JPH0768314B2 - Langmuir-Blodgett film composed of fluorine-containing polymer compounds - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a Langmuir-Blodgett film made of a novel fluorine-containing polymer compound.

[0002]

2. Description of the Related Art A polymer compound modified with a long-chain perfluoroalkyl group exhibits excellent properties such as water / oil repellency, dust resistance, and corrosion resistance, and is used as a surface modifier for substrate protection. However, the perfluoroalkyl group-introduced polymer compound is difficult to dissolve in a solvent due to the water and oil repellency of the perfluoroalkyl group, and is difficult to handle as a film material. That is, it is difficult to form an ultrathin film, which is an important element as a surface modifier and a substrate protective material. Further, it is important to arrange perfluoroalkyl groups, which are functional groups such as water and oil repellency, on the polymer surface in order to enhance the performance of these functions, but it is not easy to control the orientation to the surface. Absent.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a Langmuir-Blodgett film excellent in water and oil repellency.

[0004]

Means for Solving the Problems The present inventor has conducted extensive studies on a method for forming an ultrathin film utilizing the hydrophobicity of a perfluoroalkyl group, and as a result, a part of amino groups of polyallylamine is perfluorinated by an amide bond. The polymer compound obtained by alkylation was found to be suitable as a Langmuir-Blodgett film material, and has completed the present invention. According to the invention, the general formula

[Chemical 1] (In the formula, Rf represents a perfluoroalkyl group having 6 to 15 carbon atoms, m represents a number of 10 to 1500, and n represents O <n.
The number is ≦ 0.4 m), and a Langure-Blodgett film made of a fluorine-containing polymer material is provided.

The fluorine-containing polymer compound represented by the general formula (I) according to the present invention comprises a polyallylamine represented by the following general formula (II) and an alkyl perfluorocarboxylate represented by the general formula (III). It is prepared by reacting according to the formula.

[Chemical 2] However, in the above formula, Rf, m, and n have the same meanings as described above, and R is an alkyl group having 1 to 5 carbon atoms. The reaction can be carried out using alcohols as a reaction solvent and a reaction temperature of −10 ° C. to 50 ° C., preferably 15 ° C. to 30 ° C.

Polyallylamine is obtained by neutralizing polyallylamine hydrochloride with a base. In order to preferably carry out the reaction, a solution portion obtained by neutralizing polyallylamine hydrochloride in alcohol, or an alcohol solution of polyallylamine obtained by dissolving polyallylamine in alcohol,
Add alkyl perfluoroalkylcarboxylate. The perfluoroalkyl group can be introduced into the polyallylamine at an arbitrary ratio by changing the amount of the perfluoroalkylcarboxylic acid added. When obtaining the polymer compound of the general formula (I), the reaction is carried out in a homogeneous system. After stirring the reaction solution for several minutes, the reaction solution is concentrated and washed with water, and the obtained polymer compound is dried. This product was identified as a fluorine-containing polyallylamine represented by the above general formula (I) by the fluorine analysis value and IR spectrum.

The above-mentioned fluorine-containing polymer compound of the general formula (I) dissolves in a solvent and easily forms a monomolecular film on the water surface, and a Langmuir-Blodgett accumulated film (Y film) can be prepared. As a result of obtaining the film thickness of this ultrathin film and the critical surface tension γc for the n-alkane, the following was found. That is, when the amount of introduced perfluoroalkyl group is small, the film thickness is thin (20Å), γc is close to 18.5 of polytetrafluoroethylene, and when it is large, it is thick (30Å), γc.
Is smaller than 18.5 (CF ₃ is lined up on the film surface)
I understand. Furthermore, the area occupied by one perfluoroalkyl group is 29Å ² (cross-sectional area of the CF ₂ chain) when the amount of introduced perfluoroalkyl group is larger than the limit area from the FA curve of the Langmuir-Blodgett film, which is small. And will be larger than this. Also, a film can be formed by drying the solution of the fluorine-containing polymer compound on the substrate, and the γc of this film
It can be seen that CF ₃ appears on the surface from the small value of. From this, it can be seen that the perfluoroalkyl groups can be stood on the surface, laid down, arranged closely or at intervals by changing the film forming method and the amount of the introduced perfluoroalkyl groups.

[0008]

The fluorine-containing polymer compound of the general formula (I) can be made into an ultrathin film by the Langmuir-Blodgett method, and can be used as an unprecedented ultrathin film surface-modifying substance. Further, in this fluorine-containing polymer compound, the orientation of the perfluoroalkyl group, which is a functional group, can be controlled intramolecularly or intermolecularly on the film surface. Conventionally, there is no example in which the perfluoroalkyl group in a polymer is controlled by the Langmuir-Blodgett method within a molecule or between molecules. The fluorine-containing polymer substance that can be advantageously applied as a Langmuir-Blodgett film material in the present invention is one in which n in the general formula (I) satisfies n <0 ≦ 0.4 m. When n is larger than 0.4 m, it becomes unsuitable as a film material. The Langmuir-Blodgett film referred to in this document means a monomolecular film and an asbestos film obtained by the well-known Langmuir-Blodgett method.

[0009]

EXAMPLES The present invention will now be described in more detail with reference to Examples. Example 1 0.23 g of sodium metal was added to 15 ml of methanol, and 0.936 g of polyallylamine hydrochloride (average molecular weight: about 9000) was added after the generation of hydrogen was stopped, and the mixture was covered and stirred. Precipitated sodium chloride is removed by filtration, washed with 10 ml of methanol, and the washing solution is returned to the filtrate. To this solution, 0.8 g of ethyl perfluoctanoate is dissolved in 5 ml of methanol and added all at once. The obtained uniform reaction solution is a fluorinated polyallylamine solution, which can be used as it is for forming a thin film. The solvent was removed from this solution under reduced pressure, and the solution was further washed with water and dried to obtain a polymer in which 20% of amino groups in polyallylamine were amidated and perfluoroheptyl groups were introduced. This was confirmed by the fluorine analysis value 41.5% (calculated value 41.8%) of the obtained polymer compound and the infrared absorption spectrum. Amide bond: 1708, 1555 cm ¹ , carbon-fluorine bond: 1
It was confirmed by the strong absorption of 300-1100 cm ¹ . In the same manner, ethyl perfluorooctanoate or ethyl perfluorononanoate was used, and the reaction was carried out by changing the molar ratio to polyallylamine. The fluorine analysis values of the obtained polymer compound are shown in the following order.
That is, the ratio (%) of the fluorine-containing ester to the amino group in polyallylamine: fluorine analysis value (%), fluorine analysis calculation value (%). When using ethyl perfluorooctanoate: (1) 4
0, 52.5, 52.9; (2) 20, 41.5, 4
1.8; (3) 5, 18.0, 18.5; with ethyl perfluorononanoate: (1) 40, 54.4,
A result of 54.9 was obtained.

Example 2 In the Langmuir-Blodgett method, amino groups in polyallylamine were mixed with 5 mol% of ethyl perfluorooctanoate (PAAF5) and 20% (P
AAF20) modified fluoropolymer methanol
The results of measuring the relationship between the surface pressure and the area per molecule (FA curve) when the dilute benzene mixed solution was developed are shown in the drawing. From this, the cross-sectional area of the molecule in the film, that is, the limiting area is 2 for one fluoroalkyl group in PAAF20.
In 9Å ^2, PAAF5 indicated a value of 70 Å ² and 100 Å ^2.

Example 3 PAAF5 and PAAF20 shown in Example 2 were treated at 17 ° C.
The surface pressure of 20 mN /
The film was transferred as a monomolecular film and a cumulative film on a glass substrate at m. The accumulating film was a Y film and accumulated up to 7 layers. The reaction solution shown in Example 1 was diluted with methanol three times and dried on a glass substrate to obtain a film.

Example 4 The surface roughness and the film thickness of the 7-layer cumulative film of Langmuir-Projet produced in Example 3 were measured by the Taly step. As a result, PAAF5 had a film thickness of 22.
Å, PAAF20 is 29Å, the surface irregularities are about 2
A height of 4Å was observed.

Example 5 The contact angle with the n-alkane of the film obtained in Example 3 was measured, and the critical surface tension γ determined from the Zisman plot was obtained.
c was measured. As a result, the PAAF20 monolayer is 1
The cumulative film of 8.2 and 7 layers was 17.6, the cumulative film of 7 layers of PAAF5 was 19.3, the film of PAAF20 obtained by air-drying the solution was 14.4, and the film of PAAF5 was 20.1. The contact angle with water was 74 ° for the polyallylamine film, but 106 ° for the monomolecular film of PAAF20, 110 ° for the seven-layer cumulative film, and 107 for the seven-layer cumulative film of PAAF5.
The film of PAAF20 obtained by air-drying the solution was 115 °,
It was 93 ° in PAAF5.

[Brief description of drawings]

FIG. 1 shows an FA curve of a Langmuir-Blodgett film of a fluorine-containing polymer compound according to the present invention.

Claims (1)

[Claims] 1. A general formula: (In the formula, Rf represents a perfluoroalkyl group having 6 to 15 carbon atoms, m represents a number of 10 to 1500, and n represents 0 <n.
It is a number that satisfies ≦ 0.4 m. ) A Langmuir-Blodgett film composed of a fluorine-containing polymer compound represented by