CN115716932B - Porous single-domain liquid crystal elastomer, preparation method thereof and capacitive flexible sensor based on porous single-domain liquid crystal elastomer - Google Patents
Porous single-domain liquid crystal elastomer, preparation method thereof and capacitive flexible sensor based on porous single-domain liquid crystal elastomer Download PDFInfo
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Abstract
The invention belongs to the technical field of capacitive flexible sensors, and particularly relates to a porous single-domain liquid crystal elastomer, a preparation method thereof and a capacitive flexible sensor based on the same. The capacitive flexible sensor comprises an upper protective layer, an upper conductive layer, a dielectric layer, a lower conductive layer and a lower protective layer from top to bottom in sequence; wherein the upper conductive layer and the lower conductive layer are silver layers; the dielectric layer is porous single domain liquid crystal elastomer (P-mLCEs), and the molecular chain of the P-mLCEs is provided with double hydrogen bonds and metal coordination bonds. The porous single-domain liquid crystal elastomer provided by the invention contains double hydrogen bonds and metal coordination bonds, and the liquid crystal elastomer is used as a dielectric layer, and the carbonyl bonds on the molecular chain of the liquid crystal elastomer are coordinated and combined with metal ions, so that the dielectric constant of the liquid crystal elastomer is greatly improved, and the response/recovery speed of the dielectric layer of the flexible sensor is increased.
Description
Technical Field
The invention belongs to the technical field of capacitive flexible sensors, and particularly relates to a porous single-domain liquid crystal elastomer, a preparation method thereof and a capacitive flexible sensor based on the same.
Background
In recent years, with the rapid development of flexible electronic materials and sensing technologies, wearable flexible sensors have developed very rapidly. The core technology of the wearable flexible sensor is to effectively convert external deformation into an electrical signal. However, conventional semiconductor and metal-based pressure sensors have low sensitivity, narrow sensing range, limited stretching capability and low resolution, and are difficult to apply to devices requiring flexible contact or wearable. In the prior art, the capacitive pressure sensor is most widely applied to flexible pressure sensors with any curved surfaces. However, the parasitic capacitance and the distributed capacitance of the capacitive pressure sensor have a large influence on sensitivity and measurement accuracy, and a connection circuit is complex. The dielectric layer of the capacitive flexible pressure sensor is mostly made of PDMS, ecoflex and other materials, and has the problems of high dielectric loss, low dielectric constant, slow response speed, long rebound time, small sensitivity under high pressure and the like, and the preparation process is complex.
In view of the above-mentioned drawbacks of the prior art, the present inventors have studied and innovated based on years of experience and expertise in such materials, along with theoretical analysis, to develop a porous single domain liquid crystal elastomer, a method for preparing the same, and a capacitive flexible sensor based on the same.
Disclosure of Invention
The first object of the invention is to provide a porous single domain liquid crystal elastomer (P-mLCEs) which is an intelligent flexible material with good biocompatibility and has the characteristics of random elongation and compression, bending and folding, quick response, high sensitivity and the like.
The technical aim of the invention is realized by the following technical scheme:
the porous single domain liquid crystal elastomer provided by the invention has a double hydrogen bond and a metal coordination bond on a molecular chain, and the molecular structural formula is as follows:
wherein M is n+ Representing metal ions.
The invention provides a liquid crystal elastomer containing double hydrogen bonds and metal coordination bonds; by introducing the intermediate, a chain segment containing an amide bond and a Schiff base bond is embedded in a molecular chain of the liquid crystal polymer, and metal ions are doped, so that a double hydrogen bond is formed between the amide bonds in the molecular chain, and the Schiff base bond and the metal ions form a coordination bond. As is well known, the dielectric constant is an important parameter for discriminating the polarity of a polymer material. The ionic liquid crystal elastomer prepared by the method is used as a dielectric layer, and the binding capacity of the ionic liquid crystal elastomer to charges is further enhanced due to the formation of coordination bonds, namely electronegativity is increased. The greater the electronegativity, the stronger the polarizability, thereby greatly improving the dielectric constant. Meanwhile, since the double hydrogen bonds and the metal coordination bonds exist at the same time, the crosslinking density of the liquid crystal polymer is increased, resulting in a sharp increase in the tensile strength at break thereof. It has a faster response/recovery speed as a dielectric layer of the pressure sensor than other flexible sensors.
Meanwhile, the liquid crystal elastomer dielectric layer is partially subjected to pore-forming (conventional pore-forming method), so that the sensitivity of the flexible sensor is further improved, and the flexible sensor has excellent performance at high temperature.
Further, M n+ Is Fe 3+ 、Cu 2+ Or Zn 2+ Any one of the following. When the electronegativity of the central atom (ion) and the coordinating atom differ slightly, a coordinate bond tends to be formed. The N atoms have higher electronegativity (3.04), iron 1.83, copper 1.9 and zinc 1.65, which are close to the N atoms.
The second object of the present invention is to provide a method for preparing a porous single domain liquid crystal elastomer, which has the same technical effects.
The technical aim of the invention is realized by the following technical scheme:
the preparation method of the porous single domain liquid crystal elastomer provided by the invention comprises the following operation steps: preparing an intermediate DMG-IP by adopting a reaction of dimethylglyoxime and dimethylmethane diisocyanate; dissolving a liquid crystal monomer RM257, a chain extender, a cross-linking agent and a catalyst in a solvent, adding an intermediate DMG-IP, metal salt and a photoinitiator after the reaction is finished, and uniformly stirring to obtain a liquid crystal elastomer precursor liquid; pouring the liquid crystal elastomer into a mould, standing for film formation, washing after heating, and mechanically stretching under UV illumination to obtain the porous single domain liquid crystal elastomer.
Further, the molar ratio of the liquid crystal monomer RM257, the chain extender and the cross-linking agent is 1 (0.7-0.9): 0.05-0.1; the content of the catalyst is 20-50 mu L; the molar ratio of the liquid crystal monomer RM257, the intermediate DMG-IP and the metal salt is 1 (0.05-0.25): 0.1-2; the content of the photoinitiator is 0.5 percent by weight of the liquid crystal monomer; wherein the liquid crystal monomer RM257 is 3.2-4.0 g.
Further, the preparation method of the porous single domain liquid crystal elastomer specifically comprises the following operation steps:
s1, an intermediate DMG-IP: dissolving dimethylglyoxime and dimethylmethane diisocyanate in 10mL of tetrahydrofuran solvent according to the molar ratio of 1:2, and reacting for 3-6 hours at 60-80 ℃ under the nitrogen atmosphere to obtain an intermediate DMG-IP;
s2, liquid crystal elastomer precursor liquid: dissolving a liquid crystal monomer RM257, a chain extender, a cross-linking agent tetra (3-mercaptopropionic acid) pentaerythritol ester and a catalyst di-n-propylamine in a tetrahydrofuran solvent, and reacting for 12-24 hours; continuously and sequentially adding the DMG-IP, the metal salt and the photoinitiator 2, 2-dimethoxy-2-phenylacetophenone in the step S1, and fully stirring to completely dissolve the DMG-IP, the metal salt and the photoinitiator 2, 2-dimethoxy-2-phenylacetophenone to obtain a liquid crystal elastomer precursor liquid;
s3, a porous single domain liquid crystal elastomer: pouring the liquid crystal elastomer precursor liquid in the step S2 into a mould uniformly full of NaCl particles, and standing for 24 hours to form a film; heating the membrane in deionized water at 80 ℃ for 10-12 h, continuing to carry out ultrasonic treatment for 1-2 h, and washing out NaCl particles to obtain a porous liquid crystal elastomer film with the aperture of 100-200 mu m;
pore-forming is a common method of improving the sensitivity of the sensor, and the smaller the pore size, the larger the dielectric constant, and the more pronounced the sensitivity improvement. However, it is difficult to obtain a porous liquid crystal elastomer film having a smaller pore size due to limitations limited to the physical pore-forming technique and the material of the present invention. However, on one hand, too large pore diameter can greatly reduce Young's modulus, reduce rebound resilience of a dielectric layer and influence sensitivity; on the other hand, the porosity of the material increases, the dielectric constant decreases, and the sensitivity decreases.
Mechanically stretching 50-100% under UV light to obtain the porous single domain liquid crystal elastomer.
Further, the crosslinking agent is pentaerythritol tetrakis (3-mercaptopropionate).
Further, the initiator is 2, 2-dimethoxy-2-phenylacetophenone.
Further, the mechanical stretching has a degree of stretching of 50 to 100%.
Further, the chain extender is one of bis (2-mercaptoethyl) ether, 1, 4-butanediol bis (mercaptoacetate) and 3, 6-dioxa-1, 8-octanedithiol.
Further, the metal salt is FeCl 3 、CuCl 2 Or ZnCl 2 One of them.
A third object of the present invention is to provide a capacitive flexible sensor based on a porous single domain liquid crystal elastomer having a sensor sensitivity of 16.25X10 at a pressure of 0 to 30kPa -3 KPa -1 The pressure sensing sensitivity is 2.08X10 under 30-160 KPa pressure -3 KPa -1 The problem that other flexible matrixes limit the detection limit of the sensor is effectively solved; the sensor shows more excellent performance under the high-temperature environment, namely, the response/recovery speed is faster, and the response/recovery speed is respectively 20ms and 34ms under 25KPa, so that the application range of the capacitive sensor is further widened; and the sensor still exhibits excellent stability under pressure loading/release exceeding 2000 times.
The technical aim of the invention is realized by the following technical methods:
the invention provides a capacitive flexible sensor based on a porous single-domain liquid crystal elastomer, which sequentially comprises the following components from top to bottom: the upper protective layer, the upper conductive layer, the dielectric layer, the lower conductive layer and the lower protective layer are silver layers; the dielectric layer is a porous single domain liquid crystal elastomer; the upper protective layer and the lower protective layer are organic silicon.
As the preferable technical scheme, the preparation method comprises the following operation steps: pre-stretching the porous single-domain liquid crystal elastomer by 10-30%, and putting the porous single-domain liquid crystal elastomer into vacuum sputtering equipment to steam silver coating on two sides to obtain a porous single-domain liquid crystal elastomer film with two silver layers; and coating an upper protective layer and a lower protective layer on the two sides of the porous single-domain liquid crystal elastomer film, and packaging to obtain the capacitive flexible sensor of the porous single-domain liquid crystal elastomer.
As the optimization of the technical scheme, a refiner is adopted for spin coating to obtain a compact and uniform upper protective layer and a compact and uniform lower protective layer, and the stress is uniform during use; the encapsulation is to spin-coat the organosilicon on the two sides of the flexible sensor by a homogenizer at 8000rpm/min for 3min to obtain an outer protective film with the thickness of 0.3 mm.
In summary, the invention has the following beneficial effects:
1. the liquid crystal elastomer containing double hydrogen bonds and metal coordination bonds prepared by the invention has the advantages that the carbonyl bonds on the molecular chain of the liquid crystal elastomer are coordinated and combined with metal ions, so that the dielectric constant of the liquid crystal elastomer is 42 under 1000Hz, and the dielectric loss is 0.42 under 1000 Hz; meanwhile, under the synergistic effect of double hydrogen bonds, the mechanical tensile strength is 5.1MPa.
2. The invention designs the liquid crystal elastomer containing double hydrogen bonds and metal coordination bonds as a porous structure single domain liquid crystal elastomer, and is applied to a capacitive flexible sensor, and the sensitivity of the sensor under the pressure of 0-30 kPa is 16.25 multiplied by 10 - 3 KPa -1 The pressure sensing sensitivity is 2.08X10 under 30-160 KPa pressure -3 KPa -1 The problem that other flexible matrixes limit the detection limit of the sensor is effectively solved; the sensor shows faster response/recovery speed under the high-temperature environment, and respectively 20ms and 34ms under 25KPa, so that the application range of the capacitive sensor is further widened; still exhibit excellent stability to pressure loading/release of the sensor over 2000 times.
3. The capacitive flexible sensor provided by the invention also has a low-cost sensor array with excellent response performance, and has great application potential in the fields of electronic equipment and wearable application; the sensor provided by the invention has the advantages of simple preparation process, sensitive product detection, wide detection range, stable and controllable performance, and can be applied to mass production.
Drawings
FIG. 1 is a schematic diagram of a capacitive flexible sensor made in accordance with the present invention;
FIG. 2 is a molecular structure of the intermediate DMG-IP of the present invention and its corresponding nuclear magnetic pattern;
FIG. 3 dielectric constants of the dielectric layers of the capacitive flexible sensors prepared in example 1 and comparative examples 1-2;
FIG. 4 shows the dielectric loss of the dielectric layers of the capacitive flexible sensors prepared in example 1 and comparative examples 1-2 of the present invention;
FIG. 5 is a diagram showing the structure of micropores of a dielectric layer of a capacitive flexible sensor prepared in example 1 of the present invention after silver evaporation;
FIG. 6 is a plot of sensitivity for the capacitive flexible sensor dielectric layers prepared in example 1 of the present invention without holes, half holes and full holes;
FIG. 7 is a plot of sensitivity of the capacitive flexible sensor prepared in example 1 and comparative example 1 of the present invention;
FIG. 8 is a graph of response/recovery speed of the capacitive flexible sensor prepared in example 1 of the present invention;
FIG. 9 is a graph showing the performance change of the capacitive flexible sensor prepared in example 1 of the present invention under 2000 presses;
FIG. 10 is a graph showing capacitive response of the capacitive flexible sensor prepared in example 1 of the present invention bent at different angles.
Reference numerals
1. An upper protective layer, an upper conductive layer, a dielectric layer, a lower conductive layer and a lower protective layer.
Detailed Description
In order to further illustrate the technical means and effects adopted by the invention to achieve the preset aim, the invention provides a porous single domain liquid crystal elastomer, a preparation method thereof and a capacitive flexible sensor based on the porous single domain liquid crystal elastomer, and specific embodiments, characteristics and effects thereof are described in detail below.
Example 1
The capacitive flexible sensor based on the liquid crystal elastomer dielectric layer provided in this embodiment, as shown in fig. 1, is an upper protection layer 1, an upper conductive layer 2, a dielectric layer 3, a lower conductive layer 4 and a lower protection layer 5 sequentially from top to bottom; wherein the upper conductive layer 2 and the lower conductive layer 4 are silver layers; the dielectric layer 3 is a porous single domain liquid crystal elastomer (P-mLCEs), and the molecular chain of the P-mLCEs is provided with double hydrogen bonds and metal coordination bonds, and the structure is as follows:
wherein M is n+ Is Fe 3+ 。
The preparation method of the porous single-domain liquid crystal elastomer provided by the embodiment is as follows:
s1, an intermediate DMG-IP: 0.08g of Dimethylglyoxime (DMG) and 0.226g of dimethylmethane diisocyanate (IP) are dissolved in 10mL of tetrahydrofuran solvent and reacted for 6 hours at 60 ℃ under the nitrogen atmosphere to obtain an intermediate DMG-IP;
s2, liquid crystal elastomer precursor liquid: 3.6g of the liquid crystal monomer, RM257, 0.84g of DSH, 0.092g of PETMP and 20 mu LDPA are dissolved in 6mL of tetrahydrofuran solvent and reacted for 12h; continuing to sequentially add DMG-IP and 0.22g FeCl in the step S1 3 0.018g of photoinitiator 2, 2-dimethoxy-2-phenylacetophenone is fully stirred to be completely dissolved, so as to obtain liquid crystal elastomer precursor liquid;
s3, a porous single domain liquid crystal elastomer: pouring the liquid crystal elastomer precursor liquid in the step S2 into a mould uniformly full of NaCl particles, and standing for 24 hours to form a film; heating the membrane in deionized water at 80 ℃ for 12 hours, continuing to carry out ultrasonic treatment for 1 hour, and eluting NaCl particles to obtain a porous liquid crystal elastomer film with the aperture of 100 mu m; mechanically stretching 100% under UV illumination to obtain the porous single domain liquid crystal elastomer.
The embodiment also provides a capacitive flexible sensor, which is prepared by the following steps: pre-stretching the porous single-domain liquid crystal elastomer prepared in the embodiment by 30%, and putting the porous single-domain liquid crystal elastomer into vacuum sputtering equipment to steam silver layers on both sides to obtain a porous single-domain liquid crystal elastomer film with 50nm silver layers on both sides; and spin-coating the organosilicon on the two surfaces of the film by adopting a refiner at 8000rpm/min for 3min to obtain an outer protective film with the thickness of 0.3mm, thus obtaining the capacitive flexible sensor based on the dielectric layer of the liquid crystal elastomer.
Example 2
The capacitive flexible sensor based on the liquid crystal elastomer dielectric layer provided in this embodiment, as shown in fig. 1, is an upper protection layer 1, an upper conductive layer 2, a dielectric layer 3, a lower conductive layer 4 and a lower protection layer 5 sequentially from top to bottom; wherein the upper conductive layer and the lower conductive layer are silver layers; the dielectric layer is a porous single domain liquid crystal elastomer (P-mLCEs), and the molecular chain of the P-mLCEs is provided with double hydrogen bonds and metal coordination bonds, and the structure is as follows:
wherein M is n+ Is Cu 2+ 。
The preparation method of the porous single-domain liquid crystal elastomer provided by the embodiment is as follows:
s1, an intermediate DMG-IP: 0.08g of Dimethylglyoxime (DMG) and 0.226g of dimethylmethane diisocyanate (IP) are dissolved in 8mL of tetrahydrofuran solvent and reacted for 3 hours at 80 ℃ under the nitrogen atmosphere to obtain an intermediate DMG-IP;
s2, liquid crystal elastomer precursor liquid: 3.2g of a liquid crystal monomer, RM257, 1.022g of EDDET, 0.184g of PETMP and 35. Mu.L of DPA were dissolved in 6mL of a tetrahydrofuran solvent and reacted for 18 hours; continuing to sequentially add the DMG-IP and 0.187g CuCl in the step S1 2 0.016g of photoinitiator 2, 2-dimethoxy-2-phenylacetophenone is fully stirred to be completely dissolved, so as to obtain liquid crystal elastomer precursor liquid;
s3, a porous single domain liquid crystal elastomer: pouring the liquid crystal elastomer precursor liquid in the step S2 into a mould uniformly full of NaCl particles, and standing for 24 hours to form a film; heating the membrane in deionized water at 80 ℃ for 10 hours, continuing to carry out ultrasonic treatment for 2 hours, and eluting NaCl particles to obtain a porous liquid crystal elastomer film with the pore diameter of 200 mu m; mechanically stretching 50% under UV light to obtain the porous single domain liquid crystal elastomer.
The embodiment also provides a capacitive flexible sensor, which is prepared by the following steps: pre-stretching the porous single-domain liquid crystal elastomer prepared in the embodiment by 20%, and putting the porous single-domain liquid crystal elastomer into vacuum sputtering equipment to steam silver layers on both sides to obtain a porous single-domain liquid crystal elastomer film with 50nm silver layers on both sides; and spin-coating the organosilicon on the two surfaces of the film by adopting a refiner at 8000rpm/min for 3min to obtain an outer protective film with the thickness of 0.3mm, thus obtaining the capacitive flexible sensor based on the dielectric layer of the liquid crystal elastomer.
Example 3
The capacitive flexible sensor based on the liquid crystal elastomer dielectric layer provided in this embodiment, as shown in fig. 1, is an upper protection layer 1, an upper conductive layer 2, a dielectric layer 3, a lower conductive layer 4 and a lower protection layer 5 sequentially from top to bottom; wherein the upper conductive layer and the lower conductive layer are silver layers; the dielectric layer is a porous single domain liquid crystal elastomer (P-mLCEs), and the molecular chain of the P-mLCEs is provided with double hydrogen bonds and metal coordination bonds, and the structure is as follows:
wherein M is n+ Is Zn 2+ 。
The preparation method of the porous single-domain liquid crystal elastomer provided by the embodiment is as follows:
s1, an intermediate DMG-IP: 0.08g of Dimethylglyoxime (DMG) and 0.226g of dimethylmethane diisocyanate (IP) are dissolved in 8mL of tetrahydrofuran solvent and reacted for 4 hours at 70 ℃ under the nitrogen atmosphere to obtain an intermediate DMG-IP;
s2, liquid crystal elastomer precursor liquid: 4g of a liquid crystal monomer, namely, R257, 1.194g of BDBT, 0.184g of PETMP and 20 mu LDPA are dissolved in 6mL of tetrahydrofuran solvent and reacted for 18h; continuing to sequentially add DMG-IP and 0.186g CuCl in the step S1 2 Fully stirring 0.02g of photoinitiator 2, 2-dimethoxy-2-phenylacetophenone to completely dissolve the photoinitiator to obtain a liquid crystal elastomer precursor solution;
s3, a porous single domain liquid crystal elastomer: pouring the liquid crystal elastomer precursor liquid in the step S2 into a mould uniformly full of NaCl particles, and standing for 24 hours to form a film; heating the membrane in deionized water at 80 ℃ for 11 hours, continuing to carry out ultrasonic treatment for 1.5 hours, and washing out NaCl particles to obtain a porous liquid crystal elastomer film with the aperture of 150 mu m; mechanically stretching 70% under UV light to obtain the porous single domain liquid crystal elastomer.
The embodiment also provides a capacitive flexible sensor, which is prepared by the following steps: pre-stretching the porous single-domain liquid crystal elastomer prepared in the embodiment by 10%, and putting the porous single-domain liquid crystal elastomer into vacuum sputtering equipment to steam silver layers on both sides to obtain a porous single-domain liquid crystal elastomer film with 50nm silver layers on both sides; and spin-coating the organosilicon on the two surfaces of the film by adopting a refiner at 8000rpm/min for 3min to obtain an outer protective film with the thickness of 0.3mm, thus obtaining the capacitive flexible sensor based on the dielectric layer of the liquid crystal elastomer.
Comparative example 1
This example is different from the preparation method of the liquid crystal elastomer of example 1, and the other technical schemes are the same.
The preparation method of the liquid crystal elastomer provided by the embodiment is as follows:
s1, a liquid crystal elastomer precursor liquid: 3.6g of a liquid crystal monomer, 0.84g of DSH, 0.092g of PETMP and 20 mu LDPA are dissolved in 6mL of tetrahydrofuran solvent and reacted for 24 hours to obtain a liquid crystal elastomer precursor liquid;
s2, a porous single domain liquid crystal elastomer: pouring the liquid crystal elastomer precursor liquid in the step S2 into a mould uniformly full of NaCl particles, and standing for 24 hours to form a film; heating the membrane in deionized water at 80 ℃ for 12 hours, continuing to carry out ultrasonic treatment for 1 hour, and eluting NaCl particles to obtain a porous liquid crystal elastomer film with the aperture of 150 mu m; mechanically stretching 100% under UV illumination to obtain the porous single domain liquid crystal elastomer.
Comparative example 2
A capacitive flexible sensor was prepared using commercially available PDMS instead of the liquid crystal elastomer provided in example 1 as a dielectric layer, and the preparation method was the same as in example 1.
The capacitive flexible sensors prepared in examples 1 to 3 and comparative examples 1 to 2 described above were tested for dielectric constant at 1KHz, dielectric loss at 1K Hz, sensitivity, response time at 120 ℃ and stability at 2000 cycles, respectively, and the results are shown in table 1. The flexible sensor has no relevant test standard at present, and part of data (sensitivity, response/recovery time at 120 ℃,2000 times of pressure load/release and the like) in the invention is tested in the standard of GB/T28854-2012 silicon capacitive pressure sensor in the rigid capacitive sensor; the dielectric constant and dielectric loss were tested by Keysight equipment.
The data in Table 1 are combined to show that the capacitive flexible sensors of examples 1-3 are significantly better than those of comparative examples 1-2; wherein the dielectric constant of example 1 was increased by 500% and 1400%, respectively, and the response/recovery time was shortened by an order of magnitude, as compared to comparative examples 1-2; in the embodiment, although the dielectric loss is slightly increased, the sensitivity is obviously improved, and the 2000-time pressure load/release stability is good.
The present invention is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical matters of the present invention can be made by those skilled in the art without departing from the scope of the present invention.
Claims (9)
1. The porous single-domain liquid crystal elastomer is characterized in that the molecular chain of the porous single-domain liquid crystal elastomer is provided with double hydrogen bonds and metal coordination bonds, and the molecular structural formula is as follows:
wherein M is n+ Represents metal ions; the M is n+ Is Fe 3+ 、Cu 2+ Or Zn 2+ Any one of the following.
2. The method for preparing the porous single domain liquid crystal elastomer according to claim 1, comprising the following operation steps: preparing an intermediate DMG-IP by adopting a reaction of dimethylglyoxime and dimethylmethane diisocyanate; dissolving a liquid crystal monomer RM257, a chain extender, a cross-linking agent and a catalyst in a solvent, adding an intermediate DMG-IP, metal salt and a photoinitiator after the reaction is finished, and uniformly stirring to obtain a liquid crystal elastomer precursor liquid; pouring the liquid crystal elastomer into a mould, standing for film formation, washing after heating, and mechanically stretching under UV illumination to obtain the porous single domain liquid crystal elastomer.
3. The method of preparing a cellular mono-domain liquid crystal elastomer according to claim 2, wherein the cross-linking agent is pentaerythritol tetrakis (3-mercaptopropionate).
4. The method of preparing a cellular mono-domain liquid crystal elastomer according to claim 2, wherein the initiator is 2, 2-dimethoxy-2-phenylacetophenone.
5. The method of producing a cellular mono-domain liquid crystal elastomer according to claim 2, wherein the mechanical stretching has a degree of stretching of 50 to 100%.
6. The method for preparing a porous mono-domain liquid crystal elastomer according to claim 2, wherein the chain extender is one of bis (2-mercaptoethyl) ether, 1, 4-butanediol bis (mercaptoacetate), 3, 6-dioxa-1, 8-octanedithiol.
7. The method for preparing a porous single domain liquid crystal elastomer according to claim 2, wherein the metal salt is FeCl 3 、CuCl 2 、ZnCl 2 One of them.
8. A capacitive flexible sensor based on the porous single domain liquid crystal elastomer of any one of claims 1 or 2, comprising, in order from top to bottom: the device comprises an upper protective layer, an upper conductive layer, a dielectric layer, a lower conductive layer and a lower protective layer and is characterized in that the upper conductive layer and the lower conductive layer are silver layers; the dielectric layer is the porous single domain liquid crystal elastomer; the upper protective layer and the lower protective layer are organic silicon.
9. The capacitive flexible sensor based on a porous mono-domain liquid crystal elastomer according to claim 8, characterized in that its preparation method comprises the following operating steps: pre-stretching the porous single-domain liquid crystal elastomer by 10-30%, and putting the porous single-domain liquid crystal elastomer into vacuum sputtering equipment to steam silver coating on two sides to obtain a porous single-domain liquid crystal elastomer film with two silver layers on two sides; and respectively coating an upper protective layer and a lower protective layer on both sides of the double-sided silver layer porous single-domain liquid crystal elastomer film, and packaging to obtain the capacitive flexible sensor of the porous single-domain liquid crystal elastomer.
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