KR20020021675A - Method of modifying a surface of polymer membrane by ion assisted reaction - Google Patents

Abstract

PURPOSE: In a method of modifying a surface of polymer membrane by ion assisted reaction, the surface of the polymer membrane is processed according to the dose of the ion irradiation and the kind of the ion beam, thereby varying the membrane surface to hydrophilicity. In addition, the size of the pores is controlled according to the irradiation dose of the ion beam, thereby enabling water penetration or electrolyte transmission. The surface modification does not change the characteristics of the membrane itself. Since the surface characteristics are merely changed, even if the membrane is used for a long time, the membrane characteristics do not deteriorate. Moreover, the size of the pores can be adjusted, thereby easily controlling porosity of the various kinds of polymer membranes requiring the selective penetrability. Also, the electrolyte penetrability is remarkably improved. CONSTITUTION: The surface modification method for a polymer membrane by using an ion assisted reaction to control the size and number of pores on the surface of the polymer membrane and to form hydrophilic groups on the polymer membrane, comprises irradiating an ion beam to the polymer membrane; and injecting simultaneously a reaction gas.

Description

Surface Modification Method of Polymer Membrane Using Ion Beam Assisted Reaction Method {METHOD OF MODIFYING A SURFACE OF POLYMER MEMBRANE BY ION ASSISTED REACTION}

Polymer membranes have not only been researched and developed for a relatively long time compared to other materials, but also have selective permeability and permeability to be commercially applicable. It has the disadvantage of low degradation resistance of the membrane. In order to broaden the applicability of the membrane, it is required to develop a membrane of a material that can be used even under severe operating conditions without decomposing the membrane and deforming the microstructure.

In recent years, the use of separators can be regarded as endless not only in the existing environmental field but also in the precision industry or the medical industry. For example, the electrolyte permeation membrane of a portable battery or the filtration membrane that filters harmful substances to the human body are advanced technologies in the separation membrane field preparing for the 21st century.

At present, polymer membranes have a pore size of 0.1 ~ 10 ㎛, but it is difficult to manufacture reproducibly without defects, as well as microstructure control such as membrane uniformity, pore size and distribution and surface characteristics of membrane. It is difficult to reform and is still at the research level.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-modified polymer separation membrane using an ion beam assisted reaction method and a surface modification method thereof, and more particularly, to a method for controlling pore and improving electrolyte permeability of a polymer separation membrane using an ion beam assisted reaction method.

More particularly, the present invention relates to a membrane surface modification method having conditions suitable for use of a membrane by modifying the surface of the polymer membrane with hydrophilicity using an ion beam such as argon or hydrogen and controlling the size of pores.

1 is a schematic diagram of an ion beam auxiliary reactor of the present invention.

2a to 2e are photographs showing the microstructure change of the polymer membrane according to the change in the ion dose of the polymer membrane treated by the ion beam assisted reaction method.

3 is a graph showing a contact angle with respect to water after ion beam treatment of the polymer membrane shown in FIG. 2.

4 is a graph showing a contact angle with respect to water after the polymer liquid separation membrane treated with the ion beam assisted reaction method.

5A and 5B are photographs showing changes in microstructure before and after treatment of a liquid separation membrane.

6 is a graph showing a change in the contact angle with respect to water according to the change in the ion irradiation amount of the specimen treated by the ion beam assisted reaction method of the polymer filter membrane.

FIG. 7 is a graph showing a change in contact angle with respect to formamide according to a change in the amount of ion irradiation of the specimen treated by the ion beam assisted reaction method of the polymer filtration membrane.

8A to 8E are photographs showing the microstructure change of the sample treated by the ion beam assisted reaction method of the polymer filtration membrane.

9a to 9d are photographs showing the change in permeation of the solution according to the time change of the polymer filtration membrane.

An object of the present invention is to improve the function as a filtration membrane by controlling the size of the pores by surface modification of the membrane (membrane) of the polymer material using the ion beam assisted reaction method.

The present invention is an ion beam assisted reaction method for controlling the size and quantity of pores on the surface of the polymer membrane and forming a hydrophilic functional group inside the polymer membrane by irradiating an ion beam having a constant acceleration energy and current density to the polymer membrane while injecting a reactive gas It provides a surface modification method and a surface-modified polymer membrane of the polymer membrane used.

The ion beam uses oxygen or hydrogen, the acceleration energy is 0.6 ~ 1.4 keV, the current density is 7.1 ~ 14.2 μA / cm ² , the dosage of implanted ions is 5 × 10 ¹⁴ ~ 1 × 10 ¹⁷ ions / cm ² Is preferred. On the other hand, oxygen is used as the reactive gas, and the injection amount of the reactive gas is preferably 2 to 8 ml / min.

The present invention treats the surface of the polymer membrane used for electrolyte separation, various medical filter separators and environmental purification by ion beam using ion beam assisted reaction method, not only changes the surface of the membrane to hydrophilicity, but also changes the size of the pores according to the ion beam dosage. By controlling it, it is possible to improve the problem that water permeation or electrolyte permeation is impossible. In particular, since the properties of the whole membrane do not change but only the properties of the surface, the properties of the membrane do not deteriorate even after long-term use, and the size of the pores can be controlled, making it easier to control porosity of various polymer membranes requiring selective permeability. Permeability is improved.

The surface-modified polymer separation membrane and the surface modification method using the ion assisting reaction method according to the present invention will be described in detail with reference to the following examples.

1 is an apparatus diagram of an ion beam assisted reaction method used in the present invention. The ion implantation gas 4 is irradiated onto the sample 3 attached to the substrate 1 through the ion gun 6, and at the same time, the reaction gas 2 is injected into the chamber to reform the surface of the sample. Reference numeral 5 denotes a pump for maintaining a vacuum in the chamber.

2A to 2E are photographs showing the microstructure after surface treatment of various polymer separators by varying ion implantation of the polyethylene separator for electrolyte permeation of a portable battery by ion assist reaction method. In the case of Figure 2a shows the surface of the polymer membrane not treated with an ion beam, it can be seen that the straw-shaped pores occupy about half in the membrane matrix. As will be described later, the surface of the polymer has a very high contact angle with water and no permeability to the electrolyte. This is because no hydrophilic functional groups are formed on the surface of the separator, so that penetration of the electrolyte is not easy. On the contrary, in FIG. 2B, when the hydrogen ion beam is irradiated with 1 keV at 1 × 10 ¹⁵ ions / cm ² and oxygen gas is blown at 4 ml / min, the microstructure of the separator surface is changed. Compared to the case of Figure 2a it can be seen that the shape is also increased as the number of pores in the shape of straw. 2C and 2D correspond to the case of irradiation with 5 × 10 ¹⁵ ions / cm ² and 1 × 10 ¹⁶ ions / cm ² , respectively, and as the amount of irradiated ions increases, the shape of pores is not treated by the ion beam assisted reaction method. It can be seen that the increase compared to the membrane. However, in the case of FIG. 2E, the ion beam is irradiated with 1 × 10 ¹⁷ ions / cm ² , and the excess ion is irradiated to show that the surface of the separator is severely damaged. As a result, pores on the surface of the separator are reduced.

3 is a graph showing a change in the contact angle of water of the samples treated by the ion beam assisted reaction method for the polyethylene separation membrane. It can be seen that the contact angle was greatly reduced as the ion implantation amount increased.

Figure 4 is a graph measuring the contact angle with respect to water after modifying the surface of the polyethylene separator widely used as a liquid separator in another form of the polymer separator by the ion beam assisted reaction method. As shown in the figure, the contact angle of the specimen without ion beam reaches 120 ° and shows very hydrophobic characteristics. On the other hand, in the case of specimens treated with the ion beam assisted reaction method, the contact angle began to decrease with the amount of ion irradiation, and when the dose was 1 × 10 ¹⁶ ions / cm ² , the contact angle was less than 20 °, and the surface of the membrane changed to a hydrophilic membrane. It can be seen that. This is a form of hydrophilic polymer treatment of the present invention when using the ion beam assisted reaction method can be seen that not only the pores of the membrane is expanded but also the permeability to water is increased by converting the membrane surface into hydrophilic.

FIG. 5 is a photograph showing a change in the microstructure of the surface of the polyethylene (UHMW-PE) separator by the ion beam assisted reaction method, showing that water permeability is improved. 5A illustrates a surface of a separator before ion beam treatment, in which thin microfilms, such as an osmotic membrane of an egg, are filled between a polymer-like polymer matrix. FIG. 5B shows a surface treatment process of irradiating a separator with a hydrogen ion beam having an energy of about 1 keV while blowing oxygen into the reaction gas in an amount of 5 × 10 ¹⁶ ions / cm ² . As the microfilms are removed under the influence of the ion beam, pores are formed on the surface. At the same time, the contact angle with water is lowered by changing the surface to be hydrophilic due to oxygen ions reacted to the surface.

6 is a graph showing a result of treating the surface of a polyethylene (UHMW-PE) separation membrane. The irradiated ion beam used oxygen and its energy was 1 keV. Reactive gas was subjected to surface modification while changing the oxygen from 2 to 8 ml / min under the condition that the ion beam current density was 7.1 μA / cm ² . As the ion dosage increased from 5 × 10 ¹⁴ ions / cm ² to 1 × 10 ¹⁷ ions / cm ² , the contact angle of water on the surface of the polymer membrane changed. It can be seen that the contact angle with respect to water is significantly lowered in the part showing high ion irradiation amount.

7 is a hydrophilic polyethylene (UHMW-PE) separator, the contact angle with the formamide was measured to determine the relationship between the surface hydrophilic treatment and surface energy. The surface energy selected in the present invention was measured by Owens method. Table 1 shows the results of surface energy calculated using the results of FIGS. 6 and 7.

Surface energy change for ion beam treatment Ion irradiation amount (ions / ㎠) Polar force (γ _p ) Dispersion force (γ _d ) Surface energy (γ _s ) Untreated 0.46 17.0 17.4 5 × 10 ¹⁴ 0.3 49.6 49.9 1 × 10 ¹⁵ 0.03 66.3 66.3 5 × 10 ¹⁵ 0.1 35.9 35.9 1 × 10 ¹⁶ 0.04 37.2 37.2 5 × 10 ¹⁶ 2.3 60.8 63.0 1 × 10 ¹⁷ 11.3 47.9 59.2

8A to 8E are photographs showing surface microstructure changes of a polyethylene (U-PE) liquid separator. FIG. 8A is a photograph before ion beam treatment, and shows a structure in which fiber-like yarns are connected to one another between the mother and the mother like other separators. 8B to 8D illustrate surface microstructure changes of the liquid separator by surface treatment while increasing the amount of ion beams. It can be seen that due to the increase in the ion beam irradiation, due diligence is cut off and the amount decreases. In the case of FIG. 8E, only the mother remains, and eventually, pores through which water or other liquids can penetrate are formed.

9a to 9d are diagrams showing the penetration of water after the surface treatment of the liquid filtration membrane treated by the present invention. In order to easily distinguish the naked eye, the aqueous ink was dropped on the untreated specimen (left) and the treated specimen (right), respectively, and the transmission form was observed. Treatment conditions are as follows. The hydrogen ion beam was used with an ion beam energy of 1.4 keV, an ion beam current density of 14.2 μA / cm ² , an ion irradiation amount of 5 × 10 ¹⁶ ions / cm ² , and oxygen of 6 ml / min as a reactive gas. In the case of the ion beam-treated specimen, the contact angle with the separator decreases with time, and it is understood that the specimen penetrates into the separator and penetrates to the opposite side, and the penetration is completed within 10 minutes. However, it can be seen that the specimen without ion beam remains intact even after 10 minutes.

In summary, when the surface of the polymer membrane is treated by the ion beam assisted reaction method, water penetration, which has previously been difficult to permeate, becomes possible, and even after such surface treatment, the mechanical properties of the membrane are not deteriorated or the durability is not changed.

According to the present invention, the surface of the polymer membrane is treated according to the amount of ion irradiation and the type of ion beam to not only change the surface of the membrane to hydrophilicity but also to control the size of the pores according to the amount of ion beam irradiation, thereby preventing water penetration or electrolyte permeation. It can be improved. The surface modification of such a membrane does not change the properties of the entire membrane but only the properties of the surface, so even after long-term use, the properties of the membrane do not deteriorate and the pore size can be controlled to control the porosity of various polymer membranes requiring selective permeability. It is easy to control and the electrolyte permeability is greatly improved.

Claims (8)

Polymer membrane using ion beam assisted reaction method to control the size and quantity of pores on the surface of the polymer membrane and to form hydrophilic functional groups inside the polymer membrane by irradiating ion beam with constant acceleration energy and current density to the polymer membrane while injecting reactive gas Surface modification method. The method of claim 1, wherein the ion beam uses oxygen or hydrogen. The method of claim 1, wherein the ion beam energy is 0.6 to 1.4 keV. The method of claim 1, wherein the current density is in the range of 7.1 to 14.2 μA / cm ² . The method of claim 1, wherein the irradiation amount of the ion beam ranges from 5 × 10 ¹⁴ ions / cm ² to 1 × 10 ¹⁷ ions / cm ² . The method of claim 1, wherein the reactive gas is oxygen. The method of claim 1, wherein the injection amount of the reactive gas is in the range of 2 to 8 ml / min. A polymer membrane surface-modified by the method of claim 1.