WO2001092384A1 - Method of modifying a surface of polymer membrane by ion assisted reaction - Google Patents

Method of modifying a surface of polymer membrane by ion assisted reaction Download PDF

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Publication number
WO2001092384A1
WO2001092384A1 PCT/KR2000/000572 KR0000572W WO0192384A1 WO 2001092384 A1 WO2001092384 A1 WO 2001092384A1 KR 0000572 W KR0000572 W KR 0000572W WO 0192384 A1 WO0192384 A1 WO 0192384A1
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Prior art keywords
membrane
polymer membrane
ion
ion beam
polymer
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PCT/KR2000/000572
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French (fr)
Inventor
Seok-Keun Koh
Jung Cho
Cheol-Su Lee
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Korea Institute Of Science And Technology
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Application filed by Korea Institute Of Science And Technology filed Critical Korea Institute Of Science And Technology
Priority to KR1020027001201A priority Critical patent/KR20020021675A/en
Priority to PCT/KR2000/000572 priority patent/WO2001092384A1/en
Publication of WO2001092384A1 publication Critical patent/WO2001092384A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/009—After-treatment of organic or inorganic membranes with wave-energy, particle-radiation or plasma
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12—Chemical modification
    • C08J7/16—Chemical modification with polymerisable compounds
    • C08J7/18—Chemical modification with polymerisable compounds using wave energy or particle radiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/26—Polyalkenes
    • B01D71/261—Polyethylene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12—Chemical modification
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • H01M6/18—Cells with non-aqueous electrolyte with solid electrolyte
    • H01M6/181—Cells with non-aqueous electrolyte with solid electrolyte with polymeric electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • H01M6/18—Cells with non-aqueous electrolyte with solid electrolyte
    • H01M6/188—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a modified polymer membrane by an ion assisted reaction, and in particular to an improved method to control the porosity and electrolyte penetrability of a polymer membrane by using an ion assisted reaction. More particularly, the present invention relates to a method of modifying a membrane surface which improves the polymer membrane, by modifying the surface of the polymer membrane into hydrophilic groups and controlling the size of pores simultaneously, by using an ion beam such as argon or hydrogen.
  • an ion beam such as argon or hydrogen.
  • the polymer membrane has sufficient penetrability and transmissibility to be industrially applicable.
  • the polymer membrane has many disadvantages, such as low thermal stability, deterioration by penetration of electrolytes and impurities, and low resistivity to dissolution by solvent and microorganisms.
  • a polymer membrane of a material which can be used under severe conditions, without dissolution or deformation of the microstructure.
  • polymer membranes have been variously employed in the fields of the environment, precision industry and medical care.
  • an electrolyte permeable membrane of a portable battery or a filter membrane for filtering harmful elements resulted from the advanced technology in the membrane field.
  • the size of pores of the polymer membrane can be controlled from 0.1 to 10 ⁇ m.
  • a surface modification method for the polymer membrane by using an ion assisted reaction that controls the size and number of pores on the surface of the polymer membrane to form a hydrophilic groups on the polymer membrane, by irradiating an ion beam having a predetermined acceleration energy and current density to the polymer membrane while injecting reaction gas.
  • the ion beam used is oxygen or hydrogen.
  • the acceleration energy of the ion beam is from 0.6 to 1.4keV
  • the current density thereof is 7.1 to 14.2 ⁇ A/cm 2
  • an irradiation dose of implanted ions is 5 x 10 H to 1 x 10 17 ions/cm 2 .
  • Oxygen is used as the reaction gas.
  • the flow of the reaction gas is advantageously 2 to 8ml/min.
  • the surface of the polymer membrane which is used for electrolyte separation, various medical filtering separation agents, or environmental purification is processed with the ion beam by an ion assisted reaction, and thus the surface is modified to hydrophilic groups.
  • the size of pores are controlled according to the irradiation dose of the ion beam, thereby overcoming the disadvantage of the conventional art in that water penetration or electrolyte penetrability is impossible.
  • characteristics of the membrane are not changed, but the characteristics of the surface are changed. Therefore, a long use of the membrane does not deteriorate the characteristics thereof.
  • the size of the pores can be controlled, it is easier to control the porosity of various kinds of polymer membranes requiring selective penetrability, and the electrolyte penetrability is improved.
  • Figure 1 is a schematic diagram illustrating an ion assisted reaction apparatus in accordance with the present invention
  • Figures 2a to 2e are photographs respectively showing variations of the microstructure of a polymer membrane processed by an ion assisted reaction according to variations of an ion irradiation dose;
  • Figure 3 is a graph showing a contact angle to water after ion beam processing the polymer membrane of Figure 2;
  • Figure 4 is a graph showing a contact angle to water after processing a polymer liquid membrane according to the ion assisted reaction;
  • Figures 5a and 5b are photographs respectively showing variation of a microstructure of the liquid membrane before and after the processing
  • Figure 6 is a graph showing variations of a contact angle to water of a sample obtained by processing a polymer filter membrane by the ion assisted reaction according to variations of the ion irradiation dose;
  • Figure 7 is a graph showing variations of a contact angle to formamide of the sample obtained by processing the polymer filter membrane by the ion assisted reaction according to variations of the ion irradiation dose;
  • Figures 8a to 8e are photographs respectively showing variation of a microstructure of the sample obtained by processing the polymer filter membrane by the ion assisted reaction;
  • Figures 9a to 9d are photographs respectively showing variation of solution penetration according to time variations of the polymer filter membrane.
  • a polymer membrane having a modified surface by an ion assisted reaction and a surface modification method thereof in accordance with the preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.
  • Figure 1 illustrates an ion assisted reaction apparatus used for the present invention.
  • An ion implantation gas 4 is irradiated onto a sample 3 adhered to a substrate 1 through an ion gun 6.
  • a reaction gas 2 is injected into a chamber, the gas reacts thereby modifying a surface of the sample 3.
  • Reference numeral 5 denotes a pump for maintaining vacuum in the chamber.
  • Figures 2a to 2e are photographs respectively showing the microstructure of the surface after surface-processing a polyethylene membrane for electrolyte penetrability of a portable battery by varying the ion dose according to the ion assisted reaction of the present invention.
  • Figure 2a shows a surface of the polymer membrane which is not processed with the ion beam.
  • the straw sandal shaped pores occupy half the membrane matrix.
  • the surface of the polymer has a high contact angle to water and does not have a penetrating property to electrolytes, as will be discussed later.
  • the electrolyte cannot easily penetrate the membrane because hydrophilic groups are not formed on the surface of the membrane.
  • Figure 2b shows a variation of the microstructure of the surface of the membrane in the case after a hydrogen ion beam of 1 x 10 15 ions/cm 2 is irradiated by 1 keV and an oxygen gas of 4ml/min was injected.
  • Figures 2c and 2d show the cases of irradiating the ion beam of 5 x 10 15 ions/cm 2 and 1 x 10 16 ions/cm 2 , respectively.
  • the dose of the irradiated ions was increased, the size of the pores was also increased.
  • Figure 3 is a graph showing variations of contact angle to water of the samples obtained by processing the polyethylene membrane according to the ion assisted reaction. As shown therein, as the ion dose increased, the contact angle remarkably decreased.
  • Figure 4 is a graph showing contact angle to water after modifying surface of the polyethylene membrane which is widely employed as a liquid membrane, according to the ion assisted reaction.
  • the contact angle of the sample which was not processed with the ion beam reached up to 120°, and the sample was very hydrophobia
  • the contact angle of the sample processed by the ion assisted reaction decreased according to the ion irradiation dose.
  • the irradiation dose was 1 x 10 16 ions/cm 2
  • the contact angle was less than 20° and the surface of the membrane became hydrophilic.
  • the ion assisted reaction was used as a type of hydrophilic polymer processing in accordance with the present invention, the pores of the membrane expand, and the surface of the membrane becomes hydrophilic, thereby improving transmissibility to water.
  • Figure 5 is a photograph showing variations of microstructure of the surface of the polyethylene (UHMW-PE) polymer membrane according to the ion assisted reaction. Consequently, the water transmissibility is improved.
  • Figure 5a shows a surface of the membrane before the ion beam processing. Fine thin films similar to osmotic films of eggs are filled between the thread shaped polymer matrixes.
  • Figure 5b shows the result of irradiating hydrogen ion beam of 5 x 10 16 ions/cm 2 having an energy of approximately 1keV to the surface of the membrane, while simultaneously injecting oxygen as the reaction gas. The fine films are removed by the ion beam, and thus pores are formed on the surface. At the same time, the surface becomes hydrophilic due to the oxygen ions reacting with the surface, thereby lowering the contact angle to water.
  • Figure 6 is a graph showing the result of processing the surface of a polyethylene (UHMW-PE) membrane.
  • Oxygen was used as the irradiated ion beam, and an energy thereof was 1 keV.
  • the surface modification was performed by varying oxygen from 2 to 8 ml/min at an ion beam current density of 7.1 ⁇ A/cm 2 .
  • the ion irradiation dose was varied from 5 x 10 14 ions/cm 2 to 1 x 10 17 ions/cm 2 , the contact angle to water of the surface of the polymer membrane was varied. The contact angle to water was considerably lowered at a high ion irradiation dose.
  • Figure 7 shows a measurement result of a contact angle to formamide in order to find the correlation between the surface hydrophilic processing and the surface energy in the hydrophilic processed polyethylene (UHMW-PE) membrane.
  • the measurement of the surface energy was performed by the Owens method.
  • Table 1 shows the computation result of the surface energy by using the results of Figures 6 and 7.
  • Figures 8a to 8e are photographs respectively showing variation of the microstructure of a surface of a polyethylene (U-PE) liquid membrane.
  • Figure 8a is a photograph before the ion beam processing.
  • the fiber-shaped threads are connected among the matrixes.
  • Figures 8b to 8d are photographs showing variation of the microstructure of the surface of the liquid membrane when the ion beam was increased. As the irradiation dose of the ion beam was increased, the threads gradually disconnected and decreased. As shown in Figure 8e, only the matrixes remained. As the result, the pores formed allowing water or other liquid to be transmitted.
  • FIGS 9a to 9d are photographs showing water penetration after the surface-processing a liquid filter membrane in accordance with the present invention.
  • water ink was dropped on the processed (right) and non-processed (left) samples, then observing the transmission process.
  • the processing conditions are as follows. Hydrogen ions were used at an ion beam energy of 1.4keV, a current density of 14.2 ⁇ A/cm 2 and an ion irradiation dose of 5 x 10 16 ions/cm 2 , and oxygen of 6ml/min was used as the reaction gas.
  • the surface of the polymer membrane was processed according to the dose of the ion irradiation and the kind of the ion beam, thereby varying the membrane surface to hydrophilicity.
  • the size of the pores was controlled according to the irradiation dose of the ion beam, thereby enabling water penetration or electrolyte transmission.
  • the surface modification did 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 deteriorated.
  • the size of the pores can be adjusted, thereby easily controlling the porosity of the various kinds of polymer membranes requiring selective penetrability. Also, the electrolyte penetrability is remarkably improved.

Abstract

A surface modification method for a polymer membrane by using an ion assisted reaction, and the polymer membrane having a modified surface with controlled pore size and number of pores on the surface of the polymer membrane, and having hydrophilic groups on the polymer membrane, by irradiating an ion beam having a predetermined acceleration energy and current density, and by simultaneously injecting a reaction gas thereto. In the present invention, 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.

Description

METHOD OF MODIFYING A SURFACE OF POLYMER MEMBRANE BY ION ASSISTED REACTION
TECHNICAL FIELD
The present invention relates to a modified polymer membrane by an ion assisted reaction, and in particular to an improved method to control the porosity and electrolyte penetrability of a polymer membrane by using an ion assisted reaction. More particularly, the present invention relates to a method of modifying a membrane surface which improves the polymer membrane, by modifying the surface of the polymer membrane into hydrophilic groups and controlling the size of pores simultaneously, by using an ion beam such as argon or hydrogen.
BACKGROUND ART
Research and development into a polymer membranes have been conducted for many years, as compared with other materials. The polymer membrane has sufficient penetrability and transmissibility to be industrially applicable. However, the polymer membrane has many disadvantages, such as low thermal stability, deterioration by penetration of electrolytes and impurities, and low resistivity to dissolution by solvent and microorganisms. In order to improve the applicability of the polymer membrane, there is a demand for a polymer membrane of a material which can be used under severe conditions, without dissolution or deformation of the microstructure.
Recently, the polymer membranes have been variously employed in the fields of the environment, precision industry and medical care. For example, an electrolyte permeable membrane of a portable battery or a filter membrane for filtering harmful elements resulted from the advanced technology in the membrane field.
Currently, the size of pores of the polymer membrane can be controlled from 0.1 to 10μm. However, it is difficult to fabricate the polymer membrane having reproducibility without defects. Furthermore, it is also difficult to control the microstructure, such as uniformity of the membrane and the size and distribution of the pores, and to modify the characteristics of the surface of the membrane.
DISCLOSURE OF THE INVENTION
Therefore, it is an object of the present invention to provide a polymer filter membrane with improved function, by modifying the surface of a polymer membrane by an ion assisted reaction, controlling the size of pores, and hydrophilic-processing the surface thereof.
In order to achieve the above-described object of the present invention, there is provided a surface modification method for the polymer membrane by using an ion assisted reaction that controls the size and number of pores on the surface of the polymer membrane to form a hydrophilic groups on the polymer membrane, by irradiating an ion beam having a predetermined acceleration energy and current density to the polymer membrane while injecting reaction gas. The ion beam used is oxygen or hydrogen. Preferably, the acceleration energy of the ion beam is from 0.6 to 1.4keV, the current density thereof is 7.1 to 14.2μ A/cm2, and an irradiation dose of implanted ions is 5 x 10H to 1 x 1017ions/cm2. Oxygen is used as the reaction gas. The flow of the reaction gas is advantageously 2 to 8ml/min.
According to the present invention, the surface of the polymer membrane which is used for electrolyte separation, various medical filtering separation agents, or environmental purification is processed with the ion beam by an ion assisted reaction, and thus the surface is modified to hydrophilic groups. Additionally, the size of pores are controlled according to the irradiation dose of the ion beam, thereby overcoming the disadvantage of the conventional art in that water penetration or electrolyte penetrability is impossible. Especially, characteristics of the membrane are not changed, but the characteristics of the surface are changed. Therefore, a long use of the membrane does not deteriorate the characteristics thereof. In addition, since the size of the pores can be controlled, it is easier to control the porosity of various kinds of polymer membranes requiring selective penetrability, and the electrolyte penetrability is improved.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram illustrating an ion assisted reaction apparatus in accordance with the present invention;
Figures 2a to 2e are photographs respectively showing variations of the microstructure of a polymer membrane processed by an ion assisted reaction according to variations of an ion irradiation dose;
Figure 3 is a graph showing a contact angle to water after ion beam processing the polymer membrane of Figure 2; Figure 4 is a graph showing a contact angle to water after processing a polymer liquid membrane according to the ion assisted reaction;
Figures 5a and 5b are photographs respectively showing variation of a microstructure of the liquid membrane before and after the processing;
Figure 6 is a graph showing variations of a contact angle to water of a sample obtained by processing a polymer filter membrane by the ion assisted reaction according to variations of the ion irradiation dose;
Figure 7 is a graph showing variations of a contact angle to formamide of the sample obtained by processing the polymer filter membrane by the ion assisted reaction according to variations of the ion irradiation dose; Figures 8a to 8e are photographs respectively showing variation of a microstructure of the sample obtained by processing the polymer filter membrane by the ion assisted reaction; and
Figures 9a to 9d are photographs respectively showing variation of solution penetration according to time variations of the polymer filter membrane.
MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS
A polymer membrane having a modified surface by an ion assisted reaction and a surface modification method thereof in accordance with the preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.
Figure 1 illustrates an ion assisted reaction apparatus used for the present invention. An ion implantation gas 4 is irradiated onto a sample 3 adhered to a substrate 1 through an ion gun 6. At the same time, a reaction gas 2 is injected into a chamber, the gas reacts thereby modifying a surface of the sample 3. Reference numeral 5 denotes a pump for maintaining vacuum in the chamber.
Figures 2a to 2e are photographs respectively showing the microstructure of the surface after surface-processing a polyethylene membrane for electrolyte penetrability of a portable battery by varying the ion dose according to the ion assisted reaction of the present invention. Figure 2a shows a surface of the polymer membrane which is not processed with the ion beam. The straw sandal shaped pores occupy half the membrane matrix. The surface of the polymer has a high contact angle to water and does not have a penetrating property to electrolytes, as will be discussed later. The electrolyte cannot easily penetrate the membrane because hydrophilic groups are not formed on the surface of the membrane. Figure 2b shows a variation of the microstructure of the surface of the membrane in the case after a hydrogen ion beam of 1 x 1015ions/cm2 is irradiated by 1 keV and an oxygen gas of 4ml/min was injected. As compared with Figure 2a, the number and size of the straw sandal shaped pores are increased. Figures 2c and 2d show the cases of irradiating the ion beam of 5 x 1015ions/cm2 and 1 x 1016ions/cm2, respectively. As the dose of the irradiated ions was increased, the size of the pores was also increased. In the case of Figure 2e, ion beam of 1 x 1017ions/cm2 was irradiated, and as a result the surface of the membrane was seriously damaged due to excessive ions. Accordingly, the number of pores on the surface of the membrane decreased.
Figure 3 is a graph showing variations of contact angle to water of the samples obtained by processing the polyethylene membrane according to the ion assisted reaction. As shown therein, as the ion dose increased, the contact angle remarkably decreased.
Figure 4 is a graph showing contact angle to water after modifying surface of the polyethylene membrane which is widely employed as a liquid membrane, according to the ion assisted reaction. As shown therein, the contact angle of the sample which was not processed with the ion beam reached up to 120°, and the sample was very hydrophobia Conversely, the contact angle of the sample processed by the ion assisted reaction decreased according to the ion irradiation dose. When the irradiation dose was 1 x 1016ions/cm2, the contact angle was less than 20° and the surface of the membrane became hydrophilic. As a result, in the case that the ion assisted reaction was used as a type of hydrophilic polymer processing in accordance with the present invention, the pores of the membrane expand, and the surface of the membrane becomes hydrophilic, thereby improving transmissibility to water.
Figure 5 is a photograph showing variations of microstructure of the surface of the polyethylene (UHMW-PE) polymer membrane according to the ion assisted reaction. Consequently, the water transmissibility is improved. Figure 5a shows a surface of the membrane before the ion beam processing. Fine thin films similar to osmotic films of eggs are filled between the thread shaped polymer matrixes. Figure 5b shows the result of irradiating hydrogen ion beam of 5 x 1016ions/cm2 having an energy of approximately 1keV to the surface of the membrane, while simultaneously injecting oxygen as the reaction gas. The fine films are removed by the ion beam, and thus pores are formed on the surface. At the same time, the surface becomes hydrophilic due to the oxygen ions reacting with the surface, thereby lowering the contact angle to water.
Figure 6 is a graph showing the result of processing the surface of a polyethylene (UHMW-PE) membrane. Oxygen was used as the irradiated ion beam, and an energy thereof was 1 keV. The surface modification was performed by varying oxygen from 2 to 8 ml/min at an ion beam current density of 7.1 μ A/cm2. As the ion irradiation dose was varied from 5 x 1014ions/cm2 to 1 x 1017ions/cm2, the contact angle to water of the surface of the polymer membrane was varied. The contact angle to water was considerably lowered at a high ion irradiation dose.
Figure 7 shows a measurement result of a contact angle to formamide in order to find the correlation between the surface hydrophilic processing and the surface energy in the hydrophilic processed polyethylene (UHMW-PE) membrane. In the present invention, the measurement of the surface energy was performed by the Owens method. Table 1 shows the computation result of the surface energy by using the results of Figures 6 and 7.
Table 1. Variations of Surface Energy by Ion Beam Processing
Figure imgf000008_0001
Figure imgf000009_0001
Figures 8a to 8e are photographs respectively showing variation of the microstructure of a surface of a polyethylene (U-PE) liquid membrane. Figure 8a is a photograph before the ion beam processing. Similarly to other membranes, the fiber-shaped threads are connected among the matrixes. Figures 8b to 8d are photographs showing variation of the microstructure of the surface of the liquid membrane when the ion beam was increased. As the irradiation dose of the ion beam was increased, the threads gradually disconnected and decreased. As shown in Figure 8e, only the matrixes remained. As the result, the pores formed allowing water or other liquid to be transmitted.
Figures 9a to 9d are photographs showing water penetration after the surface-processing a liquid filter membrane in accordance with the present invention. In order to easily distinguish them, water ink was dropped on the processed (right) and non-processed (left) samples, then observing the transmission process. The processing conditions are as follows. Hydrogen ions were used at an ion beam energy of 1.4keV, a current density of 14.2μ A/cm2 and an ion irradiation dose of 5 x 1016ions/cm2, and oxygen of 6ml/min was used as the reaction gas. In the case of the ion beam processed sample, as the time lapsed, the contact angle to the membrane was lowered, and the water ink penetrated into the membrane and permeated to the opposite side. The whole penetration process took 10 minutes. However, in the case of the non-processed sample, after 10 minutes, the ink remained.
As a result, when the surface of the polymer membrane was processed according to the ion assisted reaction, the water penetrated into the membrane, differently from the conventional art. After the surface-processing, the mechanical characteristics or durability of the membrane did not deteriorate.
According to the present invention, the surface of the polymer membrane was 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 was controlled according to the irradiation dose of the ion beam, thereby enabling water penetration or electrolyte transmission. The surface modification did 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 deteriorated. Moreover, the size of the pores can be adjusted, thereby easily controlling the porosity of the various kinds of polymer membranes requiring selective penetrability. Also, the electrolyte penetrability is remarkably improved.

Claims

1. A 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, comprising; irradiating an ion beam to the polymer membrane; and injecting simultaneously a reaction gas.
2. The method according to claim 1 , wherein the ion beam is oxygen or hydrogen.
3. The method according to claim 1 , wherein the acceleration energy of the ion beam is from 0.6 to 1 ,4keV.
4. The method according to claim 1 , wherein the current density is 7.1 to 14.2μ A/cm2.
5. The method according to claim 1 , wherein an irradiation dose of the ion beam is 5 x 1014 to 1 x 1017ions/cm2.
6. The method according to claim 1 , wherein the reaction gas is oxygen.
7. The method according to claim 1 , wherein a dose of the reaction gas is 2 to 8ml/min.
PCT/KR2000/000572 2000-06-01 2000-06-01 Method of modifying a surface of polymer membrane by ion assisted reaction WO2001092384A1 (en)

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WO2008100330A2 (en) * 2006-07-26 2008-08-21 President And Fellows Of Harvard College Surface modification of polymer surface using ion beam irradiation
US20110070411A1 (en) * 2009-09-23 2011-03-24 Hyundai Motor Company Plastic with improved gloss properties and surface treatment method
US20110076460A1 (en) * 2009-09-28 2011-03-31 Hyundai Motor Company Plastic with nano-embossing pattern and method for preparing the same
JP2012500905A (en) * 2009-10-08 2012-01-12 コリア・インスティテュート・オブ・サイエンス・アンド・テクノロジー Silicon-containing diamond-like carbon thin film, method for producing the same, and use thereof

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KR20040026733A (en) * 2002-09-25 2004-04-01 주식회사 피앤아이 Method and Apparatus for Formation of Thick Layer on the Surface Modified Substrate
KR100710909B1 (en) * 2005-12-23 2007-04-27 고려대학교 산학협력단 Method for modifying surface of ptfe and method for preparing ptfe substrate deposited with metal film

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JPH09124807A (en) * 1995-10-30 1997-05-13 Nissin Electric Co Ltd Polymer article having high gas barrier property and its production
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008100330A2 (en) * 2006-07-26 2008-08-21 President And Fellows Of Harvard College Surface modification of polymer surface using ion beam irradiation
WO2008100330A3 (en) * 2006-07-26 2008-10-09 Harvard College Surface modification of polymer surface using ion beam irradiation
US20110070411A1 (en) * 2009-09-23 2011-03-24 Hyundai Motor Company Plastic with improved gloss properties and surface treatment method
US20110076460A1 (en) * 2009-09-28 2011-03-31 Hyundai Motor Company Plastic with nano-embossing pattern and method for preparing the same
JP2012500905A (en) * 2009-10-08 2012-01-12 コリア・インスティテュート・オブ・サイエンス・アンド・テクノロジー Silicon-containing diamond-like carbon thin film, method for producing the same, and use thereof

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