KR100743836B1 - Production method of polymer thin film using corona discharge and the polymer thin film made by the method - Google Patents

Abstract

A method for forming a polymer thin film using corona discharge and a polymer thin film formed by the same are provided to increase a surface area of a fine structure and quickly form the uniform polymer thin film. An anode and a plate-shaped cathode(2) are prepared, and then a substrate(3) is put on the plate-shaped cathode. A polymer solution is applied on the entire surface of the substrate. Corona discharge is generated from the anode installed in the polymer solution, so that solvent among the polymer solution is vaporized to form a polymer thin film. The anode is made of tungsten, while the cathode is made of copper. A heater is installed on a lower portion of the cathode to adjust a temperature of the cathode.

Description

Production method of polymer thin film using corona discharge and the polymer thin film made by the method

1 is an explanatory diagram showing a state in which a polymer thin film is formed by corona discharge.

FIG. 2 is a simplified diagram of an apparatus used for producing a polymer thin film using corona discharge.

3 is a schematic diagram of the corona discharge device used in the embodiment of the present invention.

4 is a photograph of a corona discharge device actually used in Examples 1 to 4. FIG.

5 is the result of Example 1. FIG. It is the result of measuring the surface state of the polymer thin film manufactured using toluene and 1,2-dichloromethane as a solvent by an optical microscope.

FIG. 6 shows results of forming a polymer thin film according to a voltage and an electrode distance during corona discharge as a result of Example 2. FIG.

7 is a result of Example 3, (a) is a method of using a corona discharge, (b) is a result of AFM measurement of the MEH-PPV / PMMA blend polymer thin film prepared by the method using a spin coating.

8 is a TEM result of the polymer thin film of Example 3.

FIG. 9 is a TEM result of each polymer thin film prepared by deep coating and corona discharge of PS- b -P4VP having a molecular weight of 20 K as a result of Example 4. FIG.

** Description of the main symbols in the drawings **

1 anode 2 cathode

3: substrate 4: polymer solution

5: corona 6: heater

7: cathode stand 8: anode stand

10: chamber 20: power

30: Vent Line 40: Power Supply

50: heater controller

The present invention relates to a method for producing a polymer thin film using corona inversion and to a polymer thin film produced by the method.

First, it looks at the method used in the production of a conventional polymer thin film. Conventionally, the most widely used method for preparing a polymer thin film is spin coating or inkjet printing. Among these, spin coating is the most representative method for producing a polymer thin film. In spin coating, the thickness of the thin film is controlled by adjusting the concentration of the polymer solution and the rotational speed of the spin coater. It is very economical and large-area polymer thin film can be produced, so it is most widely used. However, if a certain pattern in the thin film is required, there is a disadvantage that patterning of the thin film is impossible through spin coating.

Inkjet printing, unlike spin coating, enables patterned thin films and is a very economical method. Recently, researches on using organic TFT and polymer LED devices as patterns are being actively conducted. However, although inkjet printing has the advantage of relatively easy pattern formation, the interface between the substrate and the polymer is not stable compared to the spin coating method, there is also a problem that the functional degradation of the polymer due to the residual solvent occurs.

Dip coating is a method of manufacturing a polymer thin film by putting the substrate in a polymer solution and then taken out and dried. Dip coating has the advantage that the thin film can be manufactured with a relatively simple equipment, but the uniformity of the thin film is not as good as the spin coating, and the thickness control of the thin film is relatively difficult. Recently, dip coating has been widely used to prepare multilayer thin films of ionic polymers.

 Therefore, the present inventors have solved the problems of the conventional polymer thin film manufacturing method, can be patterned in the polymer thin film, a large area thin film can be produced, a novel polymer without problems such as functional degradation of the polymer due to the residual solvent As a result of research to provide a method for manufacturing a thin film, a method of manufacturing a polymer thin film using corona discharge, which will be described later, has been developed.

An object of the present invention is the disadvantage that the patterning of the thin film is not possible when manufacturing the polymer thin film using the spin coating conventional and the interface between the polymer and the substrate is unstable when manufacturing the polymer thin film using inkjet printing, the function of the polymer thin film due to the residual solvent is deteriorated There is provided a novel method for producing a polymer thin film that overcomes the problems.

In order to achieve the above object, the present invention provides a method for producing a polymer thin film using a corona discharge.

Specifically, the present invention

Preparing an anode and an anode in the form of a plate (I);

Placing a substrate on the plate-shaped cathode (II);

Coating (III) the polymer solution so that it spreads throughout the substrate; And

Initiating a corona discharge from the anode installed on the polymer solution, the step of forming a polymer film while evaporating the solvent in the solution (IV)

It provides a method for producing a polymer thin film using a corona discharge, characterized in that comprises a.

In particular, the anode is preferably in the form of a tip or blade (blade).

In particular, it is preferable that the material of the positive electrode is tungsten, and the material of the negative electrode is copper.

In particular, in order to control the temperature of the plate-shaped cathode, it is preferable to heat the lower portion or the body of the cathode using a heater.

In particular, it is preferable to use a nonpolar solvent as the solvent of the polymer solution.

In particular, it is preferable to use any one selected from toluene, xylene, and cyclohexane as the nonpolar solvent.

In particular, it is preferable that the corona discharge time is between 5 and 30 seconds.

The present invention also provides a polymer thin film produced by the method for producing a polymer thin film using the corona discharge.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is an explanatory view showing a polymer thin film formed by a corona discharge, Figure 2 is a simplified view of the apparatus used for the production of a polymer thin film using a corona discharge, the present invention with reference to Figures 1 and 2 It will be described as follows.

In FIGS. 1 and 2, an anode 1 in the form of a tip is used. However, when a large area thin film is manufactured, a cathode in the form of a blade must be used. Depending on the type of polymer and the solvent used therein, in the case of using a positive electrode in the form of a tip, only a polymer thin film having a diameter of about 1 cm may be manufactured.

The cathode 2 is preferably in the form of a circular plate, that is, a cylinder of low height. Corona emission using a positive electrode and a negative electrode is a well-known technique, so a description of corona emission will be omitted.

In the preparation of the polymer thin film, the polymer solution dropped on the cathode needs to be heated to a high temperature to facilitate rapid evaporation of the solvent, so that the cathode itself is preferably heated. The heating may be heated by using a heating plate or the like under the cathode, or the cathode may be heated by inserting a cylinder heater having a small diameter after drilling a hole of a predetermined depth in the side of the cylindrical cathode. The heating method of the cathode may be variously implemented by a conventional method.

A substrate 3, for example a silicon wafer, is placed on the cathode 2, and the polymer solution 4 is dropped thereon to spread over the entire substrate 3. After the polymer solution 4 is evenly spread over the entire substrate 3, the power supply is turned on so that corona discharge is generated, and the corona 5 is released from the positive electrode 1 in the form of a tip or a blade.

Due to the discharge of the corona 5, the polymer solution 4 on the substrate 3 spreads laterally, and together with evaporation of the solvent in the polymer solution, the polymer thin film is gradually formed. This process takes place in a very short time, and a corona discharge between approximately 5 and 30 seconds is sufficient.

The ionized gas molecules generated during the corona discharge are in contact with the polymer solution in the electric field and act as nucleus for the formation of the polymer microstructure, thereby forming a uniform and large number of microdomains.

Hereinafter, the present invention will be described through specific examples.

3 is a schematic view showing a polymer thin film manufacturing apparatus using a corona discharge used in the embodiment of the present invention.

In the chamber 10, a positive electrode 1 and a positive electrode stand 8, a negative electrode 2 and a negative electrode stand 7 are installed, and an opening is provided on the side of the negative electrode 2 to heat the negative electrode 2. In order to adjust the temperature of the cathode 2 by installing a heater 6 in the form of a cylinder. The chamber 10 is provided with a vent line 30 for venting (= discharging) the volatile solvent gas, and at the rear end of the vent line, there are facilities such as a fan or a pump for venting (not shown in FIG. 3).

Outside the chamber 10, there is a power supply 40 for supplying power to the positive electrode 1 and the negative electrode 2, the heater regulator 50 for controlling the temperature of the heater 6 is provided.

Example  1: thin film formation according to solvent

4 is an actual device photograph produced according to FIG. 3. Using the apparatus of FIG. 4, the thin film formation according to the solvent in the polymer solution during the preparation of the polymer thin film using the corona discharge was examined.

First, only pure solvents were placed on the silicon wafer in order to find a solvent in which the spreading phenomenon was caused by corona discharge. Then, power corona discharge was generated. Toluene, dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone and 1,2-dichloroethane were used as the solvent. As a result, spreading phenomenon was observed in toluene and 1,2-dichloroethane.

After dissolving MEH-PPV (poly- [2-methoxy, 5- (2'-ethyl-hexyloxy) phenylene vinylene]) in toluene and 1,2-dichloroethane where spreading is observed, the polymer thin film was After preparation, the film surface condition was measured. The film was produced by exposure to corona discharge for 20 seconds, and a silicon wafer was used as the substrate. A tungsten tip was used as the positive electrode and a cylindrical copper negative electrode was used as the negative electrode.

In the case of using each of the above solvents, the results of measuring the presence or absence of the polymer thin film and the film surface state of the formed polymer were obtained.

Table 1

In particular, in order to confirm the surface state of the polymer thin film prepared using toluene and 1,2-dichloroethane as a solvent, the surface was measured using an optical microscope as shown in the photograph of FIG. 5.

As a result of Table 1, it is preferable to use a non-polar solvent as a solvent for preparing a polymer solution when preparing a polymer thin film using the corona discharge of the present invention. The nonpolar solvent is thought to be able to maximize the spreading phenomenon by the relatively large repulsive force acting on the polar particles. It is also preferable to use a solvent having a low boiling point. This is because the solution can be more easily spread through the low binding force between the molecules constituting the solvent and lower the possibility of remaining solvent.

Example  2: voltage vs. Polymer thin film formation experiment according to electrode spacing

In order to determine the formation of polymer thin film according to the voltage applied to the corona discharge and the gap between the electrodes (cathode and anode), PS- b -P4VP (polystyrene- b- 4-vinylpyridine) is used as a polymer, and toluene is used as a solvent. Was used, and the remaining conditions were performed in the same manner as in Example 1 to form a polymer thin film.

FIG. 6 is a result showing whether a polymer thin film is formed according to a voltage and an electrode distance for corona discharge. In FIG. 6, a polymer thin film forming reference refers to a case in which a thin film having a uniform thickness is widely formed. When the applied voltage was low, it was observed that the polymer thin film was well formed when the distance between the electrodes was short, and when the applied voltage was high, the distance between the electrodes was long. When the distance between the electrodes is short and the applied voltage is high, sparks are generated to burn the polymer solution, and when the distance between the electrodes and the applied voltage is low, the corona discharge is weak and the corona discharge does not contribute to the formation of the polymer thin film. Can be interpreted as not being generated.

In addition, as a result of the experiment observation of Example 2, when the applied voltage became high and the intensity | strength of corona discharge became strong, it observed that the evaporation rate of a solvent became fast.

Example  3: MEH -PPV / PMMA In blends  Thin film forming experiment

PMMA (polymethylmetacrylate) and MEH-PPV (poly- [2-methoxy, 5- (2'-ethyl-hexyloxy) phenylene vinylene]) are dissolved together in toluene to form a solution, using spin coating and corona discharge of the present invention. A polymer thin film was prepared.

The solvent used in the preparation of the blend solution was toluene, and the remaining experimental method was the same as in Example 1. The weight ratio of PMMA: MEH-PPV was 1: 3. A polymer thin film was prepared using spin coating and corona discharge, respectively. As a result of AFM measurement, AFM images were obtained as shown in FIG.

In FIG. 7, (a) shows a method using a corona discharge, and (b) shows a result using a conventional spin coating method. As shown in the results of the AFM image, when the polymer thin film was manufactured using corona discharge, it was found that the domain size of the PMMA was significantly reduced (the part of the AFM image shown in FIG. 7 as the dot is the domain of the PMMA).

In addition, as a result of measuring by TEM to confirm the microdomains of the PMMA / MEH-PPV polymer thin film manufactured by the method using a corona discharge, the results as shown in FIG. 8, it can be seen that the domain size of PMMA is about 50 nm, and the domain size is significantly reduced compared to the domain size of 200 to 300 nm, which can be obtained by normal spin coating. The surface area of the entire domain is increased, and as a result, it was confirmed that the polymer thin film manufactured by the method of the present invention can be applied to the field of polymer LED, in which the area of the interface is very important.

Example  4: Experiment of Manufacturing Polymer Thin Film on Block Copolymer Polymer

A polymer thin film was prepared using polystyrene- b -poly-4-vinypyridine (PS- b -P4VP) having a molecular weight of 70K (68,500g / mol) and 20K. Toluene was used as the solvent, and the experimental method was the same as in Example 1.

PS- b- P4VP is a block copolymer polymer having a micellar form, and was an experiment for observing the shape of the microdomains when the method for preparing a polymer thin film of the present invention was applied to a block copolymer polymer having a micelle.

First, PS- b- P4VP having a molecular weight of 20 K was prepared by using a conventional dip coating and the corona discharge method of the present invention, and then TEM measurement results were obtained with the results of FIG. 9. As shown in FIG. 9, in the case of using the corona discharge of the present invention, it was possible to observe a form in which micelles continued, and in some regions, a form in which micelles of sagging forms were mixed was observed. )

As described above, when the polymer thin film is manufactured using corona discharge as a novel method for manufacturing the polymer thin film, not only a uniform polymer thin film can be produced in a short time but also the microstructure in the thin film is also conventional. Compared to spin coating of about 10 times smaller can be obtained.

Therefore, since the surface of the microstructure is significantly increased compared to the polymer thin film manufactured by the conventional method, the polymer thin film manufactured by the present invention has a high surface area. The present invention can be applied.

Claims (9)

delete Preparing an anode and an anode in the form of a plate (I); Placing a substrate on the plate-shaped cathode (II); (III) allowing a polymer solution to spread throughout the substrate; And Starting a corona discharge from an anode installed on the polymer solution to form a polymer thin film as the solvent in the polymer solution evaporates (IV) Method for producing a polymer thin film using a corona discharge, characterized in that comprises a. 3. The method of claim 2, wherein the anode is in the form of a tip or a blade. The method of manufacturing a polymer thin film using corona discharge according to claim 2, wherein the material of the anode is tungsten and the material of the cathode is copper. The method of manufacturing a polymer thin film using corona discharge according to claim 2, wherein a heater is provided at a lower portion of the cathode or a cathode body for temperature control of the cathode. The method for producing a polymer thin film using corona discharge according to claim 2, wherein a nonpolar solvent is used as a solvent of the polymer solution. The method of manufacturing a polymer thin film using corona discharge according to claim 6, wherein the nonpolar solvent is any one selected from toluene, xylene, and cyclohexane. The method of manufacturing a polymer thin film using corona discharge according to claim 2, wherein the corona discharge time is between 5 and 30 seconds. delete

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