JP2021014490A - Base material with polymer thin film and method for producing the same - Google Patents

Abstract

To provide a base material with a polymer thin film having excellent piezoelectric performance, and a method of producing the same.SOLUTION: The present invention provides a base material with a polymer thin film, wherein, on the base material, formed is a polymer thin film comprising multiple chain aromatic polymer molecules oriented in a predetermined direction. The chain aromatic polymer molecules are, for example, wholly aromatic polyester; asymmetric aromatic monomers are polymerized to form a chain; and the chain aromatic polymer molecules are oriented in a direction vertical to the base material.SELECTED DRAWING: Figure 1

Description

The present invention relates to a substrate with a polymer thin film containing polymer molecules oriented in a predetermined direction and a method for producing the same.

A piezoelectric material that generates a voltage when pressure is applied to a specific material to cause strain is known as a piezoelectric material. As the piezoelectric material, for example, an insulator single crystal such as quartz, lithium niobate, lithium tantalate, barium titanate, and piezoelectric ceramics such as PZT (lead zirconate titanate) are known and widely used. There is. These materials have some manufacturing limitations due to the high temperature of the fabrication process, the high rigidity, and the difficulty of forming into various shapes. The piezoelectric phenomenon occurs not only in the above-mentioned inorganic materials but also in polymer materials that are organic materials. Since the polymer material has flexibility, moldability, etc. that the inorganic material does not have, it can be applied to applications different from those of the conventional inorganic material. Moreover, the polymer can be produced at a lower temperature than the inorganic material.

As the polymer material having piezoelectricity, polyvinyl chloride, polyvinyl fluoride, polyvinylidene fluoride, polyurea and the like are known. The piezoelectricity of such a polymer material is not as good as that of an inorganic material such as PZT. Therefore, the emergence of polymer materials with excellent piezoelectricity is expected. In order to improve the piezoelectricity, it is conceivable to increase the piezoelectric constant, which is an index of the piezoelectricity. Since the piezoelectric constant is determined by the amount of electrically active phases, it is considered that increasing the ratio of such phases increases the piezoelectric constant.

By the way, thin-film polymerization is known as a method for forming a polymer film on a base material using a raw material monomer (see Patent Documents 1 to 3). Vapor deposition polymerization is a film formation method in which a polymer film is formed by polymerizing a monomer on a substrate by heating during vapor deposition, instead of directly forming a film by vapor deposition using a polymer as a film material. Is. The film formation of the polymer film by vapor deposition polymerization makes it possible to form a polymer film having a structure different from that of the polymer film obtained by directly forming the polymer on the substrate.

Japanese Unexamined Patent Publication No. 9-278805 Japanese Unexamined Patent Publication No. 2003-300273 Japanese Unexamined Patent Publication No. 2006-182847

When forming a polymer thin film on a substrate by thin-film polymerization, if an asymmetric monomer having a dipole moment can be used and the thin film can be oriented in a certain direction, the thin film as a whole has a large dipole moment. It is expected that the piezoelectricity will be exhibited. However, in the vapor deposition polymerization described in Patent Documents 1 to 3, it is not considered to orient the monomer in a certain direction, and it is difficult to form a polymer thin film exhibiting the above-mentioned piezoelectricity. ..

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a base material with a polymer thin film having a polymer thin film having excellent piezoelectricity, and a method for producing the same.

One aspect of the present invention that solves the above problems is as follows.
(1) A substrate with a polymer thin film in which a polymer thin film containing a large number of chain-like aromatic polymer molecules oriented in a predetermined direction is formed on the substrate.
The chain-like aromatic polymer molecule is a total aromatic polyester and / or a total aromatic polyester amide in which an asymmetric aromatic monomer having an asymmetric molecular structure is polymerized to form a chain, and the following condition 1 or 2 is satisfied. Fill, substrate with polymer thin film.
(Condition 1) aromatic wherein the polymer thin film, and the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by transmission method (A), constituting the polymer film the ratio of the absorption peak at a wave number 1600 cm ^-1 the sample containing the same aromatic polymer molecule and family polymer molecules unoriented state for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis according to KBr tablet method (B) and the The ratio value (A / B) is 0 to 0.67.
Against (Condition 2) the polymer film, and the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by high sensitivity reflection method (A), constituting the polymer film Ratio of absorption peak at wave number 1600 cm ^{-1 to} absorption peak at wave number 1740 cm ^-1 measured by infrared analysis by KBr tablet method for a sample containing the same aromatic polymer molecule as the aromatic polymer molecule in an unoriented state (B) The value of the ratio (A / B) with and is 2 or more.

(2) With the polymer thin film according to (1) above, the asymmetric aromatic monomer is a monomer having a structure of any of the structural units represented by the following structural formulas (I) to (IV). Base material.

(3) The substrate with a polymer thin film according to (1) or (2) above, wherein the polymer thin film has a film thickness of 30 to 700 nm or more.

(4) A surface treatment agent having a functional group capable of reacting with any one of a hydroxyl group, a carboxyl group and an amino group to form a bond is used, and the surface of the base material is exposed so that the functional group is exposed. And the process of modifying with
A step of forming a polymer thin film on the surface of the base material by vapor phase polymerization using an asymmetric aromatic monomer having an asymmetric molecular structure that can react with a functional group of the surface treatment agent to form a bond. Including
A method for producing a base material with a polymer thin film, which comprises a step of discharging by-products generated by the polymerization reaction from the reaction system during the vapor phase polymerization.

(5) The method for producing a base material with a polymer thin film according to (4) above, wherein the step of discharging the by-product from the reaction system is executed at predetermined time intervals.

(6) In the gas phase polymerization, the asymmetric aromatic monomer is evaporated at a temperature 150 to 50 ° C. lower than the boiling point of the asymmetric aromatic monomer in an environment of a vacuum degree of 1 × 10 ² Pa, and the above. Production of the base material with a polymer thin film according to (4) or (5) above, wherein the temperature of the base material is set to a temperature 100 to 0 ° C. lower than the boiling point of the asymmetric aromatic monomer and gas phase polymerization is performed. Method.

(7) Any of the above (4) to (6), wherein the asymmetric aromatic monomer is a monomer having any of the structures of the structural units represented by the following structural formulas (I) to (IV). The method for producing a substrate with a polymer thin film according to the above.

(8) The method for producing a substrate with a polymer thin film according to (7) above, wherein the asymmetric aromatic monomer is acylated.

According to the present invention, it is possible to provide a base material with a polymer thin film having a polymer thin film having excellent piezoelectricity, and a method for producing the same.

It is a schematic diagram which shows the state which the base material with a polymer thin film of this embodiment is seen from the side. It is a schematic diagram which shows the vapor deposition polymerization apparatus used in this embodiment.

<Base material with polymer thin film>
In the base material with a polymer thin film of the present embodiment, a polymer thin film containing a large number of chain-like aromatic polymer molecules (hereinafter, also simply referred to as “polymer molecules”) oriented in a predetermined direction is formed on the base material. It is a base material with a polymer thin film. Then, the chain-shaped aromatic polymer molecule is a total aromatic polyester and / or a total aromatic polyester amide in which an asymmetric aromatic monomer having an asymmetric molecular structure is polymerized to form a chain. In addition, the following condition 1 or 2 is satisfied.
(Condition 1) Ratio of absorption peak at wave number 1600 cm ^{-1 to} absorption peak at wave number 1740 cm ^-1 measured by infrared analysis by transmission method with respect to polymer thin film (A) (hereinafter, simply "ratio of absorption peak (absorption peak ratio) It is also called A). ”), And the absorption peak at a wave number of 1740 cm- ¹ measured by infrared analysis by the KBr tablet method for a sample containing the same aromatic polymer molecule as the aromatic polymer molecule constituting the polymer thin film in an unoriented state. The value (A / B) of the ratio (A / B) to the ratio (B) of the absorption peak at a wave number of 1600 cm- ¹ to 1600 cm- ¹ (hereinafter, also simply referred to as “the ratio of absorption peaks (B)”) is 0 to 0.67.
Against (Condition 2) polymer films, and the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by high sensitivity reflection method (A), aromatic constituting the polymer film the ratio of the absorption peak at a wave number 1600 cm ^-1 the sample containing the same aromatic polymer molecule and family polymer molecules unoriented state for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis according to KBr tablet method (B) and the The ratio value (A / B) is 2 or more.

In the base material with a polymer thin film of the present embodiment, as shown in FIG. 1, a large number of polymer molecules 14 are oriented in the direction perpendicular to the base material 12 on the base material 12, and a large number of polymer molecules 14 are formed on the polymer thin film 16. To configure. The polymer molecule 14 has a chain shape formed by binding asymmetric aromatic monomers. Note that FIG. 1 schematically shows the form of the base material 10 with a polymer thin film, and does not correspond to the actual dimensional ratio.

In the substrate with a polymer thin film of the present embodiment, the polymer thin film contains a large number of chain polymer molecules oriented in a predetermined direction. Then, when the base material has infrared transmission, condition 1 is satisfied, and when the base material is infrared non-transmissive, condition 2 is satisfied. Conditions 1 and 2 both indicate that the polymer molecules constituting the polymer thin film are oriented substantially perpendicular to the substrate. Here, the "generally perpendicular direction to the base material" includes not only the direction of 90 ° but also the direction of 90 ± 45 °. It should be noted that it is not strict whether the base material is infrared transmissive or infrared transmissive, and it is distinguished by whether the measurement method of infrared analysis is suitable for the transmission method or the high-sensitivity reflection method. Will be done.

The value (A / B) of the ratio of the absorption peak ratio (A) and the absorption peak ratio (B) under the conditions 1 and 2 will be described. The absorption peak at a wave number of 1600 cm ^-1 indicates the absorption of the benzene ring for skeletal vibration in the C1-C4 direction. When the benzene ring is oriented substantially perpendicular to the substrate, the skeletal vibration in the C1-C4 direction has a ratio (A) of the absorption peaks smaller than the ratio (B) of the absorption peaks. Become. That is, the value (A / B) of the ratio of the absorption peak ratio (A) to the absorption peak ratio (B) is 0 to 0.67 in the case of condition 1, and 2 in the case of condition 2. The above indicates that the polymer molecular chains are oriented substantially perpendicular to the substrate.

The basis of the ratio value (A / B) specified in each of the conditions 1 and 2 will be described.
In the permeation method, a detailed analysis is performed by spatial integration when the polymer molecular chain is oriented at an angle θ tilted from the normal of the base material (from Jiro Fujimori's 1992 master's thesis at Tokyo Institute of Technology). The ratio A of the absorption peaks when the polymer molecular chain is oriented at an angle θ tilted from the normal of the base material is ( ² sin ² θ) / (cos ² θ + 1) of the ratio B of the absorption peaks in the non-oriented state. Double. Since the function shown by this equation is monotonically increasing with respect to θ, the upper limit of the above ratio value (A / B) is 2/3, that is, when the orientation is performed with a slope smaller than θ = 45 °. It becomes about 0.67.
Similarly, in the case of the high-sensitivity reflection method, it is 2cot ² θ times, and since the function shown by this equation is monotonically decreasing, the value of the above ratio is obtained when the orientation is inclined with a slope smaller than θ = 45 °. The lower limit of (A / B) is 2.
In condition 2, when the polymer molecular chain is oriented perpendicular to the base material, that is, when the inclination angle θ of the polymer molecular chain from the normal line of the base material is 0 °, division by zero is performed. In the present embodiment, the case where the inclination angle θ is 0 ° is also included.

In the present embodiment, as described above, a sample containing the same aromatic polymer molecules as the aromatic polymer molecules constituting the polymer thin film in an unoriented state is used. Then, the ratio of the absorption spectrum at a specific wave number obtained by measuring the sample by infrared analysis by the KBr tablet method is used as a criterion for judgment. When the polymer molecule constituting the polymer thin film is a homopolymer of 4-hydroxybenzoic acid, a sample containing the homopolymer of 4-hydroxybenzoic acid in an unoriented state can be obtained, for example, as follows.
The following raw material monomers, fatty acid metal salt catalyst, and acylating agent are charged in a polymerization vessel equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a depressurization / outflow line, and nitrogen substitution is started.
(material)
4-Hydroxybenzoic acid; 172.5 g (100 mol%)
Acylating agent (acetic anhydride); 87 g
After charging the raw materials into the polymerization vessel, the temperature of the reaction system is raised to 140 ° C., and the reaction is carried out at 140 ° C. for 1 hour. Then, the temperature is further raised to 325 ° C. over 3.5 hours, and then the pressure is reduced to 10 Torr (that is, 1330 Pa) over 15 minutes while distilling acetic acid, excess acetic anhydride, and other low boiling points. Perform melt polymerization. When the outflow amount reaches 121 ml, nitrogen is introduced to change the pressure from the reduced pressure state to the pressurized state through normal pressure, and the polymer (homopolymer of 4-hydroxybenzoic acid) is discharged from the lower part of the polymerization vessel.

In the present embodiment, the polymer molecule constituting the polymer thin film is a total aromatic polyester and / or a total aromatic polyester amide in which an asymmetric aromatic monomer is polymerized to form a chain. The asymmetric aromatic monomer has a dipole moment, and when a large number of them are bonded to form a chain, the asymmetric aromatic monomer has a large dipole moment along the polymer molecular chain. As a result, the polymer thin film is excellent in piezoelectricity, pyroelectricity and ferroelectricity. Moreover, since it is also excellent in thermal conductivity, it is also useful as a thermal conductive material.

[Polymer thin film]
As described above, the polymer thin film contains a large number of chain polymer molecules formed by polymerizing asymmetric aromatic monomers having an asymmetric molecular structure. That is, the polymer molecule is oriented perpendicular to the substrate and has a large dipole moment along the molecular chain of the polymer molecule as described above. In order for the polymer molecule to have a large dipole moment, it is preferable that the direction of the bond in the polymer molecule (in the case of an ester bond, the direction of "-COO-") is constant.

Because the asymmetric aromatic monomer from which the polymer molecule is derived has an aromatic group, a pair of functional groups that can react with each other to form a bond, and each functional group faces 180 ° in opposite directions. It becomes a chain by binding. Examples of the combination of the pair of functional groups include a combination of a hydroxyl group and a carboxyl group and a combination of an amino group and a carboxyl group. The former combination is aromatic polyester and the latter combination is aromatic polyamide.

The asymmetric aromatic monomer is preferably a monomer having any of the structures represented by the following structural units (I) to (IV).

Examples of the monomer having a structural unit represented by the structural formula (I) include 4-hydroxybenzoic acid (hereinafter, also referred to as “HBA”).
Examples of the monomer having a structural unit represented by the structural formula (II) include 6-hydroxy-2-naphthoic acid (hereinafter, also referred to as “HNA”).
Examples of the monomer having a structural unit represented by the structural formula (III) include 4-hydroxy-4'-biphenylcarboxylic acid (hereinafter, also referred to as "HBCA").
Examples of the monomer having a structural unit represented by the structural formula (IV) include N-acetyl-aminobenzoic acid.
It should be noted that all of them may be structural units represented by the structural formulas (I) to (IV) after polymerization, and are not limited to the monomers exemplified above. For example, an acylated monomer having a hydroxyl group or an amino group may be used.

In the present embodiment, the film thickness of the polymer thin film is preferably 30 to 700 nm, more preferably 100 to 500 nm.

[Base material]
The base material used in the present embodiment is not limited as long as it has durability against the process temperature of 200 to 300 ° C. For example, a silicon substrate, an aluminum substrate, a ceramic thin film, a glass substrate and the like can be mentioned. The thickness of the base material is not particularly limited and can be appropriately set. Further, examples of the shape of the base material include a plate shape, a sheet shape, a foil shape, and the like, and the base material may have a three-dimensional shape.

Since the above-mentioned substrate with a polymer thin film of the present embodiment is excellent in piezoelectricity, pyroelectricity, ferroelectricity, and thermal conductivity, it can be suitably used as a piezoelectric material, a pyroelectric material, and a ferroelectric material. ..

Further, the substrate with a polymer thin film of the present embodiment can be used as a high thermal conductive material, a heat-resistant electron / optical element (polymer transistor, photoconductivity, organic EL, electric light effect, nonlinear optical effect, etc.). it can.

<Manufacturing method of base material with polymer thin film>
The above polymer thin film can be produced by the method for producing a polymer thin film of the present embodiment. In the method for producing a base material with a polymer thin film of the present embodiment, a surface treatment agent having a functional group capable of reacting with any one of a hydroxyl group, a carboxyl group and an amino group to form a bond is used, and the functional group is exposed. The step of modifying the surface of the base material with a surface treatment agent (hereinafter, also referred to as “step A”) and the asymmetry having an asymmetric molecular structure capable of reacting with the functional group of the surface treatment agent to form a bond. A step of forming a polymer thin film on the surface of a base material by vapor phase polymerization using an aromatic monomer (hereinafter, also referred to as “step B”) is included, and by-products generated by a polymerization reaction during gas phase polymerization are included. It is characterized by including a step of discharging a substance from the reaction system.

In the method for producing a base material with a polymer thin film of the present embodiment, the surface of the base material is modified with a surface treatment agent in step A to expose a functional group capable of reacting with a hydroxyl group or the like to form a bond. Then, in step B, the asymmetric aromatic monomer is polymerized by vapor phase polymerization starting from the exposed functional group. Therefore, a large number of asymmetric aromatic monomers are bonded from the functional group of the surface treatment agent in the direction perpendicular to the substrate to form a chain polymer molecule, and a polymer thin film containing a large number of the chain polymer molecules is formed. Moreover, since the polymerization reaction (polycondensation reaction) proceeds from the functional group of the surface treatment agent, the direction of the bond in the polymer molecule (in the case of an ester bond, the direction of "-COO-") becomes constant. Since the polymerization reaction of each polymer molecule proceeds uniformly starting from the functional group of the surface treatment agent, the bonding direction is constant for all the polymer molecules in the polymer thin film. As a result, a large number of asymmetric aromatic monomers having a dipole moment are bonded to the base material in the vertical direction to form a chain polymer molecule, so that a large dipole moment is generated in the direction perpendicular to the base material. As a result, the base material with a polymer thin film of the present embodiment is rich in piezoelectricity, pyroelectricity and ferroelectricity, and is useful as a piezoelectric material, a pyroelectric material or a ferroelectric material.
Hereinafter, each step will be described.

[Step A]
In step A, a surface treatment agent having a functional group capable of reacting with any one of a hydroxyl group, a carboxyl group and an amino group to form a bond is used, and the surface of the base material is modified so that the functional group is exposed to the outside. It is a process. In this step, first, a surface treatment agent having the above functional groups is prepared. Then, the surface treatment agent is applied to the surface of the base material so that the functional groups are exposed, and the surface of the base material is modified with the surface treatment agent. In this state, the functional groups are exposed on the surface of the base material, and in step B, an asymmetric aromatic monomer having an asymmetric molecular structure capable of reacting with the functional groups of the surface treatment agent to form a bond is produced. It will be in a state where it can be combined.

The base material that can be used in this embodiment is the same as the base material described above. Since the examples and preferable examples of the base material are the same as those described above, the description thereof will be omitted here.

The surface treatment agent that can be used in the present embodiment has a functional group that can react with any one of a hydroxyl group, a carboxyl group and an amino group to form a bond, and the functional group includes an amino group. Examples thereof include an epoxy group, an isocyanate group, a vinyl group, a styryl group, a methacryl group, an acrylic group, a ureido group, and a mercapto group. Specific examples of the surface treatment agent include a silane coupling agent and the like.

Examples of the silane coupling agent include 3- (2-aminoethylamine) propyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, and N-2- (aminoethyl) -3-. Aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyl Trimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxy Silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3 -Isocyanoxide triethoxysilane, 3-trimethoxysilylpropyl succinate anhydride and the like can be mentioned.

In step A, the method of modifying the surface of the base material with the surface treatment agent is not particularly limited, and for example, the base material may be immersed in a solution containing the surface treatment agent, or may be applied to the surface of the base material. This may be done by applying a solution containing a surface treatment agent. The immersion or coating time, the temperature conditions at that time, and the like can be appropriately set. When a solution containing a surface treatment agent is applied to the surface of the base material, it is preferable to rinse after application.

Further, the surface treatment agent to be used is preferably used so that the amount per unit area on the base material is 1 × 10 ^-6 to 1 × 10 ^-3 g / cm ² .

Before the base material is modified with the surface treatment agent, it is preferable to clean the surface of the base material by ultrasonic cleaning, UV ozone cleaning or the like.

[Step B]
Step B is a step of forming a polymer thin film on the surface of a base material by vapor phase polymerization using an asymmetric aromatic monomer having an asymmetric molecular structure that can react with a functional group of a surface treatment agent to form a bond. is there. In this step, the asymmetric aromatic monomer has a pair of functional groups capable of reacting with each other, and one of the functional groups is a functional group capable of reacting with a hydroxyl group of a surface treatment agent or the like to be bonded. .. Then, by vapor phase polymerization, the asymmetric aromatic monomer first reacts with the functional group of the surface treatment agent and is bonded, and the asymmetric aromatic monomer bonded to the functional group is then combined with another asymmetric aromatic monomer. By binding and repeating such bonding, that is, by polymerizing, a large number of asymmetric aromatic monomers are bonded to form a chain. Further, since the functional group of the surface treatment agent is oriented in the direction perpendicular to the base material, the asymmetric aromatic monomer bonded to the functional group of the surface treatment agent is also oriented in the direction perpendicular to the base material. That is, the chain polymer molecules formed by the vapor deposition polymerization are oriented in the direction perpendicular to the substrate. Moreover, as described above, the bonding direction is constant for any polymer molecule in the polymer thin film.

As described above, the asymmetric aromatic monomer used in step B contains an aromatic group and has an asymmetric molecular structure. It also has a pair of functional groups that can react with each other, one of which can react with the functional groups of the surface treatment agent to form a bond. In addition, the pair of functional groups capable of reacting with each other are oriented 180 ° opposite. Other examples and preferable examples of the asymmetric aromatic monomer are the same as those described above, and thus the description thereof will be omitted here.
As the monomer having the structural unit represented by the structural formulas (I) to (IV), it is preferable to use an acylated monomer because the reaction becomes gentle.

Here, as an example of the apparatus used for gas phase polymerization, the vapor deposition polymerization apparatus will be described with reference to FIG. The thin-film polymerization apparatus 20 shown in FIG. 2 includes a vacuum chamber 22, a pipe (not shown) connected to the vacuum apparatus, and a pipe 24 communicating with the outside. The pipe 24 is provided with a valve 26, and the inside of the vacuum chamber 22 can be switched between an open space and a closed space by opening and closing the valve 26. In the vacuum chamber 22, a raw material monomer container 28 for accommodating the raw material monomer and a base material 30 as a target for forming a polymer thin film are provided. A heater is provided in the raw material monomer container 28 and the base material 30, and each is heated separately.
In the vapor deposition polymerization apparatus 20 having the above configuration, when vapor phase polymerization (deposited polymerization) is performed, the vacuum apparatus is first operated to keep the inside of the vacuum chamber 22 in a vacuum. Next, the raw material monomer container 28 containing the raw material monomer is heated to a temperature equal to or higher than the boiling point of the raw material monomer to evaporate (or sublimate) the raw material monomer. At the same time, the base material is heated to a temperature equal to or higher than the temperature at which the raw material monomer causes a polymerization reaction. In such a state, the evaporated raw material monomer undergoes a polymerization reaction on the surface of the base material starting from the functional group of the surface treatment agent to form a chain polymer molecule.

In the present embodiment, the pressure in the vacuum chamber in the gas phase polymerization is preferably 10 ^−0.1 to 10 ⁻³ Pa.
In addition, as the temperature condition, in order to minimize the energy lost until the raw material monomer reaches the base material, the temperature of the entire system is kept high and the energy is not lower than the activation energy of the polymerization reaction of the raw material monomer. It is preferable to heat the material to a high temperature. The evaporation temperature of such an asymmetric aromatic monomer and the heating temperature of the base material will be described later.

The present embodiment includes a step of discharging by-products generated by the polymerization reaction from the reaction system during the vapor phase polymerization. When the asymmetric aromatic monomer is, for example, an acylated (acetylated) HBA, acetic acid is produced as a by-product as the vapor deposition polymerization proceeds. When the ratio of acetic acid is increased, the product is hydrolyzed and the polymerization reaction is affected. Further, since the concentration of by-products increases in the reaction system, an equilibrium state is reached and the polymerization reaction is stopped. Therefore, it is necessary to discharge the by-products while exhausting the polymerization vessel. Therefore, in the present embodiment, a step of discharging the by-product generated by the polymerization reaction from the reaction system is provided. As a result, the influence of the by-product on the polymerization reaction is reduced, the polymerization reaction proceeds, and the molecular chain of the polymer molecule becomes long. In the vapor deposition polymerization apparatus shown in FIG. 2, by-products can be discharged by opening the valve 26.

In order to grow the chain polymer molecule longer, it is preferable to carry out the discharge step at predetermined time intervals. For example, it is preferable to carry out the polymerization reaction for 0.1 to 3 hours in vacuum and then provide a discharge step for 1 to 60 minutes. Then, it is preferable to repeat the cycle of such a polymerization reaction and a discharge step 1 to 100 times.

In gas phase polymerization, the asymmetric aromatic monomer is evaporated at a temperature 150 to 50 ° C. lower than the boiling point of the asymmetric aromatic monomer in an environment of a vacuum degree of 1 × 10 ² Pa to make the temperature of the substrate asymmetric. It is preferable to set the temperature 100 to 0 ° C. lower than the boiling point of the aromatic monomer. By setting the evaporation temperature of the asymmetric aromatic monomer and the temperature of the base material in this way, the asymmetric aromatic monomer scatters toward the base material, and when it reaches the surface of the base material, the polymerization reaction occurs at that moment. I will get up. As a result, the polymerization reaction proceeds favorably, and the polymer film can be efficiently formed.

Hereinafter, the present embodiment will be described in more detail with reference to Examples, but the present embodiment is not limited to the following Examples.

[Example 1]
First, an aluminum-deposited glass substrate (thickness: 1.5 mm) was used as a base material, and acetone and ethanol were immersed in this order, and ultrasonic cleaning was performed for 10 minutes each. Further, UV ozone washing was performed for 10 minutes. Then, the surface of the substrate was modified with the surface treatment agent by immersing it in ethanol containing 3% by mass of 3- (2-aminoethylamino) propyltrimethoxysilane as a surface treatment agent for 1 day.

4-Acetoxybenzoic acid was charged as an asymmetric aromatic monomer into the raw material monomer container of the vapor deposition polymerization apparatus. At the same time, the base material modified with the surface treatment agent as described above was placed in a predetermined position. In this state, vapor deposition polymerization was carried out by creating a vacuum of 1.2 × 10 ³ Pa while heating the raw material monomer container to 180 ° C. and the base material temperature to 240 ° C., respectively. After 1 hour, exhaust was performed for 3 minutes to remove by-products from the system. Such exhaust every hour was repeated 3 times.
As described above, a polymer thin film having a thickness of 80 nm was formed on the base material to obtain a base material with the polymer thin film.

The obtained substrate with a polymer thin film was subjected to infrared analysis by a high-sensitivity reflection method. An FT-IR spectrometer FTIR-6100 manufactured by JASCO Corporation was used as an infrared spectroscope, and the measurement was performed 128 times with a resolution of 4.0 cm- ¹ . Then, to determine the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by high sensitivity reflection method (A).
As a sample containing the same aromatic polymer molecule as the aromatic polymer molecule constituting the polymer thin film in an unoriented state, a sample containing a homopolymer of 4-hydroxybenzoic acid in an unoriented state was used. Then, with respect to the sample, perform infrared analysis by KBr tablet method was determined the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at a wavenumber 1740cm ^-1 (B).
The ratio value (A / B) was determined from the ratio of the obtained absorption peaks and found to be 3.2. In the present embodiment, infrared analysis is performed by the high-sensitivity reflection method, and since condition 2 is satisfied, it is shown that the formed polymer molecules are oriented perpendicularly to the substrate.

[Example 2]
In the vapor deposition polymerization, a substrate with a polymer thin film was obtained in the same manner as in Example 1 except that the exhaust was not performed every hour, and a polymer thin film having a thickness of 5 nm was formed on the substrate. Further, the obtained substrate with a polymer thin film was subjected to infrared analysis by a high-sensitivity reflection method, and the ratio value (A / B) was obtained in the same manner as in Example 1 and found to be 3.2. That is, since the condition 2 is satisfied as in Example 1, it is shown that the formed polymer molecules are oriented perpendicularly to the base material.

[Example 3]
A polymer thin film having a diameter of 45 nm with respect to the base material in the same manner as in Example 1 except that the asymmetric aromatic monomer was replaced with 4-hydroxybenzoic acid and a silicon substrate (thickness: 1 mm) was used as the base material. A substrate with a polymer thin film was obtained. Further, the obtained substrate with a polymer thin film was subjected to infrared analysis by a transmission method, and the ratio value (A / B) was determined in the same manner as in Example 1 and found to be 0.5. In the present embodiment, infrared analysis is performed by the transmission method, and since condition 1 is satisfied, it is shown that the formed polymer molecules are oriented perpendicularly to the substrate.

[Comparative Example 1]
A polymer having a diameter of 100 nm with respect to the base material in the same manner as in Example 1 except that the asymmetric aromatic monomer was replaced with 4-hydroxybenzoic acid and a base material not modified with a surface treatment agent was used. A substrate with a polymer thin film on which a thin film was formed was obtained. Further, the obtained substrate with a polymer thin film was subjected to infrared analysis by a high-sensitivity reflection method, and the ratio value (A / B) was determined in the same manner as in Example 1 and found to be 1.0. That is, since the condition 2 is not satisfied, it is considered that the polymer molecules were not vertically oriented.

The above Examples 1 to 3 and Comparative Example 1 are summarized in Table 1 below. In Table 1, the case where the exhaust was performed for 3 minutes every hour was shown as “Yes”. Further, the case where the polymer molecule was oriented perpendicularly to the substrate was indicated by “◯”, and the case where the polymer molecule was not oriented vertically was indicated by “x”.

From Table 1, it can be seen that in Examples 1 to 3, polymer thin films in which the polymer molecules were vertically oriented were obtained. On the other hand, in Comparative Example 1 using the base material not modified with the surface treatment agent, the polymer molecules were not vertically oriented. In Example 2, although the polymer was vertically oriented, the polymer molecules having a sufficient length were not formed because the exhaust was not performed, and the polymer thin film was thinner than in the other examples.

10 Base material with polymer thin film 12 Base material 14 Polymer molecule 16 Polymer thin film 20 Vapor deposition polymerization equipment 22 Vacuum chamber 28 Raw material monomer container 30 Base material

Claims (8)

A substrate with a polymer thin film in which a polymer thin film containing a large number of chain-like aromatic polymer molecules oriented in a predetermined direction is formed on the substrate.
The chain-like aromatic polymer molecule is a total aromatic polyester and / or a total aromatic polyester amide in which an asymmetric aromatic monomer having an asymmetric molecular structure is polymerized to form a chain, and the following condition 1 or 2 is satisfied. Fill, substrate with polymer thin film.
(Condition 1) aromatic wherein the polymer thin film, and the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by transmission method (A), constituting the polymer film the ratio of the absorption peak at a wave number 1600 cm ^-1 the sample containing the same aromatic polymer molecule and family polymer molecules unoriented state for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis according to KBr tablet method (B) and the The ratio value (A / B) is 0 to 0.67.
Against (Condition 2) the polymer film, and the ratio of the absorption peak at a wave number 1600 cm ^-1 for absorption peak at wave number 1740 cm ^-1 as measured by infrared analysis by high sensitivity reflection method (A), constituting the polymer film Ratio of absorption peak at wave number 1600 cm ^{-1 to} absorption peak at wave number 1740 cm ^-1 measured by infrared analysis by KBr tablet method for a sample containing the same aromatic polymer molecule as the aromatic polymer molecule in an unoriented state (B) The value of the ratio (A / B) with and is 2 or more. The substrate with a polymer thin film according to claim 1, wherein the asymmetric aromatic monomer is a monomer having any of the structures represented by the following structural units (I) to (IV).

The substrate with a polymer thin film according to claim 1 or 2, wherein the polymer thin film has a film thickness of 30 to 700 nm or more. A surface treatment agent having a functional group capable of reacting with any of a hydroxyl group, a carboxyl group and an amino group to form a bond is used, and the surface of the base material is modified with the surface treatment agent so that the functional group is exposed. Process and
A step of forming a polymer thin film on the surface of the base material by vapor phase polymerization using an asymmetric aromatic monomer having an asymmetric molecular structure that can react with a functional group of the surface treatment agent to form a bond. Including
A method for producing a substrate with a polymer thin film, which comprises a step of discharging by-products generated by the polymerization reaction from the reaction system during the vapor phase polymerization. The method for producing a substrate with a polymer thin film according to claim 4, wherein the step of discharging the by-product from the reaction system is executed at predetermined time intervals. In the gas phase polymerization, the asymmetric aromatic monomer is evaporated at a temperature 150 to 50 ° C. lower than the boiling point of the asymmetric aromatic monomer in an environment of a degree of vacuum of 1 × 10 ² Pa, and the base material is subjected to. The method for producing a base material with a polymer thin film according to claim 4 or 5, wherein the temperature is set to a temperature 100 to 0 ° C. lower than the boiling point of the asymmetric aromatic monomer to perform vapor phase polymerization. The item according to any one of claims 4 to 6, wherein the asymmetric aromatic monomer is a monomer having a structure of any of the structural units represented by the following structural formulas (I) to (IV). A method for producing a substrate with a polymer thin film.

The method for producing a substrate with a polymer thin film according to claim 7, wherein the asymmetric aromatic monomer is acylated.

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