KR101807459B1 - Self-healing method of self-healing polymer using defect-healed reduced graphene oxide heater - Google Patents

Abstract

The present invention relates to a self-healing method of a self-healing polymer using a defect-healed and reduced graphene oxide heater. More specifically, the defects of a reduced graphene oxide (RGO) caused by chemical stripping can be healed by using metal atom layer deposition (ALD) method. The RGO with defects healed in advance can be used to prepare a heater. The RGO heater can be applied to a self-healing system of a self-healing polymer, thereby minimizing the consumption of the metal precursors while uniformly healing the defects of the RGO. The physical properties of RGO can be enhanced. The thermal properties of the heater made of the defect-healed RGO can be used to effectively restore damaged self-healing polymers.

Description

[0001] SELF-HEALING METHOD OF SELF-HEALING POLYMER USING DEFECT-HEALED REDUCED GRAPHENE OXIDE HEATER [0002]

The present invention relates to a method of self-healing a self-healing polymer using a defect-healed reduced graphene oxide heater, and more particularly, to a method of self-healing a self- (ALD), and the heater is fabricated with transparent RGO which is healed by the defects. Then, the RGO heater is applied to the self-healing system of the self-healing polymer, thereby minimizing the consumption of the metal precursor, Healing, uniformly healing, further enhancing the physical properties of RGO, and utilizing the thermal properties of the heater made of defect-healing RGO to effectively repair the damaged self-healing polymer. And a self-healing method of the healing polymer.

Graphene is a hexagonal hexagonal lattice of sp ² -bonding carbon atoms and has excellent properties such as high transparency, flexibility, mechanical strength and electrical conductivity. Based on these excellent properties, graphene is expected to be applied to various fields such as flexible display, energy device, and transparent electrode.

Methods for synthesizing graphene include physical and chemical stripping, chemical vapor deposition (CVD), and epitaxy synthesis. Among them, the physical exfoliation method is very simple, but since the size of graphene synthesized is only micrometer level, there are many limitations in practical application. On the other hand, the chemical vapor deposition (CVD) is excellent in the quality of graphene, but it is required to set conditions such as the type and thickness of the metal catalyst and the additional process, and is required to be a high temperature process condition, which is a great obstacle for industrial use. In addition, although the epitaxial synthesis method can synthesize a uniform graphene film, it has a drawback that it is relatively difficult to manufacture a device as well as its electrical characteristics are poorer than that of a graphene produced by CVD. On the other hand, graphene produced by a chemical peeling method (for example, Modified Hummer's method) has a high proportion of grains obtained by a single layer, can be mass-produced at a low cost, and can be used in a wide variety of applications There are advantages to be able to.

However, the graphene produced by the chemical stripping method can not be completely reduced, leaving a lot of defects, which is disadvantageous in that the reliability of the electrical properties is deteriorated. This is because when the graphene oxide (GO) is reduced to reduced graphene oxide (RGO), functional groups remain on the graphene surface or the graphene oxide does not recover to its original structure Because.

To overcome the disadvantages of graphene, a method of complementing the deterioration of graphene properties through subsequent processes (Kholmanov et al., Nano Letters , Vol. 12, No. 11, pp. 5679, 2012) Li et al., CARBON , vol. 48, p. 1124, 2010). In other words, as shown in FIG. 2, there have been studies to improve the characteristics of graphene by randomly spraying commercially available metal nanostructures on the surface of graphene or bonding them with metal particles.

However, these studies have been disadvantageous in that the purpose of graphene conductivity enhancement is more concentrated than defect healing, and particularly, defect healing is limited to local area and unnecessary consumption of metal precursor is very large.

In other words, in order to solve the problem of graphene, many researches are underway, but most of the research focused on local area and local improvement of conductivity.

In order for graphene, which is called new material of dream, to be applied and put to practical use in various fields such as semiconductors, displays, and medicine, it is essential to solve the defect problem. Particularly, the reduced graphene oxide (RGO) A new technology is needed that can heal the defects very uniformly, not in-healing.

Atomic Layer Deposition (ALD) is an atomic layer deposition method in which a precursor, which is a compound containing a desired element, is deposited on the substrate surface by each deposition separated by an inert gas (Ar, N _2, etc.) And the deposition is repeatedly performed in order to deposit a desired thickness. That is, unlike chemical vapor deposition (CVD) in which a thin film is deposited by a gas phase reaction of a reactive gas, one precursor is chemisorbed onto a substrate on which a thin film is deposited, and then a second or third gas is injected, Self-limiting reaction, which is a reaction in which a thin film is formed while adsorption takes place (Fig. 1).

This atomic layer deposition (ALD) enables formation of nanoscale thin films on the basis of alternating chemisorption, surface reaction, and by-product desorption of reactants, It is possible to produce a high-quality thin film which is easy to control precise thickness and composition, excellent in step coverage, less impurities, and free from defects such as pinholes (surface fine holes) And has an advantage of excellent electrical characteristics.

On the other hand, self-healing polymer is one of the next-generation materials that can be applied to various fields such as coating materials, building materials, and medical materials.

In this respect, development of a new system capable of maximizing the self-healing effect of self-healing polymers has also attracted attention, but to date there has been no application of graphene-based heaters to self-healing systems of self-healing polymers.

The present invention relates to a method of uniformly healing defects of reduced graphene oxide (RGO) while minimizing the amount of a metal precursor using an atomic layer deposition (ALD) method, a method of manufacturing a heater using RGO, The development of a method for applying the RGO heater to the self-healing system of the self-healing polymer is newly required.

Iskandar N Kholmanov et al., "Improved electrical conductivity of graphene films integrated with metal nanowires ", Nano Letters 12 (11) 5679-5683.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a method for uniformly healing defects of graphene oxide (RGO) reduced to a minimum amount of metal precursor by atomic layer deposition (ALD) A method of manufacturing a heater, and a method of applying the manufactured RGO heater to a self-healing system of a self-healing polymer.

In order to accomplish the above object, the present invention provides a method of manufacturing a reduced graphene oxide (RGO) by thermally reducing a graphene oxide (GO) stripped by a chemical stripping method step; b) uniformly healing defects on the reduced graphene oxide (RGO) surface by depositing a metal on the surface of the reduced graphene oxide (RGO) prepared above using ALD (Atomic Layer Deposition) ; c) fabricating a transparent RGO heater (RGO heater) using the reduced graphene oxide (RGO) healed thereby; And d) self-healing the damage of the self-healing polymer using the thermal properties of the RGO heater. The self-healing polymer self-healing polymer using the defect-healed reduced graphene oxide heater Provides a healing method.

According to another aspect of the present invention, there is provided a self-healing polymer self-healing system having a defect-healed reduced graphene oxide heater using the above-described method.

The present invention can improve the physical properties of the reduced graphene oxide (RGO) produced by the chemical stripping method with very uniform uniformity while minimizing consumption of the metal precursor.

In addition, the self-healing polymer can be effectively self-healed by a simple method using the thermal characteristics of the defective RGO heater.

The present invention can be applied not only to self-healing polymers, but also to various fields such as automobile glass, textiles, and the like.

FIG. 1 is a schematic view showing a process of an atomic layer deposition (ALD) process.
2 is a diagram related to a conventional method for complementing the characteristics of graphene (Kholmanov et al., Nano Letters , Vol. 12, No. 11, p. 5679, 2012; Li et al., CARBON , vol. 48, p. .
FIG. 3 is a graph showing physical property analysis data of a CVD-grown graphene synthesized by chemical vapor deposition, which is a control group and reduced graphene oxide (RGO), before defect repair by an atomic layer deposition (ALD) process .
FIG. 4 is a graph showing the results of the surface roughness of the reduced graphene oxide (RGO) and the surface of the CVD-grown graphene synthesized by the chemical vapor deposition method as a control group after the defect repair by the atomic layer deposition (ALD) Emission Scanning Electron Microscope (FE-SEM).
5 is a graph showing the relationship between the carbon-oxygen bond group (CO) in a graphene grown by chemical vapor deposition (CVD) and reduced graphene oxide (RGO) as a function of the deposition cycle of the atomic layer deposition (ALD) XPS (X-ray photoelectron spectroscopy) analysis of the changes in the bonding groups.
FIG. 6 is a graph showing a schematic diagram of a reduced graphene oxide (RGO) heater according to the present invention and thermal characteristics of a heater before and after a defect repair.
FIG. 7 is a view showing self-healing results obtained by applying a defect-healed reduced graphene oxide (RGO) heater to a self-healing system of self-healing polymers and using the thermal characteristics of the RGO heater.

Hereinafter, the present invention will be described in detail.

A self-healing method of a self-healing polymer using a defect-healed reduced graphene oxide heater according to the present invention includes:

a) thermally reducing graphene oxide (GO), which has been peeled off by chemical stripping, to produce reduced graphene oxide (RGO);

b) uniformly healing defects on the reduced graphene oxide (RGO) surface by depositing a metal on the surface of the reduced graphene oxide (RGO) prepared above using ALD (Atomic Layer Deposition) ;

c) fabricating a transparent RGO heater (RGO heater) using the reduced graphene oxide (RGO) healed thereby; And

d) self-healing polymer self-healing using the thermal properties of the RGO heater.

The step a) is a step of producing reduced graphene oxide (RGO) which is a defect healing object according to the present invention through chemical stripping and thermal reduction.

For example, the reduced graphene oxide (RGO) can be removed by i) contacting and oxidizing the graphite with an aqueous solution containing a strong oxidizing agent and peeling through sonication using the repulsive force present between the oxidized layers Separation into Graphene oxide (GO) sheet; ii) uniformly spin-coating the graphene oxide onto a substrate (e.g., a silicon wafer, a glass substrate, etc.) (e.g., a spinning speed of 2000 rpm); And iii) thermally reducing the coated graphene oxide substrate (e.g., at a temperature of 200 to 300 캜).

The step b) is a step of uniformly healing the defects of the reduced graphene oxide (RGO) surface by depositing a metal on the reduced graphene oxide (RGO) substrate prepared by the step a) by atomic layer deposition (ALD) .

The atomic layer deposition (ALD) is a process in which a precursor and a reactant capable of causing a chemical reaction with each other are periodically repeated (see FIG. 1) . Since the reaction of the precursors is performed only on the surface of the precursor, and the thin film is deposited on a cycle basis, the excellent step coverage can be achieved, and the thickness can be controlled at the atomic level. The thin film characteristics are excellent and the impurity formation can be suppressed There is also.

In particular, the present invention is capable of uniformly depositing a metal on a defective portion of a surface of a graphene oxide (RGO) reduced to a nanoparticle form rather than a conventional thin film form, You can heal the defects effectively while taking advantage of the characteristics.

In this step, the metal may be any metal that is thermally conductive and can be deposited on the reduced graphene oxide (RGO) through atomic layer deposition (ALD) to heal the defect, such as platinum (Pt) (Au), silver (Ag), copper (Cu), ruthenium (Ru), iridium (Ir) or the like can be used.

When the ALD is performed according to the present invention, the metal precursor may be a metal organic or a metal halide depending on the kind of a ligand bonded to a metal atom, (Such as methylcyclopentadienyltrimethyl-platinum (MeCpPtMe ₃ ) or [(1,2,5,6-η) -1,5-hexadiene] dimethylplatinum (II) (HDMP) 2 to 10) methyl groups may be used.

As the reaction gas for reacting with the metal precursor, H ₂ O, H ₂ O ₂ , O ₂ and O ₃ may be used. In order to minimize the formation of oxides containing hydroxyl groups, oxygen (O ₂ ) Is preferably used.

The deposition of the metal through this step can be performed at a temperature of 200 to 300 ° C. (eg, 300 ° C.) by adjusting the temperature of the substrate. As a result, an advantageous environment in which reduced graphene oxide (RGO) is reduced at the same time as the metal deposition (defect healing) can be created.

Specifically, in this step,

b1) placing reduced graphene oxide (RGO) in the reaction chamber (and heating to a predetermined temperature if necessary);

b2) supplying and adsorbing a vaporized metal precursor over the reduced graphene oxide (RGO) in the reaction chamber;

b3) supplying a purge gas to remove excess vaporized metal precursor from the reaction chamber;

b4) depositing metal nanoparticles on the reduced graphene oxide (RGO) surface by supplying and reacting a reactive gas onto the reduced graphene oxide (RGO) on which the metal precursor is adsorbed;

b5) supplying a purge gas to remove surplus reaction gas and reaction by-products from the reaction chamber; And

b6) repeating the steps b2) to b5) sequentially until the defective portion of the reduced graphene oxide (RGO) surface is completely healed.

The step c) is a step of fabricating an RGO heater which is transparent to transparent defective graphene oxide (RGO) through a step b).

The RGO heater may be fabricated by forming metal electrodes at both ends of a substrate where defect-healed reduced graphene oxide (RGO) is present, wherein the metal electrode is a defect-healed reduced graphene oxide (RGO) (For example, Cu tape) may be attached to both ends of an existing substrate or a metal (for example, Cu) may be vapor-deposited.

In the step d), the RGO heater manufactured through step c) is applied to a special application of the self-healing polymer of the damaged self-healing polymer to restore the self-healing polymer by using the thermal property of the RGO heater to be.

There is no particular limitation on the type of the self-healing polymer to which the RGO heater is applied according to the present invention. For example, a microcapsule containing a therapeutic substance is dispersed in a polymer having a very large molecular size, Any self-healing polymer commonly used in the art can be applied.

In this step, the self-healing of the damaged self-healing polymer can be performed by generating heat by applying a predetermined voltage to the electrode of the RGO heater in contact with the self-healing polymer, and the temperature range of self-healing may be about 50 to 60 ° C .

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. It should be understood, however, that these examples are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

Example

(1) Preparation of reduced graphene oxide (RGO)

A graphene oxide (GO) sheet was peeled off from graphite according to a modified peeling method, Modified Hummer's method, and then graphen oxide was uniformly spin-coated on the glass substrate (spinning speed: 2000 rpm).

The coated graphene oxide substrate was heated to a temperature of 300 캜 to reduce graphene oxide (GO) to reduced graphene oxide (RGO).

(2) Defect healing of reduced graphene oxide (RGO)

Atomic layer deposition (ALD) was performed at a deposition temperature of 300 占 폚 according to the following process to heal defects on the reduced graphene oxide (RGO) surface.

b1) The reduced graphene oxide (RGO) substrate obtained in (1) was placed in the reaction chamber.

b2) MeCpPtMe ₃ , which is a platinum (Pt) precursor vaporized onto the surface of the substrate in the reaction chamber, was administered for about 3 seconds with carrier gas (Ar). At this time, to obtain a proper vapor pressure of the Pt precursor, a bubbler containing the precursor was heated to about 50 DEG C, and the flow rate of the carrier gas was maintained at about 50 sccm.

b3) A surplus vaporized Pt precursor, except for the Pt precursor adsorbed physically or chemically on the substrate surface, was removed from the reaction chamber by supplying argon purging gas at a flow rate of about 50 sccm for about 3 seconds.

b4) reaction with the Pt precursor is adsorbed by the administration of oxygen (O ₂₎ for about 6 seconds as a reaction gas to the adsorption substrate Pt precursor to form a Pt nanoparticle. At this time, the flow rate of oxygen (O ₂ ) was maintained at about 200 sccm.

b5) Surplus reaction gas and reaction by-products were removed from the reaction chamber by supplying argon purging gas at a flow rate of about 50 sccm for about 3 seconds.

b6) The cycle consisting of steps b2) to b5) was repeated to coat the defective portions of the reduced graphene oxide (RGO) surface with Pt nanoparticles.

(3) Production of RGO heater

(Cu tape) was attached to both ends of a reduced graphene oxide (RGO) substrate on which defects obtained in (2) were healed to form a metal electrode.

(4) Application of self-healing polymers to self-healing systems

The prepared self-healing polymer is sandwiched with a scratch, and the damaged portion of the damaged self-healing polymer is brought into contact with the reduced graphene oxide (RGO) portion of the RGO heater fabricated in (3) And a self-healing process was performed at a temperature of 50 to 60 DEG C for about 35 minutes.

Experimental Example

(1) Before defect healing Grapina  Property Analysis

The physical properties of CVD-grown graphene analyzed by reduced graphene oxide (RGO) and a control chemical before vapor deposition of defects by atomic layer deposition are shown in FIG.

FE-SEM, Raman spectroscopy and XPS were used to analyze the characteristics of RGO and CVD-grown graphene before the defect repair process.

3 (a) and 3 (b) are SEM images of RGO and CVD-grown graphene, respectively.

In the Raman spectrum, the D band and the G band were 1329.65 cm ^-1 and 1598.54 cm ^-1 , respectively, and the 2D band was 2661.31 cm ^-1 .

In the case of RGO, the relative intensity of the D band is higher than the relative intensity of the G band, which indicates that there are many defects. The I (D) / I (G) intensity ratio of RGO was 1.44 and higher than that of CVD-grown graphene (0.02).

These results confirm that RGO is more defective than CVD-grown graphene (Fig. 3 (c), (d)).

3 (e), the XPS C 1s spectrum of RGO shows that the functional groups are Aromatic C = C (284.6 eV), Aliphatic CC (285.4 eV), Hydroxyl carbon CO (286.4 eV ), Epoxy carbon COC (287.5 eV), Carbonyl carbon C = O (288.6 eV) and Carboxylate carbon O = CO (289.4 eV).

As shown in FIG. 3 (f), the XPS C 1s spectrum of CVD-grown graphene is Aromatic C = C (284.6 eV), Aliphatic CC (285.4 eV), Hydroxyl carbon CO (286.4 eV) , And carbonyl carbon C = O (288.6 eV).

(2) After defect repair Grapina  Property Analysis

After defects were healed by atomic layer deposition, the surface of the CVD-grown graphene synthesized by the reduced graphene oxide (RGO) and the control chemical vapor deposition method was analyzed by scanning electron microscope (FE-SEM) Respectively.

In RGO, Pt was deposited from 50 cycles, whereas in CVD-grown graphene, Pt was deposited only in 150 cycles.

(3) ALD  Analysis of Carbon-Oxygen Bond Group Content Change by Deposition Cycle

As the deposition cycle of the atomic layer deposition process increases, the change of carbon-oxygen bond groups (CO bonding groups) in reduced graphene oxide (RGO) and CVD-grown graphene synthesized by chemical vapor deposition X-ray photoelectron spectroscopy (XPS) analysis is shown in FIG.

In the RGO, the area corresponding to the carbon-oxygen bond groups (CO bonding groups) decreased as the ALD Pt cycle increased. This indicates that RGO, which was thermally reduced before ALD Pt deposition, .

On the other hand, CVD-grown graphene showed almost no change in the content of carbon-oxygen bond groups even when the number of ALD Pt cycles was increased. Since the CVD-grown graphene surface has a stable chemical structure unlike the defective RGO, there is no change in the carbon-oxygen bonding group. Thus, it is difficult to uniformly deposit the metal using the ALD method in which the deposition occurs through the surface reaction (Liu et al. Small , 5, 13, 1535, 2009).

(4) Before / after healing RGO  Thermal characteristic analysis of heater

The thermal characteristics of the RGO heater before and after the defect repair were tested using a power supply (Keithley 2400), and the results are shown in FIG.

As shown in FIG. 6 (b), the temperature of the heater before the defect healing is almost unchanged even when the high voltage is applied, while the temperature after the defect healing is increased from 5 V to 20 V, I could confirm that it was going up.

(5) RGO  Analysis of Self-Healing Result of Self-Healing Polymer Using Thermal Characteristics of Heater

The results of application of defective-healed reduced graphene oxide (RGO) heater to the self-healing system of self-healing polymer are shown in FIG. To compare the transparency before and after self-healing, ultraviolet spectrometry was performed in the visible light region.

As shown in FIG. 7 (c), the permeability of the self-healing polymer before healing was 4.15 ~ 7.45%, while the permeability of the self-healing polymer after healing was 52.80 ~ 72.29%.

These results indicate that the optical transparency of the self-healing polymer can exhibit self-healing properties by the RGO heater according to the present invention.

Claims (13)

a) thermally reducing graphene oxide (GO), which has been peeled off by chemical stripping, to produce reduced graphene oxide (RGO);
b) uniformly healing defects on the reduced graphene oxide (RGO) surface by depositing a metal on the surface of the reduced graphene oxide (RGO) prepared above using ALD (Atomic Layer Deposition) ;
c) fabricating a transparent RGO heater (RGO heater) using the reduced graphene oxide (RGO) healed thereby; And
d) self-healing polymer self-healing polymer is self-healing by applying a voltage to the RGO heater while bringing the RGO heater into face-to-face contact with the self-healing polymer;
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein the thermal reduction of the step a) is carried out at a temperature of 200 to 300 ° C.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
(B) depositing a metal on a defective portion of a surface of a graphene oxide (RGO) reduced to a nanoparticle form rather than a thin film.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein step b) deposits platinum (Pt) using atomic layer deposition (ALD)
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein the metal precursor used in the atomic layer deposition (ALD) of step b) is a metal precursor containing two or more methyl groups.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein the reactive gas used in the atomic layer deposition (ALD) of step b) is oxygen (O ₂ ).
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein the metal deposition in step b) is performed at a temperature of 200-300 < 0 > C, and additional reduction of the reduced graphene oxide (RGO)
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
The step b)
b1) disposing reduced graphene oxide (RGO) in the reaction chamber;
b2) supplying and adsorbing a vaporized metal precursor over the reduced graphene oxide (RGO) in the reaction chamber;
b3) supplying a purge gas to remove excess vaporized metal precursor from the reaction chamber;
b4) depositing metal nanoparticles on the reduced graphene oxide (RGO) surface by supplying and reacting a reactive gas onto the reduced graphene oxide (RGO) on which the metal precursor is adsorbed;
b5) supplying a purge gas to remove surplus reaction gas and reaction by-products from the reaction chamber; And
b6) repeating the above steps b2) to b5) in sequence until the defective portion of the reduced graphene oxide (RGO) surface is completely healed.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
Wherein step c) comprises forming a metal electrode at both ends of the substrate on which defect-healed reduced graphene oxide (RGO) is present.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
10. The method of claim 9,
Wherein the metal electrode is formed by attaching a metal-based tape or by depositing a metal.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
11. The method of claim 10,
Wherein the metal electrode is a copper (Cu) electrode.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
The method according to claim 1,
The self-healing of the damage of the self-healing polymer in the step d) is performed at a temperature of 50 to 60 ° C by applying a voltage to the electrode of the RGO heater.
Defect - self - healing method of self - healing polymers using healing - reduced graphene oxide heater.
Use of a method according to any one of claims 1 to 12,
Defect-healing With a reduced graphene oxide heater,
Self-healing polymer self-healing system.

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