CN111361302B

CN111361302B - Preparation method of flexible film resistant to stress stretching

Info

Publication number: CN111361302B
Application number: CN202010261611.7A
Authority: CN
Inventors: 徐文涛
Original assignee: Nankai University
Current assignee: Nankai University
Priority date: 2020-04-04
Filing date: 2020-04-04
Publication date: 2021-08-03
Anticipated expiration: 2040-04-04
Also published as: CN111361302A

Abstract

The invention relates to a preparation method of a flexible film resistant to stress stretching. The method comprises the following steps: dissolving a high polymer material into a solvent to prepare high-precision printing ink; printing ink digital controllable into a long and continuous PVK nanowire mask network on a flexible substrate by using high-resolution electrofluid jet printing equipment; and (3) evaporating a rigid material on the mask network, and then removing the nanowire mask to obtain the stretchable flexible device of the rigid material distributed in an array, namely a flexible film resistant to stress stretching. The invention refines a whole piece of material which is not resistant to stress stretching into the combination of a plurality of tiny monomers, thus realizing the flexible stress stretching resistance of the material, and the method is simple and easy to implement, has low cost, can be produced in large scale and has wide application prospect.

Description

Preparation method of flexible film resistant to stress stretching

Technical Field

The invention belongs to the field of flexible electronics, and particularly relates to a preparation method for converting a flexible material film which is not resistant to stress stretching into a flexible film which is resistant to stress stretching by using a digital controllable nanowire printing technology. The method can be used for manufacturing stretchable flexible electronic devices and the like.

Background

Currently, the electronic information industry is still dominated by rigid devices and systems. Through the technology accumulation of nearly one hundred years, the rigid device has the advantages of mature processing equipment, high running speed, high accuracy, high stability and the like. However, the limitations of classical silicon-based electronics are increasingly highlighted by moore's law. The emergence of flexible electronics provides a new direction for the development of classical electronics, triggers the generation of new-form electronic equipment, and also leads people to revolutionary change in daily life. For example, the foldable, rollable and flexible display can change the existing presentation forms of pictures and movies, so that the forms of consumer electronic products such as mobile phones, televisions and the like are more novel and portable.

Flexible electronics is one of the main incarnations of flexible electronics. Based on flexible materials, micro-nano processing and integration technologies are combined, a new generation of flexible electronic components capable of realizing functions such as logic amplification, filtering, data storage, signal inversion, digital operation, sensing and the like are designed and manufactured, and the method is an urgent need for development of information technology. The flexible functional material has unique physical and chemical properties such as light, electricity, magnetism, heat, force and the like, so that the flexible electronic device can be widely applied to intelligent electronic systems such as flexible display, data encryption, wearable sensing and the like.

The flexible electronics has the advantages of lightness, thinness, low energy consumption, good biocompatibility, adjustable mechanical property and the like, and the health monitoring system can be attached to the skin of a human body for a long time without influencing daily activities of people. The intelligent wearable device can be wirelessly connected with application software and a network, so that the combination of remote office and leisure can be realized, and the idea control technology based on physiological electric monitoring can be realized. The implantable flexible electronic device provides a new treatment means for treating complex diseases, such as Parkinson, epilepsy, depression and the like.

In recent years, the development of artificial intelligence technology has promoted the precision, intellectualization and high efficiency of voice recognition, mechanical control and economic policy decision. The flexible electronics is the basic support of artificial intelligence, and leads and expands the application of the artificial intelligence technology in more fields. The flexible artificial nerve morphology chip can simulate the human brain in real time to carry out learning and high-speed operation, so that the hardware requirements of the artificial intelligence technology on super-strong processing algorithms such as cloud computing and the like are met. The intelligent nature of flexible electronics makes it irreplaceable in future information technology.

For optoelectronic devices, stretchability is not a prerequisite, since in most cases the electronic device only needs to meet the requirements of a bendable or foldable deformation. However, bionic epidermal electronics and implantable electronic devices need to adapt to the complex and large deformation characteristics of skin or biological tissues, so the stretchability of electronic materials becomes a key factor in design. For example, organs such as the heart, arteries, and alveoli can produce periodic area deformations of up to tens of percent. The conventional needle-shaped or film-shaped electrodes cannot be mounted on the surfaces of these large-deformation organs or tissues, and cannot effectively detect physiological signals or perform corresponding in-vivo treatment due to mismatch of mechanical deformation. Therefore, the highly stretchable flexible electrode is crucial to the development of skin-like electronic devices, and provides a new idea for the next generation of wearable medical health monitoring and implantable biomedical applications.

Firstly, application to human body: while power is required for the normal operation of wearable and implantable electronic devices, conventional rigid energy storage devices are bulky and cannot deform. Therefore, in order to achieve true wearable operation, a flexible stretchable energy source system needs to be designed and integrated in the wearable system. Research shows that when the piezoelectric and triboelectric generating device with biocompatibility is applied to a human body, mechanical energy can be directly obtained and converted from natural movement of a living body (such as walking, arm shaking, hand clapping, pulse, respiration, and contraction/relaxation movement of heart, lung and diaphragm muscle), and power is supplied to wearable and implantable electronic devices (such as a cardiac pacemaker) in vivo.

Secondly, the intelligent bionic robot: the electronic skin endows the bionic robot with a skin-like sensory perception function, and the flexible driver can enable the robot to realize various bionic behaviors. Among them, the flexible electrode is a key component of the electrically driven flexible driver. In order to accommodate the large strains generated during the behavior of large deformation soft body robots, researchers have developed designs for a variety of flexible conductive materials and stretchable geometries. Ionic hydrogels and ionic liquids, as a new type of low cost transparent flexible electrode, are reported for use in Dielectric Elastomer Actuators (DEAs). Due to the excellent optical transmittance, the flexible electroactive driving soft robot consisting of the DEAs and the ionic conductive hydrogel can realize the functions of camouflage and stealth navigation. The Tolley group reports a DEAs semi-transparent swimming soft robot driven by a frameless ionic liquid electrode, and shows potential application value in invisible observation and research of marine organisms.

In summary, the stretchable electrode is an essential component in flexible electronic devices. The design and manufacture of the highly stretchable and fatigue-free electrode are key links for realizing novel wearable electronic equipment, implantable medical equipment, a bionic soft body robot and a human-computer interface with biocompatibility. In the design of implantable medical electronic devices, in order to achieve safe and stable integration with living bodies, the devices are required to have good mechanical compliance with soft biological tissues and artificial muscles.

In recent years, despite many encouraging advances in the field of flexible electronics, significant challenges remain. The George whitesilicates academy of haver university in the united states first tried to process electrodes on its surface by sputtering, and the metal developed many cracks due to stress mismatch and had poor conductivity after stretching (n.bowden, s.brittain, a.g.evans, j.w. Hutchinson, and g.m.whitesilicates, Nature,393, pp.146-149,1998.). Patent CN201610205824.1 proposes a method for manufacturing stretchable flexible electronic device in a gradient packaging manner, attaching stress buffer layers on two side surfaces of a patterned conductive film, processing the conductive film into a desired pattern or circuit, packaging a multilayer packaging substrate on two sides of the patterned conductive film with the stress buffer layers, and changing the viscosity and young modulus of the multilayer packaging substrate to achieve a stretchable effect; conventional Stretchable Flexible electronic devices such as these, however, have numerous manufacturing steps and complex processes that place limitations on mass production and deployment (Flexible Electronics: Flexible Electronics and heat future. (adv.functional. mater.2018,1805924), which is elaborated by Guo-Fei & Nie et al in the review of adv.functional. mater). Therefore, it is very important to provide a simpler, more convenient and faster manufacturing method of the stress-resistant and stretch-proof flexible film.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a preparation method of a stress-stretching-resistant flexible film in order to solve the problems of multiple manufacturing steps and complex process in the prior art. The method adopts a digital controllable technology to prepare high-precision printing patterned nanowires, a nanowire fiber grid structure is printed on a flexible substrate and is used as a mask, then a non-stretching or low-stretching material with the thickness smaller than the diameter of the nanowires is vapor-deposited, and then the nanowire mask is removed to obtain a stretchable flexible device of the non-stretching or low-stretching material distributed in an array, namely a flexible stress-resistant stretching film, so that the flexible stress-resistant stretching of the non-stretching or low-stretching material is realized. The invention refines a whole piece of material which is not resistant to stress stretching into the combination of a plurality of tiny monomers, can realize the flexible resistance to stress stretching of the material, and has wide application prospect.

The technical scheme of the invention is as follows:

a method for preparing a flexible film resistant to stress stretching comprises the following steps:

step 1: dissolving a high polymer material into a solvent to prepare high-precision printing ink;

wherein the mass ratio is that the polymer material: solvent 1:10-1: 100;

step 2: printing ink digital controllable into a continuous nanowire mask network on a flexible substrate by using electrofluid printing equipment;

wherein the diameter of the nanowire in the mask network is 50 nm-5 μm; the distance between adjacent nanowires is 3-500 μm; in each printing, the distance between adjacent phase nano wires is the same or different;

and step 3: evaporating a non-stretching or low-stretching material on the mask network, and then removing the nanowire mask to obtain a stretchable flexible device, namely a stress-stretching-resistant flexible film, of the non-stretching or low-stretching material distributed in an array;

wherein the thickness of the non-stretching or low-stretching material evaporated on the mask network is in the range of 25nm-2.5 μm.

The thickness of the non-stretching or low-stretching material is less than the diameter of the nanowire from 25nm to 2.5 mu m.

The non-stretching material is metal, metal oxide, other compounds or small molecular substances; the low-stretchability material is a high molecular substance.

The metal is aluminum, copper, titanium, chromium, silver or gold, the metal oxide is zinc oxide, indium oxide, tungsten oxide, titanium oxide, vanadium oxide, copper oxide, aluminum oxide, hafnium oxide, tantalum oxide, IZO (indium zinc oxide) or IGZO (indium gallium zinc oxide), the other compound is barium strontium titanate, barium zirconate titanate, gallium arsenide, molybdenum sulfide, tungsten selenide, palladium selenide, the polymer is PS (polystyrene), PEO (polyethylene oxide), PVK (polyvinylcarbazole), P (VDF-TrFE) (poly (vinylidene fluoride-trifluoroethylene)), PAN (polyacrylonitrile), PANI (polyaniline), PVA (polyvinylalcohol), ptams (poly (alpha-methylstyrene)), P3HT (poly-3 hexylthiophene), PMMA (polymethyl methacrylate), PVP (polyvinylpyrrolidone), DH-5T (polythiophene), DPP (diketopyrrole), N2200 (poly (2, 7-bis (2-octyldodecyl) benzo [ lmn ] [3,8] phenanthroline-1, 3,6,8(2H, 7H) -tetraone-4, 9-diyl)), wherein the small molecule substance is pentacene, titanium bronze, perfluorotitanium bronze, C60 (carbon 60), C70 (carbon 70), PCBM (fullerene derivative), or C8-BTBT (2, 7-dioctyl [1] benzothiophene [3,2-b ] [1] benzothiophene);

and 3, the deformation range of the flexible film obtained finally in the step 3 in the horizontal direction is 1-1000%.

The flexible substrate described in step 2 includes, but is not limited to, SEBS (hydrogenated styrene-butadiene block copolymer), PDMS (polydimethylsiloxane), TPU (thermoplastic polyurethane elastomer rubber), ECO-Flex, or silicone.

In the electrofluid printing process of the step 2, the voltage between the syringe needle and the receiving surface is controlled to be 0.5-10kV, the distance between the syringe needle and the substrate is controlled to be 1-10 mm, the liquid outlet flow at the syringe needle is controlled to be 1-200 nl/min, and the substrate movement speed is controlled to be 1000 mm/s.

The polymer material in step 1 is PVK (polyvinylcarbazole), P (VDF-TrFE) (poly (vinylidene fluoride-trifluoroethylene)), PAN (polyacrylonitrile), PANI (polyaniline), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide) PMMA (polymethyl methacrylate), PS (polystyrene), polyalphams (poly (alpha-methylstyrene)), or PVA (polyvinyl alcohol).

The solvent in the step 1 is water, ethanol, acetone, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, chlorobenzene, chloroform or triethanolamine.

The flexible film resistant to stress stretching is applied to a thin film battery, a solar battery, a photovoltaic battery, a lithium ion battery, a sodium ion battery, a light emitting diode, a thin film transistor, an information storage device, a flexible sensor or a flexible electrode.

The invention has the substantive characteristics that:

the invention expands the application of the digitally controllable printed fiber grid structure.

The nano wire prepared by the invention has a fiber grid structure, and after the material is evaporated on the nano wire, the diameter of the nano wire is larger than that of the evaporated material, so that the non-stretchability or low-stretchability material can be separated, wherein the size and the distance of the non-stretchability or low-stretchability material can be controlled. When the fiber network structure is removed (glued off or drawn off directly), the remaining evaporated material remains on the flexible substrate, resulting in an array of stretchable flexible devices without stretch or with low stretch material, i.e. flexible films resistant to stress stretching. The present invention aims to emphasize this structure. The high-precision nanowire mask plate is used for refining a whole piece of material which is not resistant to stress stretching into a combination of a plurality of tiny monomers, and flexible stretching of the material which is not stretchable or low in stretchability can be achieved.

The invention has the beneficial effects that:

1. the preparation method of the stress-stretching-resistant flexible film provided by the invention is simple and feasible, has low cost and can be used for large-scale production;

2. the method can utilize the high-precision nanowire mask plate to refine a whole piece of material which is not resistant to stress stretching into the combination of a plurality of tiny monomers, so that the flexible stress-resistant stretching of the material without stretchability or with low stretchability can be realized, and the method has wide application prospects in the fields of information, energy, medical treatment, national defense and the like;

3. the stretchable flexible film material prepared by the method of the invention can not damage the structure of the material film under the action of larger stress (the deformation range is 1% -1000%).

Drawings

Fig. 1 is a schematic illustration of an experimental method of stretchable flexible electronic devices according to embodiments of the present invention.

Fig. 2 is a schematic diagram of the stretching effect of the stretchable flexible electronic device according to the embodiment of the invention.

Fig. 3 is an optical microscope image of the flexible film of example 1 before stretching.

Fig. 4 is an optical microscope image of the stretched flexible film of example 1.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1:

step 1: dissolving 0.0394g of PVK into 1mL of styrene to prepare high-precision printing ink;

step 2: ink is digitally and controllably printed into a long and continuous PVK nanowire mask network on a flexible substrate SEBS by using an electrofluid printing device (E-Jet). Wherein the voltage between the syringe needle and the receiving surface is controlled to be 3.6kV, the distance between the syringe needle and the substrate is 2.5mm, the liquid outlet flow at the syringe needle is 10nL/min, the substrate movement speed is 150 mm/s, the distance between the nanowire arrays is 100 mu m, and the diameter of the nanowires is 500 nm.

And step 3: simple substance aluminum with the thickness of 30nm is evaporated on the flexible substrate and the nanowire mask, and after the nanowire mask is removed, the stretchable flexible device with the gap of 500nm and the side length of 200 microns distributed in the aluminum electrode array (10 rows and 10 columns) is obtained.

And 4, step 4: and stretching the stretchable flexible devices distributed in the aluminum electrode array, namely the stress-resistant stretched flexible films, by 200% along the nanowire arrangement direction by using a stretching table, and respectively taking the flexible films before and after stretching as optical mirrors to obtain images for comparative analysis.

The schematic diagram of the experimental method of the embodiment is shown in fig. 1, the schematic diagram of the stretching effect is shown in fig. 2, the optical microscope image of the flexible film before stretching is shown in fig. 3, it can be known from the optical microscope image of fig. 3 that the pitch of the nanowire arrays is in the micrometer level, the optical microscope image of the flexible film after stretching is shown in fig. 4, and the comparison between fig. 3 and fig. 4 shows that the morphology of the flexible film before and after stretching does not change significantly, so that the flexible film prepared by the experimental method resists stress stretching.

It can be seen that the non-stretch material aluminum has been successfully attached to the flexible substrate and the flexible film as a whole has excellent stretch properties. The rigid material is formed by combining the micro monomers in a matrix shape, so that the rigid material has the characteristic of flexible stress-resistant stretching while maintaining the original excellent performance. With the selection of the types and the sizes of the rigid materials, the stretchable flexible device made of the rigid materials can be widely applied to the preparation of film batteries, solar batteries, photovoltaic batteries, lithium ion batteries or sodium ion batteries, and the stretching performance of the conventional device is improved.

Example 2

The other steps are the same as example 1, except that:

in the step 1, the mass of PVK is 0.0788 g;

in step 2, the diameter of the nanowire is 200 nm;

in step 3, the non-tensile material is copper, and the thickness is 20 nanometers;

and (4) stretching the stretchable flexible device with the copper metal array distributed in the step (4) by 500% along the nanowire arrangement direction, wherein the appearance of the flexible film device is not significantly changed before and after stretching.

Example 3

The other steps are the same as example 1, except that:

in the step 1, the mass of PVK is 0.0591 g;

in the step 2, the diameter of the nanowire is 800 nm;

in step 3, the low-stretchability material is C8-BTBT, and the thickness is 80 nanometers;

the stretchable flexible device distributed with the C8-BTBT array obtained in the step 4 is stretched by 120% along the direction of the nanowire arrangement, and the morphology of the flexible film device is not significantly changed before and after stretching.

In conclusion, the manufacturing method of the stress-stretching-resistant flexible film provided by the invention is simple and feasible, has low cost and can be used for large-scale production; meanwhile, the flexible electronic device with good quality, thin thickness and excellent performance is obtained, the flexible electronic device is used as a pixel separation in a Light Emitting Diode (LED), and is used as a device in a Thin Film Transistor (TFT), a capacitor and a battery, and an effective method is provided for realizing large-scale industrial production of stress-resistant tensile flexible electronics.

The invention is not the best known technology.

Claims

1. A method for preparing a flexible film resistant to stress stretching is characterized by comprising the following steps:

wherein the mass ratio is that the polymer material: solvent =1:10-1: 100;

wherein the diameter of the nanowire in the mask network is 50 nm-5 μm; the distance between adjacent nanowires is 3-500 μm; in each printing, the distance between adjacent nanowires is the same or different;

and step 3: evaporating a non-stretching or low-stretching material on the mask network, and then removing the nanowire mask network to obtain a stretchable flexible device, namely a stress-stretching-resistant flexible film, of the non-stretching or low-stretching material distributed in an array;

wherein, the thickness range of the non-stretchability or low-stretchability material evaporated on the mask network is 25nm-2.5 μm;

the non-stretching material is metal, metal oxide, other compounds or small molecular substances; the low-stretchability material is a high molecular substance;

the metal is aluminum, copper, titanium, chromium, silver or gold, the metal oxide is zinc oxide, indium oxide, tungsten oxide, titanium oxide, vanadium oxide, copper oxide, aluminum oxide, hafnium oxide, tantalum oxide, IZO (indium zinc oxide) or IGZO (indium gallium zinc oxide), the other compound is barium strontium titanate, barium zirconate titanate, gallium arsenide, molybdenum sulfide, tungsten selenide or palladium selenide, and the polymer is PS (polystyrene), PEO (polyethylene oxide), PVK (polyvinylcarbazole), P (VDF-TrFE) (poly (vinylidene fluoride-trifluoroethylene)), PAN (polyacrylonitrile), PANI (polyaniline), PVA (polyvinyl alcohol), P alpha MS (poly (alpha-methylstyrene)), P3HT (poly-3 hexylthiophene), PMMA (polymethyl methacrylate), PVP (polyvinylpyrrolidone), DH-5T (polythiophene), DPP (diketopyrrole) or N2200 (poly (2, 7-bis (2-octyldodecyl) benzo [ lmn ] [3,8] phenanthroline-1, 3,6,8(2H, 7H) -tetraone-4, 9-diyl)), the small molecule substance being in particular pentacene, titanium bronze, perfluorotitanium bronze, C60 (carbon 60), C70 (carbon 70), PCBM (fullerene derivative) or C8-BTBT (2, 7-dioctyl [1] benzothiophene [3,2-b ] [1] benzothiophene);

the flexible substrate in the step 2 is SEBS (hydrogenated styrene-butadiene block copolymer), PDMS (polydimethylsiloxane), TPU (thermoplastic polyurethane elastomer rubber), ECO-Flex or silica gel;

the polymer material in the step 1 is PVK (polyvinyl carbazole), P (VDF-TrFE) (poly (vinylidene fluoride-trifluoroethylene)), PAN (polyacrylonitrile), PANI (polyaniline), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide) or PVA (polyvinyl alcohol);

2. The method for preparing a flexible film resistant to stress stretching according to claim 1, wherein the amount of deformation in the horizontal direction of the flexible film obtained at the end of the step 3 is in the range of 1% to 1000%.

3. The method for preparing a flexible film with stress-resistant stretch as claimed in claim 1, wherein in the electrofluid printing process in step 2, the voltage between the syringe needle and the receiving surface is controlled to be 0.5-10kV, the distance between the syringe needle and the substrate is controlled to be 1-10 mm, the liquid outflow rate at the syringe needle is controlled to be 1-200 nl/min, and the substrate movement speed is controlled to be 100-1000 mm/s.

4. Use of a flexible film resistant to stress-stretching prepared by the process according to claim 1, characterized in that it is used in thin film batteries, lithium ion batteries, sodium ion batteries, light emitting diodes, thin film transistors, flexible sensors or flexible electrodes.