Multi-order encryption method and decryption method based on liquid crystal elastomer and storage medium

Abstract

The present application relates to a kind of multi-order encryption method based on liquid crystal elastomer, decryption method and storage medium, multi-order encryption method includes: the mixed solution for preparing liquid crystal elastomer is injected into transparent container, in the polymerization process of mixed solution, at least two kinds of intensity of electric field are loaded in the internal space of the transparent container in turn;During the loading process of each intensity of electric field, the mask corresponding to the hollow pattern is covered in the preset area outside the transparent container and is carried out first ultraviolet exposure, to carry out partial polymerization to the mixed solution under the hollow pattern, the information carried by the mask is written in the encryption exposure area corresponding to the mixed solution;The hollow pattern of the mask carries the information to be encrypted;Remove mask and electric field, make the mixed solution of non-encryption region into isotropic, carry out second ultraviolet exposure to the mixed solution in the transparent container as a whole, obtain the liquid crystal elastomer of overall polymerization.The liquid crystal elastomer of the present application can realize multi-order encryption.

Description

Technical Field

[0001] This invention relates to the field of data encryption and storage technology, and in particular to a multi-level encryption method based on liquid crystal elastomers, a multi-level decryption method based on liquid crystal elastomers, and an encrypted storage medium. Background Technology

[0002] With the rapid development of information technologies such as the Internet of Things and 5G networks, people's lives have entered a new information age. The explosive increase in information volume means that more and more people are facing the risk of information leakage, posing increasing challenges to technologies such as information encoding, encryption, and storage. In recent years, significant efforts have been made to develop advanced anti-counterfeiting materials and corresponding information encryption technologies. By combining multiple anti-counterfeiting technologies or multiple triggers for decryption (such as light, temperature, and humidity), information becomes more difficult to copy, thereby improving security levels and avoiding the threats of false information and information leakage. However, integrating different types of anti-counterfeiting materials into a single system requires complex assembly methods, and different anti-counterfeiting materials are prone to interference. Furthermore, complex decryption operations typically require expensive, large-scale decryption equipment. Therefore, achieving ideal multi-level anti-counterfeiting and encryption technologies remains a challenge.

[0003] Liquid crystal elastomers, as programmable, multi-stimulus responsive, and reversible polymeric soft matter materials, are showing broad application prospects in soft robotics, soft actuators, flexible electronic devices, and soft photonics devices. Liquid crystal elastomers combine the anisotropy of liquid crystals with the elasticity of elastomers, responding to various external stimuli such as stress, heat, light, and electricity. These properties make them one of the most promising candidate materials for data storage and encryption. However, current information encryption and storage in liquid crystal elastomers mostly rely on their reversible shape or structural color changes, failing to achieve multi-level encryption of information.

[0004] The principle of information encryption and storage in liquid crystal elastomers is generally based on the self-phase transition or the change in the orientation order of mesocrystalline molecules during the self-driven process of the liquid crystal elastomer. One technology utilizes the transformation from multiple domains to a single domain as the liquid crystal domains macroscopically align along the stretching direction, causing the liquid crystal element to become transparent; and the transformation from opaque to transparent when the liquid crystal elastomer undergoes a nematic-to-isotropic phase transition, thus achieving information storage and display. Another technology uses the interference colors formed by the changes in the thickness and refractive index of the liquid crystal elastomer during the stretching and orientation of liquid crystal molecules to achieve information encryption and storage. However, the information storage process of the above-mentioned technologies is complex, the information storage capacity is low, the information format is limited, and the resolution and contrast of the information display are poor, making it difficult to effectively guarantee information security. Yet another technology uses laser direct writing to control the breaking and healing of active bonds within the liquid crystal elastomer to achieve high-resolution information encryption and storage based on the multi-domain to isotropic transition. Although this technology has high precision, the equipment is complex and expensive, and it cannot be fabricated on a large scale, hindering mass production.

[0005] Another technology for information encryption and storage utilizes the fluorescence properties of liquid crystal elastomers combined with their programmable deformation to achieve the storage of fluorescent information and the physical obscuring of the information. However, this technology has a complex preparation process, severely impacts the environment, and is inconvenient to operate; the information format is limited, the storage capacity is low, the decryption excitation conditions are complex, and information security cannot be guaranteed. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a multi-level encryption method, decryption method and storage medium based on liquid crystal elastomers, which solves the technical problem that existing liquid crystal elastomers cannot achieve multi-level encryption.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, embodiments of the present invention provide a multi-level encryption method based on liquid crystal elastomers, comprising:

[0011] The mixture used to prepare the liquid crystal elastomer is injected into a light-transmitting container. During the polymerization process of the mixture, at least two electric fields of different intensities are applied to the internal space of the light-transmitting container.

[0012] During the electric field loading process of each intensity, a mask with a corresponding hollow pattern is used to cover a preset area on the outside of the light-transmitting container and a first ultraviolet exposure is performed to partially polymerize the mixture below the hollow pattern, and the information carried by the mask is written into the encrypted exposure area corresponding to the mixture; the hollow pattern of the mask carries information to be encrypted.

[0013] Multiple electric fields of varying intensities correspond one-to-one with multiple photomasks. During the loading of electric fields of varying intensities, the information to be encrypted carried by the corresponding photomask is written into the mixture, forming a multi-level encryption of the information to be encrypted.

[0014] The mask and electric field are removed to transform the mixture in the unencrypted region into an isotropic mixture. The mixture in the transparent container is then subjected to a second ultraviolet exposure to obtain a monolithically polymerized liquid crystal elastomer.

[0015] Optionally, injecting the mixture used to prepare the liquid crystal elastomer into the light-transmitting container includes:

[0016] The light-transparent container is a box with a first side and a second side facing each other, and both the first side and the second side are conductive glass. The conductive layer of the conductive glass faces the inside of the box and has an orientation layer.

[0017] Optionally, at least two different intensities of electric field are applied sequentially to the internal space of the light-transmitting container, including:

[0018] The conductive layers of the two conductive glass pieces are connected to a voltage source respectively. By adjusting the preset voltage values ​​applied to the two conductive layers, the electric field strength applied to the internal space of the box can be adjusted.

[0019] Optionally, the preset voltage value ranges from [0V] to [0V]. rms 2V rms ].

[0020] Optionally, the step of injecting the mixture used to prepare the liquid crystal elastomer into the light-transmitting container further includes:

[0021] The mixture comprises: liquid crystal polymer monomer A6OCB, liquid crystal monomer 6OCB, plasticizer EHA, crosslinking agent RM82 and photoinitiator MBF.

[0022] Optionally, the mole fractions of each component in the mixture are as follows:

[0023] Liquid crystal polymer monomer A6OCB: 20-28 mol%, liquid crystal monomer 6OCB: 50-60 mol%, plasticizer EHA: 1-1.4 mol%, crosslinking agent RM82: 2-5 mol%, photoinitiator MBF: 1-2 mol%.

[0024] Optionally, the exposure time for both the first and second ultraviolet exposures is 20–40 minutes, and the ultraviolet light intensity is 8–12 mW / cm². 2 .

[0025] Secondly, embodiments of the present invention provide a multi-level decryption method based on liquid crystal elastomers, including:

[0026] Stretching is performed in a direction perpendicular to the orientation of the mesocrystalline molecules of the liquid crystal elastomer, causing the encrypted exposure area of ​​the liquid crystal elastomer to generate a tensile threshold strain, forming a dark region corresponding to the cutout pattern of the mask under orthogonal polarization. Furthermore, as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure area formed by the polymerization of the liquid crystal elastomer under at least two intensities of electric field darkens successively, thereby reading out the information to be encrypted written in the liquid crystal elastomer in stages and completing the multi-level decryption of the information carried by the liquid crystal elastomer.

[0027] The liquid crystal elastomer is a liquid crystal elastomer obtained through a multi-stage encryption method.

[0028] Optionally, the multi-level decryption method further includes: stretching the liquid crystal elastomer in a direction perpendicular to the orientation of the mesocrystalline molecules, causing the encrypted exposure region of the liquid crystal elastomer to generate a tensile threshold strain. Due to the tensile response, the encrypted exposure region forms a protrusion with a thickness greater than that of the unencrypted exposure region. Furthermore, as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure region of the liquid crystal elastomer aggregated under at least two electric fields of different intensities protrudes successively, forming multi-level three-dimensional tactile information, so as to decrypt the information carried by the liquid crystal elastomer from the three-dimensional tactile direction.

[0029] And / or, the multi-level decryption method is a method for decrypting the liquid crystal elastomer prepared by the multi-level encryption method described in the first aspect.

[0030] Thirdly, embodiments of the present invention provide an encrypted storage medium, wherein the encrypted storage medium is a liquid crystal elastomer prepared using the multi-level encryption method described in the first aspect.

[0031] (III) Beneficial Effects

[0032] The multi-level encryption method proposed in this invention involves sequentially applying at least two intensities of electric fields to the internal space of a transparent container during the polymerization process of a mixture. During each electric field intensity application, a mask with a corresponding perforated pattern is used to cover a predetermined area on the outside of the transparent container and subjected to a first ultraviolet exposure to partially polymerize the mixture below the perforated pattern. The information carried by the mask is then written into the corresponding encryption exposure area of ​​the mixture. The perforated pattern of the mask carries the information to be encrypted. Multiple electric fields of varying intensities correspond one-to-one with multiple masks. During different electric field intensities, the information to be encrypted carried by the corresponding mask is written into the mixture, forming a multi-level encryption of the information to be encrypted.

[0033] In other words, the multi-level encryption method proposed in this invention, during the polymerization process of liquid crystal mixture, configures electric fields of different intensities and masks corresponding to those electric fields, so that the information to be encrypted carried by different masks is written into the same liquid crystal elastomer obtained in stages, thereby achieving multi-level encryption of information.

[0034] Furthermore, the multi-level encryption method provided by this invention can be applied to information display devices such as binary signals and tactile Braille, greatly simplifying the preparation process of traditional information anti-counterfeiting materials, improving the storage capacity and security of information, with lower cost and easier operation. Combined with traditional LCD panel production processes, it can achieve mass production. Attached Figure Description

[0035] Figure 1 A flowchart illustrating a multi-level encryption method based on liquid crystal elastomers provided in this embodiment;

[0036] Figure 2 A schematic diagram of the process for preparing a liquid crystal elastomer with intrinsic tensile response provided for the embodiments;

[0037] Figure 3 (a) is a polarization optical microscopy image of the mesocrystalline molecules of the liquid crystal elastomer orthogonal to the analyzer when the liquid crystal elastomer with intrinsic tensile response provided in the embodiment reaches the tensile strain threshold.

[0038] Figure 3 (b) is a schematic diagram showing the change of strain in the thickness direction with tensile strain during the entire stretching process of the liquid crystal elastomer with intrinsic tensile response provided in the embodiment.

[0039] Figure 4 This is a flowchart illustrating a multi-level encryption method based on liquid crystal elastomers provided in the embodiments;

[0040] Figure 5A schematic diagram illustrating the process and effect of a multi-level encryption method for two-dimensional information based on a liquid crystal elastomer and a corresponding decryption method, provided for an embodiment;

[0041] Figure 6 This is a schematic diagram illustrating the process and effect of a multi-level encryption method for three-dimensional information based on liquid crystal elastomers and a corresponding decryption method, provided as an embodiment. Detailed Implementation

[0042] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Intrinsically swellable liquid crystal elastomers without electrical charge exhibit swelling. When mechanically stretched in a direction perpendicular to the orientation of the mesocrystalline molecules, the thickness of the liquid crystal elastomer first thins and then thickens in the direction perpendicular to both the mesocrystalline molecular orientation and the mechanical stretching direction, eventually returning to its initial thickness. This strain level at which a swelling response begins is called the swelling threshold strain. At the swelling threshold strain, the liquid crystal elastomer is optically isotropic and opaque under crossed polarizers. However, at strains less than or greater than the swelling threshold strain, the liquid crystal elastomer is transparent. Under electrical charge, the mesocrystalline molecules in the charged region undergo a Frédericks transition due to the voltage. As the voltage increases, the swelling response of the polymerized intrinsically swellable liquid crystal elastomer exhibits hysteresis, the swelling threshold strain increases, and the liquid crystal elastomer requires a larger strain to return to its initial thickness. In contrast, isotropic liquid crystal elastomers do not exhibit a swelling response during stretching.

[0044] The multi-level encryption method, multi-level decryption method, and encrypted storage medium provided by this invention, based on the aforementioned tensile response of liquid crystal elastomers and the Friedrich's phase transition effect under energized conditions, allow for the fabrication of liquid crystal elastomers by combining the cutout design of the mask with the selection of the electric field strength. When the cutout pattern of the mask is a binary pattern, the liquid crystal elastomer can be used for binary information transmission and Braille information display devices.

[0045] To prepare the aforementioned liquid crystal elastomer carrying multi-level encryption information, a liquid crystal cell with a fixed thickness and double-sided alignment layers was first prepared. A liquid crystal elastomer precursor solution (also called a mixture) containing liquid crystal polymer monomers, unreacted liquid crystal monomers, a crosslinking agent, a photoinitiator, and a plasticizer was added. Subsequently, the cell was subjected to regional ultraviolet exposure using an exposure mask under an electric field to write information. Different voltages during polymerization represented different stages of information. After all information was written, the liquid crystal cell was heated above its phase transition temperature and fully exposed, ultimately yielding a liquid crystal elastomer device for multi-dimensional information encryption and storage. After polymerization, the liquid crystal cell was opened, and the liquid crystal elastomer was peeled off from the liquid crystal cell substrate. Unreacted liquid crystal monomers were washed away, resulting in a stretchable liquid crystal elastomer storing multi-level encryption information.

[0046] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0047] Example 1

[0048] like Figure 1 and 4 As shown, this embodiment provides a multi-level encryption method based on liquid crystal elastomers, including steps S1 to S3:

[0049] S1. Inject the mixture used to prepare the liquid crystal elastomer into a light-transmitting container.

[0050] Specifically, the light-transmitting container may be a liquid crystal cell, which includes a cell body with a first side and a second side disposed opposite to each other, and both the first side and the second side are conductive glass, with the conductive layer of the conductive glass facing the inside of the cell body and having an alignment layer.

[0051] The specific combination and ratio of the liquid crystal elastomer mixture can be set as follows: liquid crystal polymer monomer A6OCB: 20-28 mol%, liquid crystal monomer 6OCB: 50-60 mol%, plasticizer EHA: 1-1.4 mol%, crosslinking agent RM82: 2-5 mol%, photoinitiator MBF: 1-2 mol%.

[0052] S2. During the polymerization process of the mixture, at least two electric fields of different intensities are applied sequentially to the internal space of the transparent container.

[0053] During the electric field loading process of each intensity, a mask with a corresponding hollow pattern is used to cover a preset area on the outside of the light-transmitting container and a first ultraviolet exposure is performed to partially polymerize the mixture below the hollow pattern, and the information carried by the mask is written into the encrypted exposure area corresponding to the mixture; the hollow pattern of the mask carries the information to be encrypted.

[0054] Multiple electric fields of varying intensities correspond one-to-one with multiple photomasks. During the loading of electric fields of different intensities, the information to be encrypted carried by the corresponding photomask is written into the mixture, forming a multi-level encryption of the information to be encrypted.

[0055] S3. Remove the mask and electric field to transform the mixture in the non-encrypted area into an isotropic mixture. Then, expose the mixture in the transparent container to ultraviolet light for a second time to obtain a monolithically polymerized liquid crystal elastomer.

[0056] The multi-level encryption method proposed in this embodiment achieves multi-level encryption of information by configuring electric fields of different intensities and masks corresponding to those electric fields during the first ultraviolet exposure process of the liquid crystal mixture. This allows the information to be encrypted carried by different masks to be written into the liquid crystal elastomer in stages. Based on the liquid crystal cell electro-exposure process, and combined with the selection of the electric field intensity in the transparent container and the design of the exposure mask, two or more levels of information encryption and storage can be achieved. The multi-level encryption method provided in this embodiment can be applied to information display devices such as binary signals and tactile Braille, greatly simplifying the preparation process of traditional information anti-counterfeiting materials, improving the storage capacity and security of information, reducing costs, and making it easier to operate. Combined with traditional liquid crystal panel production processes, it can achieve mass production.

[0057] Example 2

[0058] To verify the effect of different electric field strengths on the performance of the liquid crystal elastomer provided in this embodiment, this embodiment first conducts experiments and explanations on the properties of liquid crystal elastomers with intrinsic tensile response formed by polymerization under different electric field strengths.

[0059] like Figure 2 and 3 As shown, the steps are as follows:

[0060] 101. Preparation of four liquid crystal cells: Two 5cm × 2cm indium tin oxide conductive glass substrates were ultrasonically cleaned. After hydrophilic treatment, a 1wt% polyvinyl alcohol (PVA) aqueous solution was spin-coated as an alignment layer at 4500 rpm for 60 seconds. After baking at 100℃ for 10 minutes, the substrates were rubbed for alignment at 1000 rpm. A 100μm thick PET plastic film was sandwiched between the edges of the two conductive glass substrates to ensure an internal height of 100μm for the liquid crystal cells. Adhesive was used to bond the two conductive glass substrates together to ensure a strong bond.

[0061] 102. A liquid crystal elastomer mixture containing liquid crystal polymer monomer A6OCB, liquid crystal monomer 6OCB, plasticizer EHA, crosslinking agent RM82 and photoinitiator MBF is mixed, with molar fractions of 24.4 mol%, 54.6 mol%, 1.16 mol%, 3.5 mol% and 1.5 mol%, respectively, and the mixture is poured into a liquid crystal cell at 50°C.

[0062] It should be noted that since the internal space formed by the two conductive glass pieces is only 100μm, the above-mentioned method of filling the liquid crystal cell can be specifically as follows: use a pipette to draw a certain amount of the mixture and apply it to the gap between the two conductive glass pieces. The mixture can enter the internal space of the liquid crystal cell under capillary action.

[0063] 103. After the mixture returned to room temperature, electric fields of different intensities were applied to the four liquid crystal cells, and they were then subjected to ultraviolet light for polymerization. The electric field intensities applied to the four liquid crystal cells were 0V and 0V respectively. rms 1.2V rms 1.4V rms 1.6V rms The exposure time for ultraviolet light was 20–40 minutes, and the ultraviolet light intensity was 8–12 mW / cm². 2 This allows the mixture in the liquid crystal cell to polymerize and form a liquid crystal elastomer. More preferably, the ultraviolet light intensity is 10 mW / cm². 2 The exposure time for all samples was 30 minutes.

[0064] Specifically, the conductive layers of the two conductive glass pieces can be connected to a voltage source respectively, and the electric field strength applied to the internal space of the box can be adjusted by adjusting the preset voltage values ​​applied to the two conductive layers.

[0065] 104. Open the liquid crystal cell, peel the liquid crystal elastomer from the conductive glass substrate, and clean away the unreacted 6OCB to obtain a liquid crystal elastomer with intrinsic tensile response.

[0066] 105. Optical and mechanical characterization of intrinsically swellable liquid crystal elastomers prepared under different polymerization conditions.

[0067] Specifically, the four liquid crystal elastomers mentioned above are mechanically stretched in a direction perpendicular to the orientation of their mesocrystalline molecules.

[0068] like Figure 3 As shown, during the mechanical stretching process, for an electric field strength of 0V... rms The liquid crystal elastomer polymerized under certain conditions has a tensile threshold strain of ~60% (i.e., when the ratio of the deformation of the liquid crystal elastomer to its initial length under zero mechanical tension is approximately 60%, the liquid crystal elastomer exhibits a tensile response). At the ~60% strain, the liquid crystal elastomer exhibits a dark state under orthogonal polarizers. From Figure 3 (b) It can be seen that when the strain exceeds 60%, the stretched liquid crystal elastomer begins to thicken, and its thickness gradually recovers to the initial thickness. Experiments show that the tensile threshold strain at which a tensile response begins to appear increases continuously with the increase of the applied electric field strength during the first ultraviolet exposure process. When the electric field strength increases to 1.2V during the first ultraviolet exposure process... rms At this point, the tensile threshold strain is ~80%; when increased to 1.4V... rms At that time, this value was ~90%; while when increased to 1.6V... rms At this point, the tensile threshold strain will become ~100%.

[0069] Example 3

[0070] Based on Embodiments 1 and 2, this embodiment provides a specific multi-level encryption method and a corresponding multi-level decryption method for liquid crystal elastomers, such as... Figure 4 and 5 As shown, the specific steps include:

[0071] 201. The mixture used to prepare the liquid crystal elastomer is injected into the liquid crystal cell.

[0072] The mixture is the same as the mixture provided in Example 2, and the liquid crystal cell is the same as the liquid crystal cell provided in Example 2.

[0073] 202. During the first ultraviolet exposure of the mixture, at least two electric fields of varying intensities are applied sequentially to the internal space of the liquid crystal cell. During each electric field application process, a mask with a corresponding perforated pattern is used to cover a predetermined area on the outside of the transparent container and subjected to the first ultraviolet exposure to partially polymerize the mixture below the perforated pattern. The information carried by the mask is written into the encrypted exposure area corresponding to the mixture; the perforated pattern of the mask carries information to be encrypted.

[0074] Preferably, the conductive layers of the two conductive glass pieces are respectively connected to a voltage source. By adjusting the preset voltage values ​​applied to the two conductive layers, the electric field strength applied to the internal space of the box is adjusted. The preset voltage values ​​range from [0V] to [0V].rms 2V rms ].

[0075] Specifically, such as Figure 5 As shown, the information to be written into the liquid crystal elastomer is a 3×3 square hole array pattern. In order to perform multi-level encryption, the 3×3 square hole array pattern can be divided into a first mask with three holes cut out in the lower left corner, a first mask with three holes cut out in the diagonal, and a third mask with three holes cut out in the upper right corner.

[0076] First, apply a strength of 0V to the liquid crystal cell. rms An electric field is applied to cover the top surface of the liquid crystal cell with a first mask, while ultraviolet exposure is performed simultaneously, causing the mixture corresponding to the cutout positions of the first mask to polymerize; then, an electric field of 1.2V is applied to the liquid crystal cell. rms An electric field is applied to cover the top surface of the liquid crystal cell with a second mask, while simultaneously performing ultraviolet exposure to cause the mixture corresponding to the cutout positions of the second mask to polymerize; then, an electric field of 1.6V is applied to the liquid crystal cell. rms An electric field is applied to cover the top surface of the liquid crystal cell with a third mask, while ultraviolet exposure is performed simultaneously, causing the mixture corresponding to the cutout positions of the third mask to polymerize.

[0077] The exposure time for the ultraviolet exposure in step 202 is 30 minutes, and the ultraviolet light intensity is 10 mW / cm². 2 .

[0078] 203. Remove all masks and electric fields. Place the liquid crystal cell on a 60°C hot stage to convert the non-encrypted exposure areas of the liquid crystal elastomer (excluding the information areas) into isotropic regions. Perform a second ultraviolet exposure on the entire mixture within the liquid crystal cell to obtain a monolithically polymerized liquid crystal elastomer. The ultraviolet exposure time is 30 minutes, and the ultraviolet light intensity is 10 mW / cm². 2 .

[0079] 204. Open the liquid crystal cell, peel the liquid crystal elastomer from the conductive glass substrate, and clean away the unreacted 6OCB to obtain a liquid crystal elastomer for writing information in three stages.

[0080] like Figure 5 As shown, for the liquid crystal elastomer carrying multi-level encrypted two-dimensional information prepared in steps 201 to 204 above, the corresponding multi-level decryption methods include:

[0081] Stretching is performed in a direction perpendicular to the orientation of the mesocrystalline molecules of the liquid crystal elastomer, causing the encrypted exposure area of ​​the liquid crystal elastomer to generate a tensile threshold strain, forming a dark region corresponding to the cutout pattern of the mask under orthogonal polarization. Furthermore, as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure area formed by the polymerization of the liquid crystal elastomer under at least two intensities of electric field darkens successively, thereby reading out the information to be encrypted written in the liquid crystal elastomer in stages and completing the multi-level decryption of the information carried by the liquid crystal elastomer.

[0082] The multi-level encryption method provided in this embodiment relies on the angle between the orientation direction of the mesonic molecules in the liquid crystal elastomer and the direction of the mechanical tension during decryption for information security. Information can only be correctly decrypted when both are orthogonal. Specifically, for the liquid crystal elastomer carrying multi-level encryption information, the liquid crystal elastomer prepared in steps 201 to 204 is sheet-like, with the orientation of the mesonic molecules perpendicular to the surface of the sheet-like liquid crystal elastomer. Therefore, the stretching direction during decryption is parallel to the surface of the liquid crystal elastomer.

[0083] As measured in Example 2, the above-mentioned liquid crystal elastomer at 0V rms 1.2V rms 1.6V rms After polymerization under an electric field strength, the corresponding tensile strain thresholds are ~60%, ~80%, and ~100%, respectively. Therefore, tensile forces can be applied to the liquid crystal elastomer to make its strain reach ~60%, ~80%, and ~100%, respectively. Dark areas corresponding to the patterns on the first mask, second mask, and third mask can be read on the liquid crystal elastomer, thereby realizing multi-level decryption of the liquid crystal elastomer.

[0084] Based on the above multi-level encryption and decryption methods, various forms of encryption can actually be achieved by combining the cutout pattern of the mask, the electric field strength applied during the first ultraviolet exposure process, and the order of writing in the polymerization stage, so as to improve the security of information.

[0085] For example, the information to be encrypted can be divided into three parts and written into the liquid crystal elastomer in stages under different electric field intensities according to a pre-agreed order; the information to be encrypted can be placed in only one of the three masks corresponding to different electric field intensities, while interference information is placed in the other two masks to improve information security; the information to be encrypted can be digitally encrypted using a codebook (e.g., Braille information) or an existing encryption algorithm and then converted into binary data, and then the binary data can be converted into a binary pattern of the mask (e.g., 1 indicates that the corresponding position is cut out, and 0 indicates that the corresponding position is not cut out), and then the binary pattern can be written into the liquid crystal elastomer multiple times during the first ultraviolet exposure process to physically encrypt it.

[0086] This embodiment achieves two or more levels of information encryption and storage by selecting the electric field strength and designing the exposure mask, greatly reducing the difficulty of anti-counterfeiting material preparation and increasing the amount of information stored. The information capacity of the liquid crystal elastomer depends on the area of ​​the liquid crystal elastomer and the resolution of the mask (i.e., the number of circular holes that can be set per unit area). The larger the area of ​​the liquid crystal elastomer and the higher the resolution of the mask, the greater the data capacity of the liquid crystal elastomer.

[0087] The multi-level encryption and decryption method provided in this embodiment breaks through the requirements of existing technologies for complex preparation and decryption methods, realizes multi-dimensional and multi-stage information storage, and can achieve simple encryption and decryption of information while ensuring information security. It meets the needs of security information anti-counterfeiting materials with high information storage capacity, simple production, low cost, large area and mass production.

[0088] In addition, this embodiment also provides an encrypted storage medium, which is a liquid crystal elastomer prepared using the multi-level encryption method described in Embodiment 1 or 3.

[0089] Example 4

[0090] Corresponding to the above multi-level encryption methods, such as Figure 6 As shown, this embodiment also provides a multi-level decryption method based on the three-dimensional information or Braille information of the liquid crystal elastomer, which is used to decrypt the liquid crystal elastomer prepared in Embodiment 1 or 3 above.

[0091] Because liquid crystal elastomers exhibit tensile strain at the threshold strain level under mechanical tension and gradually recover to their initial thickness under zero mechanical tension, in addition to decrypting information through changes in brightness and darkness, decryption can also be achieved by identifying changes in the surface morphology of the liquid crystal elastomer, i.e., changes in three-dimensional tactile information. Furthermore, the tensile response of the liquid crystal elastomer begins at the tensile strain threshold strain point and requires a long period of strain accumulation to form a sufficient height difference to realize tactile information. Therefore, under the same mechanical stress excitation, the decryption of two-dimensional information and the decryption of three-dimensional information do not interfere with each other, thus enabling the decryption of information carried by the liquid crystal elastomer from a three-dimensional tactile perspective.

[0092] Specifically, the multi-level decryption method includes: stretching the liquid crystal elastomer in a direction perpendicular to the orientation of the mesocrystalline molecules, causing the encrypted exposure region of the liquid crystal elastomer to generate a tensile threshold strain, forming a protrusion in the encrypted exposure region with a thickness greater than that in the unencrypted exposure region, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure region of the liquid crystal elastomer aggregated under at least two electric fields of different intensities protrudes successively, forming multi-level three-dimensional tactile information, so as to decrypt the information carried by the liquid crystal elastomer from the three-dimensional tactile direction.

[0093] like Figure 6 As shown, taking a Braille information device as an example, a liquid crystal elastomer is prepared based on steps 201 to 203. The difference is that in this embodiment, the mask used in step 202 is a 2×3 pixel pattern to correspond to the format of Braille information. During the first ultraviolet exposure process, the electric field strength is 0V. rms 1.2V rms 1.6V rms Information is written multiple times using the corresponding hollow pattern.

[0094] During the decryption process, a mechanical tensile force is applied to the liquid crystal elastomer. During the stretching process, when the strain reaches 60%, it relies on 0V. rms The written tactile information first begins to appear, but cannot yet be felt; when the strain is 80%, at 1.2V... rms The tactile information written at that time begins to appear, and at this time, 0V rms The written tactile information has undergone a 20% strain expansion response; this portion of tactile information is now fully manifested and can be felt, while 1.2V rms The tactile information written at that time cannot be felt; subsequently, when the strain reaches 90%, it relies on 0V. rms and 1.2V rms The written tactile information can be fully displayed at 1.6V. rms The written tactile information has not yet appeared. Figure 6 Line graphs ①②③④ respectively show the surface morphology of the densified exposure area at 90% strain. The x-axis represents the strain of the liquid crystal elastomer in the direction parallel to its surface, and the y-axis represents the strain in the direction perpendicular to its surface. It can be seen that at 90% strain, 0V... rms and 1.2V rms The written tactile information has already appeared, and 1.6V rms The written tactile information has not yet appeared.

[0095] It should be noted that any reference numerals placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims that enumerate several means, several of these means may be embodied by the same hardware. The use of the terms first, second, third, etc., is merely for convenience of expression and does not indicate any order. These terms can be understood as part of the component names.

[0096] Furthermore, it should be noted that in the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0097] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims should be interpreted to include both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0098] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

Claims

1. A multi-level encryption method based on liquid crystal elastomers, characterized in that, include: The mixture used to prepare the liquid crystal elastomer is injected into a light-transmitting container. During the polymerization process of the mixture, at least two electric fields of different intensities are applied to the internal space of the light-transmitting container. During the electric field loading process of each intensity, a mask with a corresponding hollow pattern is used to cover a preset area on the outside of the light-transmitting container and a first ultraviolet exposure is performed to partially polymerize the mixture under the hollow pattern and write the information carried by the mask into the encrypted exposure area corresponding to the mixture. The cutout pattern of the mask carries information to be encrypted; Multiple electric fields of varying intensities correspond one-to-one with multiple photomasks. During the loading of electric fields of varying intensities, the information to be encrypted carried by the corresponding photomask is written into the mixture, forming a multi-level encryption of the information to be encrypted. The mask and electric field are removed to transform the mixture in the unencrypted region into an isotropic mixture. The mixture in the transparent container is then subjected to a second ultraviolet exposure to obtain a monolithically polymerized liquid crystal elastomer.

2. The multi-level encryption method according to claim 1, characterized in that, The step of injecting the mixture used to prepare the liquid crystal elastomer into the light-transmitting container includes: The light-transparent container is a box with a first side and a second side facing each other, and both the first side and the second side are conductive glass. The conductive layer of the conductive glass faces the inside of the box and has an orientation layer.

3. The multi-level encryption method according to claim 2, characterized in that, At least two different intensities of electric field are applied sequentially to the internal space of the light-transmitting container, including: The conductive layers of the two conductive glass pieces are connected to a voltage source respectively. By adjusting the preset voltage values ​​applied to the two conductive layers, the electric field strength applied to the internal space of the box can be adjusted.

4. The multi-level encryption method according to claim 3, characterized in that, The preset voltage value ranges from [0V] to [0V]. rms 2V rms ].

5. The multi-level encryption method according to claim 1, characterized in that, The step of injecting the mixture used to prepare the liquid crystal elastomer into the light-transmitting container further includes: The mixture comprises: liquid crystal polymer monomer A6OCB, liquid crystal monomer 6OCB, plasticizer EHA, crosslinking agent RM82 and photoinitiator MBF.

6. The multi-level encryption method according to claim 5, characterized in that, The mole fractions of each component in the mixture are as follows: Liquid crystal polymer monomer A6OCB: 20~28 mol%, liquid crystal monomer 6OCB: 50~60 mol%, plasticizer EHA: 1~1.4 mol%, crosslinking agent RM82: 2~5 mol%, photoinitiator MBF: 1~2 mol.

7. The multi-level encryption method according to claim 5, characterized in that, The exposure time for both the first and second ultraviolet exposures was 20-40 minutes, and the ultraviolet light intensity was 8-12 mW / cm². 2 .

8. A multi-stage decryption method based on liquid crystal elastomers, characterized in that, include: Stretching is performed in a direction perpendicular to the orientation of the mesocrystalline molecules of the liquid crystal elastomer, causing the encrypted exposure area of ​​the liquid crystal elastomer to generate a tensile threshold strain, forming a dark region corresponding to the cutout pattern of the mask under orthogonal polarization. Furthermore, as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure area formed by the polymerization of the liquid crystal elastomer under at least two intensities of electric field darkens successively, thereby reading out the information to be encrypted written in the liquid crystal elastomer in stages and completing the multi-level decryption of the information carried by the liquid crystal elastomer. The multi-level decryption method is a method for decrypting the liquid crystal elastomer prepared by the multi-level encryption method according to any one of claims 1 to 7.

9. The multi-level decryption method according to claim 8, characterized in that, The multi-level decryption method further includes: stretching the liquid crystal elastomer in a direction perpendicular to the orientation of the mesocrystalline molecules, causing the encrypted exposure region of the liquid crystal elastomer to generate a tensile threshold strain. Due to the tensile response, the encrypted exposure region forms a bulge with a thickness greater than that of the unencrypted exposure region. Furthermore, as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure region aggregated by the liquid crystal elastomer under at least two electric fields of different intensities bulges successively, forming multi-level three-dimensional tactile information, so as to decrypt the information carried by the liquid crystal elastomer from the three-dimensional tactile direction.

10. An encrypted storage medium, characterized in that, The encrypted storage medium is a liquid crystal elastomer prepared using the multi-level encryption method described in any one of claims 1 to 7.

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