Programmable light response type liquid crystal film and preparation method thereof

Abstract

The invention belongs to the technical field of liquid crystal materials, and particularly discloses a programmable light response type liquid crystal film and a preparation method thereof.The preparation method comprises the steps that firstly, a molecular motor M-1 is synthesized and mixed with liquid crystal monomers to be cross-linked, and a liquid crystal polymer network (LCN) is formed; the molecular motor rotates in the LCN, so that the macroscopic movement of the LCN material is synergistically amplified, and meanwhile, the unique characteristic of dynamic chirality of the molecular motor is introduced into the LCN, so that quick and efficient movement orientation is realized. In addition, the alignment layer of the liquid crystal substrate is pre-arranged in combination with the photoetching technology, and the LCN materials with different rotation directions are allowed to achieve complex orthogonal spiral motion. According to the invention, how to program the rotational motion of the molecular motor in the photoresponsive material is shown, and a way is laid for the design of advanced responsive and adaptive soft materials and the realization of induced complex motion.

Description

Technical Field

[0001] The invention relates to the technical field of liquid crystal materials, in particular to a programmable light-responsive liquid crystal film and a preparation method thereof. Background Art

[0002] Liquid crystal polymer (LCN) materials can produce anisotropic changes in shape or size by changing the arrangement of liquid crystal elements under external stimuli (light, heat, electricity, magnetism, etc.). Compared with other stimuli, light is considered to be an ideal external stimulus. By simply adjusting the intensity, frequency and wavelength of light, the material can be remotely, non-contactly and selectively controlled to achieve real-time precise regulation and switching functions. Therefore, light-responsive liquid crystal materials have broad application prospects in the fields of bionic and intelligent micromechanical systems such as self-cleaning, adaptive surfaces, artificial muscles, microrobots, micropumps, sensors, etc.

[0003] At present, photoresponsive LCN materials usually use azobenzene and its derivatives as molecular photoswitches. Under light irradiation, azobenzene undergoes photoisomerization, transforming from a rod-like (E) structure to a crescent-like (Z) structure, causing the originally ordered structure to tend toward a disordered state. The photoisomerization of azobenzene causes anisotropic deformation of the liquid crystal material, that is, the material produces macroscopic movement during the dimensional change process, that is, mechanical energy is generated. Mechanical energy is a form of energy that can be directly utilized and can have a direct impact on production and life. At present, systems that can simultaneously achieve mechanical motion and orthogonal helical motion have not been successfully developed. However, this goal has attracted much attention because it is expected to promote the development of artificial responsive materials with higher complexity, precision, and richer forms of mechanical motion. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a programmable light-responsive liquid crystal film and a preparation method thereof. The prepared programmable light-responsive liquid crystal film can realize mechanical motion and orthogonal spiral motion simultaneously.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0006] One of the technical solutions of the present invention is: a method for preparing a programmable light-responsive liquid crystal film, comprising the following steps:

[0007] S1. Compound 1, i.e., 6-methoxy-2,4,7-trimethyl-2,3-dihydro-1H-inden-1-one, was used as a raw material. The methoxy group in 6-methoxy-2,4,7-trimethyl-2,3-dihydro-1H-inden-1-one was reduced to a phenolic hydroxyl group with AlCl3 to obtain compound 2. The phenolic hydroxyl group was then protected with tert-butyldimethylsilyl chloride to obtain compound 3. Compound 3 was reacted with Lawesson's reagent in ultra-dry toluene to convert the ketone into thioketone to obtain compound 4, which is the rotor part of the motor. Compound 5, i.e., 2-hydroxy-9H-fluorene-9-one, was used as a raw material. The condensation reaction was carried out with hydrazine hydrate to obtain compound 4. A hydrazone compound 6 is obtained, and then the hydrazone compound 6 is oxidized with manganese dioxide to obtain a diazo compound 7 of the stator part of the motor; Compound 4 and Compound 7 are mixed to undergo a coupling reaction to obtain an intermediate ethylene sulfide compound, and then triphenylphosphine is used for desulfurization to obtain molecular motors 8-E and 8-Z; Compound 8-E is deprotected with NaOH to obtain compound 9-E, and the obtained compound 9-E undergoes a bimolecular nucleophilic substitution reaction with 1-bromohexyl alcohol in the presence of potassium carbonate to obtain compound 10-E; finally, compound 10-E undergoes a nucleophilic acyl substitution reaction with acryloyl chloride to obtain the molecular motor M-1;

[0008] S2, performing racemization treatment on the molecular motor M-1 to obtain the racemic molecular motor M-1;

[0009] S3, 3 wt% of racemic molecular motor M-1, 18 wt% of RM 23 liquid crystal monomer, 31 wt% of RM 82 liquid crystal monomer, 46 wt% of RM 105 liquid crystal material monomer and 2 wt% of IRG 819 photoinitiator were mixed, and then 2 mL of dichloromethane solution was added to make the mixture fully dissolved and uniform; then, the mixture was stirred at 40° C. overnight to volatilize the solvent, and a liquid crystal mixture was obtained;

[0010] S4, covering the two glass substrates coated with the photo-alignment agent SD1 with a mask, and then exposing them to 405nm ultraviolet polarized light for the first exposure, so as to generate an alignment layer with a polarization direction parallel to the UV light on the exposed parts of the two glass substrates; then rotating the two glass substrates clockwise, and then covering the exposed parts of the glass substrates during the first exposure with a mask, and performing a second exposure on the unexposed parts during the first exposure; after two exposures, a glass substrate with an alternating arrangement is formed, and the two glass substrates are bonded together with glue of a fixed thickness to form parallel alignment layers in different directions, thereby obtaining a liquid crystal box;

[0011] S5, pour the liquid crystal mixture into the liquid crystal box by capillary adsorption at 80℃, and then cool it to 40℃; 2The liquid crystal is irradiated with a mercury lamp for 5 minutes to polymerize the mixture. The mercury lamp is equipped with a cutoff filter that can only transmit light with a wavelength of 455 nanometers. It is then annealed at 125°C for 10 minutes, cooled to room temperature, and the liquid crystal polymer film is opened to obtain the liquid crystal polymer film. The liquid crystal polymer film is cut along the design direction of the orientation layer to obtain a liquid crystal film of a specific shape.

[0012] Furthermore, in step S3, the racemic molecular motor M-1 contains 1 wt% of (R)-M1 or (S)-M1.

[0013] Preferably, in step S4, each exposure time is 60 seconds.

[0014] Preferably, in step S4, before the second exposure, the two glass substrates are rotated clockwise by an angle of 45°-135°.

[0015] The second technical solution of the present invention is: a programmable light-responsive liquid crystal film prepared by the above method.

[0016] Compared with the prior art, the present invention uses a rotary molecular motor as a molecular photoswitch, which can achieve rapid directional motion after being mixed with liquid crystal monomers and cross-linked; and applies the unique element of dynamic chirality to LCN materials, which helps to collaboratively amplify and directional motion at all length scales; in addition, photolithography technology is combined to pre-arrange the orientation layer of the liquid crystal substrate, allowing LCN materials with different handedness to achieve complex orthogonal spiral motion; the present invention demonstrates how to program the rotational motion of molecular motors in photoresponsive materials, paving the way for the design of advanced responsive and adaptive soft materials and the induction of complex motion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Light-driven rotation of molecular motor M1: (A) the rotation cycle of M-1; (B) the E-M1 part 1 H-NMR graphs before illumination (red curve), after illumination (green curve) and after standing in the dark at room temperature for 2 hours (blue curve); (C) Z-M1 part 1 H-NMR graphs before illumination (red curve), after illumination (green curve) and after standing in the dark at room temperature for 2 hours (blue curve).

[0018] Figure 2 :(A) UV-visible spectrum of Stable-E in dichloromethane (DCM) under UV irradiation (253K, 3.8×10 -5 M); (B) UV-visible spectrum of stabilized-Z in DCM under UV irradiation (253K, 3.8×10 -5M); (C) Circular dichroism spectrum of (S)-M1 in DCM under UV irradiation (253K, 3.8×10 -5 M); (D) Circular dichroism spectrum of (R)-M1 in DCM under UV irradiation (253K, 3.8×10 -5 M).

[0019] Figure 3 : (A) Two-step procedure for preparing the alignment layer. The black arrow indicates the polarization direction of the UV light. Before the second exposure step, the sample was rotated 90°; (B) Light-triggered wave motion of a liquid crystal polymer film; (C) Light-triggered translational motion of a liquid crystal polymer film on a rough surface. The UV light intensity was 100 mW / cm 2 .

[0020] Figure 4 : (A) Chemical structures of (R)- and (S)-M1; (B) Light-triggered twisting of chiral nematic liquid crystal films. When the ribbon contains (S)-M1, the film shows right-handed rotation and vice versa; (C) Two-step procedure for preparing the alignment layer. The black arrow indicates the polarization direction of the UV light. Before the second exposure step, the sample is rotated 90°; (D) Light-triggered biomimetic motion of polymer films with different shapes. The UV light intensity is 230 mW / cm 2 .

[0021] Figure 5 :(A) Left-right, left-right-left, right-left-right and left-right-left-right spiral motions are realized synchronously in a film under UV light; (B) Two-step procedure for preparing the alignment layer, with the black arrow indicating the polarization direction of the UV light; (C) The resulting "V"-shaped film exhibits different spiral motions under light, with the intensity of the UV light being 230 mw / cm 2 . DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0023] Unless otherwise specified, the reagents and raw materials used in the following examples were all commercially available.

[0024] 1) SD1 is a photosensitive azo dye, whose chemical name is sodium 5,5'-((1E,1'E)-(2,2'-disulfonic acid-[1,1'-biphenyl]-4,4'-diyl)bis(diazene-2,1-diyl))bis(2-hydroxybenzoic acid), and is a photoalignment agent. The working principle of the photoalignment agent SD1 involves the change of its molecular structure under ultraviolet light. When SD1 is exposed to ultraviolet light, the conformation of its molecules changes, resulting in changes in the orientation of the molecules. This change can be controlled by the polarization direction and light intensity of ultraviolet light, thereby affecting the arrangement direction of liquid crystal molecules on the surface of the substrate. Therefore, the photoalignment agent SD1 can achieve directional control of liquid crystal molecules according to the characteristics of light, thereby achieving directional orientation of liquid crystal materials.

[0025] Example 1

[0026] Synthesis of molecular motor: Under nitrogen environment, the raw material compound 1, i.e., 6-methoxy-2,4,7-trimethyl-2,3-dihydro-1H-inden-1-one (0.50 g, 2.45 mmol), AlCl3 (1.63 g, 12.25 mmol) and ultra-dry toluene (19 mL) were mixed and condensed and refluxed at 75°C for 3 h to obtain compound 2. Compound 2 (0.37 g, 2.10 mmol) and imidazole (0.50 g, 7.10 mmol) were dissolved in ultra-dry N,N-dimethylformamide (20 mL), and then tert-butyldimethylsilyl chloride (0.86 g, 5.68 mmol) was added to the mixture, and the mixture was stirred at room temperature overnight under nitrogen environment to obtain compound 3. Compound 3 (0.50 g, 1.52 mmol) and Lawesson's reagent (1.39 g, 3.44 mmol) were dissolved in ultra-dry toluene (50 mL), and condensed and refluxed at 110 ° C for 3 h to obtain compound 4 of the rotor part of the motor. Under nitrogen environment, the raw material compound 5, i.e. 2-hydroxy-9H-fluorene-9-one (0.70 g, 2.26 mmol) and hydrazine hydrate (20 mL, 22.60 mmol) were mixed with ethanol (50 mL), and placed at 75 ° C for condensation and reflux for 2 h to obtain compound 6. Then compound 6 (0.70 g, 2.16 mmol) and catalyst manganese dioxide (1.20 g, 13.40 mmol) were mixed with ultra-dry tetrahydrofuran (10 mL), and stirred at room temperature for 2 h to obtain diazo compound 7 of the stator part of the motor. Then the obtained compound 4 and compound 7 were mixed in ultra-dry tetrahydrofuran, heated to 75°C under nitrogen atmosphere, and condensed under reflux for 3 hours; after 3 hours, triphenylphosphine (0.70 g, 2.60 mmol) was added to the mixture, and the mixture was stirred at 75°C overnight to obtain molecular motors 8-E and 8-Z. NaOH (0.14 g, 3.50 mmol) was added to motor 8-E (0.33 g, 0.70 mmol) dissolved in ultra-dry N, N-dimethylformyl (10 mL), and the mixture was stirred at room temperature for 2 hours to obtain compound 9-E. Potassium carbonate (0.20 g, 1.45 mmol), tetrabutylammonium iodide (0.086 g, 0.23 mmol) and 6-bromo-1-hexanol (0.15 mL, 1.16 mmol) were added to a solution of compound 9-E (0.1 g, 0.29 mmol) dissolved in acetonitrile (10 mL); the mixture was stirred overnight at 85 ° C under a nitrogen atmosphere to obtain compound 10-E. At 0 ° C, triethylamine (0.61 mL, 4.4 mmol) and acryloyl chloride (0.04 mL, 0.49 mmol) were added to a solution of 10-E (0.10 g, 0.22 mmol) dissolved in tetrahydrofuran (5 mL), and then the mixture was warmed to room temperature and stirred for 2 h to obtain the final product molecular motor M-1. The specific reaction formula of its synthesis process is as follows:

[0027]

[0028] 2) Adoption 1 H-NMR studies, starting from the stable E-M1, follow the isomerization processes involved in the M-1 rotation, e.g. Figure 1 (A) shows the rotation cycle of M-1 (only one enantiomer is shown here), step 1 and step 3 are photoisomerization processes, and step 2 and step 4 are thermal helical inversion processes; Figure 1 The red curve in (B) shows the fraction of the stable E-isomer in deuterated dichloromethane solution. 1 H-NMR spectrum. The characteristic peaks of the motor part are the signals of aliphatic protons Hb, Hc and Hd, and the proton of the methyl -Me group at the stereo center. The doublet at 2.55ppm is considered to be the signal of the proton Hb, the dd peak at 3.16ppm is the signal of Hc, the multiplet at 3.94ppm is the signal of the proton Hd, and the doublet at 1.29ppm is considered to be the methyl group at the stereo center. The sample was then irradiated at -40°C (λ = 365nm), and obvious changes were observed in the spectrum, indicating the formation of a new unstable isomer Z-M1 ( Figure 1 (B), green curve). The proton Hb shifted from 2.55ppm (doublet) to 2.81ppm (doublet), and 3.36ppm and 6.80ppm are the signals of unstable Z-M1 Hc and Ha. In addition, the signal of the methyl group shifted from 1.29ppm to 1.52ppm, which indicates the conformational change of the methyl group of the stable isomer. When the light was illuminated until there was no obvious change in the hydrogen spectrum, the photostable state (PSS) was obtained. By integration, its ratio was determined to be 85:15 (unstable-Z-M1: stable-E-M1). The sample was placed in the dark at room temperature for 2 hours, which caused further changes in the spectrum ( Figure 1 (B), blue curve), indicating that thermal helix inversion (THI) occurred, and the unstable-Z-M1 transformed into the stable-Z-M1. The Ha signal in the unstable-Z-M1 moved from 6.80ppm to 7.00ppm, indicating the formation of the stable-Z-M1. And the ratio of the stable-Z-M1:stable-E-M1 (85:15) is the same as the ratio of the unstable-Z-M1:stable-E-M1. This confirms the unidirectionality of the unstable Z-M1 thermal isomerization. Under the same conditions, the stable Z-M1 sample also underwent similar changes, such as Figure 1 (C) in.

[0029] 3) The rotational motion of the M-1 motor was further studied using UV-visible spectroscopy and circular dichroism. At 253K, the UV / visible absorption spectrum of the steady-state E-M1 (3.8×10-5M) dissolved in dichloromethane (DCM) under UV irradiation showed an absorption band centered at 380nm ( Figure 2 (A), black curve); The UV / visible absorption spectra of both the steady-state-E-M1 and the steady-state-Z-M1 in CH2Cl2 at 253K show an absorption band centered at 380nm ( Figure 2 (B) and (C), black curves). After UV light (λmax = 365 nm) was irradiated on both samples, the absorption band at 380 nm red-shifted to 410 nm, indicating that the photochemically induced formation of an unstable isomer ( Figure 2 (B) and (C), red curves). The sample undergoes a thermal helical inversion step in the dark to form the corresponding stable isomers and restore the original absorption.

[0030] 4) 3 wt % of the racemic molecular motor M-1, 18 wt % of the RM 23 liquid crystal monomer, 31 wt % of the RM 82 liquid crystal monomer, 46 wt % of the RM 105 liquid crystal material monomer and 2 wt % of the IRG 819 photoinitiator were mixed, and then 2 mL of dichloromethane solution was added to fully dissolve the mixture; then, the mixture was stirred at 40° C. overnight to evaporate the solvent, to obtain a liquid crystal mixture;

[0031] 5) Cover the two glass substrates coated with the photo-alignment agent SD1 with a mask, and then expose them to 405nm ultraviolet polarized light for the first exposure to generate an alignment layer with a polarization direction parallel to the UV light on the exposed parts of the two glass substrates; then rotate the two glass substrates 90° clockwise, and then cover the exposed parts of the glass substrates during the first exposure with a mask, and expose the unexposed parts during the first exposure for the second time; after two exposures, a glass substrate with alternating vertical arrangement is formed, and the two glass substrates are bonded together with 20μm thick glue to form a liquid crystal box, as shown in the schematic diagram Figure 3 As shown in (A);

[0032] 6) The liquid crystal mixture was poured into the liquid crystal cell at 80°C by capillary adsorption, and then cooled to 40°C; 2 The mixture was polymerized by irradiating the liquid crystal with a mercury lamp for 5 minutes. The mercury lamp was equipped with a cut-off filter that could only transmit light with a wavelength of 455 nanometers. The mixture was then annealed at 125°C for 10 minutes, cooled to room temperature, and the liquid crystal polymer film was opened to obtain the liquid crystal polymer film. The liquid crystal polymer film was cut along the design direction of the orientation layer to obtain a liquid crystal film of a specific shape (0.5×3 cm 2 ),like Figure 3As shown in (A), the liquid crystal film (0.5×3cm 2 ) is twisted; the cut liquid crystal film (0.5×3cm 2 ) are irradiated with ultraviolet light separately. When irradiated, they bend toward or against the light source and return to their original positions immediately after the light is turned off. Figure 3 As shown in (B) in FIG. 1 , the first and third parts of the film strip are bent toward the light, while the second and fourth parts are bent against the light. Subsequently, it is placed on a rough surface and then irradiated with ultraviolet light from front to back, by alternately undulating toward or against the surface, as shown in FIG. Figure 3 As shown in (C) in the figure, the liquid crystal film can move forward in one direction at a speed of 3.5 cm / min.

[0033] Example 2

[0034] The difference from Example 1 is that the racemic molecular motor M-1 contains 1 wt% of (R)-M1 or (S)-M1. Due to its special axial chirality, the molecular motor is an excellent chiral dopant for producing a cholesteric phase, and can therefore induce spiral motion in LCN. A chiral liquid crystal mixture is filled into a parallel-oriented liquid crystal box to prepare a chiral nematic liquid crystal film. When the liquid crystal film strips cut along the orientation direction are irradiated with ultraviolet light, the film containing (R)-M1 shows left-handed spiral motion, while the film containing (S)-M1 shows right-handed spiral motion, as shown in FIG. Figure 4 As shown in (B) in .

[0035] Example 3

[0036] The difference from Example 1 is that the racemic molecular motor M-1 contains 1 wt% (R)-M1 or (S)-M1. In order to achieve more complex spiral motion, a liquid crystal cell with a "programmable" alignment layer was prepared to precisely control the deformation of the liquid crystal film.

[0037] (a) “Windmill” shaped liquid crystal film

[0038] The glass substrate spin-coated with SD1 was exposed to 405nm ultraviolet polarized light by the mask method. After the first exposure, the polarized light and the mask were rotated 90° clockwise, and the glass substrate was exposed for the second time, with each exposure time of 60s. The two layers of glass substrates were then bonded together with a fixed thickness of 50μm to form parallel alignment layers in different directions. The chiral liquid crystal mixture was filled into the liquid crystal box, and a chiral nematic liquid crystal film was obtained after polymerization. The liquid crystal film was cut along the "designed" direction of the alignment layer to obtain a "cross" shaped liquid crystal film. Under irradiation of 365nm, the rotation of the chiral motor and the change in helicity induced the LCN liquid crystal film to undergo curling, bending or folding motion. The film containing (R)-M1 showed a left-handed spiral pinwheel shape, while the film containing (S)-M1 showed a right-handed spiral pinwheel shape, such as Figure 4 As shown in (D) in .

[0039] (b) Liquid crystal film in the shape of a flower

[0040] Through the mask method, the glass substrate spin-coated with SD1 was exposed to 405nm ultraviolet polarized light. After the first exposure, the linearly polarized light and the mask were rotated clockwise by 45°, 90° and 135°, and then the glass substrate was exposed in sequence, with each exposure time of 60 seconds. The two glass substrates obtained were bonded together with glue of a fixed thickness of 50 microns to form a liquid crystal box with planar arrangements in different directions. Similarly, the chiral liquid crystal mixture was filled into the liquid crystal box, and the sample was cured by ultraviolet light to form a liquid crystal polymer film. The sample was cut along the "designed" direction of the orientation layer to obtain a "M" shaped liquid crystal film. Under irradiation of 365nm, the film containing (R)-M1 showed a left-handed spiral flower shape, while the film containing (S)-M1 showed a right-handed spiral flower shape, such as Figure 4 As shown in (D) in .

[0041] Example 4

[0042] The difference from Example 1 is that the racemic molecular motor M-1 contains 1 wt% (R)-M1 or (S)-M1. The simultaneous expression of multiple chiralities is achieved by single wavelength irradiation:

[0043] (a) Imitating the winding vines of plants in nature

[0044] Tendrils usually perform complex synchronized spiral motions to support themselves, so here we mimic the strips of tendrils in nature to achieve multiple different spiral motions. Chiral liquid crystal mixtures containing (R) or (S)-M1 are alternately filled from the same side of a parallel-oriented liquid crystal cell. Due to the high viscosity of the liquid crystal mixture, the influence of diffusion is small within a certain time range. After polymerization, we can obtain liquid crystal films with chiral sequences of (R)-(S), (S)-(R)-(S), (R)-(S)-(R), and (R)-(S)-(R)-(S). Under UV irradiation, multiple spiral motions can be observed in different regions of the film. For the first time, synchronized left-right, left-right-left, right-left-right, and left-right-left-right-right motions can be achieved in a film by single-wavelength irradiation, such as Figure 5 As shown in (A) in .

[0045] (b) “V” shaped liquid crystal film

[0046] We combined the simultaneous expression of multiple chiralities with simple photolithography to construct a complex liquid crystal actuator. Similarly, using the mask method, the glass substrate was exposed to 405nm linearly polarized light. After the first exposure, the glass substrate was rotated 60° clockwise and exposed for the second time. Figure 5 As shown in (B) in the figure. The two obtained glass substrates were bonded together with a fixed thickness of 50 μm to obtain a liquid crystal box with a special orientation. The liquid crystal mixture containing different chiral motors was alternately filled into the liquid crystal box at 80°C and then cooled to 40°C. The sample was polymerized with 455nm light at this temperature. After the polymer films were formed, they were cut along the "predetermined" direction of the orientation layer. The "V"-shaped polymer films selectively move "inward" or "outward" according to the chiral order (R)-(S) or (S)-(R) filled in the molecular motor M1, as shown in FIG. Figure 5 As shown in (C) in .

[0047] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a programmable light-responsive liquid crystal film, characterized in that: The following steps are involved: S1. Compound 1, i.e., 6-methoxy-2,4,7-trimethyl-2,3-dihydro-1H-inden-1-one, was used as a raw material. The methoxy group in 6-methoxy-2,4,7-trimethyl-2,3-dihydro-1H-inden-1-one was reduced to a phenolic hydroxyl group with AlCl3 to obtain compound 2. The phenolic hydroxyl group was then protected with tert-butyldimethylsilyl chloride to obtain compound 3. Compound 3 was reacted with Lawesson's reagent in ultra-dry toluene to convert the ketone into thioketone to obtain compound 4, which is the rotor part of the motor. Compound 5, i.e., 2-hydroxy-9H-fluorene-9-one, was used as a raw material. The condensation reaction was carried out with hydrazine hydrate to obtain compound 4. A hydrazone compound 6 is obtained, and then the hydrazone compound 6 is oxidized with manganese dioxide to obtain a diazo compound 7 of the stator part of the motor; Compound 4 and Compound 7 are mixed to undergo a coupling reaction to obtain an intermediate ethylene sulfide compound, and then triphenylphosphine is used for desulfurization to obtain molecular motors 8-E and 8-Z; Compound 8-E is deprotected with NaOH to obtain compound 9-E, and the obtained compound 9-E undergoes a bimolecular nucleophilic substitution reaction with 1-bromohexyl alcohol in the presence of potassium carbonate to obtain compound 10-E; finally, compound 10-E undergoes a nucleophilic acyl substitution reaction with acryloyl chloride to obtain the molecular motor M-1; S2, performing racemization treatment on the molecular motor M-1 to obtain the racemic molecular motor M-1; S3, 3 wt% of racemic molecular motor M-1, 18 wt% of RM 23 liquid crystal monomer, 31 wt% of RM 82 liquid crystal monomer, 46 wt% of RM 105 liquid crystal material monomer and 2 wt% of IRG 819 photoinitiator were mixed, and then 2 mL of dichloromethane solution was added to make the mixture fully dissolved and uniform; then, the mixture was stirred at 40° C. overnight to volatilize the solvent, and a liquid crystal mixture was obtained; S4, covering the two glass substrates coated with the photo-alignment agent SD1 with a mask, and then exposing them to 405nm ultraviolet polarized light for the first exposure, so as to generate an alignment layer with a polarization direction parallel to the UV light on the exposed parts of the two glass substrates; The two glass substrates are then rotated clockwise, and then the exposed portion of the glass substrate during the first exposure is covered with a mask, and the portion not exposed during the first exposure is exposed for the second time; after two exposures, a glass substrate with an alternating arrangement is formed, and the two glass substrates are bonded together with glue of a fixed thickness to form parallel alignment layers in different directions, thereby obtaining a liquid crystal box; S5, pour the liquid crystal mixture into the liquid crystal box by capillary adsorption at 80℃, and then cool it to 40℃; 2 The liquid crystal is irradiated with a mercury lamp for 5 minutes to polymerize the mixture. The mercury lamp is equipped with a cutoff filter that can only transmit light with a wavelength of 455 nanometers. It is then annealed at 125°C for 10 minutes, cooled to room temperature, and the liquid crystal polymer film is opened to obtain the liquid crystal polymer film. The liquid crystal polymer film is cut along the design direction of the orientation layer to obtain a liquid crystal film of a specific shape.

2. The method for preparing a programmable light-responsive liquid crystal film according to claim 1, characterized in that: In the step S3, the racemic molecular motor M-1 contains 1 wt% of (R)-M1 or (S)-M1.

3. The method for preparing a programmable light-responsive liquid crystal film according to claim 1 or 2, characterized in that: In step S4, each exposure time is 60 seconds.

4. The method for preparing a programmable light-responsive liquid crystal film according to claim 1 or 2, characterized in that: In the step S4, before the second exposure, the two glass substrates are rotated clockwise by an angle of 45°-135°.

5. A programmable light-responsive liquid crystal film prepared by the method according to any one of claims 1 to 4.

Images