JPH04315042A - Preparation of ion responsive membrane - Google Patents

Abstract

PURPOSE:To obtain an ion responsive membrane measuring a chlorine ion with high sensitivity and excellent in org. contamination resistance and membrane strength by combining a specific unit with a unit constituting a straight chain polymer into which a specific hydrophobic group is introduced and adding specific polyether to crosslink both units. CONSTITUTION:An non responsive membrane is prepared by molding a membrane from a composition prepared by adding a polyether compound represented by general formula IV to a straight chain polymer consisting of 10-90mol.% of a unit represented by general formula I or II and 90-10mol.% of a unit represented by general formula III in an amount of 3-30% by wt. of the straight chain polymer and subsequently crosslinking the straight chain polymer. The straight chain polymer to be used contains a unit having a specific quaternary ammonium group represented by the general formula I or II in its molecule. The quaternary ammonium group enhances the selectivity to a chlorine ion of the ion responsive membrane. This ion responsive membrane can measure the chlorine ion in body fluids with high sensitivity and imparts an ion selective electrode excellent in org. contamination resistance and membrane strength.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a novel ion-sensitive membrane for use in an ion-selective electrode for measuring the activity of ions in a solution. Specifically, the present invention is a method for producing an ion-sensitive membrane that has sufficient membrane strength and excellent sensitivity to chloride ions when used as a boundary membrane of an ion-selective electrode.

[Prior Art] In recent years, there have been many attempts to apply ion-selective electrodes for medical purposes to quantify ions dissolved in biological fluids such as blood and urine, such as sodium ions, potassium ions, and chloride ions. is being carried out. This is based on the fact that the concentration of specific ions in biological fluids is closely related to the metabolic reactions of the body, and by measuring the concentration of these ions, various symptoms such as hypertension, heart disease, kidney disease, neurological disorders, etc. can be detected. It is used for diagnosis. Generally, as shown in FIG. 1, an ion-selective electrode is constructed by placing an internal electrolyte 13 in a cylindrical container 11, which has an ion-sensitive membrane 12 as a boundary membrane in the part (generally the bottom) that is immersed in the sample solution. and an internal reference electrode 14. FIG. 2 shows a typical structure of an ion measuring device for measuring the activity of ions in a solution using such an ion-selective electrode. That is, the ion-selective electrode 21 and the salt bridge 22 are immersed in the sample solution 23, and the other end of the salt bridge is immersed together with the reference electrode 24 in the saturated potassium chloride solution 26. The potential difference between both electrodes is read by an electrometer 25, and the ionic activity of a specific ion species in the sample solution can be determined from the potential difference. The performance of the ion-selective electrode used in such an ion measuring device is determined by the performance of the ion-sensitive membrane used therein. Conventionally, various membranes have been proposed as ion-sensitive membranes for selectively detecting anions, particularly chloride ions. For example, (a) a solid formed film mainly composed of silver chloride, (b) a film formed by mixing a polymer such as polyvinyl chloride, an ion-sensitive substance such as a quaternary ammonium salt, and a plasticizer, and (c) a film made of trimethylammonium. Membranes such as anion exchange membranes made of polymers having ion exchange groups such as pyridinium groups and pyridinium groups are known. However, in an ion-selective electrode using an ion-sensitive membrane of type (a), if bromide ions, cyanide ions, thiocyanate ions, etc. are present in the solution, the membrane surface will undergo chemical changes due to the influence of these ions. Therefore, it is difficult to stabilize the potential, and in extreme cases, potential measurement may become impossible. Furthermore, in measurements of various biological fluids, etc., they are easily affected by proteins, etc., and also have the drawback that the potential is not stable. An ion-selective electrode using an ion-sensitive membrane of the type (b) has the drawback of slow response and short electrode life because the ion-sensitive substance in the membrane gradually dissolves into the solution. (c)
The ion-selective electrode using the type of ion-sensitive membrane is
Because ionic groups are covalently introduced into the polymer that makes up the membrane, it has the advantage of long life. When used as an ion-sensitive membrane, it has the disadvantage that it is greatly affected by interfering ions other than chlorine ions, such as phosphate ions and hydrogen carbonate ions, and the potential obtained is unstable. . The present inventor proposed an ion-sensitive membrane made of a linear polymer into which a specific hydrophobic group such as a long-chain alkyl group is introduced in order to improve the selectivity of the ion-sensitive membrane to chloride ions. (Unexamined Japanese Patent Publication No. 01-232250). However, although this ion-sensitive membrane shows good ion selectivity, it has the problem of being easily contaminated by organic matter in the sample solution, so we made further improvements and proposed a cross-linkable ion-sensitive membrane, but the membrane strength was insufficient. It turned out there was a problem.

[Problems to be Solved by the Invention] Therefore, the present invention seeks to develop an ion-sensitive membrane that can measure chloride ions in biological fluids with high sensitivity and provides an ion-selective electrode with excellent resistance to organic contamination and membrane strength. This is the purpose.

[Means for Solving the Problems] The present inventors have conducted intensive research in order to develop an ion-sensitive membrane that can solve the above problems. As a result, by combining a specific unit with the unit constituting the linear polymer into which a specific hydrophobic group is introduced, which makes up the ion-sensitive membrane, and by crosslinking it with a specific polyether, it is possible to The present inventors have discovered that it is possible to obtain an ion-sensitive membrane having excellent ion sensitivity, good resistance to organic contamination, and excellent membrane strength, and have completed the present invention. That is, the present invention relates to the following general formula [I] or [II] [However, Y is a group selected from hydrogen, an alkyl group, and a cyano group, X- is a halogen ion or an atomic group forming an anion, and Z teeth

[Chemical 3] -COOR3-, -OCOR3, -CONHR3-, and -NHCOR3- {However, R3 is -(CH2)m-, -CH2(CH2O
CH2)m-CH2-, or -CH2-(CH(CH3
)OCH2)m-CH(CH3)-, (where m is 1 to
(an integer of 10), n is an integer of 1 to 10. }, R1 and R2 are the same or different groups selected from alkyl groups having 5 or less carbon atoms, halogenated alkyl groups, hydroxyalkyl groups, and benzyl groups, and A is a group with two or three long atoms. It is a nonionic monovalent group having either a chain hydrophobic group or a straight chain hydrophobic group containing a rigid part in the chain, and B1 and B2 are the same or different nonionic monovalent groups. indicates a long chain hydrophobic group. ), and the following general formula [III] (wherein, Y is a group selected from hydrogen, an alkyl group, and a cyano group, and R4 is hydrogen or an alkyl group having 5 or less carbon atoms). A linear polymer containing 90 to 10 mol% of a unit represented by the following general formula [IV] (in which,
β represents an alkyl group having 12 or more carbon atoms, α represents hydrogen or a methyl group, x represents an integer of 10 or more, and y represents 0 or 1. )
After forming a composition containing a polyether compound represented by 3 to 30% by weight based on the linear polymer into a film shape,
This is a method for producing an ion-sensitive membrane characterized by crosslinking the linear polymer. The linear polymer used in the method of the present invention has the general formula [I] or [I] in its molecule.
Contains a unit having a specific quaternary ammonium group shown in [I]. The quaternary ammonium group is necessary to dramatically improve the selectivity of the ion-sensitive membrane to chlorine ions. In the present invention, the general formula [I]
In and [II], the alkyl group represented by Y is not limited in terms of the number of carbon atoms, but those having 1 to 4 carbon atoms are preferably used from the viewpoint of easy availability of raw materials. As the halogen ion represented by X-, fluorine, chlorine, bromine, and iodine ions are used, and as the atomic group forming the stable anion represented by X-, known atomic groups can be used without particular restriction. However, generally NO3-, ClO4-, OH-, SCN
-, CH3COO-, etc. are preferably used. Furthermore, in the general formulas [I] and [II], an alkyl group having 5 or less carbon atoms represented by R1 and R2, or a halogen-substituted product thereof,
Alternatively, as the hydroxyl group substituted product, generally known ones can be used without particular restriction, but examples of those preferably used include methyl group, ethyl group, propyl group, butyl group,
Pentyl group, chloromethyl group, 2,2-dichloroethyl group, 2-chloroethyl group, 3-chloropropyl group, 2-
These include bromoethyl group, hydroxymethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, and the like. When the number of carbon atoms in the alkyl group is 6 or more, the selectivity of the resulting ion-sensitive membrane may decrease. The general formula [I]
and [II], Z is selected from the following groups, obtaining raw materials,
From the viewpoint of ease of polymer production, m is preferably 1 to 4, and n is preferably 1 to 4.

[Chemical 4] -COOR3-, -OCOR3, -CONHR3-, and -NHCOR3- {However, R3 is -(CH2)m-, -CH2(CH2O
CH2)m-CH2-, or -CH2-(CH(CH3
)OCH2)m-CH(CH3)-, (where m is 1 to
(an integer of 10), n is an integer of 1 to 10. } In the present invention, in the general formula [I], A is a nonionic group having either two or three long-chain hydrophobic groups, or one straight-chain hydrophobic group containing a rigid part in the chain. It is a monovalent group (hereinafter abbreviated as a hydrophobic group). The presence of the hydrophobic group in the polymer constituting the ion-sensitive membrane of the present invention improves the selective sensitivity of the resulting ion-sensitive membrane and increases its stability when used in water. Can be done. In the present invention, the long-chain hydrophobic group among the hydrophobic groups is a straight-chain alkyl group having 10 to 30 carbon atoms or a halogen-substituted product thereof, in view of the ion selectivity of the resulting ion-sensitive membrane and the ease of obtaining raw materials. It is preferable. In addition, the long-chain hydrophobic group as used in the present invention includes not only completely linear groups but also branched groups having up to 2 carbon atoms. One embodiment of the hydrophobic group of the present invention has two or three long-chain hydrophobic groups. If there is only one long-chain hydrophobic group, the resulting ion-sensitive membrane will not have sufficient water resistance, and if there are four or more long-chain hydrophobic groups, it will be difficult to obtain raw materials for polymer production. In addition, in another embodiment of the hydrophobic group, which is a nonionic monovalent group having one linear hydrophobic group containing a rigid part in the chain, the rigid part is one of the following (1) and (2). and the groups shown in (1). ■ A divalent group consisting of at least two aromatic rings connected directly or via a carbon-carbon multiple bond, a carbon-nitrogen multiple bond, an ester bond, an amide bond, etc. For example, if you show

Examples include divalent groups such as [Image Omitted]. ■ A divalent group in which the bonds between the aromatic rings are multiple or a single bond with or without an atomic group, and the rotation of which is energetically constrained. For example,

[Chemical 6] ■ A divalent group in which aromatic rings form a condensation, and when this condensed ring is stacked between multiple molecules, the rotation of the condensed rings is sterically constrained to each other. To give a concrete example,

Examples include divalent groups such as [Image Omitted]. The carbon number of the straight chain hydrophobic group of the hydrophobic group having one straight chain hydrophobic group containing a rigid part in the chain is 4 to 30 in view of the water resistance of the resulting ion-sensitive membrane and the ease of obtaining raw materials. It is preferable. The number of carbon atoms referred to herein means the number of carbon atoms in the portion excluding the rigid portion and the bonding portion between the rigid portion and the linear hydrophobic group. The bond between the rigid portion and the linear hydrophobic group is generally preferably a carbon-carbon bond, an ester bond, or an ether bond. It is necessary that the number of linear hydrophobic groups containing a rigid portion in the chain is one. That is, if the number of linear hydrophobic groups is two or more, it will be extremely difficult to mix with the polymer and the subsequent molding process, and the stability of the ion-sensitive membrane will often be compromised, which is undesirable. In the present invention, the hydrophobic group is not particularly limited as long as it satisfies the above conditions, and known hydrophobic groups can be used. Representative ones that are generally suitably used are specifically shown below. ■

embedded image ■ However, R5, R6, D, and j are the same as above, and l is 1 or 2. ■ However, R5 and R6 are the same as above,
k is a positive integer. ■R7-V-G- [D]
However, R7 is an alkyl group, alkyloxy group, or alkyloxycarbonyl group having 4 to 22 carbon atoms, or a halogen-substituted product thereof, and V is

[Chemical Formula 9] In the above general formulas [A], [B], [C], [D], k, p
may be any positive integer, but is generally preferably from 1 to 16 from the viewpoint of easy availability of raw materials. Furthermore, in the above general formula [A], h and i can be positive integers without any restriction, but are generally preferably 1 to 4 from the viewpoint of easy availability of raw materials. Furthermore, the above general formula [A], [B]
, [C] and [D], examples of the halogen atom of the halogen-substituted alkyl group represented by R5 and R6 include fluorine, chlorine, bromine, and iodine atoms. The general formula [
II], B1 and B2 are the same or different nonionic monovalent long-chain hydrophobic groups. The presence of the long-chain hydrophobic group in the polymer used in the present invention improves the selectivity of the resulting ion-sensitive membrane and increases its stability when used in water. The long-chain hydrophobic group is selected from a straight-chain alkyl group having 12 to 30 carbon atoms, a halogen-substituted product thereof, a straight-chain alkylcarboxyalkyl group, or a straight-chain alkyloxycarbonylalkyl group in view of easy availability of raw materials. It is preferable that it is a group. Further, specific examples of more suitable groups are as follows. R8-(T-U)j- [E] However, R8 is a linear alkyl group having 12 to 30 carbon atoms or a halogen-substituted product thereof, and T is -COO- or -O
CO-, U is -(CH2)q-, and j is as defined above. In the above general formula [E], q can be used without any restriction as long as it is a positive integer, but it is preferably 1 to 5 from the viewpoint of easy availability of raw materials. Further, the halogen atom of the halogen-substituted alkyl group represented by R8 includes fluorine, chlorine, bromine, and iodine atoms. The linear polymer used in the method of the present invention contains a unit having a specific methylol group in its molecule represented by the above general formula [III], which dramatically improves the organic contamination resistance of the ion-sensitive membrane. It is necessary to improve. In the polymer constituting the ion-sensitive membrane of the present invention, the alkyl group represented by Y in the general formula [III] is not limited in terms of the number of carbon atoms, but it has 1 to 4 carbon atoms due to easy availability of raw materials. is preferably used. The group represented by R4 is not particularly limited as long as it is hydrogen or an alkyl group having 5 or less carbon atoms, but hydrogen is particularly preferably used because it facilitates the crosslinking reaction described below. In the present invention, the molar fraction of units represented by general formula [I] or [II] constituting the linear polymer based on the total polymer is 10 mol% or more, preferably 30 mol% or more. preferable. If the fraction of the above unit is less than 10 mol %, the chloride ion selectivity of the resulting ion-sensitive membrane may become insufficient, and the stability when used in water may deteriorate. Furthermore, in the polymer constituting the ion-sensitive membrane of the present invention, the molar fraction of the unit represented by the general formula [III] based on the total polymer is 10 mol% or more, preferably 30 mol% or more.
It is preferable that it is mol% or more. If the fraction of the above unit is less than 10 mol %, the crosslinking of the resulting ion-sensitive membrane may be insufficient and the organic stain resistance may not be improved. The linear polymer used in the present invention has the general formula [
It is sufficient that the unit basically consists of at least one type of unit represented by [I] or [II] and at least one type of unit represented by [III]. May be included. As such a unit, a unit represented by the following formula [V] is preferably used. However, P is hydrogen, a halogen atom, a cyano group, an alkyl group, or a carboxyl group, and Q is an alkyl group,
These include carboxyl group, phenyl group, naphthyl group, alkylcarboxyl group, alkyloxycarbonyl group, aminocarbonyl group, alkyloxy group, amino group, alkylamino group, trimethylammonioalkyl group, and halogen-substituted or hydroxyl-substituted products thereof. The above general formula [V]
The number of carbon atoms in the unit represented by is preferably 10 or less, taking into consideration the ease of obtaining raw materials and the film formability of the resulting polymer. Also, the mole fraction for the polymer is 4
It is preferably 0 mol% or less. The molecular weight of the linear polymer used in the present invention is not particularly limited, but preferably has a number average molecular weight of 5,000 or more, more preferably 10,000 or more. When the number average molecular weight is 5000 or less, the resulting ion-sensitive membrane becomes fragile. Moreover, when the number average molecular weight is 10,000 or less, the resulting ion-sensitive membrane may have insufficient stability in water. The linear polymer used in the present invention has the general formula [
A polymer having a specific amount or more of units represented by [I] or [II] and [III] (hereinafter abbreviated as an ion-exchangeable polymer) is a constituent component. The method for producing the ion-exchangeable polymer is not particularly limited and any known method may be employed, but generally preferred methods include the following methods. (2) A method of copolymerizing a monomer having a structure represented by the following general formula [VI] or [VII] with a monomer having a structure represented by the following general formula [VIII]. (However, Y, Z, X-, R1, R2, R4, A, B1,
The definition and preferred examples of B2 are as described above. ) An ion-exchangeable polymer containing a third component can also be obtained by adding a vinyl monomer copolymerizable with these monomers during the above polymerization. As the vinyl monomer copolymerizable with the monomer represented by general formula [VI] or [VII] and [VIII],
Known monomers can be used without particular limitation. Typical examples that are generally preferably used include, for example, olefin compounds such as ethylene, propylene, and butene; halogen derivatives of olefin compounds such as vinyl chloride and hexafluoropropylene; and aromatic compounds such as styrene and vinylnaphthalene. Group vinyl compounds; vinyl ester compounds such as vinyl acetate; methyl acrylate, methyl methacrylate,
Acrylic acid derivatives and methacrylic acid derivatives without methylol groups such as 2-hydroxyethyl methacrylate, acrylamide, and methacrylamide; Unsaturated nitrile compounds such as acrylonitrile; Vinyl ether compounds such as methyl vinyl ether; Methyl vinyl pyridinium iodide, trimethyl chloride Examples include quaternary ammonium compounds such as ammonioethyl methacrylate. In addition to the above, vinyl carboxylic acid compounds such as acrylic acid and methacrylic acid; sulfonic acid compounds such as styrene sulfonic acid and vinyl sulfonic acid can also be suitably used; however, when using the anionic monomer, Since this may result in an ion-sensitive membrane that does not respond to anions, the ratio of anionic groups to cationic groups (equivalence ratio) in the polymer needs to be less than 1. The polymerization method used to produce the ion-exchangeable polymer is not limited to ionic polymerization, radical polymerization, etc., but it is preferable to carry out the polymerization in the presence of a radical initiator. As for the polymerization operation, generally known operations can be used without particular restriction, but solution polymerization is preferably used from the viewpoints of uniformity of the obtained polymer and ease of adjusting the composition ratio of the copolymer. The solvent for solution polymerization is not particularly limited as long as it dissolves the monomers used. Water, methanol,
Examples include ethanol, acetone, benzene, dimethylformamide, dichloromethane, tetrachloromethane, chloroform, tetrahydrofuran, dichloroethane, and chlorobenzene. Two or more of the above solvents may be used in combination. The polymerization temperature is preferably 0°C to 150°C, more preferably 40°C to 100°C. In addition, various methods known in the art can be used to isolate the ion exchange polymer, but in the case of solution polymerization, the reaction mixture is poured into a solvent that does not dissolve the produced polymer. A reprecipitation method is preferred. (2) A method in which a monomer having a structure represented by the following general formula [VI] or [VII] is copolymerized with a monomer having a structure represented by the following general formula [IX], and then the polymerized product is methylolized. (However, Y, Z, X-, R1, R2, R4, A, B1,
The definition and preferred examples of B2 are as described above. ) An ion-exchangeable polymer containing a third component can also be obtained by adding a vinyl monomer copolymerizable with these monomers during the above polymerization. As the vinyl monomer copolymerizable with the monomer represented by general formula [VI] or [VII] and [IX], known monomers can be used without particular limitation. Typical examples that are generally preferably used include, for example, olefin compounds such as ethylene, propylene, and butene; halogen derivatives of olefin compounds such as vinyl chloride and hexafluoropropylene; and aromatic compounds such as styrene and vinylnaphthalene. Group vinyl compounds; vinyl ester compounds such as vinyl acetate; methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, acrylic ester derivatives and methacrylic ester derivatives; unsaturated nitrile compounds such as acrylonitrile; vinyl ethers such as methyl vinyl ether Compounds include quaternary ammonium compounds such as methylvinylpyridinium iodide and trimethylammonioethyl chloride. In addition to the above, vinyl carboxylic acid compounds such as acrylic acid and methacrylic acid; sulfonic acid compounds such as styrene sulfonic acid and vinyl sulfonic acid may also be suitably used;
When such anionic monomers are used, the resulting ion-sensitive membrane may not respond to anions, so the ratio of anionic groups to cationic groups (equivalence ratio) in the polymer is
Must be less than The polymerization method for producing the above polymer is not particularly limited, such as ionic polymerization or radical polymerization, but it is desirable to carry out the polymerization in the presence of a radical initiator. As for the polymerization operation, generally known operations can be used without particular restriction, but solution polymerization is preferably used from the viewpoints of uniformity of the obtained polymer and ease of adjusting the composition ratio of the copolymer. The solvent for solution polymerization is not particularly limited as long as it dissolves the monomers used. Those generally preferably used include water, methanol, ethanol, acetone, benzene, dimethylformamide, dichloromethane, tetrachloromethane, chloroform, tetrahydrofuran, dichloroethane, and chlorobenzene. Two or more of the above solvents may be used in combination. The polymerization temperature is preferably 0°C to 150°C, more preferably 40°C to 100°C. In addition, various methods known in the art can be used to isolate the ion exchange polymer, but in the case of solution polymerization, the reaction mixture is poured into a solvent that does not dissolve the produced polymer. A reprecipitation method is preferred. As a method for methylolizing the above-mentioned polymer, generally known methods can be used without particular restriction. Examples of generally preferred methods are as follows. That is, a polymer is placed in an aqueous formaldehyde solution and heated at a temperature of 5°C or higher.
How to react for more than 0 minutes. At this time, a water-miscible solvent may be present in the formaldehyde aqueous solution. If the reaction temperature is 0° C. or less or the reaction time is 30 minutes or less, the methylolization of the resulting ion-exchangeable polymer may be insufficient and the organic contamination resistance of the ion-sensitive membrane may be poor. The ion exchange polymer produced as described above is generally a colorless, white or pale yellow solid. Further, although it is sparingly soluble in water, it dissolves in organic solvents such as dimethylformamide, chloroform, tetrachloromethane, dichloromethane, tetrachloroethane, and tetrahydrofuran at room temperature to 100°C. Generally, the general formulas [I] or [II] and [
III] is determined by elemental analysis. The polyether compound used in the present invention is represented by general formula [IV]. The presence of the polyether compound in the membrane material significantly improves the strength of the membrane material after the crosslinking reaction. In the general formula [IV], x represents an integer of 10 or more. When x is 10 or less, the strength of the film-like material may not be improved. Furthermore, from the viewpoint of easy availability of raw materials, x is preferably 10,000 or less. General formula [I
The necessity for α in V] to be hydrogen or a methyl group is due to the ease of obtaining raw materials. The long-chain alkyl group represented by β in the general formula [IV] is necessary to improve the compatibility with the linear polymer when formed into a film-like product. General formula [
If the number of carbon atoms in β in [IV] is less than 12, the compatibility and water resistance of the film may deteriorate when formed into a film. Examples of long-chain alkyl groups that are generally suitably used include n-decyl group, n-undecyl group, n-
dodecyl group, n-tridecyl group, n-tetradecyl group,
n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n
-eicosyl group, etc. In the present invention, the polyether compound is contained in a proportion of 3% by weight or more based on the amount of the ion-exchangeable polymer. If the content of the polyether compound is less than 3% by weight, the resulting ion-sensitive membrane may have insufficient strength. Moreover, if it exceeds 30% by weight, the water resistance and uniformity of the resulting ion-sensitive membrane may become insufficient. The method for synthesizing the polyether compound represented by the general formula [IV] is not particularly limited, and any known method may be employed. When y is 0, it can be obtained by mixing and heating a raw material polyether compound having a hydroxyl group at the terminal and an alkyl halide in a suitable solvent in the presence of an alkali. Potassium hydroxide, sodium hydroxide, etc. are preferably used as the alkali. Moreover, toluene, benzene, etc. are preferably used as the solvent. The temperature during mixing is suitably 50°C to 100°C. When y is 1, it can be obtained by mixing a raw material polyether having a hydroxyl group at the terminal and a long-chain carboxylic acid chloride in a suitable solvent in the presence of a suitable base. As the solvent, chloroform, benzene, tetrahydrofuran, etc. are preferably used. In addition, the base is pyridine,
Triethylamine and the like are preferably used. Generally, a column purification method is preferably used for isolation and purification of polyether compounds. The polyether compounds produced in this way are generally colorless viscous liquids or colorless waxy solids, and can be prepared using methanol, ethanol, acetone, benzene,
Soluble in toluene, dimethylformamide, dichloromethane, tetrachloromethane, chloroform, tetrahydrofuran, dichloroethane, chlorobenzene, etc. In the present invention, the ion-sensitive membrane is obtained by forming an ion-exchangeable polymer and a polyether compound into a membrane, and then subjecting the membrane to a crosslinking reaction. The method for forming the ion exchange polymer obtained by the above production method and the polyether compound obtained by the above production method into a film-like material is not particularly limited, and any method may be used. Examples of generally preferred methods are as follows. A method of obtaining a film-like material by dissolving an ion exchange polymer and a polyether compound in a soluble solvent, casting the solution onto a suitable substrate, and then removing the solvent. The solvent used here is not particularly limited as long as it dissolves the ion exchange polymer and the polyether compound, but the soluble solvents described in the above-mentioned method for producing an ion exchange polymer are preferably used. To remove the above-mentioned solvent, air drying, vacuum drying, etc. are generally used without particular limitation. The thickness of the film-like material obtained by the above molding is not particularly limited, but is generally 0.1 μm to 5 mm.
, preferably in the range of 5 to 100 μm, since this can provide the obtained ion-sensitive membrane with a film strength sufficient for practical use. In the present invention, the ion-sensitive membrane is obtained by crosslinking a membrane-like material made of the above-mentioned ion-exchangeable polymer and a polyether compound. As the crosslinking method, a generally known crosslinking method for N-methylol groups can be used as is. Examples of generally preferred methods are as follows. (2) A method of crosslinking the film-like material by heating it. It is desirable to perform heating in water for ease of temperature control. At this time, it is effective to conduct the reaction at a temperature of 30° C. or higher, more preferably 40° C. or higher, in order to cause a sufficient crosslinking reaction. (2) A method of immersing the film-like material in an acid aqueous solution and crosslinking it. Generally known acid aqueous solutions can be used as the acid aqueous solution, but examples of acid solutions that are preferably used include hydrochloric acid, hydrobromic acid, sulfuric acid, perchloric acid, para-toluenesulfonic acid, nitric acid, and acetic acid. , phosphoric acid, etc. A water-miscible organic solvent may be present in the acid aqueous solution used. The immersion is generally carried out at 5° C. or higher for 5 minutes or more, which is necessary to improve the organic contamination resistance of the resulting ion-sensitive membrane. More preferably, immersion in an acid aqueous solution at 50° C. or higher for 10 minutes or more is effective for significantly improving the organic contamination resistance of the resulting ion-sensitive membrane. Generally, the formation of the above-mentioned crosslinking reaction can be confirmed by the fact that the obtained ion-sensitive membrane becomes insoluble in the solvent that dissolves the above-mentioned ion-exchangeable polymer. The ion-sensitive membrane obtained as described above generally often exhibits liquid crystallinity as its basic property. The temperature range exhibiting liquid crystallinity is in the range of 0 to 200°C. Liquid crystallinity is generally confirmed by measurement using a differential scanning calorimeter. In the case of a liquid crystal, the amount of heat accompanying the transition from solid to liquid crystal is observed at a certain temperature, and that temperature is called the solid-liquid crystal transition temperature. It is desirable that the ion-sensitive membrane obtained by the method of the present invention be used at a temperature below the above-mentioned solid-liquid crystal transition temperature, more preferably at least 10° C. lower than the solid-liquid crystal transition temperature. When used at temperatures above the solid-liquid crystal transition temperature, the selectivity for various anions, particularly divalent anions, may be reduced. In order to improve the selectivity of the ion-sensitive membrane of the present invention to chlorine ions, it is preferable to immerse the membrane-like material used in water at a temperature equal to or higher than its solid-liquid crystal transition temperature for 1 minute or more before crosslinking. This operation improves the selectivity and sensitivity of the resulting ion-sensitive membrane to chlorine ions, and when used as a sensitive membrane for an ion-selective electrode, chloride ions can be measured with high sensitivity. The applied potential is also often stable. In the method of the present invention, by including a linear alcohol having 10 or more carbon atoms in the ion exchange polymer, the selective sensitivity of the resulting ion-sensitive membrane to chlorine ions can be further improved. That is,
The ion-sensitive membrane of the present invention has good selective sensitivity of chloride ions to divalent anions and is suitable for measuring chloride ions in biological fluids. By the presence of tens or more linear alcohols, the selective sensitivity to divalent anions is not reduced, and the sensitivity to fat-soluble monovalent anions such as thiocyanate ion, perchlorate ion, and nitrate ion is improved. We found that selection sensitivity could be further improved. If the number of carbon atoms in the linear alcohol is less than 10, the resulting ion-sensitive membrane will have insufficient water resistance. Further, the need for the alcohol to be linear is to improve compatibility with other constituent components. The linear alcohol used in the present invention is not particularly limited as long as it satisfies the above conditions, and any known one can be used. In general, considering the water resistance of the resulting ion-sensitive membrane and the ease of obtaining raw materials, the number of carbon atoms is 16 to
18 linear alcohols are preferably employed. In the present invention, the linear alcohol is contained in a proportion of 10 to 200% by weight based on the amount of the ion-exchangeable polymer. If the linear alcohol content is less than 10% by weight, the ion selectivity of the resulting ion-sensitive membrane may not be sufficiently improved. Moreover, if it exceeds 200% by weight, the water resistance and strength of the resulting ion-sensitive membrane may become insufficient. Also, considering the operability when handling film-like materials,
The linear alcohol is preferably contained in a proportion of 30 to 120% by weight. The method of adding and mixing a linear alcohol together with a polyether compound to the ion-exchangeable polymer and forming it into a film-like material is not particularly limited, and any method may be used. Examples of methods that are generally used publicly and privately are as follows. A method of obtaining a film-like material by dissolving an ion exchange polymer, a polyether compound, and a linear alcohol in a soluble solvent, casting the solution onto a suitable substrate, and then removing the solvent. The solvent used here is not particularly limited as long as it dissolves the ion exchange polymer, polyether, and linear alcohol, but the soluble solvents described in the above-mentioned method for producing an ion exchange polymer are preferably used. It will be done. To remove the above-mentioned solvent, air drying, heat drying, reduced pressure drying, etc. are generally used without particular limitation.

Effects of the Invention The ion-sensitive membrane obtained by the present invention has a quaternary ammonium group having a specific structure, which is an ion-sensitive moiety, fixed in a polymer by covalent bonds. Therefore, there is almost no elution of the constituent components and the product has a long life. In addition, the ion-sensitive membrane of the present invention has extremely high responsiveness of chloride ions to interfering ions such as bicarbonate ions and phosphate ions that exist in biological fluids such as blood and urine, and therefore has a high ion-selectivity. By using it as an ion-sensitive membrane of an electrode, it is possible to quantify chloride ions in biological fluids such as blood and urine with extremely high accuracy. Furthermore, because the ion-sensitive membrane has a crosslinked structure, it has excellent resistance to organic contamination.
It is possible to stably measure the quantitative determination of chloride ions in biological fluids over a long period of time. Furthermore, since it contains a polyether compound, it has a practically sufficient film strength despite its crosslinked structure, and will not break due to impact or the like. Generally, the organic contamination resistance of an ion-sensitive membrane can be confirmed by the stability of the potential of an aqueous solution containing a specific concentration of chloride ions after immersion in an aqueous solution containing an anionic surfactant. In addition, the selectivity of chlorine ions to fat-soluble anions such as nitrate ions, perchlorate ions, and thiocyanate ions can be improved by allowing a linear alcohol having a carbon number of 10 or more to exist in the ion-sensitive membrane. This makes it possible to more accurately quantify chloride ions in biological fluids. From the above points, the industrial value of the ion-sensitive membrane of the present invention is extremely large. The ion-selective electrode to which the ion-sensitive membrane obtained by the method of the present invention can be applied may have any known structure without particular limitation. Generally, it is preferable to have a structure in which an internal standard electrode and an internal electrolyte are housed in a container in which at least a portion of the part to be immersed in the sample solution is constituted by the ion-sensitive membrane. For example, a typical example is the structure shown in FIG. 1 above. That is, the ion-selective electrode shown in FIG.
An internal electrolytic solution 13 is filled in a container configured by attaching an internal reference electrode 14. Note that 15 is an O-ring for liquid sealing. In the electrode, the material other than the ion-sensitive membrane is not particularly limited, and
Conventional methods can be adopted without restriction. For example, the electrode cylinder material may be polyvinyl chloride, polymethyl methacrylate, etc., the internal electrolyte may be a sodium chloride aqueous solution, potassium chloride aqueous solution, etc., and the internal reference electrode may be a conductive material such as platinum, gold, carbon graphite, etc. Slightly soluble metal chlorides such as silver-silver chloride and mercury-mercury chloride are used. The ion-selective electrode to which the ion-sensitive membrane obtained by the method of the present invention can be applied is not limited to the structure shown in FIG. 1, but may have any structure as long as it has the ion-sensitive membrane. Examples of other suitable ion-selective electrodes include ion-selective electrodes formed by pasting the ion-sensitive membrane on a conductor such as gold, platinum, or graphite, or an ion conductor such as silver chloride or mercury chloride. sexual electrodes, etc. Further, an ion-selective electrode using such an ion-sensitive membrane can be used in a known manner. For example, the basic usage mode is as shown in FIG. 2 described above. That is,
The ion selective electrode 21 is connected to the sample solution 23 along with the salt bridge 22.
The other end of the salt bridge, together with the reference electrode 24, is immersed in a saturated potassium chloride solution 26. Generally known reference electrodes are employed as the reference electrode, examples of which are publicly used include a calomel electrode, a silver-silver chloride electrode, a platinum plate, and carbon graphite.

[Examples] Examples are given below to explain the present invention more specifically, but the present invention is not limited to these Examples. In the examples of the present invention, the mole fraction of the unit represented by the general formula [I] or [II] in the ion exchange polymer is the hydrophobic unit fraction, and the mole fraction of the unit represented by [III] The ratio is abbreviated as methylol unit fraction. Production Example 1 5 mmol of the monomer shown in Table 1, 7.5 mmol of N-methylolacrylamide, and 5 mg of azobisisobutyronitrile were placed in a test tube together with 10 ml of benzene and 10 ml of ethanol. After placing the inside of the test tube under a nitrogen atmosphere,
The container was sealed and polymerized at 50° C. for 48 hours. The contents were poured into 500 ml of methanol and the resulting precipitate was collected by filtration. By drying under reduced pressure, a solid substance as an ion exchange polymer was obtained in the amount shown in Table 1. The unit fraction of each unit in the ion exchange polymer was determined by elemental analysis. The results are summarized in Table 1.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5] Production Example 2 Monomers shown in Table 2 in amounts shown in Table 2, N-methylolacrylamide 10 mmol, benzoyl peroxide 7 mg
was placed in a test tube along with 30 ml of chloroform and 5 ml of methanol. After placing the inside of the test tube under a nitrogen atmosphere, the test tube was sealed tightly and polymerized at 60° C. for 30 hours. Dilute the contents with methanol 5
The precipitate formed was collected by filtration. By drying under reduced pressure, a solid substance as an ion exchange polymer was obtained in the amount shown in Table 2. The unit fraction of each unit in the ion exchange polymer was determined by elemental analysis. The results are summarized in Table 2.

[Table 6]

[Table 7] Manufacturing example 3 10 mmol of the monomer shown below,

embedded image (Mixture of meta-isomer and para-isomer; m:p=2.1:1) 10 mmol of N-methylolacrylamide, 10 mmol of the monomer shown in Table 3, and azobisisobutyronitrile 2
mg was placed in a test tube with 30 ml of a benzene-ethanol mixed solvent (1:1, weight ratio). After placing the inside of the test tube under a nitrogen atmosphere, the test tube was sealed tightly and polymerized at 65° C. for 30 hours. The contents were poured into 800 ml of methanol and the resulting precipitate was collected by filtration. By drying under reduced pressure, a solid substance as an ion exchange polymer was obtained in the amount shown in Table 3. The unit fraction of each unit in the ion exchange polymer was determined by elemental analysis. The results are summarized in Table 3.

[Table 8] Production Example 4 10 mmol of monomer shown in Table 4 and 10 acrylamide
mmol and 2 mg of azobisisobutyronitrile in 40 ml of benzene-ethanol mixed solvent (1:1, weight ratio)
I put it in a test tube with l. After placing the inside of the test tube under a nitrogen atmosphere, the test tube was sealed tightly and polymerized at 45° C. for 60 hours. The contents were poured into 1000 ml of acetonitrile and the resulting precipitate was collected by filtration. By drying under reduced pressure, solid matter as a polymer was obtained in the amount shown in Table 4. The unit fraction of each unit in the polymer was determined by elemental analysis. The results are summarized in Table 4.

[Table 9]

[Table 10]

[Table 11]

[Table 12]

[Table 13] Production Example 5 10 g of the raw material polyether compound shown in Table 5 and 10 g of the carboxylic acid chloride shown in Table 5 were mixed under ice cooling using 500 ml of chloroform as a solvent. After reacting at room temperature for 12 hours, the reaction solution was washed with water and the solvent was distilled off under reduced pressure. The residue was isolated and purified using a silica gel column (developing solvent: chloroform/methanol (98/2)). Table 5 summarizes the results.
Shown below.

[Table 14] Film Formation Example 1 Production No. 1 produced in Production Examples 1 to 3. 500 mg of the ion exchange polymers Nos. 1 to 41 and the polyether compound produced in Production Example 5 were dissolved in 10 ml of chloroform in the amount shown in Table 6, and cast into a petri dish made of polytetrafluoroethylene (hereinafter abbreviated as PTFE). . Chloroform at 60℃
Evaporation under atmospheric pressure conditions yielded a uniform, transparent film. Each of the obtained film-like materials was attached to an electrode as shown in FIG. 1, and then heat-treated under the conditions shown in Table 6. After cooling, Table 6
The crosslinking reaction was carried out under the conditions shown below. Table 6 summarizes the numbers of the obtained membranes and their solubility in chloroform.

[Table 15]

[Table 16] As can be seen from Table 6, the obtained ion-sensitive membrane was insoluble in chloroform, indicating that a crosslinking reaction had occurred. Film Formation Example 2 Production No. 2 produced in Production Example 4. 42-63 polymer 50
0mg and manufacturing no. P14 polyether compound 50m
g and were dissolved in 10 ml of chloroform and cast in a PTFE petri dish. Chloroform was evaporated at 60° C. and atmospheric pressure to obtain a uniform and transparent film. After each of the obtained membranes was attached to the electrode shown in Figure 1, 1M-Na
Heat treatment was performed in a Cl solution at 90°C for 5 minutes. After cooling,
Methylolation was performed under the conditions shown in Table 7. Table 7 shows the methylol unit fraction obtained by elemental analysis. Subsequently, a crosslinking reaction was carried out under the conditions shown in Table 7. Table 7 summarizes the obtained membrane numbers and solubility in chloroform.
It was shown to.

[Table 17] As can be seen from Table 7, methylol groups were introduced into the obtained ion-sensitive membrane by formaldehyde treatment, and a crosslinking reaction occurred. Example 1 Film No. 1 obtained in Film Formation Examples 1 and 2 The relationship between the concentration and potential difference at room temperature was measured for various anions using the apparatus shown in FIG. 2 using ion-sensitive membranes Nos. 1 to 64. From the obtained results, a known method [G. J. Moody, J. D
．． The chloride ion selectivity coefficient for each anion was determined by the method described in "Ion Selective Electrode" by John Thomas, translated by Makoto Munemori and Kazuo Nikishiro, Kyoritsu Shuppan, p. 18 (1977). The results are summarized in Table 8. In addition, as comparative membrane 1, an ion-sensitive membrane containing polyvinyl chloride, methyltridodecylammonium chloride, and dibutyl phthalate [
Analytical Chemistry,56,5
35-538 (1984)] obtained in a similar manner, and also for Comparative Membrane 2, a commercially available ion exchange membrane (trade name Neocepta A).
Table 8 also shows the chlorine ion selectivity coefficients determined in the same manner for CS (manufactured by Tokuyama Soda Co., Ltd.).

[Table 18] The ion selection coefficient in this example indicates that the smaller the value, the better the selectivity of the ion-sensitive membrane to chloride ions. As can be seen from Table 8, the ion-selective electrode using the ion-sensitive membrane of the present invention has high selectivity for chloride ions with respect to sulfate ions, phosphate ions, acetate ions, bicarbonate ions, and iodine ions present in biological fluids. It is excellent and suitable for measuring chloride ion concentration in biological fluids. Furthermore, in order to examine the organic contamination resistance of the obtained ion-sensitive membrane, a contamination test with sodium dodecyl sulfate (hereinafter abbreviated as SDS) was conducted. That is, using the apparatus shown in FIG. 2, the potential difference is measured when the following solutions are used as samples in order. 1. 100mM sodium chloride aqueous solution 2. 0.1 wt% SDS aqueous solution 3. 100mM sodium chloride aqueous solution At this time, the value of the potential difference at 3 is ±1 compared to the value of the potential difference at 1
The time required for the voltage to fall within mV was measured and used as an index of contamination resistance. Generally, when an ion-sensitive membrane adsorbs SDS, the value of the potential difference becomes smaller. Subsequently, by immersion in a sodium chloride solution, the adsorbed SDS is gradually redissolved in the solution, so that the potential difference returns to its original value. It can be said that the shorter the redissolution time, the better the organic contamination resistance of the ion-sensitive membrane. Table 9 shows the results of the SDS contamination test of the obtained ion-sensitive membrane. For comparison, a similar test was conducted on an ion-sensitive membrane of the same composition without crosslinking reaction, and the results are also shown in Table 9.

[Table 19] As can be seen from Table 9, the ion-sensitive membrane of the present invention has significantly improved resistance to organic contamination due to the crosslinking reaction. It is suitable as an ion-sensitive membrane for a polar electrode. Film Formation Example 3 Production No. 3 produced in Production Examples 1 to 3. 500 mg of ion exchange polymers No. 1 to 41, Production No. 1 produced in Production Example 5;
50 mg of the polyether compounds P1 to P15 and the linear alcohols shown in Table 10 in the amounts shown in Table 10 were dissolved in 10 ml of chloroform and cast in a PTFE Petri dish. Chloroform was evaporated at 60° C. and atmospheric pressure to obtain a uniform and transparent film. The obtained ion-sensitive membranes were each attached to an electrode as shown in FIG. 1, and then heat-treated under the conditions shown in Table 11. After cooling, a crosslinking reaction was carried out under the conditions shown in Table 11. Table 11 summarizes the numbers of the obtained membranes and their solubility in chloroform.

[Table 20]

[Table 21]

[Table 22]

[Table 23] As can be seen from Table 11, the obtained ion-sensitive membrane was insoluble in chloroform, indicating that a crosslinking reaction had occurred. Film Formation Example 4 Production No. 4 produced in Production Example 4. 42-63 polymer 50
0mg and Production No. produced in Production Example 5. 50 mg of polyether compound of PP14 and 3 stearyl alcohol
00 mg was dissolved in 10 ml of chloroform and cast into a PTFE petri dish. Chloroform was evaporated at 60° C. and atmospheric pressure to obtain a uniform and transparent film. After each of the obtained membranes was attached to an electrode as shown in Figure 1, 1M
- Heat treatment was performed at 90° C. for 5 minutes in a NaCl solution. After cooling, methylolization was performed under the conditions shown in Table 12. Table 1
2 shows the methylol unit fraction obtained by elemental analysis. Subsequently, a crosslinking reaction was carried out under the conditions shown in Table 12. Table 12 summarizes the numbers of the obtained membranes and their solubility in chloroform.

[Table 24] As can be seen from Table 12, methylol groups were introduced into the obtained ion-sensitive membrane by formaldehyde treatment, and a crosslinking reaction occurred. Example 2 Film No. 2 obtained in Film Forming Examples 3 and 4 The relationship between the concentration and potential difference at room temperature of various anions was measured using the apparatus shown in FIG. 2 using 65 to 128 ion-sensitive membranes. From the obtained results, the chloride ion selectivity coefficient for each anion was determined in the same manner as in Example 1. The results are shown in Table 13.

[Table 25]

[Table 26] As can be seen from Table 13, by incorporating a linear alcohol into the ion-sensitive membrane of the present invention, the selectivity of chloride ions to fat-soluble anions such as thiocyanate ions, perchlorate ions, and nitrate ions was improved. It is suitable for measuring chloride ion concentration in biological fluids. Table 14 shows the SD of the obtained ion-sensitive membrane obtained in the same manner as in Example 1.
The results of the S contamination test are shown. For comparison, a similar test was conducted on an ion-sensitive membrane of the same composition without crosslinking reaction, and the results are also shown in Table 14.

[Table 27] As can be seen from Table 14, the ion-sensitive membrane of the present invention has significantly improved resistance to organic contamination due to the crosslinking reaction, and is suitable for ion selection for accurately measuring samples such as biological fluids over a long period of time. It is suitable as an ion-sensitive membrane for a polar electrode. Example 3 Film No. 3 formed in Film Formation Example 1. Membranes No. 1 to 10 and Membrane No. 1 formed in Film Formation Example 2. In order to examine the breakability of the films No. 64 to 73, they were immersed in water at 60°C for 10 minutes, left in air for 30 minutes, and dried for 20 cycles.
The test was repeated several times. Table 1 shows the presence or absence of cracks after the test.
They are summarized in 5. For comparison, a similar operation was performed on a membrane not containing a polyether compound, and the results are also summarized in Table 15.

[Table 28] As can be seen from Table 15, in the membrane containing the polyether compound, almost no cracks were observed even after the test, and the operability when used as an ion-sensitive membrane was significantly improved. Example 4 Membrane No. 64 and the apparatus shown in FIG.
The potential difference between a reference electrode (calomel electrode) and an ion-selective electrode was measured at 20° C. using an aqueous sodium chloride solution in the range of 4 M to 10 −1 M as a sample solution. Table 16 and FIG. 3 show the relationship between the obtained potential difference and the chloride ion concentration of the sample solution. As can be seen from FIG. 3, the ion-selective electrode using the ion-sensitive membrane of the present invention exhibits a linear response in the range of 10-4M to 10-1M. Also, at this time, the potential gradient was 58 mV/
It was a decade. This value agrees well with the calculated value of 59 mV/decade obtained from the Nernst equation. From this result, it is clear that the ion-sensitive membrane of the present invention has sufficient sensitivity to chlorine ions.

[Table 29] Example 5 Membrane No. Table 17 shows the difference in output potential when the concentration of sodium chloride in the sample solution was rapidly changed from 1.2 mM to 3.3 mM using the apparatus shown in FIG. Further, FIG. 4 shows the relationship between the concentration of sodium chloride and the output potential difference. As can be seen from FIG. 4, the ion-selective electrode using the ion-sensitive membrane of the present invention has a 98% response within 4 seconds, allowing rapid measurement. Further, even after repeating the above measurement 500 times, almost no change in the output potential difference was observed.

[Table 30] Application example Membrane No. obtained in Example 2 described above. 64-10
The ion-sensitive membrane No. 1 was immersed in water at 90° C. for 10 minutes and then attached to an electrode as shown in FIG. Using this and the apparatus shown in FIG. 2, the output potential was measured when 1 mM and 4 mM sodium chloride aqueous solutions were used as sample solutions. A calibration curve of chloride ion concentration and output potential was created from the measured values. On the other hand, the output potential was measured using an aqueous solution containing 3mM of sodium chloride, 1mM of sodium bicarbonate, 1mM of sodium monohydrogen phosphate, 0.005mM of sodium nitrate, and 10mM of sodium sulfate as a test solution. The obtained values were substituted into the calibration curve to determine the chloride ion concentration. Table 1 shows the results.
8. The chloride ion concentration was determined for Comparative Membranes 1 and 2 in the same manner. The results are also shown in Table 18. As can be seen from Table 18, the measured values obtained using the ion-sensitive membrane of the present invention are in good agreement with the actual chloride ion concentration of 3 mM in the test solution, and the ion selection using the ion-sensitive membrane of the present invention is in good agreement with the actual chloride ion concentration of 3 mM in the test solution. It is clear that the polar electrode can accurately measure chloride ion concentration in solutions containing various anions.

[Table 31]

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of an example of an ion-selective electrode using the ion-sensitive membrane of the present invention.

FIG. 2 is an explanatory diagram of an apparatus for measuring a potential difference using the ion-selective electrode of FIG. 1.

FIG. 3 is a diagram showing the relationship between chloride ion concentration and potential difference measured in Example 1.

FIG. 4 is a diagram showing the response speed of the ion-selective electrode of the present invention measured in Example 3.

[Explanation of symbols]

11 Electrode cylinder 12 Ion-sensitive membrane 13 Internal electrolyte 14 Internal reference electrode 15 O-ring 21 Ion-selective electrode 22 Salt bridge 23 Sample solution 24 Reference electrode 25 Electrometer 26 Saturated potassium chloride aqueous solution, 27 Recorder

Claims (2)

[Claims] [1] (i) General formula [wherein Y is a group selected from hydrogen, an alkyl group, and a cyano group, X- is a halogen ion or an atomic group forming an anion, and Z is [ Chemical 1] -COOR3-, -OCOR3, -CONHR3-, and -NHCOR3- {However, R3 is -(CH2)m-, -CH2(CH2O
CH2)m-CH2-, or -CH2-(CH(CH3
)OCH2)m-CH(CH3)-, (where m is 1 to
(an integer of 10), n is an integer of 1 to 10. }, R1 and R2 are the same or different groups selected from alkyl groups having 5 or less carbon atoms, halogenated alkyl groups, hydroxyalkyl groups, and benzyl groups, and A is a group with two or three long atoms. It is a nonionic monovalent group having either a chain hydrophobic group or a straight chain hydrophobic group containing a rigid part in the chain, and B1 and B2 are the same or different nonionic monovalent groups. indicates a long chain hydrophobic group. ] 10 to 90 mol% of the unit represented by the formula (ii) (wherein Y is a group selected from hydrogen, an alkyl group, and a cyano group, and R4 is hydrogen or an alkyl group having 5 or less carbon atoms) 90 mol% to 90 mol% of units represented by
A linear polymer containing 10 mol% and [2] General formula (where β is an alkyl group having 12 or more carbon atoms, α is hydrogen or a methyl group, x is an integer of 10 or more, and y is 0 or 1) ) is formed into a film from a composition containing 3 to 30% by weight of the linear polymer, and then the linear polymer is crosslinked. A method for producing a sensitive membrane. [1] (i) General formula (wherein Y is a group selected from hydrogen, an alkyl group, and a cyano group, X- is a halogen ion or an atomic group forming an anion, and Z is [ Chemical formula 2] -COOR3-, -OCOR3, -CONHR3-, and -NHCOR3- {However, R3 is -(CH2)m-, -CH2(CH2O
CH2)m-CH2-, or -CH2-(CH(CH3
)OCH2)m-CH(CH3)-, (where m is 1 to
(an integer of 10), n is an integer of 1 to 10. }, R1 and R2 are the same or different groups selected from alkyl groups having 5 or less carbon atoms, halogenated alkyl groups, hydroxyalkyl groups, and benzyl groups, and A is a group with two or three long atoms. It is a nonionic monovalent group having either a chain hydrophobic group or a straight chain hydrophobic group containing a rigid part in the chain, and B1 and B2 are the same or different nonionic monovalent groups. indicates a long chain hydrophobic group. ), and (ii) general formula (wherein, Y is a group selected from hydrogen, an alkyl group, and a cyano group, and R4 is hydrogen or an alkyl group having 5 or less carbon atoms). A linear polymer containing 90 to 10 mol% of the unit represented by the selected group) and [2] general formula (where β is an alkyl group having 12 or more carbon atoms, α is hydrogen or methyl group, x is an integer of 10 or more, y is 0 or 1) in an amount of 3 to 30% by weight based on the linear polymer; A method for producing an ion-sensitive membrane, comprising forming a composition containing 10 to 200% by weight of a linear alcohol based on the linear polymer into a film, and then crosslinking the linear polymer. .