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

Abstract

The invention relates to a multi-order encryption method and decryption method based on a liquid crystal elastomer and a storage medium, and the multi-order encryption method comprises the following steps: injecting a mixed solution for preparing the liquid crystal elastomer into a light-transmitting container, and in the polymerization process of the mixed solution, loading electric fields with at least two intensities into the internal space of the light-transmitting container in sequence; in the loading process of the electric field with each intensity, covering a preset area on the outer side of the light-transmitting container with a mask plate corresponding to the hollow-out pattern and carrying out first ultraviolet exposure so as to partially polymerize the mixed solution below the hollow-out pattern, and writing information carried by the mask plate into an encrypted exposure area corresponding to the mixed solution; the hollowed-out pattern of the mask carries information to be encrypted; and removing the mask and the electric field, converting the mixed solution in the non-encrypted area into isotropy, and integrally performing second ultraviolet exposure on the mixed solution in the light-transmitting container to obtain the integrally polymerized liquid crystal elastomer. The liquid crystal elastomer can realize multi-order encryption.

Description

Technical Field

[0001] The present invention relates to the technical field of data encryption storage, and in particular to a multi-stage encryption method based on liquid crystal elastomer, a multi-stage decryption method based on liquid crystal elastomer and an encrypted storage medium. Background Art

[0002] With the rapid development of information technology such as the Internet of Things and 5G networks, people's lives have entered a new information age, and the explosive increase in the amount of information has made more and more people face the risk of information leakage, which has posed more and more challenges to technologies such as information encoding, information encryption, and information storage. In recent years, people have made great efforts to develop advanced anti-counterfeiting materials and their corresponding information encryption technologies. By combining multiple anti-counterfeiting technologies or multiple stimuli that trigger decryption (such as light, temperature, humidity, etc.), information is made more difficult to copy, thereby improving the security level to avoid the threat of false information and information leakage. However, integrating different types of anti-counterfeiting materials into a system requires complex assembly methods, and different anti-counterfeiting materials are prone to interfere with each other, and complex decryption operations usually require expensive large-scale decryption equipment. Therefore, it is still challenging to achieve ideal multi-stage anti-counterfeiting and encryption technologies.

[0003] Liquid crystal elastomers are a type of polymer soft matter that is programmable, multi-stimulus responsive, and reversibly deformable. They currently show broad application prospects in the fields of soft robots, soft actuators, flexible electronic devices, and soft photonics devices. Liquid crystal elastomers have both the anisotropy of liquid crystals and the elasticity of elastomers, and can respond to a variety of external stimuli such as stress, heat, light, and electricity. These characteristics make liquid crystal elastomers one of the most promising candidate materials for data storage and encryption. However, at present, most of the information encryption and storage in liquid crystal elastomers use their reversible shape or structural color changes, and cannot achieve multi-level encryption of information.

[0004] The principle of realizing information encryption and storage of liquid crystal elastomers is generally based on the phase change of the liquid crystal elastomer itself or the change of the order of the orientation of the mesogen molecules during the self-driving process of the liquid crystal elastomer. One of the technologies utilizes the fact that when the liquid crystal domains in the liquid crystal elastomer are arranged macroscopically along the stretching direction, the liquid crystal element becomes transparent along with the transition from multi-domain to single domain; and when the liquid crystal elastomer changes from the nematic phase to the isotropic phase, the liquid crystal element will also change from opaque to transparent to realize the storage and display of information. Another technology realizes the encryption and storage of information through the interference color formed by the change of the thickness and refractive index of the liquid crystal elastomer during the stretching and oriented liquid crystal molecules. However, the information storage process stored by the above-mentioned technologies is complicated, the information storage capacity is low, the information form is single, and the resolution and contrast of the information display are poor, and the information security is difficult to be effectively guaranteed. There is also a technology that controls the breaking and healing of active bonds in the liquid crystal elastomer through laser direct writing to realize high-resolution information encryption and storage based on the transition from multi-domain to isotropic. Although this technology has high precision, the device is complex and expensive, and it cannot be prepared on a large scale, which is not conducive to mass production.

[0005] Another technology to achieve information encryption and storage is to use the self-fluorescence characteristics of liquid crystal elastomers combined with their own programmable deformation to achieve the storage of fluorescent information and physical shielding of information. This technology has a complex preparation process, seriously affects the environment and is not easy to operate; the information form is single, the information storage capacity is low, the decryption excitation conditions are complex, and the information security cannot be guaranteed. Summary of the invention

[0006] 1. Technical issues to be resolved

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

[0008] (II) Technical solution

[0009] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, an embodiment of the present invention provides a multi-stage encryption method based on a liquid crystal elastomer, comprising:

[0011] Injecting a mixed solution for preparing a liquid crystal elastomer into a light-transmitting container, and during the polymerization process of the mixed solution, applying electric fields of at least two intensities to the inner space of the light-transmitting container in sequence;

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

[0013] The electric fields of multiple strengths correspond to the multiple masks one by one. During the process of loading the electric fields of different strengths, the information to be encrypted carried by the corresponding masks is written into the mixed liquid, forming a multi-stage encryption of the information to be encrypted.

[0014] The mask and the electric field are removed to make the mixed liquid in the non-encrypted area become isotropic, and the mixed liquid in the light-transmitting container is subjected to a second ultraviolet exposure to obtain a liquid crystal elastomer that is polymerized as a whole.

[0015] Optionally, injecting the mixed solution for preparing the liquid crystal elastomer into a light-transmitting container comprises:

[0016] The light-transmitting container is a box body with a first surface and a second surface arranged opposite to each other, and the first surface and the second surface are both conductive glass, the conductive layer of the conductive glass faces the inside of the box body and is provided with an orientation layer.

[0017] Optionally, at least two electric fields of different strengths are sequentially applied to the inner space of the light-transmitting container, including:

[0018] The conductive layers of the two conductive glasses are connected to a voltage source respectively, and the electric field strength loaded in the inner space of the box is adjusted by adjusting the preset voltage values ​​loaded on the two conductive layers.

[0019] Optionally, the preset voltage value is in the range of [0V rms ,2V rms ].

[0020] Optionally, the step of injecting the mixed solution for preparing the liquid crystal elastomer into a light-transmitting container further comprises:

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

[0022] Optionally, the molar fractions of the components in the mixed solution are:

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

[0024] Optionally, the exposure time of the first ultraviolet exposure and the second ultraviolet exposure are both 20 to 40 minutes, and the ultraviolet light intensity is both 8 to 12 mW / cm 2 .

[0025] In a second aspect, an embodiment of the present invention provides a multi-stage decryption method based on a liquid crystal elastomer, comprising:

[0026] Stretching is performed in a direction perpendicular to the orientation of the mesogen molecules of the liquid crystal elastomer, so that the encrypted exposure region of the liquid crystal elastomer generates a tensile expansion threshold strain, forming a dark state region corresponding to the hollow pattern of the mask under orthogonal polarization, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure region formed by the polymerization of the liquid crystal elastomer under at least two electric fields of intensity successively darkens, thereby reading out the information to be encrypted written in the liquid crystal elastomer in stages, and completing the multi-stage decryption of the information carried by the liquid crystal elastomer;

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

[0028] Optionally, the multi-stage decryption method further comprises: stretching in a direction perpendicular to the orientation of the mesogen molecules of the liquid crystal elastomer, so that the encrypted exposure region of the liquid crystal elastomer generates a tensile expansion threshold strain, the encrypted exposure region forms a bulge with a thickness greater than that of the non-encrypted exposure region due to the tensile expansion response, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure regions of the liquid crystal elastomer polymerized under at least two electric fields of strength bulge successively, forming multi-stage 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-stage decryption method is a method for decrypting the liquid crystal elastomer prepared by the multi-stage encryption method described in the first aspect.

[0030] In a third aspect, an embodiment of the present invention provides an encrypted storage medium, wherein the encrypted storage medium is a liquid crystal elastomer prepared using the multi-stage encryption method described in the first aspect.

[0031] (III) Beneficial effects

[0032] The multi-stage encryption method proposed by the present invention uses at least two intensities of electric field to load the internal space of the light-transmitting container in the polymerization process of the mixed liquid; in the process of loading the electric field of each intensity, a mask with a corresponding hollow pattern is used to cover the preset area outside the light-transmitting container and perform a first ultraviolet exposure to partially polymerize the mixed liquid below the hollow pattern, and write the information carried by the mask into the encryption exposure area corresponding to the mixed liquid; the hollow pattern of the mask carries the information to be encrypted. The electric fields of multiple intensities correspond to the multiple masks one by one, and in the process of loading the electric fields of different intensities, the information to be encrypted carried by the corresponding mask is written into the mixed liquid, forming a multi-stage encryption of the information to be encrypted.

[0033] That is to say, the multi-stage encryption method proposed in the present invention, during the polymerization process of the liquid crystal mixture, configures electric fields of different intensities and masks corresponding to the electric fields of the same intensities, so that the information to be encrypted carried by different masks is written in stages into the same liquid crystal elastomer finally obtained, thereby realizing multi-stage encryption of information.

[0034] Furthermore, the multi-stage encryption method provided by the present invention can be applied to information display devices such as binary signals and tactile Braille, which greatly simplifies the preparation process of traditional information anti-counterfeiting materials, improves the storage capacity and security of information, is low-cost, easier to operate, and can be combined with traditional LCD panel production processes to achieve mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic flow chart of a multi-stage encryption method based on liquid crystal elastomer provided in an embodiment;

[0036] Figure 2 A schematic diagram of a process for preparing a liquid crystal elastomer having an intrinsic auxetic response provided in an embodiment;

[0037] Figure 3 (a) is a polarized optical microscopic image of a liquid crystal elastomer with an intrinsic tensile response provided in an embodiment, in which the orientation of the mesogen molecules of the liquid crystal elastomer is orthogonal to the analyzer when the strain reaches the tensile threshold;

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

[0039] Figure 4 A schematic flow chart of a multi-stage encryption method based on liquid crystal elastomer provided in an embodiment;

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

[0041] Figure 6 A schematic diagram of the process and effect of a multi-stage encryption method for three-dimensional information based on liquid crystal elastomer and a corresponding decryption method provided in an embodiment. DETAILED DESCRIPTION

[0042] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0043] For the intrinsic auxetic liquid crystal elastomer without power supply, there is auxetic phenomenon. When mechanically stretched in the direction perpendicular to the orientation of mesogen molecules, the thickness of the liquid crystal elastomer first becomes thinner and then thicker in the direction perpendicular to the orientation of mesogen molecules and the mechanical stretching direction, and then returns to the initial thickness. This strain degree at which the auxetic response begins to appear is called the auxetic threshold strain. At the auxetic threshold strain, the liquid crystal elastomer is in an optically isotropic state and opaque under orthogonal polarizers, while under the condition of less than or greater than the auxetic threshold strain, the liquid crystal elastomer is in a transparent state; in the powered state, the mesogen molecules in the powered area produce a Fréedericksz transition arrangement due to the influence of voltage. As the voltage increases, the auxetic response of the intrinsic auxetic liquid crystal elastomer after polymerization is delayed, the auxetic threshold strain increases, and the liquid crystal elastomer also needs a larger strain to return to the initial thickness; while for the isotropic liquid crystal elastomer, there is no auxetic response during the stretching process.

[0044] The multi-stage encryption method, multi-stage decryption method and encrypted storage medium provided by the present invention can prepare the liquid crystal elastomer according to the hollow design of the mask combined with the selection of electric field strength based on the above-mentioned tensile expansion response of the liquid crystal elastomer and the Friedrich phase change effect in the powered state. When the hollow 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] In order to prepare the above-mentioned liquid crystal elastomer carrying multi-level encrypted information, first prepare a liquid crystal box with a fixed thickness coated with an orientation layer on both sides, add a liquid crystal elastomer precursor solution (also called a mixed solution) containing liquid crystal polymer monomers, liquid crystal monomers that do not participate in the reaction, a crosslinking agent, a photoinitiator and a plasticizer, and then use an exposure mask to perform regional ultraviolet exposure to write information under an electric field. Different voltages during polymerization represent information at different stages. After all information is written, the liquid crystal box is heated to above the phase transition temperature and fully exposed, and finally a liquid crystal elastomer device for multi-dimensional information multi-level encryption and storage is obtained. After the polymerization is completed, the liquid crystal box is opened, the liquid crystal elastomer is peeled off from the liquid crystal box substrate, and the liquid crystal monomers that do not participate in the polymerization reaction are washed off to obtain a stretchable liquid crystal elastomer storing multi-level encrypted information.

[0046] In order to better understand the above technical solution, 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 accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0047] Embodiment 1

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

[0049] S1. Injecting a mixed solution for preparing a liquid crystal elastomer into a light-transmitting container.

[0050] Specifically, the light-transmitting container may be a liquid crystal box, which includes a box body with a first surface and a second surface arranged opposite to each other, and the first surface and the second surface are both conductive glass, the conductive layer of the conductive glass faces the inside of the box body and is provided with an orientation layer.

[0051] The combination and proportion of the mixed liquid of the liquid crystal elastomer can be specifically set as: liquid crystal polymer monomer A6OCB: 20-28 mol%, liquid crystal monomer 6OCB: 50-60 mol%, plasticizer EHA: 1-1.4 mol%, crosslinker RM82: 2-5 mol%, photoinitiator MBF: 1-2 mol%.

[0052] S2. During the polymerization process of the mixed solution, at least two electric fields of different intensities are applied to the inner space of the light-transmitting container.

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

[0054] Electric fields of multiple strengths correspond to multiple masks one by one. During the loading process of electric fields of different strengths, the information to be encrypted carried by the corresponding mask is written into the mixed liquid, forming multi-stage encryption of the information to be encrypted.

[0055] S3, removing the mask and the electric field to transform the mixed liquid in the non-encrypted area into isotropic liquid, and performing a second ultraviolet exposure on the entire mixed liquid in the light-transmitting container to obtain an overall polymerized liquid crystal elastomer.

[0056] The multi-stage encryption method proposed in this embodiment, during the first ultraviolet exposure process of the liquid crystal mixture, configures electric fields of different strengths and masks corresponding to the electric fields of the strengths, so that the information to be encrypted carried by different masks is written into the liquid crystal elastomer in stages, thereby realizing multi-stage encryption of information. Based on the liquid crystal box power-on exposure process, combined with the selection of the electric field strength in the light-transmitting container and the design of the exposure mask, more than two levels of information encryption and storage can be realized. The multi-stage 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, with low cost and easier operation. Combined with the traditional liquid crystal panel production process, it can achieve mass production.

[0057] Embodiment 2

[0058] In order to verify the influence of different electric field strengths on the performance of the liquid crystal elastomer provided in this embodiment, this embodiment first tests and illustrates the properties of the liquid crystal elastomer 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. Prepare four liquid crystal boxes: Two 5cm×2cm indium tin oxide conductive glass substrates were ultrasonically cleaned, and after hydrophilic treatment, 1wt% polyvinyl alcohol (PVA) aqueous solution was spin-coated as an orientation layer at a speed of 4500rpm for 60s. After baking at 100℃ for 10min, friction orientation was performed at a friction machine speed of 1000rpm. A PET plastic film with a thickness of 100μm was sandwiched between the edges of the two conductive glass sheets so that the internal space height of the liquid crystal box was 100μm. In order to ensure that the two conductive glass sheets are firmly bonded, glue can be used to bond the two sheets.

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

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

[0063] 103. After the mixed solution returned to room temperature, electric fields of different strengths were applied to the four liquid crystal boxes and polymerized under ultraviolet light. The electric field strengths applied to the four liquid crystal boxes were 0V and rms , 1.2V rms , 1.4V rms , 1.6V rms The exposure time of UV exposure is 20 to 40 minutes, and the UV intensity is 8 to 12 mW / cm 2 , so that the mixed liquid in the liquid crystal box polymerizes to form a liquid crystal elastomer. More preferably, the intensity of the ultraviolet light is 10mW / cm 2 The exposure time is 30min.

[0064] Specifically, the conductive layers of the two conductive glasses can be connected to a voltage source respectively, and the electric field strength loaded in the inner space of the box body can be adjusted by adjusting the preset voltage values ​​loaded on the two conductive layers.

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

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

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

[0068] like Figure 3 As shown, during the mechanical stretching process, for an electric field strength of 0 V rms The liquid crystal elastomer polymerized under the conditions has a tensile threshold strain of ~60% (that is, when the ratio of the deformation of the liquid crystal elastomer to its initial length under zero mechanical tension is about 60%, the liquid crystal elastomer exhibits tensile response). At the strain of ~60%, the liquid crystal elastomer exhibits a dark state under orthogonal polarizers. Figure 3 (b) It can be seen that when the strain is greater than 60%, the stretched liquid crystal elastomer begins to thicken, and its thickness slowly returns to its initial thickness. Experiments have shown that the threshold strain for the onset of the tensile response will continue to increase with the increase of the electric field strength applied during the first UV exposure process. When the electric field strength increases to 1.2V during the first UV exposure process, the strain at which the tensile response begins to increase will gradually increase. rms When the strain is increased to 1.4V, the threshold strain of the tensile expansion is 80%. rms When the voltage is increased to 1.6V, the value is ~90%; rms When , the auxetic threshold strain becomes ~100%.

[0069] Embodiment 3

[0070] Based on the first and second embodiments, this embodiment provides a specific multi-stage encryption method and a corresponding multi-stage decryption method of a liquid crystal elastomer, such as Figure 4 and 5 As shown, the specific steps include:

[0071] 201. Inject the mixed solution for preparing the liquid crystal elastomer into the liquid crystal box.

[0072] The mixed liquid is the mixed liquid provided in the second embodiment, and the liquid crystal box is the liquid crystal box provided in the second embodiment.

[0073] 202. During the first ultraviolet exposure process of the mixed liquid, at least two electric fields of different strengths are sequentially applied to the internal space of the liquid crystal box. During each electric field loading process, a mask having a corresponding hollow pattern is used to cover a preset area outside the light-transmitting container and perform the first ultraviolet exposure, so as to partially polymerize the mixed liquid below the hollow pattern and write the information carried by the mask into the encrypted exposure area corresponding to the mixed liquid; the hollow pattern of the mask carries the information to be encrypted.

[0074] Preferably, the conductive layers of the two conductive glasses are connected to a voltage source respectively, and the electric field strength loaded on the inner space of the box body is adjusted by adjusting the preset voltage value loaded on the two conductive layers, and the preset voltage value range is [0Vrms ,2V rms ].

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

[0076] First, a 0V voltage is applied to the liquid crystal cell. rms The first mask is covered on the top surface of the liquid crystal box, and ultraviolet exposure is performed at the same time, so that the mixed liquid corresponding to the hollow position of the first mask is polymerized; then, an electric field with an intensity of 1.2V is applied to the liquid crystal box. rms The second mask is covered on the top surface of the liquid crystal box, and ultraviolet exposure is performed at the same time, so that the mixed liquid corresponding to the hollow position of the second mask is polymerized; then, an electric field with an intensity of 1.6V is applied to the liquid crystal box. rms An electric field is applied to cover the top surface of the liquid crystal box with a third mask, and ultraviolet exposure is performed at the same time, so that the mixed liquid corresponding to the hollowed-out position of the third mask is polymerized.

[0077] The exposure time of the UV exposure in step 202 is 30 minutes, and the UV intensity is 10 mW / cm 2 .

[0078] 203. All masks and electric fields are removed, and the liquid crystal box is placed on a hot stage at 60°C to make the non-encrypted exposure area of ​​the liquid crystal elastomer, except the information area, become isotropic. The mixed liquid in the liquid crystal box is subjected to a second UV exposure to obtain a fully polymerized liquid crystal elastomer. The exposure time of the UV exposure is 30 minutes, and the UV intensity is 10mW / cm 2 .

[0079] 204. Open the liquid crystal box, peel off the liquid crystal elastomer from the conductive glass substrate and wash away the unreacted 6OCB to obtain a liquid crystal elastomer with information written in three stages.

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

[0081] The liquid crystal elastomer is stretched in a direction perpendicular to the orientation of the mesogen molecules, so that the encrypted exposure area of ​​the liquid crystal elastomer produces a tensile expansion threshold strain, forming a dark state area corresponding to the hollow pattern of the mask under orthogonal polarization, and 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 electric fields of intensities darkens successively, thereby reading out the encrypted information written in the liquid crystal elastomer in stages, completing the multi-stage decryption of the information carried by the liquid crystal elastomer.

[0082] In the multi-level encryption method provided in this embodiment, the security of information depends on the angle between the orientation direction of the mesogen molecules in the liquid crystal elastomer and the direction of the mechanical tension during decryption, and the information can be correctly decrypted only when the two are orthogonal. Specifically, for the above-mentioned liquid crystal elastomer carrying multi-level encrypted information, the liquid crystal elastomer prepared in steps 201 to 204 is in the form of a sheet, and the orientation of the mesogen molecules is perpendicular to the surface of the sheet-like liquid crystal elastomer, so the stretching direction during decryption is parallel to the surface of the liquid crystal elastomer.

[0083] It has been measured in Example 2 that the above liquid crystal elastomer is rms , 1.2V rms , 1.6V rms After polymerization under an electric field strength of , the corresponding tensile expansion threshold strains are ~60%, ~80%, and ~100%, respectively. Therefore, tensile force can be applied to the above-mentioned liquid crystal elastomer to make its strain reach ~60%, ~80%, and ~100%, respectively, and dark areas corresponding to the patterns on the first mask, the second mask, and the 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-mentioned multi-stage encryption and decryption method, various forms of encryption can actually be implemented through a combination of the hollow pattern of the mask, the electric field strength applied during the first ultraviolet exposure process, and the order of writing in the polymerization stage to improve the security of the information.

[0085] For example, the information to be encrypted may be cut into three parts as mentioned above, and written into the liquid crystal elastomer in stages under different electric field strengths in a pre-agreed order; the information to be encrypted may be placed only in one of the masks corresponding to the three different electric field strengths, and interference information may be placed in the other two masks to improve information security; the information to be encrypted may also be converted into binary data after being digitally encrypted through a code book (such as Braille information) or an existing encryption algorithm, and then the binary data may be converted into a binary pattern of the mask (for example, 1 indicates that the corresponding position is hollowed out, and 0 indicates that the corresponding position is not hollowed out), and then the above binary pattern may be written into the liquid crystal elastomer multiple times during the first ultraviolet exposure process to physically encrypt it.

[0086] This embodiment can achieve more than two levels of information encryption and storage by selecting the electric field strength and designing the exposure mask, which greatly reduces the difficulty of preparing anti-counterfeiting materials and increases the amount of information storage. 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-stage encryption and decryption method provided in this embodiment breaks through the requirements of the prior art for complex preparation methods and complex decryption methods, realizes multi-dimensional and multi-stage storage of information, and can realize simple encryption and decryption of information under the premise of ensuring information security, meeting 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-stage encryption method described in the first or third embodiment.

[0089] Embodiment 4

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

[0091] Because the liquid crystal elastomer has a tensile threshold strain under mechanical tension and gradually recovers to its initial thickness under zero mechanical tension, in addition to decrypting the information through the changes in the above-mentioned light and dark states, it can also be decrypted by identifying the surface morphology of the liquid crystal elastomer, that is, the changes in three-dimensional tactile information. Moreover, the tensile reaction of the liquid crystal elastomer just starts from the tensile threshold strain, and it takes a long time for strain accumulation to form a sufficient height difference to realize tactile information. Therefore, under the stimulation of the same mechanical stress, the decryption of two-dimensional information and the decryption of three-dimensional information do not interfere with each other, so it can support the decryption of the information carried by the liquid crystal elastomer from the three-dimensional tactile direction.

[0092] Specifically, the multi-stage decryption method includes: stretching in a direction perpendicular to the orientation of the mesogen molecules of the liquid crystal elastomer, so that the encrypted exposure area of ​​the liquid crystal elastomer produces a tensile stress threshold strain, and the encrypted exposure area forms a protrusion with a thickness greater than that of the non-encrypted exposure area, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure areas of the liquid crystal elastomer polymerized under at least two electric fields of intensities protrude successively, forming multi-stage 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 the Braille information device as an example, a liquid crystal elastomer is prepared based on steps 201 to 203. The difference is that the mask used in step 202 of this embodiment is a 2×3 format pixel pattern, corresponding to the format of the Braille information. In the first ultraviolet exposure process, the electric field strength is 0V. rms , 1.2V rms , 1.6V rms Use the corresponding hollow pattern to write information multiple times.

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

[0095] It should be noted that in the claims, any reference numerals placed between brackets shall 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 may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the claims enumerating several means, several of these means may be embodied by the same hardware. The use of the words first, second, third, etc., is for convenience of expression only and does not indicate any order. These words may be understood as part of the component name.

[0096] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations 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 one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0097] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

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

Claims

1. A multi-stage encryption method based on liquid crystal elastomer, characterized in that: include: Injecting a mixed solution for preparing a liquid crystal elastomer into a light-transmitting container, and during the polymerization process of the mixed solution, applying electric fields of at least two intensities to the inner space of the light-transmitting container in sequence; During the electric field loading process of each intensity, a mask plate corresponding to the hollow pattern is used to cover the preset area outside the light-transmitting container and perform a first ultraviolet exposure to partially polymerize the mixed liquid below the hollow pattern, and write the information carried by the mask plate into the encrypted exposure area corresponding to the mixed liquid; The hollow pattern of the mask carries information to be encrypted; The electric fields of multiple strengths correspond to the multiple masks one by one. During the process of loading the electric fields of different strengths, the information to be encrypted carried by the corresponding masks is written into the mixed liquid, forming a multi-stage encryption of the information to be encrypted. The mask and the electric field are removed to make the mixed liquid in the non-encrypted area become isotropic, and the mixed liquid in the light-transmitting container is subjected to a second ultraviolet exposure to obtain a liquid crystal elastomer that is polymerized as a whole.

2. The multi-stage encryption method according to claim 1, characterized in that: The step of injecting the mixed solution for preparing the liquid crystal elastomer into a light-transmitting container comprises: The light-transmitting container is a box body with a first surface and a second surface arranged opposite to each other, and the first surface and the second surface are both conductive glass, the conductive layer of the conductive glass faces the inside of the box body and is provided with an orientation layer.

3. The multi-stage encryption method according to claim 2, characterized in that: The electric fields of at least two intensities are sequentially applied to the inner space of the light-transmitting container, comprising: The conductive layers of the two conductive glasses are connected to a voltage source respectively, and the electric field strength loaded in the inner space of the box is adjusted by adjusting the preset voltage values ​​loaded on the two conductive layers.

4. The multi-stage encryption method according to claim 3, characterized in that: The preset voltage value range is [0V rms ,2V rms ].

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

6. The multi-stage encryption method according to claim 5, characterized in that: The amount fractions of the components in the mixed solution are: Liquid crystal polymer monomer A6OCB: 20-28 mol%, liquid crystal monomer 6OCB: 50-60 mol%, plasticizer EHA: 1-1.4 mol%, cross-linking agent RM82: 2-5 mol%, photoinitiator MBF: 1-2 mol%.

7. The multi-stage encryption method according to claim 5, characterized in that: The exposure time of the first ultraviolet exposure and the second ultraviolet exposure are both 20 to 40 minutes, and the ultraviolet light intensity is 8 to 12 mW / cm 2 .

8. A multi-stage decryption method based on liquid crystal elastomer, characterized in that: include: Stretching is performed in a direction perpendicular to the orientation of the mesogen molecules of the liquid crystal elastomer, so that the encrypted exposure region of the liquid crystal elastomer generates a tensile expansion threshold strain, forming a dark state region corresponding to the hollow pattern of the mask under orthogonal polarization, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure region formed by the polymerization of the liquid crystal elastomer under at least two electric fields of intensity successively darkens, thereby reading out the information to be encrypted written in the liquid crystal elastomer in stages, and completing the multi-stage decryption of the information carried by the liquid crystal elastomer; The liquid crystal elastomer is a liquid crystal elastomer obtained by a multi-stage encryption method.

9. The multi-stage decryption method according to claim 8, characterized in that: The multi-level decryption method further includes: stretching in a direction perpendicular to the orientation of the mesogen molecules of the liquid crystal elastomer, so that the encrypted exposure area of ​​the liquid crystal elastomer generates a tensile expansion threshold strain, the encrypted exposure area forms a bulge with a thickness greater than that of the non-encrypted exposure area due to the tensile expansion response, and as the strain of the liquid crystal elastomer gradually increases, the encrypted exposure areas of the liquid crystal elastomer polymerized under at least two electric fields of strength are successively bulged to form multi-level three-dimensional tactile information, so as to decrypt the information carried by the liquid crystal elastomer from the three-dimensional tactile direction; And / or, the multi-stage decryption method is a method for decrypting the liquid crystal elastomer prepared by the multi-stage encryption method according to claims 1 to 7.

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

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