CN110760075A

CN110760075A - Ti3C2TxComposite double-network hydrogel and preparation and application thereof

Info

Publication number: CN110760075A
Application number: CN201910963869.9A
Authority: CN
Inventors: 翟茂林; 林廷睿; 李爽笑; 彭静; 李久强
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2019-10-11
Filing date: 2019-10-11
Publication date: 2020-02-07
Anticipated expiration: 2039-10-11
Also published as: CN110760075B

Abstract

The invention discloses a Ti₃C₂T_xComposite double-network hydrogel and a preparation method and application thereof. The invention takes agarose or gelatin which generates physical cross-linking under the action of self hydrogen bond as a first network and Ti₃C₂T_xPolyacrylamide or polyacrylic acid which generates physical crosslinking under the non-covalent bond bridging action of the nano-sheets is taken as a second network, the two networks are interpenetrating to form a double-network structure, and the Ti is prepared by adopting a method of heating-cooling in atmospheric atmosphere and then radiation polymerization initiated by gamma rays or electron beams₃C₂T_xComposite double-network hydrogel. The composite double-network hydrogel shows over 40 times of stretchability, has high adhesion and high strain responsiveness to different base materials, and can be used as a flexible wearable strain sensor to monitor various motions of a human body.

Description

Ti3C2TxComposite double-network hydrogel and preparation and application thereof

Technical Field

The invention relates to hydrogel, in particular to Ti₃C₂T_xComposite double-network hydrogel and a preparation method and application field thereof, in particular to application in flexible wearable strain sensors.

Background

The flexible wearable strain sensor has great market value due to wide application in the fields of wearable electronic equipment, medical health monitoring, human-computer interface interaction, soft robots and the like. In particular, resistive strain sensors capable of converting mechanical strain signals into resistive signals are of particular interest. Good stretchability, sensitivity, adhesion to different substrate surfaces, biocompatibility, and the like are required for such strain sensors.

The flexible wearable strain sensor mainly comprises a flexible substrate containing a conductive material, wherein the conductive material mainly comprises a carbon-based nano material, a metal nano material, a semiconductor material or a conductive polymer material, and the like, and the flexible substrate mainly comprises an elastic polymer and hydrogel. The flexible substrate of the presently disclosed flexible wearable strain sensor is mainly based on elastic polymers, such as: the Chinese invention patent application publication CN 105841601A discloses a flexible wearable strain sensor which is assembled by taking carbonized fabric obtained by high-temperature treatment in inert atmosphere as a conductive material and taking elastic polymer as a flexible base material; and a flexible wearable strain sensor assembled by using multi-walled carbon nanotubes and polypyrrole as conductive materials and fibers as flexible substrates is prepared by adopting a mode of stretching, dip-coating conductive nanoparticles and then polymerizing conductive polymers, which is disclosed in Chinese patent application publication No. CN 109338727A. Such strain sensors have the advantage of higher sensitivity, but are less stretchable, adherent and biocompatible. The number of flexible wearable strain sensors using hydrogel as a flexible substrate is relatively small, for example, a double-network composite hydrogel strain sensor which is prepared by a soaking method and contains polypyrrole and an iron ion conductive material, uses polyvinyl alcohol chemically cross-linked with glutaraldehyde as a first network, and uses sodium carboxymethylcellulose cross-linked with iron ions as a second network is disclosed in chinese patent application publication CN 109251449 a; and, Zhou et al reported a hydroxypropyl cellulose embedded polyvinyl alcohol Hydrogel strain sensor (y. Zhou, et al. highlystretchable, Elastic, and Ionic Conductive Hydrogel for organic Soft electronics. adv. functional. mater.2019,29,1806220). Such strain sensors have the advantage of better stretchability and biocompatibility, but have the disadvantage of lower sensitivity and are still difficult to monitor for applications with large tensile strains in excess of 4000%.

Ti₃C₂T_xAs an MXene material with high electronic conductivity, it is considered to be a very potential sensor material due to its ability to produce a continuously changing interlayer distance under the action of external pressure to cause a change in conductivity. Therefore, based on Ti₃C₂T_xThe composite hydrogel also attracts great attention. For example, the Chinese patent application publication CN109232916A discloses MXene/poly (N-substituted) prepared by a chemical polymerization method using ammonium persulfate as an initiator and tetramethylethylenediamine as an acceleratorThe hydrogel consists of three networks, namely an MXene network which is physically crosslinked, a poly (N-isopropyl acrylamide) network which is chemically crosslinked by N, N' -methylene bisacrylamide, an alginate network which is crosslinked by calcium chloride ions and the like; the Chinese invention patent application publication CN107759809A discloses a method for preparing an organic/inorganic composite hydrogel by a chemical polymerization method using ammonium persulfate as an initiator, potassium persulfate and the like as an oxidant, ferrous chloride and the like as a reducing agent, wherein the hydrogel is composed of polyacrylamide or acrylic acid hydrogel chemically crosslinked by N, N' -methylene bisacrylamide compounded by polypyrrole and MXene; the Chinese invention patent application publication CN 108774343A discloses MXene composite microcrystalline cellulose hydrogel prepared by adopting a high-temperature oil bath method and a preparation method thereof; the Chinese patent application publication CN 109928713A discloses MXene hydrogel prepared by assembling graphene oxide and MXene liquid phase and prepared by using ammonia water and the like as an initiator and a liquid phase assembling method thereof; and Yang et al reported a composite Ti synthesized by a chemical polymerization process using ammonium persulfate as an initiator and tetramethylethylenediamine as an accelerator₃C₂T_xPoly (N-isopropylacrylamide) hydrogel and its near-infrared responsiveness (C.Yang, et al.Ti)₃C₂T_xNanosheets as Photothermal agents for Near-infrared ResponsiveHydrogels.Nanoscale 2018,10,15387)。

The biggest difficulty with the presently disclosed flexible wearable strain sensors is the difficulty in controlling and balancing the properties in terms of stretchability, sensitivity, adhesion to different substrate surfaces, and biocompatibility. The MXene composite hydrogel composition and the structural performance hopefully applied to the flexible wearable strain sensor are required to be further optimized, and the preparation method has the defects of high energy consumption, high temperature method, soaking method which takes several days, and additional addition of initiator, accelerator, oxidant or reducing agent required by a chemical method polymerization system.

Disclosure of Invention

The invention aims to solve the problems that the existing hydrogel for the flexible wearable strain sensor is difficult to simultaneously obtain performances in aspects of hyperstretchability, high sensitivity, high adhesion to different base material surfaces, high biocompatibility and the like by designing and synthesizing a novel hydrogel, and overcomes the defects that the existing preparation method is high in energy consumption and long in time consumption, and additional initiators, accelerators, oxidants or reducing agents are required to be added to the system.

The invention develops Ti with super-stretchability, high sensitivity, high surface adhesion and good biocompatibility₃C₂T_xThe preparation method of the composite double-network hydrogel, which is adopted to heat-cool in the atmosphere and then initiate polymerization by gamma ray or electron beam radiation, is simple, convenient and quick, and has a pure system. The hydrogel is formed by a first network of agarose or gelatin physically cross-linked under the self hydrogen bond interaction and polyacrylamide or polyacrylic acid in Ti₃C₂T_xTi formed by interpenetration of physically crosslinked second networks under non-covalent bond bridging action of nanosheets₃C₂T_xThe composite double-network hydrogel is suitable for being used as a flexible base material to be applied to a flexible wearable strain sensor.

In particular, the invention provides Ti₃C₂T_xA composite double-network hydrogel is prepared from agarose or gelatin network (FIG. 1) through forming double-helix structure by self-hydrogen bonding, and Ti₃C₂T_xThe non-covalent bonds of the nanosheets are bridged to generate a physically-crosslinked polyacrylamide or polyacrylic acid network (as shown in figure 2), the two networks are interpenetrating to form a double-network structure, and the mass ratio of the first network to the second network is preferably 0.01-1; and Ti₃C₂T_xIn the nano sheet, T is F, O, OH and one or more of Cl groups, x is the content of various groups, and the sum of the content of various groups is more than 0 but less than or equal to 2. The Ti₃C₂T_xThe nanosheet is an irregular lamellar layer with the thickness of 1-10 nm and the length or width of 100-1000 nm, and the content of the irregular lamellar layer is 0.01-2% of the mass of polyacrylamide or polyacrylic acid. Ti₃C₂T_xDouble-network structure in composite double-network hydrogelSome highly efficient energy dissipation mechanism and Ti₃C₂T_xThe strong non-covalent bridging of the nanosheets together impart the nanosheets with a super-stretchable property, and Ti₃C₂T_xThe highly strain-dependent resistance characteristics of the nanosheets give them high sensitivity strain sensor performance. In addition, the hydrogel has high adhesiveness to different substrate surfaces due to the full physical crosslinking structure, and has good biocompatibility due to the high water content.

Ti proposed by the invention₃C₂T_xThe preparation method of the composite double-network hydrogel comprises the following steps:

1) preparing Ti₃C₂T_xMixed aqueous solution of nanosheets, agarose or gelatin, acrylamide or acrylic acid monomers;

2) heating the mixed aqueous solution obtained in the step 1) to a certain temperature in an atmosphere, and then cooling the mixed aqueous solution to a certain temperature to form Ti-containing solution₃C₂T_xThe method comprises the following steps of (1) generating a first physically-crosslinked agarose or gelatin network by hydrogen bonds of nanosheets and acrylamide or acrylic acid monomers to obtain a single-network hydrogel;

3) irradiating the single-network hydrogel obtained in the step 2) in the atmosphere under gamma rays or electron beams to form Ti in the first network₃C₂T_xNon-covalent bond bridging of the nanosheets produces a physically cross-linked second network of polyacrylamide or polyacrylic acid to obtain Ti₃C₂T_xComposite double-network hydrogel.

In the mixed aqueous solution of step 1) of the above method, Ti₃C₂T_xThe mass concentration of the nanosheets is preferably 0.1-2.0 g/L, the mass concentration of agarose or gelatin is preferably 10-100 g/L, and the mass concentration of acrylamide or acrylic acid monomers is preferably 100-1000 g/L.

Preferably, the heating temperature in the step 2) of the method is 50-100 ℃, and agarose or gelatin is changed into a linear macromolecular chain in the process; and then cooling to 0-25 ℃, wherein the agarose or gelatin linear polymer chain forms a double helix structure through the self hydrogen bond action to generate a physically cross-linked first network in the process.

The dose rate and the dose of gamma ray irradiation adopted in the step 3) of the method are preferably 1-100 Gy/min and 0.1-10 kGy respectively, or the dose rate and the dose of electron beam irradiation generated by an electron accelerator are preferably 1-10 kGy/pass and 1-10 kGy respectively, and acrylamide or acrylic acid monomer is polymerized in a first network and passes through Ti₃C₂T_xThe noncovalent bonds of the nanoplatelets bridge to produce a physically crosslinked second network.

The present invention also provides the above Ti₃C₂T_xThe composite double-network hydrogel is applied to preparation of related wearable electronic equipment for detecting various motions of a human body as a base material of a flexible wearable strain sensor.

The invention relates to Ti for a flexible wearable strain sensor₃C₂T_xCompared with the currently disclosed material for the flexible wearable strain sensor, the composite double-network hydrogel has the following advantages:

1) ti of the invention₃C₂T_xThe composite double-network hydrogel has stretchability exceeding 4000% tensile strain;

2) ti of the invention₃C₂T_xThe composite double-network hydrogel has the sensitivity of more than 11 at the tensile strain of 2000 percent;

3) ti of the invention₃C₂T_xThe composite double-network hydrogel has good response performance to cyclic stretching at different rates, and excellent response stability is kept in 1000 cyclic stretching processes;

4) ti of the invention₃C₂T_xThe composite double-network hydrogel shows high adhesion to the surfaces of different substrates such as human skin, paper, polytetrafluoroethylene, glass, copper foil, aluminum foil and the like, and particularly the high adhesion to the human skin is very favorable for application in human wearable equipment;

5) ti of the invention₃C₂T_xComposite double-network hydrogel human bodyThe body has good biocompatibility and can be directly pasted on the skin of a human body to monitor the movement of fingers, wrists, faces, necks and feet;

6) ti of the invention₃C₂T_xThe preparation method of the composite double-network hydrogel by heating-cooling and then gamma-ray or electron beam radiation polymerization is simpler and more convenient to operate, consumes less time and has a purer system.

In conclusion, the Ti of the invention₃C₂T_xThe composite double-network hydrogel can simultaneously obtain excellent performances of stretchability, sensitivity, adhesion to different substrate surfaces, biocompatibility and the like, and excellent tensile responsiveness and cycling stability. And the preparation method is simple, convenient and quick, the system is pure, and the flexible wearable strain sensor has unique advantages and wide application prospect.

Drawings

To better illustrate the technical solution of the embodiment of the invention, Ti is used₃C₂T_xThe contents of the composite agarose/polyacrylamide double-network hydrogel portion are illustrated in the accompanying drawings and should not be construed as limiting the scope of the invention. Those skilled in the art will be able to derive other relevant figures from these figures without inventive effort.

FIG. 1 is a schematic diagram of agarose or gelatin networks that are physically cross-linked by forming double helix structures through self hydrogen bonding.

FIG. 2-through Ti₃C₂T_xThe noncovalent bonds of the nanoplates bridge to produce a physically cross-linked polyacrylamide or polyacrylic acid network schematic.

FIG. 3 example 1 self-made Ti₃C₂T_xCharacterization of nanoplatelets, comprising: a, b) Ti₃AlC₂Parent, multilayer Ti₃C₂T_xAnd Ti₃C₂T_xAn X-ray diffraction spectrum (a) and a scanning electron microscope picture (b) of the nanosheet; c) ti₃C₂T_xX-ray photoelectron spectrum of the nanosheet.

FIG. 4 preparation of example 2Prepared Ti₃C₂T_xAnd (3) an optical photo of the composite agarose/polyacrylamide double-network hydrogel.

FIG. 5 Ti prepared in example 2₃C₂T_xComposite agarose/polyacrylamide double-network hydrogel, polyacrylamide hydrogel, agarose hydrogel and Ti₃C₂T_xAnd (3) a microscopic infrared spectrum of the nanosheet.

FIG. 6 Ti prepared in example 2₃C₂T_xEnergy dispersive X-ray spectrogram of the composite agarose/polyacrylamide double-network hydrogel.

FIG. 7 Ti prepared in example 2₃C₂T_xScanning electron microscope picture of composite agarose/polyacrylamide double network hydrogel.

FIG. 8 examples 3 to 6 Ti under different synthesis conditions₃C₂T_xTensile properties of the composite agarose/polyacrylamide double-network hydrogel: a) different agarose concentrations; b) different polyacrylamide concentrations; c) different dosages; d) different Ti₃C₂T_xAnd (4) concentration.

FIG. 9 Ti tested in example 7₃C₂T_xAnd (3) a cycle tensile curve of the composite agarose/polyacrylamide double-network hydrogel under different maximum elongations.

FIG. 10 Ti tested in example 8₃C₂T_xConcentration to Ti₃C₂T_xInfluence of sensitivity of composite agarose/polyacrylamide double-network hydrogel: a) different Ti₃C₂T_xThe hydrogel sensitivity at concentration changes with tensile strain; b) hydrogel sensitivity with Ti at tensile strain 800%₃C₂T_xThe change in concentration.

FIG. 11 Ti tested in example 9₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has tensile sensing performance: a) relative rate of change of resistance and b) sensitivity to changes in tensile strain.

FIG. 12 Ti tested in example 10₃C₂T_xComposite agarose/polypropyleneThe compressive sensing performance of the acrylamide double-network hydrogel is as follows: a) relative rate of change of resistance and b) sensitivity to changes in compressive strain.

FIG. 13 Ti tested in example 11₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has response performance to cyclic stretching under different stretching rates.

FIG. 14 Ti tested in example 12₃C₂T_xThe relative resistance change rate of the composite agarose/polyacrylamide double-network hydrogel changes along with time in the 1000-cycle stretching process, wherein the left side and the right side of an inseted graph are respectively enlarged images of 1 st-5 th cycle stretching and 1996-2000 th cycle stretching.

FIG. 15 Ti tested in example 13₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has the adhesion to human skin, paper, polytetrafluoroethylene, glass, copper foil and aluminum foil.

FIG. 16 shows Ti in example 14₃C₂T_xMonitoring different motions of a human body by the composite agarose/polyacrylamide double-network hydrogel: a) a monitoring device diagram; b) monitoring of finger bending movements; c) monitoring the bending movement of the wrist; d) monitoring facial expression movements; e) monitoring neck bending movements; (ii) a f) Monitoring of walking movement or standing.

Detailed Description

The present invention will be described in detail below by referring to examples, but the present invention is not limited thereto. The following examples are given without specific reference to the conventional conditions, and the reagents and materials are commercially available. The calculation formula of the relative resistance change rate of the hydrogel is (R-R)₀)/R₀Sensitivity calculation formula (R-R)₀)/(εR₀) Where ε is the strain, R, of the hydrogel₀The initial resistance value of the hydrogel and R is the resistance value of the hydrogel at strain ε.

Example 1, Ti₃C₂T_xPreparation of nanosheets

4.00g LiF and 50.0mL are added to a 120mL plastic bottle with a gas-guide tube at the mouthConcentrated hydrochloric acid, stirring and mixing evenly, and slowly adding 1.50g of Ti₃AlC₂The addition was completed within 20min with stirring and reacted in an oil bath at 40 ℃ for 3 days, the tail gas was treated with 5% KOH aqueous solution. After the reaction is finished, centrifugally separating the reaction liquid, taking the lower-layer precipitate, washing the lower-layer precipitate with deionized water until the pH value is close to neutral, and obtaining the multilayer Ti₃C₂T_x. Then adding deionized water to 100mL, carrying out ultrasonic treatment for 60min in an ultrasonic instrument with 80W power, carrying out centrifugal separation for 30min at 3000rpm, and taking out an upper layer solution, namely Ti₃C₂T_xAqueous nanosheet solution.

A in FIG. 3 shows Ti₃AlC₂Parent, multilayer Ti₃C₂T_xAnd Ti₃C₂T_xX-ray diffraction spectrum of the nano-sheet. Compared with the raw material Ti₃AlC₂，Ti₃C₂T_xThe 002 peak position of the nanosheet was reduced, indicating that the Al layer was etched causing an increase in interlayer spacing, and that Ti₃C₂T_xThe absence of the 104 peak observed in the nanoplatelets also further indicates that the Al layer was etched. In addition, compared to multilayer Ti₃C₂T_x，Ti₃C₂T_xNo residual LiF is left in the nanosheets, and no 110 peak is observed, indicating high purity and nanosheet structure Ti₃C₂T_xAnd (3) successfully synthesizing the nanosheet.

B in FIG. 3 shows Ti₃AlC₂Parent, multilayer Ti₃C₂T_xAnd Ti₃C₂T_xScanning electron microscope spectrogram of the nanosheet. Ti₃AlC₂The Ti layer is changed into a plurality of layers with larger interlayer spacing under the etching of LiF and concentrated hydrochloric acid₃C₂T_xAnd stripping under the action of ultrasonic waves to obtain Ti₃C₂T_xNanosheets.

C in FIG. 3 shows Ti₃C₂T_xX-ray photoelectron spectrum of the nano-sheet. Ti₃C₂T_xThe nano-sheet contains O, F, Cl and other elements, and the terminal group of the nano-sheet contains O, OH, F, Cl and other groups.

Example 2 Ti₃C₂T_xPreparation of composite agarose/polyacrylamide double-network hydrogel

1) Preparing 0.50g/L Ti₃C₂T_xA mixed aqueous solution of nanosheets, 20g/L agarose and 242g/L acrylamide monomer;

2) heating the mixed solution obtained in the step 1) to 90 ℃ in the atmosphere, and then cooling the mixed solution to 20 ℃ to form Ti-containing solution₃C₂T_xObtaining a single-network hydrogel by using a self-physically cross-linked agarose first network of nanosheets and acrylamide monomers;

3) irradiating the first agarose network hydrogel obtained in the step 2) in the atmosphere under the gamma ray of 10Gy/min for 40

min, forming a second Ti in the first network₃C₂T_xNano sheet physical cross-linked polyacrylamide network to obtain Ti₃C₂T_xComposite agarose/polyacrylamide double-network hydrogel.

FIG. 4 shows Ti₃C₂T_xAnd (3) an optical photo of the composite agarose/polyacrylamide double-network hydrogel. Black Ti₃C₂T_xThe nano-sheets are uniformly dispersed in the hydrogel and have very good flexibility in bending and curling.

FIG. 5 shows Ti₃C₂T_xComposite agarose/polyacrylamide double-network hydrogel, polyacrylamide hydrogel, agarose hydrogel and Ti₃C₂T_xAnd (3) a microscopic infrared spectrum of the nanosheet. The composite double-network hydrogel contains vibration absorption peaks of N-H, C ═ O, C-O and O-H, which are respectively derived from polyacrylamide, agarose and Ti₃C₂T_xNanosheet component, the composition of the hydrogel was demonstrated.

FIG. 6 shows Ti₃C₂T_xEnergy dispersive X-ray spectrogram of the composite agarose/polyacrylamide double-network hydrogel. The composite double-network hydrogel shows C, O, N and Ti elements which are uniformly distributed, and proves that agarose and polyacrylamide are usedAnd Ti₃C₂T_xThe nanoplatelets give a very homogeneous mixing in the hydrogel.

FIG. 7 shows Ti₃C₂T_xScanning electron microscope picture of composite agarose/polyacrylamide double network hydrogel. The composite double-network hydrogel has a communicated porous structure, and the average pore diameter of the composite double-network hydrogel is 594 +/-228 nm.

Example 3 Synthesis of Ti at different agarose concentrations₃C₂T_xTensile property of composite agarose/polyacrylamide double-network hydrogel

In the presence of 0-40 g/L agarose, 242g/L acrylamide, 0.50g/L Ti₃C₂T_xAnd a dose of 450Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is cut into dumbbell-shaped samples with the length of a scale distance of 13.0mm, the width of 2.0mm and the thickness of 2.2mm by a dumbbell-shaped cutter respectively, and the tensile properties of the samples are tested by a material testing machine at the tensile rate of 100 mm/min.

FIG. 8 a shows Ti under different agarose concentration synthesis conditions₃C₂T_xThe tensile property of the composite agarose/polyacrylamide double-network hydrogel. The tensile strength of the hydrogel is 100-650 kPa and the elongation at break is 2600-3900% when the agarose concentration is 0-40 g/L.

Example 4 Synthesis of Ti at different acrylamide concentrations₃C₂T_xTensile property of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 121-363 g/L acrylamide, 0.50g/L Ti₃C₂T_xAnd a dose of 450Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel, sample size and tensile test conditions were the same as in example 3.

FIG. 8 b shows Ti at different acrylamide concentrations under the conditions of synthesis₃C₂T_xThe tensile property of the composite agarose/polyacrylamide double-network hydrogel. When the concentration of acrylamide is 121-363 g/L, the water is condensedThe adhesive has a tensile strength of 210 to 1070kPa and an elongation at break of 2900 to 3900%.

Example 5 Ti Synthesis at different dosages₃C₂T_xTensile property of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 0.50g/L Ti₃C₂T_xAnd preparing Ti under the synthetic condition of 350-550 Gy dosage₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel, sample size and tensile test conditions were the same as in example 3.

In FIG. 8 c shows Ti at different dose synthesis conditions₃C₂T_xThe tensile property of the composite agarose/polyacrylamide double-network hydrogel. When the dosage is 350-550 Gy, the tensile strength of the hydrogel is 340-580 kPa, and the elongation at break is 2400-3900%.

Example 6 different Ti₃C₂T_xTi under the condition of concentration synthesis₃C₂T_xTensile property of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 0-2.0 g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel, sample size and tensile test conditions were the same as in example 3.

D in FIG. 8 shows different Ti₃C₂T_xTi under the condition of concentration synthesis₃C₂T_xThe tensile property of the composite agarose/polyacrylamide double-network hydrogel. At Ti₃C₂T_xThe hydrogel has a tensile strength of 130 to 680kPa and an elongation at break of 2100 to 4300% at a concentration of 0 to 2.0 g/L. In particular, the hydrogel is in Ti₃C₂T_xA tensile strength of 590kPa and an elongation at break of 4250% were obtained at a concentration of 0.50g/L, whereas the hydrogel had Ti₃C₂T_xAt a concentration of 1.0g/L, a tensile strength of 670kPa and an elongation at break of 3730% were obtained.

Example 7 Ti₃C₂T_xCyclic tensile property of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is prepared by cutting dumbbell-shaped samples with the length of 13.0mm gauge length, the width of 2.0mm and the thickness of 2.2mm by a dumbbell-shaped cutter respectively, and testing the cyclic tensile properties of the samples at the maximum elongation of 500%, 1000%, 1500%, 2000% and 2500% by a material testing machine at the tensile rate of 200mm/min respectively.

FIG. 9 shows Ti₃C₂T_xAnd (3) a cycle tensile curve of the composite agarose/polyacrylamide double-network hydrogel under different maximum elongations. The hydrogel has huge hysteresis loops under different maximum elongations, which indicates that the hydrogel has high energy dissipation capability, and the energy dissipation value increases with the increase of the maximum elongation, which is the typical characteristic of the hydrogel with the double-network structure.

Example 8 different Ti₃C₂T_xTi under the condition of concentration synthesis₃C₂T_xSensitivity of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 0-2.0 g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is cut into dumbbell-shaped samples with the length of a scale distance of 13.0mm, the width of 2.0mm and the thickness of 2.3mm by a dumbbell-shaped cutter, the change of the resistance value along with the tensile strain is measured, and the sensitivity is calculated.

A in FIG. 10 shows different Ti₃C₂T_xConcentration to Ti₃C₂T_xSensitivity of the composite agarose/polyacrylamide double network hydrogel as a function of tensile strain, b in FIG. 10 shows Ti at 800% tensile strain₃C₂T_xComposite agarose/polyacrylamide double-network hydrogel sensitivity with Ti₃C₂T_xThe change in concentration. As can be seen from FIG. 10, the amount of Ti is 0 to 2.0g/L₃C₂T_xThe sensitivity of the hydrogel increases with increasing tensile strain in the concentration range, but at Ti₃C₂T_xThe highest sensitivity was obtained at a concentration of 1.0 g/L.

Example 9 Ti₃C₂T_xTensile sensing performance of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is cut into dumbbell-shaped samples with the length of a scale distance of 13.0mm, the width of 2.0mm and the thickness of 2.3mm by a dumbbell-shaped cutter, the change of the resistance value along with the tensile strain is measured, and the corresponding relative resistance change rate and sensitivity are calculated.

FIG. 11 shows Ti₃C₂T_xThe relative resistance change rate and sensitivity of the composite agarose/polyacrylamide double-network hydrogel change along with the change of tensile strain. The relative rate of change of resistance and sensitivity of the hydrogel increased with increasing tensile strain. In particular, the hydrogel has a sensitivity of up to 11.1 at a tensile strain of 2000%.

Example 10, Ti₃C₂T_xCompressive sensing performance of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is cut into cylindrical samples with the diameter of 15.5mm and the height of 6.2mm by a circular cutter, the change of the resistance value along with the compressive strain is measured, and the corresponding relative resistance change rate and sensitivity are obtained by calculation.

FIG. 12 shows Ti₃C₂T_xComposite agarose/polyacrylThe relative rate of change of resistance and sensitivity of amine double network hydrogels changes with compressive strain. The relative rate of change of resistance and sensitivity of the hydrogel decreased with increasing compressive strain.

Example 11, Ti₃C₂T_xResponse performance of composite agarose/polyacrylamide double-network hydrogel to different stretching rates

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe method comprises the steps of compounding agarose/polyacrylamide double-network hydrogel, cutting a dumbbell-shaped sample with the length of a scale distance of 13.0mm, the width of 2.0mm and the thickness of 2.3mm by using a dumbbell-shaped cutter, measuring the change of resistance along with tensile strain in the cyclic stretching process at the stretching rate of 100-500 mm/min, and calculating to obtain the corresponding relative resistance change rate.

FIG. 13 shows Ti₃C₂T_xAnd (3) the change of the relative resistance change rate of the composite agarose/polyacrylamide double-network hydrogel in the cyclic stretching process at different stretching rates. The relative resistance change rate of the hydrogel keeps almost consistent with the change of tensile strain within the range of 100-500 mm/min of tensile rate, which shows that the hydrogel has excellent tensile response.

Example 12, Ti₃C₂T_xCyclic stretching response stability of composite agarose/polyacrylamide double-network hydrogel

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is cut into dumbbell-shaped samples with the length of a gauge length of 20.0mm, the width of 4.0mm and the thickness of 2.3mm by a dumbbell-shaped cutter, the change of resistance along with tensile strain in the cyclic stretching process at the stretching rate of 1000mm/min is measured, and the corresponding relative resistance change rate is obtained by calculation.

FIG. 14 shows Ti₃C₂T_xRelative electricity of composite agarose/polyacrylamide double-network hydrogel in 1000-cycle stretching processThe change rate of resistivity with time, wherein the left and right sides of the inset are magnified images of the 1 st to 5 th and 1996 to 2000 th cyclic stretches, respectively. The relative resistance change rate of the hydrogel well maintains the response to tensile strain in the 1000-cycle stretching process, which shows that the hydrogel has excellent cyclic stretching response stability.

Example 13, Ti₃C₂T_xAdhesion of composite agarose/polyacrylamide double-network hydrogel to different substrates

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy, using a mold to prepare Ti of 8.0cm by 1.0cm₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel is vertically stuck on human skin, paper, polytetrafluoroethylene, glass, copper foil and aluminum foil, and the adhesiveness of the composite agarose/polyacrylamide double-network hydrogel is observed.

FIG. 15 shows Ti₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has strong adhesiveness to human skin, paper, polytetrafluoroethylene, glass, copper foil and aluminum foil. In particular, a high adhesion to human skin would be very advantageous for its application in human wearable devices.

Example 14, Ti₃C₂T_xMonitoring of composite agarose/polyacrylamide double-network hydrogel for different motions of human body

In 20g/L agarose, 242g/L acrylamide, 1.0g/L Ti₃C₂T_xAnd a dose of 400Gy under synthetic conditions₃C₂T_xThe agarose/polyacrylamide double-network hydrogel is compounded, and a dumbbell-shaped sample with the length of a scale distance of 13.0mm, the width of 2.0mm and the thickness of 1.0mm is cut by a dumbbell-shaped cutter. The two wide ends of the dumbbell-shaped sample were sandwiched with copper foil welded with copper wires (as shown in a in fig. 16), and adhered to human fingers, wrists, faces, necks and soles for human movement monitoring.

B-f in FIG. 16 show Ti₃C₂T_xComposite agarose/polyacrylamide double-network hydrogel pairThe monitoring of different human body motions shows that the hydrogel can very sensitively monitor human body finger bending motion, wrist bending motion, facial expression motion, neck bending motion, walking motion or standing motion and the like, and has wide application prospect in manufacturing related wearable electronic equipment for detecting various human body motions.

Example 15 different Ti₃C₂T_xTi synthesized under the conditions of concentration and different dose rate gamma-ray irradiation₃C₂T_xAdhesion and strain sensor performance of composite agarose/polyacrylamide double-network hydrogel

At Ti₃C₂T_xTi synthesized under the conditions of concentration and different dose rate gamma-ray irradiation₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has almost the same tensile sensing and compressive sensing performances and sensitivity, has good response performance to cyclic stretching at different rates, keeps excellent response stability in the cyclic stretching process of 1000 times, has high adhesiveness to different base materials and has good detectability to different motions of a human body.

Example 16 Ti Synthesis under conditions of different agarose concentration, acrylamide concentration and dose Rate Gamma ray irradiation₃C₂T_xStretchable composite agarose/polyacrylamide double-network hydrogel

Ti synthesized under the conditions of different agarose concentration, acrylamide concentration, dosage rate gamma-ray irradiation and the like₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel shows almost the same performances of the flexible wearable strain sensor, such as stretchability, adhesiveness and biocompatibility, and basically the same sensitivity, responsiveness, response stability and good monitoring performance of human body movement.

Example 17 Ti synthesized by Electron Beam irradiation₃C₂T_xStretchability, adhesiveness, biocompatibility and flexible wearable strain sensor performance of composite agarose/polyacrylamide double-network hydrogel

Ti synthesized under the irradiation condition of electron beams by adopting an electron accelerator to generate 1-10 kGy/pass dosage rate and 1-10 kGy dosage₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel shows almost the same stretchability, adhesiveness and biocompatibility as those of the hydrogel synthesized by gamma ray irradiation, and basically the same performances of the flexible wearable strain sensor such as sensitivity, responsiveness, response stability and good monitoring performance of human body movement.

Example 18 Ti Synthesis by irradiation with Gamma-ray or Electron Beam₃C₂T_xStretchability, adhesion, biocompatibility and flexible wearable strain sensor performance of composite gelatin/polyacrylamide double-network hydrogel

Ti synthesized by irradiation of gamma rays or electron beams₃C₂T_xThe composite gelatin/polyacrylamide double-network hydrogel shows the same effect as that of Ti₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has the same performances of flexible wearable strain sensors, such as stretchability, adhesiveness and biocompatibility, sensitivity, responsiveness, response stability and good monitoring performance of human body movement.

Example 19 Ti Synthesis by irradiation with Gamma rays or Electron Beam₃C₂T_xStretchability, adhesion, biocompatibility and flexible wearable strain sensor performance of composite agarose/polyacrylic acid double-network hydrogel

Ti synthesized by irradiation of gamma rays or electron beams₃C₂T_xThe composite agarose/polyacrylic acid double-network hydrogel shows the same effect as that of Ti₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has the same performances of flexible wearable strain sensors, such as stretchability, adhesiveness and biocompatibility, sensitivity, responsiveness, response stability and good monitoring performance of human body movement.

Example 20 Ti Synthesis by irradiation with Gamma-ray or Electron Beam₃C₂T_xCompounded gelatin/polypropyleneStretchability, adhesion, biocompatibility and flexible wearable strain sensor performance of enoate double-network hydrogel

Ti synthesized by irradiation of gamma rays or electron beams₃C₂T_xThe compounded gelatin/polyacrylic acid double-network hydrogel shows the same effect with Ti₃C₂T_xThe composite agarose/polyacrylamide double-network hydrogel has the same performances of flexible wearable strain sensors, such as stretchability, adhesiveness and biocompatibility, sensitivity, responsiveness, response stability and good monitoring performance of human body movement.

Claims

1. Ti₃C₂T_xThe composite double-network hydrogel is formed by taking agarose or gelatin which forms a double-helix structure through self hydrogen bonds to generate physical cross-linking as a first network to pass Ti₃C₂T_xNon-covalent bond bridging of the nano sheets generates physically cross-linked polyacrylamide or polyacrylic acid as a second network, the two networks are interpenetrated to form the hydrogel with a double-network structure, wherein T is one or more of F, O, OH and Cl groups, and 0<x≤2。

2. The Ti of claim 1₃C₂T_xThe composite double-network hydrogel is characterized in that the Ti is₃C₂T_xThe composite double-network hydrogel is prepared by mixing Ti₃C₂T_xThe nano-sheet, agarose or gelatin and acrylamide or acrylic acid monomer mixed aqueous solution are prepared by firstly forming a first network by adopting a heating-cooling method in atmospheric atmosphere and then forming a second network by adopting a method of initiating polymerization by adopting gamma ray or electron beam radiation.

3. The Ti of claim 1₃C₂T_xComposite double-network hydrogel, characterized in that Ti in the second network₃C₂T_xThe nano sheet is an irregular sheet layer with the thickness of 1-10 nm and the length or width of 100-1000 nm.

4. The Ti of claim 1₃C₂T_xComposite double-network hydrogel, characterized in that Ti in the second network₃C₂T_xThe content of the nanosheets is 0.01-2% of the mass of the polyacrylamide or polyacrylic acid.

5. The Ti of claim 1₃C₂T_xThe composite double-network hydrogel is characterized in that the mass ratio of the first network to the second network is 0.01-1.

6. Ti as set forth in claim 1₃C₂T_xThe preparation method of the composite double-network hydrogel comprises the following steps:

1) preparing Ti₃C₂T_xMixed aqueous solution of nanosheets, agarose or gelatin and acrylamide or acrylic acid monomers;

2) heating the mixed aqueous solution obtained in the step 1) in an atmosphere to a certain temperature, and then cooling the mixed aqueous solution to a certain temperature to form a first agarose or gelatin network which generates physical cross-linking by self hydrogen bonds to obtain Ti-containing solution₃C₂T_xA single-network hydrogel of nanosheets and acrylamide or acrylic acid monomers;

3) irradiating the single-network hydrogel obtained in the step 2) in the atmosphere under gamma rays or electron beams to form Ti in the first network of agarose or gelatin₃C₂T_xNon-covalent bond bridging of the nanosheets produces a physically cross-linked second network of polyacrylamide or polyacrylic acid to obtain Ti₃C₂T_xComposite double-network hydrogel.

7. The method of claim 6, wherein the mixed aqueous solution of step 1) contains Ti₃C₂T_xThe mass concentration of the nano-sheets is 0.1-2.0 g/L, the mass concentration of agarose or gelatin is 10-100 g/L, and the mass concentration of acrylamide or acrylic acid monomer isThe amount concentration is 100-1000 g/L.

8. The method according to claim 6, wherein the agarose or gelatin is changed into a linear polymer chain by heating to 50-100 ℃ in the step 2); and then cooling to 0-25 ℃ to enable the agarose or gelatin linear polymer chain to form a double helix structure through self hydrogen bond action so as to generate a physically cross-linked first network.

9. The method according to claim 6, wherein the gamma irradiation is performed at a dose rate and dose of 1 to 100Gy/min and 0.1 to 10kGy in step 3), or at a dose rate and dose of 1 to 10kGy/pass and 1 to 10kGy in step 3), and the acrylamide or acrylic acid monomer is polymerized in the first network and passes Ti₃C₂T_xThe noncovalent bonds of the nanoplatelets bridge to produce a physically crosslinked second network.

10. The Ti as set forth in any one of claims 1 to 5₃C₂T_xApplication of the composite double-network hydrogel in a flexible wearable strain sensor.