WO2010120006A1

WO2010120006A1 - Method for controlling surface characteristics through exchange of super hydrophobic/super hydrophilic surface coating and anion using polymer electrolyte with ammonium groups

Info

Publication number: WO2010120006A1
Application number: PCT/KR2009/002030
Authority: WO
Inventors: 조길원; 임호선
Original assignee: 포항공과대학교 산학협력단
Priority date: 2009-04-17
Filing date: 2009-04-17
Publication date: 2010-10-21

Abstract

The present invention relates to a smart surface, and more specifically to a novel smart surface and method for manufacturing the same which enable the control of moisture conditions on the surface of materials ranging from super hydrophobic to super hydrophilic states. According to the present invention, the smart surface can be manufactured by graft-polymerizing a polymer electrolyte having ions which can be exchanged on a substrate surface with micro or nano scale roughness. According to the present invention, the method for manufacturing the smart surface can also be applied to substrates with flat surfaces, thereby enabling free control of the moisture condition of surfaces of various materials.

Description

Super water- and super-hydrophilic surface coating using an electrolyte polymer having an ammonium group and a method of controlling its surface properties through anion exchange

The present invention relates to a smart surface, and more particularly to a novel smart surface and a method of manufacturing the same that can adjust the wettability of the surface of the material from the superhydrophobic to superhydrophilic.

Intelligent surfaces with adjustable surface wetting for a variety of external stimuli are receiving a lot of attention due to a variety of applications ranging from self-cleaning to microfluidics and biosensors.

Ion exchange is a reversible process in which ions are exchanged between a cation or anionic electrolyte and a complex, and through direct exchange of counter ions, the surface function and physicochemical properties can be controlled.

Conventional methods for producing superhydrophobic / superhydrophilic surfaces include photolithography, plasma, sol-gel, solidification of alkyl chitin dimers, formation of fibrils on the surface, phase separation of polymers, and silica using layer-by-layer. Although self-assembly of particles is used, these methods show only a single property of superhydrophobic / superhydrophilic.

Electrolyte polymers with quaternary ammonium groups (QA ⁺ ), for example poly [2- (methacryloyloxy) ethyltrimethylammonium chloride] (PMETAC), are chemical structures of polymer brushes on the surface during direct exchange of counter ions. Is reorganized, and the surface wettability is greatly changed depending on the characteristics of the counter ion. It is also known that the introduction of micro and nanoscale surface roughness can greatly amplify the wettability of solid surfaces.

The present invention relates to a smart surface having wettability that can be reversibly programmed in the superhydrophilic to superhydrophilic range by selection of an appropriate counter ion.

The present invention provides a new method for precisely controlling the wettability of a surface by easily attaching or removing ion-paired counterions.

The present invention provides a rough surface whose wettability is adjustable through ion exchange.

Intelligent surface according to the present invention is characterized by being prepared by graft polymerization of an ion-exchangeable electrolyte polymer on the surface of the substrate having a surface roughness of micro to nano scale as a surface having an adjustable wettability.

In the present invention, the electrolyte polymer is composed of various electrolyte polymers including cations so as to be able to exchange anions in pairs with anions, and are preferably electrolyte polymers containing an ammonium group. In a preferred embodiment of the invention, the ammonium group may use a tetravalent ammonium group.

In the present invention, it is preferable that the electrolyte polymer is grafted through the surface-initiated atomic transfer radical polymerization on the surface of the substrate.

In one embodiment of the present invention, the electrolyte polymer is poly [2- (methacryloyloxy) ethyltrimethylammonium chloride].

In the present invention, the electrolyte polymer is preferably formed to a thickness that can maintain the influence of the rough surface of the substrate on the surface wettability. In one embodiment of the invention, the thickness of the electrolyte polymer is 13-18 nm, even when formed on a substrate having a surface roughness of micro to nanoscale can be maintained the roughness of the substrate.

In the present invention, the substrate having a micro-to-nano scale roughness may be manufactured by various methods, and preferably by a method of forming fine protrusions on a flat substrate surface. In a preferred embodiment of the present invention, it is preferable that a dendritic protrusion is formed on the surface of the substrate. The dendritic protrusion may form protrusions having micro-scale roughness by combining protrusions having nano-scale roughness.

In the practice of the present invention, the dendritic protrusion is preferably a cluster made of gold, and the gold cluster may be easily formed through a galvanic cell exchange reaction.

In one embodiment of the invention, the substrate is a silicon substrate, preferably a p-type silicon substrate may be made of a gold cluster through a galvanic battery exchange. In the practice of the present invention, the roughness of the substrate on which the gold cluster is formed may have an RMS of roughness of 0.74 ± 0.05 μm.

In one aspect, the present invention provides a method of controlling surface wettability of a substrate by exchanging ions of the electrolyte polymer in a substrate having a surface roughness of micro-to-nano scale grafted with the electrolyte polymer.

In the present invention, the electrolyte polymer may be poly [2- (methacryloyloxy) ethyltrimethylammonium chloride] containing a tetravalent ammonium group, and surface wettability by exchanging chlorine ions with various anions through an anion exchange reaction. Can be controlled.

In the practice of the present invention, chloride ions and negative ions to be exchanged it may be a hydrophobic anion or a hydrophilic anionic, hydrophobic anions as an example is ^{_{^{F -, PF 6 -, n}}} -octylsulfate, bis (trifluoromethylsulfonyl) imide (TFSI), perfluorosulfonic acid Can be. In another embodiment, the hydrophilic anion is Br ^- may ^{be, poly (phosphate) -, SCN} -, ClO 4. The substrate exhibits hydrophilicity when the hydrophilic anions are exchanged and hydrophobicity when the hydrophobic anions are exchanged, thereby controlling surface wettability.

In one aspect, the present invention provides an intelligent substrate having a surface roughness of micro to nano scale and grafted with an electrolyte polymer capable of ion exchange on the surface thereof.

In another aspect, the present invention provides a substrate having a surface roughness of micro to nano scale, and having a surface grafted with an electrolyte polymer including tetravalent ammonium groups ion-exchanged on the surface.

In the present invention, the tetravalent ammonium ions can be paired with various anions, preferably paired with Cl anions, and then exchanged with other anions to be paired with various anions.

In one embodiment of the invention, the tetravalent ammonium ions are paired with SCN ^- cation to form a hydrophilic substrate, in another embodiment of the invention, the tetravalent ammonium ions are paired with a TFSI anion to form a hydrophobic substrate To form.

In the present invention, the wettability of the substrate is extremely improved hydrophobicity and hydrophilicity by the dendritic protrusion formed on the surface, and the water contact angle is changed to 0-175 °.

In accordance with an aspect of the present invention, a method of forming a metal cluster having a micro-to-nano scale roughness using a galvanic cell exchange reaction on a surface of a substrate; Imparting an OH functional group to the metal cluster; Replacing the OH functional group with an initiator for surface induced polymerization of a polymer brush; Graft polymerizing an electrolyte polymer containing an ammonium group in the cluster using atomic transfer radical polymerization; And exchanging anions bound to the electrolyte polymer, the surface having an adjustable wettability, wherein the metal is a noble metal, more preferably gold.

In one aspect, the present invention provides a method of forming a gold cluster having a micro-to-nano scale roughness on a substrate surface by using a galvanic cell exchange reaction.

The smart surface manufacturing method according to the present invention can be applied to a substrate having a flat surface, thereby providing a method of arbitrarily controlling the surface wettability of various materials.

1 is a schematic view showing the manufacturing process of the surface having an adjustable wettability.

2 is a FESEM image of a FMETAC gold micro / nano scale surface formed by a galvanic cell substitution reaction, a) low magnification image, b) magnification image, c) magnification image of image b, d) cross section of image a, e) CLSM image to be.

3 a) Photographs of water drops on flat and rough substrates. The contact angle of water on the flat surface was changed from 90 ° ± 2 ° to 65 ° ± 1 °, and on the surface of the gold cluster, it changed from 171 ° ± 3 ° to 5 ° or less, which replaced TFSI ion with SCN-ion Means changing from to superhydrophile. b) A graph showing the reversible change in wettability between PMETAC-modified flat substrate (□) and nanostructured substrate (■) through direct ion exchange.

4 is a) FTIR spectra of a complex of TFSI and SCN-ions and a PMETAC brush of Cl-ions. b) X-ray photoelectron spectra of nanostructured PMETAC films at levels F 1s, c) N 1s, d) S 2p.

Hereinafter, the present invention will be described in more detail with reference to the drawings and examples. The following examples illustrate the invention and in no case should be construed as limiting the scope of the invention.

The washed p-silicon (100) wafer was immersed in an aqueous solution of HAuCl 4 (5 mM) and HF (5 mM) at 45 ° C. for 5 minutes in the dark. The prepared gold nanostructured substrate was washed with excess water and dried over flowing nitrogen. The substrate was then immersed in 11-mercapto-1-undecanol (1 mM) solution at room temperature for 12 hours to prepare an OH-functional gold substrate. The OH-functional gold substrate was placed at room temperature for 12 hours in an initiator solution in which (4-chloromethyl) benzoyl chloride was dissolved in toluene, then washed with toluene, ethanol, and ionized water, and dried under nitrogen flow. Polymerization of 2- (methacryloyloxy) ethyltrimethylammonium chloride (METAC) was initiator-grafted into a degassed METAC solution in 80% methanol aqueous

solution containing CuCl

2, 4,4-bipyridyl and L-ascorbic acid. It was done by immersing the substrate. Samples were washed thoroughly with methanol and Milli-Q water and dried under nitrogen gas. To exchange counter ions, PMETAC-modified substrates were immersed in 10 mM solution of appropriate counter ions for 3 hours. Images of the nanostructured surface were taken by SEM (Hitachi S-4800). Confocal laser microscope (Olympus, OLS 3100) was used to measure the surface microstructure and surface roughness. Surface contact angle was measured at saturation humidity.

Gold surface of micro / nano roughness can be identified by field-emission scanning electron microscopy (FE-SEM) and confocal laser scanning microscopy (CLSM), and irregular gold clusters of many dendritic micro / nano structures. Is a surface covering a silicon surface, each cluster including a fractal structure, as shown in FIG. 1B, having a size of several micrometers and, when enlarged, a plurality of protrusions having a diameter of 50 nm or less. . The gold surface of the present invention has a hierarchical structure with micro and nano scale roughness.

The thickness of the coated PMETAC brush on flat substrates is about 15.4 ± 2.4 nm, so even irregular porous structures on the surface can be partially filled by the PMETAC brush, and the micro- and nanostructures of the substrates are present after polymerization. The cross-sectional structure of FIG. 1D can be seen that the surface consists of a forest of densely packed gold microstructures 5-7 μm high.

The surface roughness of the manufactured gold microstructure has a rms of 0.74 ± 0.05 μm, which is sufficient to be super water / superhydrophilic, and the nanostructured PMETAC film has a super water repellency according to the change of ion-pairing. The properties can vary from to superhydrophilic.

When the nanostructured surface according to the present invention contains Cl ⁻ ions, it exhibits superhydrophilic properties, and after being immersed in a TFSI solution, it exhibits superhydrophobic properties. Although not limited in theory, it is believed that the high water contact angle of 171 ± 3 ° and the sliding angle below 5 ° are due to the trapped air under the liquid.

Claims

A method for producing a surface having controllable wettability, characterized in that graft polymerization of an ion-exchangeable electrolyte polymer on a surface of a substrate having a surface roughness of micro to nano scale.
The method of claim 1, wherein the electrolyte polymer is an electrolyte polymer containing an ammonium group.
The method of claim 1 wherein the ammonium group is a tetravalent ammonium group.
The method of claim 1 wherein the electrolyte polymer is grafted on the surface.
The method of claim 4, wherein the electrolyte polymer is a poly [2- (methacryloyloxy) ethyltrimethylammonium chloride] electrolyte polymer.
The method of claim 4, wherein the electrolyte polymer has a thickness of at least 10 nm.
The method of claim 1, wherein the substrate surface has a dendritic protrusion.
8. The method of claim 7, wherein the protrusion is a gold cluster.
The method of claim 8, wherein the gold cluster is formed through a galvanic cell exchange reaction.
The method of claim 1 wherein the substrate is a silicon substrate.
8. The method of claim 7, wherein the RMS of the substrate roughness is at least 50 nm.
A method of controlling the surface wettability of a substrate by exchanging ions of the electrolyte polymer in a substrate having a micro to nano scale surface roughness grafted with the electrolyte polymer.
13. The method of claim 12, wherein the electrolyte polymer contains a tetravalent ammonium group.
The method of claim 13, wherein the electrolyte polymer is poly [2- (methacryloyloxy) ethyltrimethylammonium chloride].
The method of claim 13, wherein the ion exchange is an anion exchange reaction.
The method of claim 15, wherein the anion is a hydrophobic anion.
The method of claim 16, wherein the hydrophobic anion is F − , PF 6 − , n-octylsulfate, bis (trifluoromethylsulfonyl) imide, or perfluorosulfonic acid.
The method of claim 15, wherein the anion is a hydrophilic anion.
The method of claim 18, wherein the hydrophilic anion is Cl − , Br − , SCN − , ClO 4 − , poly (phosphate).
Intelligent substrate having a surface roughness of micro to nano scale, the surface is grafted electrolyte polymer capable of ion exchange.
21. The intelligent substrate of claim 20, wherein the electrolyte polymer comprises a tetravalent ammonium group.
21. The intelligent substrate of claim 20, wherein the substrate has a dendritic protrusion.
23. The intelligent substrate of claim 22, wherein the dendritic protrusion is a gold cluster.
22. The intelligent substrate of claim 21, wherein the electrolyte polymer is poly [2- (methacryloyloxy) ethyltrimethylammonium chloride].
21. The intelligent substrate of claim 20, wherein the intelligent substrate is a substrate whose surface wetting is controlled.
A substrate having a surface roughness of micro to nano scale, the surface is grafted with an electrolyte polymer comprising a tetravalent ammonium group capable of ion exchange.
The substrate of claim 27, wherein the tetravalent ammonium ions are paired with Cl − ions.
27. The substrate of claim 26, wherein the tetravalent ammonium ions pair SCN - with ions.
27. The substrate of claim 26, wherein the tetravalent ammonium ions are paired with TFSI ions.
27. The substrate of claim 26, wherein the substrate varies in water contact angle by 0-175 degrees.
Forming a gold cluster having micro to nano scale roughness on the surface of the substrate by using a galvanic cell exchange reaction;

Imparting an OH functional group to the gold cluster;

Replacing the OH functional group with an initiator for surface induced polymerization of a polymer brush;

Graft polymerizing an electrolyte polymer containing an ammonium group in the cluster using atomic transfer radical polymerization; And

Exchanging anions bound to the electrolyte polymer

Method for producing a surface having an adjustable wettability comprising a.
A method of forming a gold cluster having a micro to nano scale roughness using a galvanic cell exchange reaction on the substrate surface.