CN114496398B - Preparation method of stretchable electrode with fold structure - Google Patents

Abstract

A preparation method of a stretchable electrode with a fold structure comprises the steps of preparing a PDMS (polydimethylsiloxane) substrate, depositing a metal layer on the surface of the PDMS substrate by magnetron sputtering, coating TPU (thermoplastic polyurethane elastomer) solution on the surface of the metal layer, drying, and stripping a TPU film with the metal layer from the surface of the PDMS. The stretchable electrode with the fold structure prepared by the invention has excellent conductivity, along with stretching deformation, the resistance change is obvious, when the stretching deformation rate reaches 50%, the resistance change rate reaches 800 times, and the stretchable electrode with the fold structure is used as an electrode for wearable electronic equipment, has high sensitivity, has randomly formed fold structures, can realize uniform stretching in all directions, has good uniformity of the resistance change after stretching, has excellent stability, overcomes the limitation that stretching can only be carried out in one direction in the prior art, does not need to prestretch a substrate material in the preparation process, and has higher practicability in the production process.

Description

Preparation method of stretchable electrode with fold structure

Technical Field

The invention relates to the technical field of wearable electronic devices, in particular to a preparation method of a stretchable electrode with a fold structure.

Background

The rapid development of wearable electronic devices places higher demands on the flexibility of the device. As a core of wearable electronic devices, flexible electrode materials having stretchable properties have become a research hotspot.

The conventional metal electrode materials (Au, ag, cu, etc.) do not have flexibility by themselves, and electrodes having a certain flexibility but no stretchability can be obtained by thinning the metal layer thickness. And through optimization strategies such as fold structure design, the metal electrode with certain stretchability can be realized. For example, the lock-in rigid group is based on pre-stretched elastomer technology, producing stretchable interconnects with elastic electronic surfaces that give gold conductors good stretch properties on P DM S films (Proceedings of the IEEE 2005,93,1459). The Pardoen group uses the roughness effect in combination with the pre-stretching of the elastomer to form random wrinkles in the gold film, thereby further improving the tensile properties of the gold film (A c taMaterialia 2013,61,540). The Khine group uses a prestretching method to produce a flexible pleated stretchable metal film, so that the originally fragile metal film can be stretched to 200% or more (Applied Physics Letters 2016,108,061901). The common point of the above methods is that the pre-stretching method is adopted, and because the pre-stretching method is difficult to apply in practical production and can only stretch in a single direction, and it is difficult to uniformly stretch in all directions, the prepared conductive electrode has orientation in the stretching dimension, and it is necessary to provide an electrode which can stretch in all directions and has good conductivity, and a preparation method thereof.

Disclosure of Invention

The invention aims to provide a preparation method of a stretchable electrode with a fold structure.

The invention aims at realizing the following technical scheme:

a preparation method of a stretchable electrode with a fold structure is characterized by comprising the following steps: preparing a PDMS (polydimethylsiloxane) substrate, depositing a metal layer on the surface of the PDMS substrate by magnetron sputtering, coating TPU (thermoplastic polyurethane elastomer) solution on the surface of the metal layer, and peeling the TPU film with the metal layer from the surface of the PDMS after drying.

Further, the metal layer includes a Mn, au, or Cu layer.

Preferably, the metal layer is an Au layer.

Further, the PDMS substrate is prepared by mixing PDMS and a curing agent according to a mass ratio of 10:1, placing the mixture in a vacuum chamber for standing for 30-40 min to remove bubbles in the liquid, and then spin-coating the mixture on a glass sheet.

Further, the spin coating speed is 4500-5500 rpm, spin coating is carried out for 10-15 s, and after spin coating, the glass sheet is solidified for 4h at 80 ℃, and then is naturally cooled in air.

Further, the vacuum degree of the magnetron sputtering deposition is 2-3 Pa, the current during sputtering is 20-30 mu A, the voltage is 220-280V, and the sputtering time is 90-200 s.

In the preparation process, a flat PDMS film matrix is prepared on a glass sheet, then a metal layer is deposited by magnetron sputtering, and when the metal is deposited on the surface of the PDMS, uneven local heat is generated on the surface of the matrix due to the magnetron sputtering, and the metal layer is subjected to non-directional shrinkage on the surface of the PDMS due to the action of the local heat. The metal layer after shrinkage and PDMS have poor binding force and are very easy to fall off from the surface of PDMS, the TPU is used as a new matrix to enable the metal layer to fall off from the surface glass of PDMS, as the TPU surface is provided with a large amount of amino groups to be combined with the metal layer to form stable chemical fixation, the metal layer forms physical fixation on the TPU through a fold structure formed on the surface of the TPU, the TPU layer can be changed along with the stretching deformation of metal through double fixation, and the problem that the metal layer is easy to fall off from the surface of the matrix to fail due to the poor binding force with the matrix in the use process is solved.

Further preferably, the magnetron sputtering time is 150 to 180 seconds.

In the preparation process, the fold structure formed on the PDMS surface is more obvious along with the increase of the time of magnetron sputtering, the fold degree is larger, when the deposition time is increased to 150-180 s, the fold degree reaches the maximum, the deposition time is continuously increased, and the fold structure gradually becomes smaller or even disappears.

Further, the concentration of the TPU solution was 20wt%.

Further, the TPU solution is prepared by heating polycaprolactone to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding acetone solution of dimethylolpropionic acid, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, cooling to 50 ℃ for reacting for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and severely stirring to obtain the TPU solution.

Further, the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL.

Further, the mass volume of dimethylolpropionic acid and acetone in the acetone solution of dimethylolpropionic acid is 0.2 g/1 mL, and dibutyltin dilaurate is 0.5-0.8 wt% of polycaprolactone.

Further, the stirring rate of the vigorous stirring was 1200 to 1500rpm, and the stirring time was 30 minutes.

Most specifically, the preparation method of the stretchable electrode with the fold structure is characterized by comprising the following steps of:

(1) Mixing PDMS and a curing agent in a mass ratio of 10:1, uniformly stirring, and standing for 30-40 min in a vacuum environment to obtain liquid PDMS;

(2) Spin-coating liquid PDMS on the surface of a glass sheet at a speed of 4000-5500 rpm for 10-15 s, solidifying for 4h at 80 ℃ after spin-coating is finished, and then naturally cooling with air to obtain a PDMS film;

(3) Depositing an Au layer on the surface of the PDMS film by magnetron sputtering, wherein the sputtering vacuum degree is 2-3 Pa, the current is 20-30 mu A, the voltage is 220-280V, and the sputtering time is 90-200 s;

(4) Heating polycaprolactone alcohol to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding an acetone solution of dimethylolpropionic acid with the concentration of 0.2g/mL, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and stirring for 30 minutes at 1200-1500 rpm to obtain a TPU solution with the concentration of 20wt%, wherein the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL of dibutyltin dilaurate is 0.5-0.8 wt% of polycaprolactone;

the TPU solution was poured onto the Au layer surface, dried naturally at room temperature, and then the TPU film with Au layer was peeled off from the PDMS surface.

The invention has the following technical effects:

the stretchable electrode with the fold structure prepared by the invention has excellent conductivity, along with stretching deformation, the resistance change is obvious, when the stretching deformation rate reaches 50%, the resistance change rate reaches 800 times, and the stretchable electrode with the fold structure is used as an electrode for wearable electronic equipment, has high sensitivity, has randomly formed fold structures, can realize uniform stretching in all directions, has good uniformity of the resistance change after stretching, has excellent stability, overcomes the limitation that stretching can only be carried out in one direction in the prior art, does not need to prestretch a substrate material in the preparation process, and has higher practicability in the production process.

Drawings

Fig. 1: the electrode preparation flow chart of the invention.

Fig. 2: the Au electrode physical prepared in the embodiment 1 of the invention stretches the physical diagram in all directions.

Fig. 3: the electrode prepared by the invention forms a two-dimensional fold structure under an atomic force microscope.

Fig. 4: resistance change rates of Au electrodes prepared in example 1 of the present invention at different draw ratios.

Detailed Description

The present invention is described in detail below by way of examples, which are necessary to be pointed out herein for further illustration of the invention and are not to be construed as limiting the scope of the invention, since numerous insubstantial modifications and adaptations of the invention will be to those skilled in the art in light of the foregoing disclosure.

Example 1

The preparation method of the stretchable electrode with the fold structure comprises the following steps:

(1) Mixing PDMS and a curing agent in a mass ratio of 10:1, uniformly stirring, and standing for 30min in a vacuum environment to obtain liquid PDMS;

(2) Spin-coating liquid PDMS on the surface of a glass sheet at a speed of 5000rpm for 10s, solidifying at 80 ℃ for 4h after spin-coating, and naturally cooling with air to obtain a PDMS film;

(3) Depositing an Au layer on the surface of the PDMS film by magnetron sputtering, wherein the sputtering vacuum degree is 2Pa, the current is 20 mu A, the voltage is 250V, and the sputtering time is 180s;

(4) Heating polycaprolactone alcohol to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding an acetone solution of dimethylolpropionic acid with the concentration of 0.2g/mL, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and stirring for 30 minutes at 1500rpm to obtain a TPU solution with the concentration of 20wt%, wherein the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL of dibutyltin dilaurate was 0.5wt% of the polycaprolactone;

the TPU solution was poured onto the Au layer surface, dried naturally at room temperature, and then the TPU film with Au layer was peeled off from the PDMS surface.

The whole process flow chart of the invention is shown in figure 1. As shown in figure 2, the prepared Au metal electrode material object taking TPU as a matrix can keep the original structure of the Au metal electrode material object not destroyed by stretching and deformation in different directions, can still return to the original structure after deformation, and the Au layer and the TPU are firmly combined without falling off. As can be seen from fig. 3, the two-dimensional corrugated metal layer prepared by the method of the present invention forms irregular corrugations without direction, which enables the metal layer to meet the deformation requirement under the condition of being stretched or deformed in different directions. In the preparation process, other common methods such as spin coating, spraying and the like are used for preparing the metal layer on the surface of the PDMS, but all the methods cannot form the unoriented and irregular fold shape required by us. The resistance change of the electrode prepared in this example at different stretching ratios is shown in fig. 4, and the resistance change increases with increasing stretching degree, and has higher sensitivity. The resistance change of the electrode prepared in this example after being stretched in different directions is shown in table 1.

Table 1: surface resistance value of electrode under different directions and tensile strain (Ω/≡)

The rotation angle was tested for different degrees of stretching in the counterclockwise direction with the horizontal direction as 0 °. Therefore, after the electrodes are subjected to the same tensile strain at different angles, the surface resistance changes tend to be consistent; corresponding tensile tests are carried out on different dimensions, the metal electrode prepared by the method has no orientation in the tensile dimension, uniform stretching in all directions can be achieved, the performance is stable, and the stability performance is not influenced by the change of the stretching degree.

Example 2

The preparation method of the stretchable electrode with the fold structure comprises the following steps:

(1) Mixing PDMS and a curing agent in a mass ratio of 10:1, uniformly stirring, and standing for 40min in a vacuum environment to obtain liquid PDMS;

(2) Spin-coating liquid PDMS on the surface of a glass sheet at the speed of 4000rpm for 15s, solidifying for 4h at 80 ℃ after spin-coating is finished, and then naturally cooling with air to obtain a PDMS film;

(3) Depositing a Mn layer on the surface of the PDMS film by magnetron sputtering, wherein the sputtering vacuum degree is 3Pa, the current is 30 mu A, the voltage is 280V, and the sputtering time is 90s;

(4) Heating polycaprolactone alcohol to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding an acetone solution of dimethylolpropionic acid with the concentration of 0.2g/mL, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and stirring for 30 minutes at 1200rpm to obtain a TPU solution with the concentration of 20wt%, wherein the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL of dibutyltin dilaurate was 0.8wt% of the polycaprolactone;

the TPU solution was poured onto the Mn layer surface, dried naturally at room temperature, and then the TPU film with the Mn layer was peeled from the PDMS surface.

The Mn metal electrode prepared by the embodiment and taking TPU as a substrate has consistent surface resistance change and stable performance after being stretched at different angles. The metal electrode prepared by the invention has no orientation in the stretching dimension, and can achieve uniform stretching in all directions. The resistance of the electrode is obviously changed in the stretching deformation process, and the electrode is suitable for wearing electronic equipment.

Example 3

The preparation method of the stretchable electrode with the fold structure comprises the following steps:

(1) Mixing PDMS and a curing agent in a mass ratio of 10:1, uniformly stirring, and standing for 35min in a vacuum environment to obtain liquid PDMS;

(2) Spin-coating liquid PDMS on the surface of a glass sheet at a speed of 5500rpm for 12s, solidifying for 4 hours at 80 ℃ after spin-coating is finished, and naturally cooling with air to obtain a PDMS film;

(3) Depositing a Cu layer on the surface of the PDMS film by magnetron sputtering, wherein the sputtering vacuum degree is 2.5Pa, the current is 25 mu A, the voltage is 220V, and the sputtering time is 200s;

(4) Heating polycaprolactone alcohol to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding an acetone solution of dimethylolpropionic acid with the concentration of 0.2g/mL, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and stirring for 30 minutes at 1200-1500 rpm to obtain a TPU solution with the concentration of 20wt%, wherein the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL of dibutyltin dilaurate was 0.6wt% of polycaprolactone;

the TPU solution was poured onto the Cu layer surface, dried naturally at room temperature, and then the TPU film with the Cu layer was peeled off from the PDMS surface.

After the Cu metal electrode prepared by the embodiment and taking TPU as a substrate is stretched at different angles, the surface resistance change of the Cu metal electrode tends to be consistent, and the performance tends to be stable. The metal electrode prepared by the invention has no orientation in the stretching dimension, and can achieve uniform stretching in all directions. The resistance of the electrode is obviously changed in the stretching deformation process, and the electrode is suitable for wearing electronic equipment.

Claims (8)

1. A preparation method of a stretchable electrode with a fold structure is characterized by comprising the following steps: preparing a PDMS (polydimethylsiloxane) substrate, depositing a metal layer on the surface of the PDMS substrate by magnetron sputtering, coating a TPU (thermoplastic polyurethane elastomer) solution on the surface of the metal layer, drying, peeling a TPU film with the metal layer from the surface of the PDMS, wherein the vacuum degree of the magnetron sputtering is 2-3 Pa, the current during sputtering is 20-30 mu A, the voltage is 220-280V, the sputtering time is 90-200 s, the TPU solution is obtained by heating polycaprolactone to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2h, cooling to 70 ℃, adding dibutyl tin dilaurate of isophorone diisocyanate, continuing stirring and reacting for 3h, then adding an acetone solution of dimethylolpropionic acid, continuing reacting for 3h to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ and reacting for 3h, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and vigorously stirring to obtain the TPU solution.

2. A method of making a corrugated stretchable electrode according to claim 1, wherein: the metal layer includes a Mn, au or Cu layer.

3. A method of making a corrugated stretchable electrode according to claim 1 or 2, wherein: and the PDMS substrate is prepared by mixing PDMS and a curing agent according to a mass ratio of 10:1, placing the mixture in a vacuum chamber, standing the mixture for 30-40 min to remove bubbles in the liquid, and then spin-coating the mixture on a glass sheet.

4. A method of making a corrugated stretchable electrode according to claim 3, wherein: the spin coating speed is 4500-5500 rpm, spin coating is carried out for 10-15 s, and after spin coating, the glass sheet is solidified for 4h at 80 ℃ and then is naturally cooled in air.

5. A method of making a corrugated stretchable electrode according to claim 4, wherein: the mass volume ratio of the polycaprolactone alcohol, the isophorone diisocyanate, the acetone solution of the dimethylolpropionic acid, the N, N-bis (2-hydroxyethyl) methacrylamide and the triethylamine is 3g:1g:1mL:5mL:0.2mL.

6. A method of making a corrugated stretchable electrode according to claim 5, wherein: the mass volume of dimethylolpropionic acid and acetone in the acetone solution of dimethylolpropionic acid is 0.2 g/1 mL, and the dibutyltin dilaurate is 0.5-0.8wt% of polycaprolactone.

7. A method of making a corrugated stretchable electrode according to claim 6, wherein: the stirring speed of the vigorous stirring is 1200-1500 rpm, and the stirring time is 30min.

8. The preparation method of the stretchable electrode with the fold structure is characterized by comprising the following steps of:

(1) Mixing PDMS and a curing agent in a mass ratio of 10:1, uniformly stirring, and standing for 30-40 min in a vacuum environment to obtain liquid PDMS;

(2) Spin-coating liquid PDMS on the surface of a glass sheet at a speed of 4000-5500 rpm for 10-15 s, solidifying for 4h at 80 ℃ after spin-coating is finished, and naturally cooling with air to obtain a PDMS film;

(3) Depositing an Au layer on the surface of the PDMS film by magnetron sputtering, wherein the sputtering vacuum degree is 2-3 Pa, the current is 20-30 mu A, the voltage is 220-280V, and the sputtering time is 90-200 s;

(4) Heating polycaprolactone alcohol to 120 ℃ under vacuum, preserving heat and mechanically stirring for 2 hours, then cooling to 70 ℃, adding dibutyltin dilaurate of isophorone diisocyanate, continuously stirring and reacting for 3 hours, then adding an acetone solution of dimethylolpropionic acid with the concentration of 0.2g/mL, continuously reacting for 3 hours to form a prepolymer solution, adding N, N-bis (2-hydroxyethyl) methacrylamide into the prepolymer solution, reducing the temperature to 50 ℃ for reacting for 3 hours, adding triethylamine to obtain a polymer, dispersing the polymer into deionized water, and stirring for 30 minutes at 1200-1500 rpm to obtain a TPU solution, wherein the mass volume ratio of the polycaprolactone alcohol to the dibutyltin dilaurate to the acetone solution of dimethylolpropionic acid to the N, N-bis (2-hydroxyethyl) methacrylamide to the triethylamine is 3g:1g:1mL:5mL:0.2mL of dibutyltin dilaurate is 0.5-0.8wt% of polycaprolactone;

the TPU solution was poured onto the Au layer surface, dried naturally at room temperature, and then the TPU film with Au layer was peeled off from the PDMS surface.

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