Intrinsic Flexible Light-Detecting Material Based on Polymer Particles, Preparation Method Thereof and Application Thereof

Abstract

The present invention belongs to the technical field of functional polymer materials, and particularly relates to an intrinsically flexible light-detecting material based on polymer particles, its preparation method and application. The intrinsically flexible light-detecting material includes: a flexible matrix, and polymer particles and a conductive material dispersed in the flexible matrix; the material of the flexible matrix includes a flexible polymer material; the polymer particles have regular morphology and contain light-responsive groups, and undergo reversible deformation under irradiation of light with a specific wavelength. The intrinsically flexible light-detecting material can be processed and formed in a variety of ways to prepare light detectors with different shapes and sizes, and has intrinsic flexibility such as bendability, foldability and stretchability, and can achieve large-area detection and sensing.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional polymer materials, and particularly relates to an intrinsically flexible light detection material based on polymer particles, its preparation method and application. Background Art

[0002] Polymer particles are a kind of polymer materials at the mesoscopic scale. By changing their structural units, preparation methods, etc., various morphologies can be formed, such as spherical, rod-shaped, tubular, linear, vesicles, etc. Introducing specific functional groups can endow polymer particles with unique responsiveness. For example, introducing azobenzene groups will make polymer particles have light-responsive properties. Due to the characteristics of small size, high specific surface area, adjustable structure and multi-functionalization of polymer particles, they have received extensive attention from researchers in recent years and have been studied and applied in fields such as imaging technology, biomedicine, and environmental governance.

[0003] A light detection material is a medium that converts the detected light signal into an electrical signal. By constructing a photodetector to detect the characteristics and changes of the electrical signal, various information originally carried in the light signal can be obtained. With the development of technology and society, light detection materials have been widely used in fields such as sensing, communication, imaging, environmental monitoring, military tracking, and medical detection. Traditional light detection sensors generally use inorganic materials such as Si, InGaAs, ZnO, MoS2, etc. Most of these materials are brittle, making it difficult to fabricate large-area flexible devices, and they are not suitable for the application requirements of wearable detection devices and more production and life fields. Moreover, limited by the preparation technology, they have small size, large mass, high manufacturing cost, complex preparation process, and are not easy to regulate the optoelectronic properties. Summary of the Invention

[0004] The purpose of the present invention is to provide an intrinsically flexible light detection material based on polymer particles, its preparation method and application.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] An intrinsically flexible light detection material based on polymer particles, comprising:

[0007] A flexible matrix and polymer particles and conductive materials dispersed in the flexible matrix;

[0008] The material of the flexible matrix includes flexible polymer materials;

[0009] The polymer particles have regular morphology and contain light-responsive groups, and undergo reversible deformation under irradiation with light of a specific wavelength.

[0010] For the intrinsic flexible light-detecting material of the present invention, the polymer serving as the photosensitive unit is compounded with the flexible matrix in particle form, which can not only make it easier to be uniformly dispersed in the flexible matrix, but also will not have too much impact on the performance of the matrix material. The polymer particles carry light-responsive groups, such as azobenzene groups on the side chains. Different structures of azobenzene groups or different positions of azobenzene groups on the side chains will cause the polymer particles to have specific absorption of light with different wavelengths. By simply designing the structure and position of the light-responsive groups, etc., a light-detecting material that responds to light with a specific wavelength can be prepared. The polymer particles can have different morphologies such as spherical, ellipsoidal, worm-like, etc., and can be obtained through various assembly methods such as solution self-assembly and polymerization-induced self-assembly. The polymer particles can undergo reversible deformation under light irradiation, such as first swelling and then shrinking back. Combining such polymer particles with regular morphologies with a conductive medium and dispersing them in the flexible matrix, the morphological changes of the polymer particles caused by light irradiation drive the movement of the conductive medium, thereby causing changes in the conductivity of the entire composite material, thus completing the conversion of light signals into electrical signals and achieving the purpose of light detection. At the same time, there is a good linear relationship between the intensity of the input light signal and the magnitude of the output electrical signal.

[0011] The "regular morphology" used in the present invention refers to the characteristics of the polymer particles, including their size, shape, and structure, which are clearly defined and shared among different particles in the same batch. It includes low aspect ratio structures, such as uniform spheres, ellipsoids, or cubes, and high aspect ratio structures, such as uniform rods or wires.

[0012] Preferably, the morphological structure of the polymer particles is spherical, ellipsoidal, parallelepipedal, rod-shaped, or worm-like.

[0013] More preferably, the morphological structure of the polymer particles is spherical, and the diameter of the sphere is 10 - 10000 nm;

[0014] Or, the morphological structure of the polymer particles is ellipsoidal, the equatorial radius of the ellipsoid is 10 - 10000 nm, and the polar radius is 5 - 10000 nm;

[0015] Or, the morphological structure of the polymer particles is parallelepipedal, and the three edge lengths of the parallelepiped are 1 - 10000 nm, and the three axial angles are 0 - 180°;

[0016] Or, the morphological structure of the polymer particles is rod-shaped, the diameter of the rod is 1 - 1000 nm, and the length is 10 - 50000 nm;

[0017] Alternatively, the morphological structure of the polymer particles is worm-like, with the diameter of the worm-like particles being 1 - 1000 nm and the length being 10 - 50000 nm. The polymer particles with the above dimensions and morphology are characterized by easy dispersion and can be uniformly mixed with most flexible polymer materials that can form a flow state without damaging the structural morphology.

[0018] Preferably, the polymer particles are poly(methyl methacrylate)-block-poly{1-[4-(4-butylphenyl)azo]phenoxymethyl acrylate}.

[0019] Preferably, the flexible polymer material is selected from one or more of polyvinyl alcohol (PVA), polyethylene glycol (PEO), and polyvinylpyrrolidone (PVP). This flexible polymer material has good hydrophilicity, can have good compatibility with the polymer particles, and is easy to mold. Other polymer materials that can be cured and formed from a flow state can also be used as the matrix, but the effect is not as good as the above materials.

[0020] Preferably, based on the mass of the flexible polymer material, the dosage of the polymer particles is 1 - 30%.

[0021] More preferably, the flexible polymer material is polyvinyl alcohol, and based on the mass of the polyvinyl alcohol, the dosage of the polymer particles is 1 - 20%.

[0022] Preferably, the material of the flexible matrix further includes a thermoplastic elastomer. In the present invention, blending the thermoplastic elastomer with the above flexible polymer material as a composite matrix can improve the mechanical properties of the matrix, and at the same time, the synergistic effect of the elastomer can accelerate the movement of the conductive medium and improve the response rate of the detector.

[0023] More preferably, the thermoplastic elastomer is selected from one or more of thermoplastic polyurethane (TPU), hydrogenated styrene-isoprene block copolymer (SEPS), and ethylene propylene diene monomer (EPDM).

[0024] More preferably, based on the mass of the flexible polymer material, the dosage of the thermoplastic elastomer is 0 - 50%.

[0025] Preferably, the conductive material is selected from one or more of ionic liquid (IL), silver nanowires (AgNWs), carbon nanotubes (CNTs), and reduced graphene oxide (RGO). In the intrinsic flexible photodetection material of the present invention, a suitable conductive medium needs to be introduced to construct a conductive path. The conductive medium moves under the influence of the deformation of the polymer particles in the detection material, causing a change in the conductivity of the entire composite material, and the electrical signal is converted and output through detection by the detection device.

[0026] Further preferably, the conductive material is an ionic liquid, and more preferably the conductive material is selected from one or more of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]).

[0027] The present invention also provides a preparation method of the above-mentioned intrinsically flexible light-detecting material based on polymer particles, comprising the following steps:

[0028] 1) Mix the polymer particles and the flexible polymer material to prepare a flexible film;

[0029] 2) Composite the conductive material in the flexible film.

[0030] Preferably, in step 1), the polymer particles, the flexible polymer material, and the thermoplastic elastomer are mixed to prepare the flexible film.

[0031] Preferably, in step 1), the flexible film is prepared by a spinning method, a casting method, or a 3D printing method.

[0032] Preferably, the conductive material is an ionic liquid, and step 2) is specifically: soaking the flexible film in the ionic liquid to fully swell it, and then drying it to obtain the product.

[0033] Further preferably, in step 1), the polymer particles, the flexible polymer material, and the optionally added thermoplastic elastomer are mixed in a solvent, stirred for 2 to 8 h to be fully mixed and dissolved, and then a flexible film is prepared by an electrospinning method. More preferably, during the electrospinning process, a DC voltage of 5 to 25 kV is used, the solution propulsion speed in the syringe is 0.1 to 2 mL / h, and the distance between the needle and the receiving device is 8 to 18 cm; 0.3 to 3 mL of the mixed solution is continuously electrospun to obtain a composite fiber film with the required thickness and size; the receiving device is a stainless steel plate with a layer of aluminum foil attached to the surface, and the composite fiber film can be torn off with tweezers after electrospinning. The size of the receiving device can be cut, and the size of the film can also be cut after tearing off the composite fiber film. By preparing the composite material by the above electrospinning method, the present invention can better disperse the polymer particles and make the prepared film matrix easier to stretch, fold, and breathe. The solvent is preferably one or more of dimethyl sulfoxide (DMSO), ethanol, and deionized water.

[0034] Preferably, the conductive material is an ionic liquid, and step 2) is specifically: soaking the flexible film in the ionic liquid for a period of time, taking it out, blotting off the excess ionic liquid with filter paper, and drying it overnight in a fume hood to obtain the intrinsic flexible light detection material based on polymer particles.

[0035] The present invention also provides the application of the above-mentioned intrinsic flexible light detection material in the fields of environmental monitoring, military encryption communication, soft robotics, intelligent switches, and electronic skin. The intrinsic flexible light detection material based on polymer particles provided by the present invention will cause different changes in electrical signal sizes when irradiated by light of different intensities. There is a good linear relationship between the intensity of the input light signal and the size of the output electrical signal, and it can be used in fields such as environmental monitoring, military encryption communication, soft robotics, intelligent switches, and electronic skin for light detection materials.

[0036] The beneficial effects of the present invention are at least as follows:

[0037] The intrinsic flexible light detection material based on polymer particles provided by the present invention, its preparation method and application, skillfully use light-responsive polymer particles with a certain morphology as photosensitive units, disperse them in a flexible matrix, and compound them with a conductive medium to obtain a new type of light detection material. This light detection material can be processed and formed in a variety of ways to prepare light detectors of different shapes and sizes, and has intrinsic flexibility such as bendability, foldability, and stretchability, and can achieve large-area detection and sensing. Compared with the preparation of light detectors using traditional optoelectronic materials, the preparation of the present invention is easier and the cost is lower.

[0038] Moreover, due to the characteristics of small size and easy doping of the polymer particles used, the intrinsic flexible light detection material provided by the present invention has strong designability. By adjusting the structure and properties of the polymer particles therein, replacing different forming matrices and conductive media, changing the processing and forming parameters or methods, light detection materials that can detect light of different wavelengths, have different material properties (such as hydrophilicity / hydrophobicity, mechanical properties, etc.), and various morphologies can be prepared, and can be flexibly designed according to the usage needs. The intrinsic flexible light detection material has important application significance in the fields of environmental monitoring, military encryption communication, soft robotics, intelligent switches, and electronic skin. Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained without creative efforts based on these drawings.

[0040] Figure 1It is a transmission electron microscope photograph of the light-responsive polymer particles Az-NPs.

[0041] Figure 2 It is a scanning electron microscope photograph (left figure) and a transmission electron microscope photograph (right figure) of the electrospun fiber film in Example 1;

[0042] Figure 3 It is a physical schematic diagram of the polymer particle ultraviolet light detection device in Example 2;

[0043] Figure 4 It is a current-time curve graph of the device in Example 2 under ultraviolet light irradiation with different intensities, where the inset is an amplified current-time graph of a single response.

[0044] Figure 5 It is a scanning electron microscope photograph of the light-responsive polymer BCP in Comparative Example 1.

[0045] Figure 6 It is a current-time curve graph of the device in Comparative Example 1 under ultraviolet light irradiation with different intensities. Detailed implementation manners

[0046] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0047] For those technical or conditions not specified in the embodiments, they shall be in accordance with the technologies or conditions described in the literature in this field, or in accordance with the product specifications. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through regular channels.

[0048] The polymer particles selected in the examples of the present invention are poly(methyl methacrylate)-block-poly{1-[4-(4-butylphenyl)azo]phenoxymethyl acrylate} (Az-NPs) prepared in the laboratory. The preparation method can refer to the article "Light-triggered reversible slimming of azobenzene-containing wormlike nanoparticles synthesized by polymerization-induced self-assembly for nanofilter switches", published in ACS Macro Letters, Volume 8, Issue 4, pages 460-465, 2019, authors Song Guan, Zichao Deng, etc. Figure 1It is a transmission electron microscope photograph (TEM image) of the light-responsive polymer particles Az-NPs. These azobenzene particles are worm-shaped with a diameter of approximately 20 - 30 nm. The center of the worm particles is the azobenzene group sensitive to ultraviolet light, and the periphery is hydrophilic polymethacrylic acid. Under ultraviolet light irradiation, the worm particles will expand and thicken, and can reversibly contract and recover under visible light irradiation. Other polymer particles containing light-responsive groups and capable of reversible deformation in the art can also be used, but the overall effect of Az-NPs is the best.

[0049] Example 1

[0050] This example provides a method for preparing a polymer particle composite fiber film, which specifically includes the following steps:

[0051] 1) Electrospinning composite fibers: Weigh 0.159 g of polyvinyl alcohol (PVA) and 0.805 g of dimethyl sulfoxide (DMSO) with an analytical balance, pour them into a small glass bottle, and then add 0.095 g of an ethanol dispersion of Az-NPs worm particles with a mass fraction of 1.7% dropwise, thus preparing an electrospinning solution with a polymer concentration of 15%. The solvent is dimethyl sulfoxide:ethanol = 9:1, and Az-NPs account for 1% of the mass of the polymer matrix. Place the glass bottle on a magnetic stirrer and heat it at 70 °C for 6 h to obtain a uniformly mixed and dissolved solution. Inject the solution into a 5 mL syringe for electrospinning. During the electrospinning process, the DC voltage used is 15 kV, the solution propulsion speed in the syringe is 0.5 mL / h, the distance between the needle and the receiving device is 14 cm, and 1 mL of the mixed solution is continuously electrospun to obtain a composite fiber film with the required thickness and size. The receiving device is a stainless steel plate with a layer of aluminum foil attached to the surface, with dimensions of 200×300 mm. After electrospinning, use tweezers to tear off the composite fiber film and dry it overnight at room temperature and normal pressure. Finally, cut the composite fiber film into small pieces of 20×20 mm for standby. Figure 2 It is the scanning electron microscope photograph (left figure) and transmission electron microscope photograph (right figure) of the electrospun fiber film;

[0052] 2) Introduction of ionic liquid conductive phase: Immerse the above composite fiber film in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), fully swell it, then use filter paper to absorb the excess ionic liquid, and place it in a fume hood to dry overnight to obtain a conductive composite film.

[0053] Example 2

[0054] In this embodiment, the above-mentioned conductive composite film is encapsulated into an ultraviolet light detection device, and the change in ultraviolet light intensity can be detected by detecting the change in the device resistance with a digital source meter. The specific steps are as follows: Take the conductive fiber film (20×20 mm) in Example 1, and use conductive silver paste to weld two thin copper strips at both ends of the film to reduce the contact resistance between the wire and the fiber film. The electrode spacing is about 15 mm. After the conductive silver paste dries naturally, an ultraviolet light detector is obtained. The schematic diagram of its physical object is as Figure 3 shown.

[0055] The ultraviolet light intensity detection and analysis system consists of equipment such as a digital source meter (2611B), an electrometer (6517B), an ultraviolet light source (365 nm), and a computer. The specific operation is as follows: The digital source meter (2611B) provides a stable DC voltage. The device is connected to the circuit, and under the irradiation of ultraviolet light with different intensities, the electrometer (6517B) detects the real-time current change to complete the recording of data such as time, current, and ultraviolet light intensity.

[0056] The current-time curve diagram of the device described in this example under ultraviolet light irradiation with different intensities is as Figure 4 shown. When the content of Az-NPs is 1%, the light detection device can generate a detectable current response to ultraviolet light with a minimum intensity of 1 mW / cm -2 . The response time (the time for the current change to reach the peak value) is 35 s, and the recovery time (the time for the current to return to the base value after turning off the light) is 50 s. The detection performance of this device is good and can meet the ultraviolet light detection needs in fields such as daily life, industrial lithography and photocuring, and environmental monitoring.

[0057] Example 3

[0058] This embodiment provides a preparation method of a polymer particle elastic composite fiber film. Compared with Example 1, the difference is that it also includes the loading operation of a thermoplastic elastomer, including the following steps: In the electrospinning composite fiber step, use an analytical balance to weigh 0.140 g of polyvinyl alcohol (PVA), 0.019 g of thermoplastic polyurethane (TPU), and 0.805 g of dimethyl sulfoxide (DMSO), pour them into a small glass bottle, and then drop 0.095 g of an ethanol dispersion of Az-NPs worm particles with a mass fraction of 1.7%, that is, still keep the polymer concentration at 15%, where the thermoplastic polyurethane accounts for 12% of the mass of the polymer solute, and mix and dissolve evenly. Other operations are the same as those in Example 1 and Example 2.

[0059] The function of the thermoplastic elastomer is to accelerate the response rate of the conductive composite film and improve the mechanical properties of the film. Under the same light conditions, the response time of the polymer particle composite fiber film obtained in this example is 25 s, and the recovery time is 30 s. Compared with the film prepared in Example 1, the response rates are all improved. By adding thermoplastic polyurethane, the obtained ultraviolet detector has higher response sensitivity and can better meet the application requirements in scenarios such as daily life and industrial production.

[0060] Comparative Example 1

[0061] The difference from Example 1 is only that the selected light-responsive polymer is poly(ethylene glycol)-block-poly{11-[4-(4-succinimidyl ester benzophenone azo)phenoxy]undecyl methacrylate} (BCP). Figure 5 It is a scanning electron microscope photograph of the light-responsive polymer BCP.

[0062] The current-time curve diagram of the device described in this comparative example under ultraviolet light irradiation with different intensities is as Figure 6 shown. The results show that when the content of the light-responsive polymer is also 1%, the photodetector made of BCP can minimally produce a distinguishable response to ultraviolet light of 3 mW / cm 2 and the responsivity is only 2% under ultraviolet light of 15 mW / cm 2 , and the signal is unstable and prone to noise. Compared with Example 2, its detection effect is far lower than that of the device made of Az-NPs. The reason for this situation is that at a lower content, amorphous BCP is difficult to form a conduction network, disturbing the conductive medium and thus causing changes in the conductive properties. The regular morphology and easy dispersion characteristics of Az-NPs solve this problem, and the photodetector prepared with Az-NPs has high-resolution ultraviolet detection ability.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intrinsically flexible light-detecting material based on polymer particles, characterized in that, Comprising: A flexible matrix, polymer particles and a conductive material dispersed in the flexible matrix; The material of the flexible matrix includes a flexible polymer material; The morphological structure of the polymer particles is worm-like and contains a photo-responsive group, and undergoes reversible deformation under ultraviolet light irradiation; The polymer particles are poly(methacrylic acid)-block-poly{1-[4-(4-butylphenyl)azo]phenoxymethyl acrylate} The preparation method of the intrinsic flexible light detection material includes: 1) Mixing the polymer particles and the flexible polymer material to prepare a flexible film; 2) Immersing the flexible film in the conductive material to fully swell, and drying to obtain The conductive material is an ionic liquid.

2. The intrinsic flexible light detection material according to claim 1, characterized in that, The diameter of the worm-like shape is 1 to 1000 nm, and the length is 10 to 50000 nm.

3. The intrinsic flexible light detection material according to claim 2, wherein The flexible polymer material is selected from one or more of polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone.

4. The intrinsic flexible light detection material according to claim 3, wherein Based on the mass of the flexible polymer material, the dosage of the polymer particles is 1 to 30%.

5. The intrinsic flexible light detection material according to claim 4, wherein The flexible polymer material is polyvinyl alcohol, and based on the mass of the polyvinyl alcohol, the dosage of the polymer particles is 1 to 20%.

6. The intrinsic flexible light detection material according to claim 5, characterized in that, The material of the flexible matrix further includes a thermoplastic elastomer.

7. The intrinsic flexible light detection material according to claim 6, wherein, The thermoplastic elastomer is selected from one or more of thermoplastic polyurethane (TPU), hydrogenated styrene-isoprene block copolymer (SEPS), and ethylene propylene diene monomer (EPDM).

8. The intrinsic flexible light detection material according to claim 7, characterized in that, The ionic liquid is selected from one or more of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium tetrafluoroborate.

9. The intrinsic flexible light detection material according to claim 8, wherein In the step 1), the polymer particles, the flexible polymer material and the thermoplastic elastomer are mixed to prepare the flexible film; And / or, in the step 1), the flexible film is prepared by a spinning method, a casting method or a 3D printing method.

10. Application of the intrinsic flexible light detection material according to any one of claims 1 to 9 in the fields of environmental monitoring, military encryption communication, soft robotics, intelligent switches, and electronic skin.

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