JP2001247540A - Method of producing photofunctional self-organized monomolecular film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To introduce an effective photopolymerization method capable of achieving a high intermolecular conjugated polymerization degree in an ultraviolet-irradiating polymerization process in a conjugate triple bond-based thiol SAM film, and capable of preventing ultraviolet oxidation on the surface of the SAM film by ultraviolet irradiation. SOLUTION: The ultraviolet irradiation is carried out in an air-evacuated closed system in a process for carrying out an intermolecular cross-linking reaction under the irradiation of the ultraviolet in the interior of a self-organized molecular film. Concretely, the production method is characterized in that the intermolecular cross-linking reaction is carried out in a sealed atmosphere substituted with an inert gas at the time of irradiation with the ultraviolet. The method for producing the self-organized molecular film is also characterized in that the intermolecular cross-linking reaction is carried out in a state of the self-organized molecular film and a substrate left in a high vacuum state by sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a molecule in which a fluorine chain is provided at the terminal of a molecule and a sulfur-based molecular functional group, for example, thiol, is present at the opposite terminal of the molecule. The present invention also relates to a method for producing a self-assembled molecular film, wherein an intermolecular cross-linking reaction is caused on a substrate surface under ultraviolet irradiation in a state where the molecules are chemically adsorbed on a solid substrate.

[0002]

2. Description of the Related Art Conventionally, molecules are spontaneously chemically adsorbed on a specific metal surface in a solution thereof to form an ordered structure and form a self-assembled monolayer (Self-assembled monolayer). -Assembled Monolayer; hereinafter also referred to as “SAM”) is known, and by applying its properties,
Research and development of functional organic thin films has been developed. In general, there are an alkanethiol SAM film utilizing specific chemical adsorption of a metal such as thiol or disulfide with a sulfur atom, and a silane coupling SAM film utilizing a chemical reaction between a silane compound and a surface hydrophilic group. In particular, a SAM film formed by a specific chemical bond between a gold thin film and a thiol is a central player in SAM film research because it can interact with a stable substrate and form a high-density molecular film arrangement.
Recently, attention has been focused on several methods for controlling intermolecular interactions arranged on a substrate in a thiol gold-based SAM film. In particular, when a conjugated triple bond is introduced into the main chain of a thiol molecule and a SAM film is formed on a gold substrate and then irradiated with light having a wavelength of 254 nm, conjugated triple bonds of the thiol molecule cause intermolecular photopolymerization. To form a covalent bond. The formation of this intermolecular covalent bond greatly improves the mechanical strength of the SAM film and increases the reliability of the film. In addition, the length of the conjugated system inside the SAM film changes depending on the degree of photopolymerization. For example, a short conjugated polymer has a property of tinged with purple or red, and a long conjugated polymer has a property of tinged with blue. Utilization is being studied for application to sensor devices. For example, this conjugated triple bond thiol SAM film is described in Mowery, M et al, J. Phys.
m. B (1997) 101, 8513;, Batchelder et al, J. Am.
Chem. Soc. (1994) 116, 1050;, Kim, T et al, J. Am.
Chem. Soc. (1997) 119, 189;, and Menzel, H et a
l, J. Phys. Chem. B (1998) each report its characteristic properties. Further, a fluorinated conjugated triple bond type thiol SAM film in which a linear fluorocarbon and a perfluorocarbon chain saturated with a fluorine atom are introduced into a tail group of a conjugated triple bond type thiol SAM film has been reported. A SAM film that has both energy, water repellency, oil repellency, and improved durability due to intermolecular conjugate polymerization has attracted much attention. However, these conjugates 3
In the process of photopolymerizing a double bond type thiol SAM film, 2
Ultraviolet light of 54 nanometers must be irradiated, but in order to obtain a SAM film having a high degree of intermolecular conjugate polymerization, irradiation must be performed for a relatively long time.
In the meantime, it has been known that the longer the UV exposure time of the SAM film is, the more the SAM film is photo-oxidized and causes surface deterioration, and the achievement of a high degree of intermolecular conjugate polymerization and the condition for suppressing UV oxidation are mutually contradictory. Therefore, it was not possible to carry out ultraviolet polymerization under the optimum conditions.

In view of the above disadvantages, the present invention achieves a high degree of intermolecular conjugate polymerization in a conjugated triple bond type thiol SAM film in the course of ultraviolet irradiation polymerization, and oxidizes the surface of the SAM film by ultraviolet irradiation. The present invention introduces an effective photopolymerization method for preventing the above. In particular, it is an object of the present invention to provide a method for effectively producing a reliable and durable water- and oil-repellent SAM film using a conjugated triple bond type thiol SAM film whose tail group is a perfluorocarbon chain.

[0004]

According to the first aspect of the present invention, a sulfur compound or a silane compound containing a fluorine chain in a main chain or a side chain and a diacetylene structure in a molecular main chain is provided. And a self-assembled molecular film characterized by being spontaneously forming a monomolecular film by being chemically adsorbed on the surface of a solid substrate.

According to the second aspect of the present invention, in a molecule in which a fluorine chain is provided at a terminal of a molecule and a sulfur-based molecular functional group, for example, thiol is present at the opposite terminal of the molecule, the diacetylene structure has a molecular principal. 2. The self-assembled molecular film according to claim 1, wherein the self-assembled molecular film is introduced into a chain, and the molecule causes an intermolecular cross-linking reaction on a substrate surface under irradiation of ultraviolet rays.

According to the third aspect of the invention, in the process of causing an intermolecular cross-linking reaction under ultraviolet irradiation inside the self-assembled molecular film, the ultraviolet irradiation is made to proceed in a closed system in which air is excluded. The self-assembled molecular film according to claim 2, wherein

According to a fourth aspect of the present invention, there is provided a self-assembled molecular film according to the third aspect, wherein an intermolecular cross-linking reaction is caused in a closed atmosphere replaced with an inert gas during ultraviolet irradiation. It is.

According to the fifth aspect of the present invention, an intermolecular cross-linking reaction occurs when the self-assembled molecular film and its substrate are hermetically sealed and left in a high vacuum state at the time of ultraviolet irradiation. 4. A self-assembled molecular film according to item 3.

According to the invention described in claim 6, the following [
The self-assembled molecular film according to claim 1, comprising the fluorine-based compound according to claim 2 represented by the general formula (1).

According to the invention of claim 7, in the general formula (1), 1 <m <15 and 6 <n <18.
2. The self-assembled molecular film according to claim 1, comprising the fluorine-based compound according to claim 2, wherein 8 <k <15.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described in detail. The basic method of forming a molecular film is to first form an adhesion layer and a gold thin film on a smooth substrate by vapor deposition. As the substrate, for example, a mica substrate having a broken wall, a quartz substrate having high smoothness, or the like is prepared. Specifically, it facilitates a quartz substrate with a thickness of about 0.8 mm,
After washing with distilled water and drying under a stream of nitrogen, it is installed in a vapor deposition device, first, an adhesion layer is formed on the surface of the substrate by vapor deposition, and then gold is vapor-deposited to a thickness of about 1000 angstroms. A gold thin film is formed. The deposition conditions at that time are as follows. After the substrate is placed in the vacuum chamber, the temperature of the substrate is raised to 550 degrees over 3 hours, and the degree of vacuum is raised to about 10-7 Torr. After depositing nickel-titanium on the substrate surface to a thickness of about 10 nm, gold deposition
The process proceeds at a rate of 0.1 nm / sec, and the substrate temperature is maintained at about 350 degrees. After the completion of the gold deposition, the substrate temperature is raised again to 550 ° C., and the substrate is allowed to stand for about one hour. Then, after cooling to room temperature, the pressure is returned to normal pressure, and the substrate on which gold is deposited is removed from the vacuum chamber.

Further, the SAM film is formed by immersing the prepared gold thin film substrate in a solution in which thiol molecules are dissolved. Specifically, first, a thiol solution is dissolved in a saturated hydrocarbon solvent such as hexane, heptane, isooctane, or a solvent such as DMF or DMSO to adjust the thiol solution concentration to about 0.5 mM. With respect to the fluorine-based diacetylenol compound, it was dissolved in an isooctane solvent to prepare respective solutions. The photopolymerization experiment was conducted using a series of compounds shown in Table 1 for the specific compounds prepared this time.

[0013]

[Table 1]

Table 1 is a list of the thiol compounds containing diacetylene in the main chain, which are used in the present invention.

ODT was obtained from Aldrich, Dia1 was obtained from Leeds University, United Kingdom, and C12 was obtained from Dojin Chemical Co., Ltd., and the respective compounds were obtained. Also, F
United States for 3, F4, F10, F13,
Obtained from the University of Houston. Although ODT is not a diacetylene-based thiol, a SAM film was prepared by ODT in order to compare physical properties with a diacetylene-based SAM film. Each gold substrate is left in each solution for 24 hours, washed with isooctane and acetone, dried under a stream of nitrogen, and placed in a photopolymerization reaction unit. The structures and surface properties of the SAM films prepared before the photopolymerization reaction were analyzed and identified using various measuring instruments. For example, Table 2 shows data obtained by measuring the contact angle of the created SAM film surface with the liquid.

[0016]

[Table 2]

Table 2 shows data obtained by measuring the contact angle of the SAM film surface with the liquid.

The contact liquid was water, and the advancing angle and the receding angle of each surface were measured with a contact angle meter. Since all of them show a high advancing angle and a receding angle, it was found that they were adsorbed on the gold surface with a high molecular density. Next, in order to analyze the microstructure of the SAM film, the vibrational spectrum derived from the molecular structure of each SAM film was identified using a reflection type Fourier transform infrared absorption measurement device (hereinafter referred to as FTIR-RAS). 1 and 2 show infrared spectra of the CH stretching vibration region and the CF stretching vibration region, respectively. Here in the tail group,
The data for SAM films with fluorine chains are mainly shown. From FIG. 1, the CH around 2920 cm-1 and 2850 cm-1
From the strength of stretching vibration absorption and the respective wave numbers, it can be seen that the methylene chain extends into the trans and forms a molecular packing having high crystallinity. From FIG. 2, it is confirmed from the absorption of CF stretching vibration and bending vibration near 1370 cm −1 and 1250 cm −1 that the saturated fluorocarbon chain is certainly chemically adsorbed on the surface of the gold substrate.
The difference in the intensity ratio between the SAM films indicates that the tilt angle of the molecular chain with respect to the substrate surface is different. Thus, the alkane thiol and the fluorinated thiol containing diacetylene in the main chain

[0019]

Embedded image Formed SAM films with high molecular coverage. Next, each SAM film is mounted on an ultraviolet irradiation unit. FIG. 3 schematically shows the apparatus. The condition of ultraviolet irradiation is a wavelength of 254 nm and 2 cm from the substrate surface.
The irradiation energy is fixed at a point that is far away, and the irradiation energy is about 4750 μW / cm 2 at that distance. The inside of the unit is set so that the air is replaced with nitrogen, and the oxygen concentration inside the unit is made as small as possible. Alternatively, the SAM film may be subjected to photopolymerization by installing an ultraviolet irradiation device in a vacuum chamber and irradiating ultraviolet light under vacuum. The degree of vacuum is
Preferably, it is lower than 10-5 Torr. The UV irradiation time was set to 300 seconds, and UV polymerization of each SAM film was performed.
After the ultraviolet irradiation, the resonance Raman spectrum of each SAM film was measured to examine the degree of photopolymerization of each SAM film. This device applies a specific visible light, for example, 5
14 nm or 633 nm was introduced, and the light caused the diacetylene conjugate 3 produced by photopolymerization.
I will excite the heavy bond-double bond system. Then SAM
A specific bond formation in the film, particularly the vibration spectrum of the unsaturated conjugate bond is amplified and can be observed as a Raman spectrum. This is because it is possible to capture the slight change in vibration of the conjugate bond inside the monolayer such as the SAM film.
This method is suitable for measuring the photopolymerization inside the M film. 4 and 5
Table 3 shows the results of resonance Raman spectroscopy of each SAM film, and comparison of photopolymerization with SAM film ultraviolet polymerization, which is not controlled under an atmosphere, respectively.

[0020]

[Table 3]

Table 3 is a comparison table of the ultraviolet ray polymerization conditions of each SAM film.

First, as shown in FIG. 4 and FIG.
Inside the film, the Raman absorption of the conjugated triple bond and double bond formed as a result of ultraviolet irradiation is 2100 cm −1 and 1
Appearing at around 500 cm −1, it was confirmed that ultraviolet polymerization was occurring inside the SAM film. In addition, it was observed that the degree of UV polymerization was different depending on the difference between the groups in which each thiol molecule was available, and this measurement revealed that the degree of polymerization decreased as the chain length increased in the case of fluorine chains. . In addition, the observations show that when the excitation wavelength of the Raman spectrum is shortened, a change in polymerization inside the SAM film is observed with higher sensitivity. Table 3 shows each of these UV-polymerized SAM films and the SAM film exposed to air.
7 shows a comparison with a SAM film irradiated with ultraviolet light. The effect of the time was also investigated by changing the ultraviolet irradiation time of each sample. Here, the degree of polymerization was evaluated by classifying the degree of polymerization into excellent, good, and unacceptable. As is clear from this table, the degree of ultraviolet polymerization of the SAM film in which the reaction field atmosphere was replaced with an inert gas was clearly different from that of the SAM film exposed to air, and the ultraviolet polymerization was considerably Proceed with efficiency. On the other hand, when exposed to air, UV polymerization did not proceed well inside the SAM film, indicating that the influence of air, especially oxygen, prevented the polymerization. As described above, it was found that the UV polymerization level of the SAM film can be improved by controlling the SAM film surface atmosphere under the photopolymerization conditions of the SAM film containing diacetylene.

[0023]

According to the present invention, in a conjugated triple bond type thiol SAM film, a high degree of intermolecular conjugate polymerization is achieved in the ultraviolet irradiation polymerization process, and the SA by ultraviolet irradiation is obtained.
An effective photopolymerization method for preventing photo-oxidation on the surface of the M film can be provided. In particular, it is possible to provide a method for effectively producing a reliable and durable water- and oil-repellent SAM film using a conjugated triple bond type thiol SAM film whose tail group is a perfluorocarbon chain.

[Brief description of the drawings]

FIG. 1 is a C-H stretching vibration infrared spectrum of each SAM film.

FIG. 2 is a C-F stretching vibration infrared spectrum of each SAM film.

FIG. 3 is an irradiation unit for UV polymerization of a SAM film.

FIG. 4: Observation of resonance Raman spectrum (excitation light: 514 nm) of each SAM film after UV polymerization.

FIG. 5 is a resonance Raman spectrum observation (excitation light: 633 nm) of each SAM film after UV polymerization.

[Explanation of symbols]

 31 Inert gas introduction path 32 UV polymerization unit sealed chamber 33 SAM film substrate 34 Distance between UV lamp and SAM film surface (2 cm) 35 UV lamp (254 nm) 36 UV lamp power supply

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 49:00 C08L 49:00 F term (Reference) 2H025 AC01 AD01 BC29 BC77 BC83 4F071 AA06 AA39 AF14 AF29 BB10 BC01 4H006 AA01 AA03 AB99 TA04 4J011 QA32 QA40 QA48 TA07 UA01 VA01 4J100 AT13P BA52P BB18P CA01 JA43

Claims (7)

[Claims] 1. A monomolecular compound comprising a sulfur compound or a silane compound containing a fluorine chain in a main chain or a side chain and a diacetylene structure in a molecular main chain. A self-assembled molecular film, which forms a film. 2. In a molecule in which a fluorine chain is provided at the terminal of the molecule and a sulfur-based molecular functional group, for example, thiol is present at the opposite terminal of the molecule, a diacetylene structure is introduced into the main chain of the molecule. 2. The self-assembled molecular film according to claim 1, wherein an intermolecular cross-linking reaction is caused on the substrate surface under ultraviolet irradiation. 3. The self-organizing system according to claim 2, wherein the ultraviolet irradiation is caused to proceed in a closed system excluding air in the process of causing an intermolecular cross-linking reaction under ultraviolet irradiation inside the self-assembled molecular film. Molecular membrane. 4. The self-assembled molecular film according to claim 3, wherein an intermolecular cross-linking reaction is caused in a sealed atmosphere replaced with an inert gas during ultraviolet irradiation. 5. The self-assembled molecular film according to claim 3, wherein an intermolecular cross-linking reaction occurs when the self-assembled molecular film and its substrate are hermetically sealed in a high vacuum state when irradiated with ultraviolet rays. 6. The composition according to claim 2, which is represented by the following general formula (1):
The self-assembled molecular film according to the above. [Formula 1] 7. In the general formula (1), 0 <m <15
3. The fluorine-containing compound according to claim 2, wherein 6 <n <18 and 8 <k <15.
The self-assembled molecular film according to the above.