JPH0598056A - Method of surface graft polymerization - Google Patents

Abstract

PURPOSE:To graft polymer chains onto the surface of an org. substrate at a low temp. (usually at about normal temp.) and thus improve the retention of properties of the substrate without detriment to its inherent characteristics. CONSTITUTION:Polymer chains are grafted onto at least a part of the surface of an org. substrate by bonding a photoreactive hydroxylated polymeric precursor to the surface and reacting the precursor with an oxidizing agent to generate free radicals at about normal temp.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel surface graft polymerization method. More specifically, the present invention is
The present invention relates to a surface graft polymerization method using a precursor polymer having a photoreactive group.

[0002]

2. Description of the Related Art Surface modification of a polymer material is one of the main issues in the development of functional materials, and surface graft polymerization is one of the important methods used for surface modification. This surface modification can be performed, for example, by forming a hydrophilic polymer layer on the surface of a hydrophobic polymer material, thereby making it possible to use a functional material having hydrophilicity without impairing the properties peculiar to the polymer material. is there.

Conventionally, as a surface graft polymerization method,
Radicals were generated in the base material by radiation irradiation, glow discharge, plasma discharge, etc., and polymerization was carried out by heating in the presence of a monomer, but when the surface modification of the molded product is performed, deterioration due to heating etc. Therefore, when these polymerization methods are used, the material used for the molded product needs to have heat resistance, and there is a problem that the use is markedly limited. Further, in the conventional graft polymerization method, there is a problem that not only the very surface of the base material, but also the graft chain penetrates into the interior, impairing the properties specific to the base material.
The current situation is that the demands for various functional materials cannot be sufficiently satisfied.

[0004]

In view of the above problems, an object of the present invention is to carry out surface modification of the extreme surface of a substrate,
It is an object of the present invention to provide a graft polymerization method which is carried out at around room temperature without heating using an appropriate base material.

A further object of the present invention is to provide a graft polymerization method in which a desired graft chain is formed only in a thin layer portion on the extreme surface of the base material without forming a graft chain inside the base material. It is in.

[0006]

In order to achieve these objects, the present inventors have earnestly studied a graft polymerization method for effective surface modification of the extreme surface of a substrate. As a result, the precursor polymer having a photoreactive group and having a hydroxyl group is preliminarily bound to the substrate using the photoreactive group, and the precursor polymer having the hydroxyl group is reacted with an oxidizing agent, It is possible to achieve the object of the present invention by performing surface modification by adding radically polymerizable monomers having the properties required for generating radicals and modifying the radicals and graft-polymerizing them. Know
The present invention has been completed based on this finding.

That is, according to the present invention, (1) a precursor polymer having a photoreactive group and having a hydroxyl group is bonded to at least a part of the surface of the organic material, and the polymer is reacted with an oxidizing agent to form a radical. Can be achieved by a surface graft polymerization method which is characterized in that

Further, according to the present invention, (2) the photoreactive group is chemically fixed on the surface of an organic material by utilizing the property of forming a covalent bond with a nearby atom via a highly reactive nitrene as an intermediate. Can be achieved by the surface graft polymerization method described in (1) above.

Further, the present invention can be achieved by the surface graft polymerization method according to the above (1), wherein (3) the polymer oxidizing agent having a hydroxyl group is Ce (IV) ion.

Furthermore, in the present invention, preferably, (4) the photoreactive group consisting of the above (2) and (3) forms a covalent bond with a nearby atom via a highly reactive nitrene as an intermediate. It can also be achieved by the surface graft polymerization method according to the above (1), wherein the oxidizing agent of the polymer which is chemically fixed on the surface of the organic material and has a hydroxyl group is Ce (IV) ion by utilizing the property of forming. it can.

[0011]

The surface graft polymerization method of the present invention will be described in detail. A phenylazide group as a photoreactive group is introduced into a precursor polymer having a large amount of hydroxyl groups (for example, polyvinyl alcohol) to form an organic polymer material. The polymer thin film is formed on the surface of the base material by coating or the like, and a phenylazide group as a photoreactive group is formed by irradiating the polymer thin film with light, preferably ultraviolet light, preferably via a highly reactive nitrene as an intermediate. The polymer thin film is chemically fixed to the surface of the base material made of an organic polymer material by utilizing the property of forming a covalent bond with a nearby atom. Then an oxidizer such as Ce (IV)
Radicals are generated by the ions on the surface of the polymer thin film by using the reaction represented by the following chemical formula 1 (in the case of Ce (IV) ions).

[0012]

[Chemical 1]

However, in the above reaction, if an excessive oxidizing agent is present, the following chemical formula 2 (in the case of Ce (IV) ion)
The reaction shown in occurs and the radical disappears.

[0014]

[Chemical 2]

That is, the grafting efficiency is influenced by the concentration of the oxidizing agent. Therefore, the determination of the concentration of oxidant is
It is desirable to find a suitable range in advance through a simple experiment as shown in the examples of the present invention. For example oxidants,
The concentration of Ce (IV) ion is 0.1 to 100 mM, especially 1.
0-50 mM is preferred. For example, a film in which a precursor polymer thin film in which a phenyl azide group is introduced into polyvinyl alcohol is formed by coating on the surface of a polyethylene terephthalate film, and this is irradiated with ultraviolet rays to chemically fix the polymer thin film on the surface of the base material. To
Immerse in 0.5N nitric acid aqueous solution and Ce at low temperature (0 ° C or less)
In the case of using (IV) ions for oxidation to generate radicals, it is preferable to adjust the concentration of the oxidizing agent so that [Ce ^IV ] = about 2 mM.

Next, in the presence of a radical-polymerizable monomer having the properties required for surface modification, at around room temperature, for example, 40 ° C.
By forming a graft chain in the polymer by graft polymerization, the surface of the base material made of an organic polymer material is modified to add arbitrary properties.

The precursor polymer used in the surface graft polymerization method of the present invention has both a photoreactive group and a hydroxyl group, and is a polymer having a hydroxyl group such as polyvinyl alcohol, cellulose, starch and chitin. It has a phenylazide group such as a sugar and a photoreactive compound, for example, p-azidobenzoic acid, p-azidobenzoyl chloride, p-azidoaniline, azidophenylcarbonyloxysuccinimide, etc. An azido group is introduced by a polymer reaction by appropriately combining the compounds to be converted.

The substrate for surface graft polymerization used in the present invention is not particularly limited as long as it is usually an organic material, and examples thereof include polyvinyl (vinyl chloride, vinyl acetate, etc.), polyethylene, polyvinylidene, polyurethane, Examples thereof include polyamide, polyacryl, polyester, various rubbers (elastomers) and various copolymers.

Next, as the oxidant for generating radicals on the polymer surface, in addition to Ce (IV) ions, for example, peroxodisulfate, sodium periodate and the like can be mentioned.

The monomer which can be graft-polymerized in the present invention may be any one as long as it is a radical-polymerizable monomer, and can be arbitrarily selected according to the purpose of use or the use thereof. Examples of such monomers include vinyl acetate, styrene, vinyl chloride, various vinyl-based monomers such as acrylonitrile, acrylic acid, and 2
-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyalkyl (meth) acrylate such as 3-hydroxypropyl (meth) acrylate, alkoxy such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate Alkylaminoalkyl (meth) acrylates such as alkyl acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, acrylamide, methacrylamide, diacetone ( Dials such as (meth) acrylamide, dimethylacrylamide, diethylacrylamide, dimethylmethacrylamide, and diethylmethacrylamide. Le (meth) acrylamide, those hydrophilic monomers such as vinyl pyridine are preferable.

Further, the temperature condition of the graft polymerization in the present invention is somewhat changed depending on the combination of the precursor polymer, the organic material base material and the monomer used, but by using a suitable oxidizing agent, the precursor polymer can be used. The reaction between the oxidant and the oxidant to generate a radical can be performed at around room temperature regardless of the high temperature. As a result, the graft polymerization can be carried out without deteriorating the characteristics peculiar to the base material of the organic material used.

[0022]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the scope of the present invention is not limited by these examples.

Example 1 p-azidobenzoyl chloride
De synthetic p- azido acid 8.16g (50 mmol) was added thionyl chloride 30 g (250 mmol). Then 8
After heating at 0 ° C. for 2 hours to make it uniform, the temperature was slowly returned to room temperature, and the mixture was further stirred for 2 hours. Unreacted thionyl chloride was distilled off under reduced pressure, and the crude product was distilled under reduced pressure (2 m
mHg, 124-126 ° C). Further, the crude product was recrystallized from hot hexane for purification to obtain p-azidobenzoyl chloride (5.9) which was a pale yellow crystalline product.
g, 66%). The result of measuring the IR spectrum of the obtained product (p-azidobenzoyl chloride) is shown in FIG.

Example 2 Conversion of phenyl azide group to PVA
To 50 ml of introduced and dried dimethyl sulfoxide (hereinafter referred to as DMSO), 2.0 g of PVA and 1.64 g of the product obtained in Example 1 (0.20 equivalent to PVA) were added,
The mixture was stirred for one day, heated at 70 ° C. for 4 hours, further added with pyridine, and heated at 70 ° C. for 3 hours. Then, the product was washed with ethyl acetate to obtain a desired product (hereinafter referred to as AzPhPVA) in which a phenylazide group was introduced into PVA (content rate: 6%, according to ¹ H-NMR measurement result). Obtained A
The measurement result of the IR spectrum of zPhPVA is shown in FIG.

Example 3 Photochemical Immobilization on Substrate Surface AzPhPVA obtained in Example 2 was added to a solvent to give a pH of 0.1.
05% solution (DMSO: methanol = 1: 1 (weight ratio)
Was cast using a spin coater on the surface of the polyethylene terephthalate film, and then dried with hot air. This film was irradiated with ultraviolet rays for 40 seconds to wash the unexposed area in DMSO. The surface of the film was measured by ESCA, and the results are shown in FIGS. 3 (a) and 3 (b). In the figure, (a) shows the results of ESCA of the film surface of the unexposed portion of ultraviolet rays, and (b) shows the results of ESCA of the film surface of the exposed portions of ultraviolet rays. From FIGS. 3A and 3B, it was confirmed that AzPhPVA was photochemically immobilized only on the exposed portion.

Example 4 Acrylation using Ce (IV) ion
Graft Polymerization of Lamide The polyethylene terephthalate film obtained by photochemically fixing AzPhPVA obtained in Example 3 was immersed in a 0.5N nitric acid aqueous solution in the presence of 5% acrylamide, and the temperature was lowered (0
Below (° C), the addition amount of Ce (IV) ions is adjusted to [Ce
^IV ] = 0, 0.2, 1, 2, and 3 mM were prepared and added, degassed, sealed, and polymerized at 40 ° C. for 2 hours. Each film obtained by changing the amount of Ce (IV) ion added was agitated for 5 hours in hot water at 70 ° C., overnight at 60 ° C., and further for 4 hours at 90 ° C. or higher, and then dried to polymerize. A film having a fixed membrane was obtained. ESC of the film surface on which the obtained polymerized film was fixed
The measurement was performed at A, and the results are shown in FIG. 3 (c) and FIG. 4, respectively. FIG. 3 (c) shows the result when [Ce ^IV ] = 2 mM,
In FIG. 4, (a) shows [Ce ^IV ] = 0 mM, (b) shows [Ce ^IV ] = 0.2 mM, and (c) shows [Ce ^IV ] = 1 m.
M, (d) [Ce ^IV ] = 2 mM and (e) [Ce ^IV ] = 2 mM
^IV ] = 3 mM for each result. In addition, N1s in FIG.
FIG. 5 shows the relationship between the value of the relative ratio N / C and the value of [Ce ^IV ] with respect to the C1s spectrum of the spectrum. From Figure 5 [C
When e ^IV ] = 2 mM, the graft amount takes a maximum value, and in the case of the maximum value, the N / C value of 0.2 is calculated from FIG.
79 (theoretical value 0.33), O / C value 0.330 (theoretical value 0.33) and the content of carbonyl carbon with respect to the total carbon of 28.7% (theoretical value 33%), From these values and the results of FIGS. 3A to 3C, it was confirmed that the acrylamide graft polymerized film was formed as the polymerized product film.

[0027]

INDUSTRIAL APPLICABILITY The surface graft polymerization method of the present invention is capable of introducing a graft chain into a base material at around room temperature, and is excellent in the retention of the base material characteristics without impairing the properties peculiar to the base material. Further, it does not directly modify the surface by directly reacting with the base material itself, but preliminarily binds an ultrathin film precursor polymer to the surface and graft-polymerizes a monomer having an arbitrary functionality to the polymer. Therefore, there is no deterioration of the base material properties due to the penetration of the graft chain into the base material itself, and the base material surface can be modified by effectively forming the desired graft chain only in the ultrathin layer portion of the base material surface. Excellent in terms.

Therefore, by using the surface graft polymerization method of the present invention, it is possible to freely design the characteristics of the substrate surface by irradiating light only on the necessary portions of the substrate surface. By changing the property of the necessary part of the substrate surface from hydrophilic to hydrophobic, the dependence of cells on the adhesion to the “hydrophobic” surface can be utilized, and cell adhesion and non-adhesion to the substrate are intended. And can be effectively utilized for cell micropatterning surface technology.

[Brief description of drawings]

FIG. 1 is a diagram showing a result of measuring an IR spectrum of a polymer substance having a phenylazide group as a photoreactive group obtained in Example 1.

FIG. 2 is a view showing a result of measuring an IR spectrum of AzPhPVA obtained in Example 2.

FIG. 3 is a diagram showing the results of ESCA measurement of the surface of a polyethylene terephthalate film obtained by photochemically fixing AzPhPVA obtained in Example 3.

FIG. 4 shows an acrylamide graft-polymerized film obtained by polymerizing AzPhPVA obtained in Example 3 with photochemically immobilized polyethylene terephthalate film by adding an acrylamide monomer and varying the Ce (IV) ion addition amount. It is a figure which shows the result of having measured on the surface of this film which consists of ESCA.

5 is a diagram showing the relationship between the value of relative ratio N / C and the value of [Ce ^IV ] of the Nls spectrum of FIG. 4 with respect to the Cls spectrum.

Claims (4)

[Claims] 1. A method of binding a precursor polymer having a photoreactive group and having a hydroxyl group to at least a part of the surface of an organic material, and further reacting the polymer with an oxidizing agent to generate a radical at around room temperature. A surface graft polymerization method characterized by: 2. The photoreactive group is chemically fixed on the surface of an organic material by utilizing the property of forming a covalent bond with a nearby atom via a highly reactive nitrene as an intermediate. The surface graft polymerization method described in 1. 3. The polymer oxidant having a hydroxyl group,
The surface graft polymerization method according to claim 1, which is Ce (IV) ion. 4. The photoreactive group is chemically fixed on the surface of an organic material by utilizing the property of forming a covalent bond with a nearby atom via a highly reactive nitrene as an intermediate, and the hydroxyl group The method for surface graft polymerization according to claim 1, wherein the oxidant of the polymer having is Ce (IV) ion.