispersing the one-dimensional nanowires in an organic solvent to form a one-dimensional nanowire solution; (2) adding a lubricant to the one-dimensional nanowire solution, depositing the mixed solution on a single surface of a quartz plate, and obtaining a precursor assembly film after drying; (3) Two identical precursor assembly films are stacked one on top of the other, and the single-side surfaces of the quartz plates on which one-dimensional nanowires are deposited are bonded together, and the two thin film assembly films are obtained by horizontal relative reciprocating friction.

2. The preparation method according to claim 1, wherein The one-dimensional nanowires include cadmium sulfide nanowires, CeMoO x nanowires and NiMoO4 nanowires; Alternatively, in step (1), the aspect ratio of the one-dimensional nanowire is greater than 1000.

3. The preparation method according to claim 1, wherein In step (1), the organic solvent is selected from one of n-hexane and cyclohexane; Alternatively, in step (1), the concentration of the one-dimensional nanowires in the one-dimensional nanowire solution is 9 to 12 g / L, preferably 10 g / L.

4. The preparation method according to claim 1, wherein In step (2), the lubricant is octadecene; Alternatively, in step (2), the volume ratio of the lubricant to the one-dimensional nanowire solution is 0.05‰ to 10‰:1, preferably 0.1‰:

1.

5. The preparation method according to claim 1, wherein In step (2), the pressure during the horizontal relative reciprocating friction process is 50 to 500 kPa, preferably 300 kPa; Alternatively, in step (2), the speed during the horizontal relative reciprocating friction process is 1 to 6 cm / s, preferably 4 cm / s; and the time of the horizontal relative reciprocating friction is 2 to 20 s, preferably 10 s.

6. The preparation method according to claim 1, wherein The method for preparing the thin film assembly membrane further comprises: A lubricant is added to the one-dimensional nanowire solution, and the mixed solution is deposited on a single surface of a quartz plate, and dried to obtain a first precursor assembly film; A solution containing dispersed metal nanoparticles or metal nanorods is deposited on the surface of a first precursor assembly film on which one-dimensional nanowires are deposited, and the precursor assembly film is obtained after drying.

7. The preparation method according to claim 6, wherein The metal nanoparticles include one or more of gold nanoparticles and silver nanoparticles; preferably, the particle size of the gold nanoparticles and silver nanoparticles is 5 to 30 nm; Alternatively, the solvent for dispersing the metal nanoparticles or metal nanorods comprises one of n-hexane, cyclohexane, and chloroform; Alternatively, the metal nanorods include one or more of gold nanorods and silver nanorods; preferably, the diameter of the gold nanorods and silver nanorods is 20-50 nm, and the long diameter is 50-200 nm.

8. The thin film assembly membrane prepared by the preparation method according to any one of claims 1 to 7.

9. A method for preparing a chiral thin film, characterized in that: include: A chiral thin film can be obtained by sticking a transparent single-sided tape on one side of the thin film assembly film according to claim 8, wherein the adhesive layer of the transparent single-sided tape is in contact with the one side of the thin film assembly film on which the nanomaterial is deposited.

10. The preparation method according to claim 9, characterized in that The nanomaterials include one-dimensional nanowires and combinations of one-dimensional nanowires and metal nanoparticles or metal nanorods; Alternatively, the clockwise angle between the center line of the transparent single-sided tape and the center line of the thin film assembly film is 0-90°, preferably 45°; the counterclockwise angle is 0-90°, preferably 45°.

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