Copolymer, resin composition, hydrophilizing agent, and article

Abstract

Provided is a polymer which has all of hydrophilicity, solubility in alcohol-based solvents, and such hydrophobicity that the polymer can be adsorbed onto a substrate. This copolymer contains a repeating unit that is derived from a monomer containing sulfobetaine in a side chain thereof, a repeating unit that is derived from a monomer containing a glycol ether in a side chain thereof, and a repeating unit that is derived from a monomer containing an alkyl chain in a side chain thereof. It is preferred that the monomer containing sulfobetaine in a side chain thereof is represented by formula (1), the monomer containing a glycol ether in a side chain thereof is represented by formula (2), and the monomer containing an alkyl chain in a side chain thereof is represented by formula (3).　

Description

Copolymer, resin composition, hydrophilizing agent, and article

[0001] The present invention relates to a copolymer, a resin composition, a hydrophilizing agent, and an article.

[0002] Rubber, resin, glass, ceramic, metal, etc. are used as materials for molded articles that are introduced into the human body for long periods of time, such as artificial blood vessels, catheters, stents, and artificial bones, as well as medical devices, such as blood storage packs and hemodialysis membranes, and cell culture vessels. Hydrophilicity is required for these materials.

[0003] Furthermore, silicone rubber has excellent heat resistance, weather resistance, and durability, and is used as a material for molded articles to be used indoors or outdoors. In some cases, the molded articles are also required to be hydrophilic.

[0004] Surface treatment with a hydrophilizing agent is one example of a hydrophilization treatment for hydrophobic substrates such as rubber, resin, glass, ceramic, and metal. Patent Document 1 discloses a hydrophilically modified substrate coated with a copolymer having a repeating unit with a betaine structure in the side chain and a repeating unit with an active functional group in the side chain. Because dry treatment such as plasma discharge is required before coating with the copolymer disclosed in Patent Document 1, substrates that cannot be subjected to dry treatment, such as the inner walls of tubes, cannot be coated with the copolymer. Because the copolymer begins to dissolve in saline within about two weeks, it is not used in fields requiring saltwater resistance, such as cell culture, medical care, and marine paints. Furthermore, because the copolymer is insoluble in ethanol, a hydrophilic coating film cannot be formed by applying an alcoholic solution of the copolymer to a substrate.

[0005] Japanese Patent Application Laid-Open No. 2021-161208

[0006] In recent years, there has been a demand for polymers that are hydrophilic, soluble in alcohol-based solvents, and hydrophobic enough to be adsorbed onto substrates.

[0007] The problem to be solved by the present invention is to provide a polymer that is hydrophilic, soluble in alcohol-based solvents, and hydrophobic enough to be adsorbed onto a substrate.

[0008] The present inventors have conducted extensive research in light of the above-mentioned problems and have found that a copolymer containing a repeating unit derived from a monomer having a sulfobetaine group in the side chain, a repeating unit derived from a monomer having a glycol ether group in the side chain, and a repeating unit derived from a monomer having an alkyl chain in the side chain is hydrophilic, soluble in alcohol-based solvents, and hydrophobic enough to be adsorbed to a substrate. The present invention was completed based on these findings.

[0009] The present invention relates to a copolymer containing a repeating unit derived from a monomer having a sulfobetaine group in the side chain, a repeating unit derived from a monomer having a glycol ether group in the side chain, and a repeating unit derived from a monomer having an alkyl chain in the side chain.

[0010] Preferably, the monomer containing sulfobetaine in a side chain is represented by the following formula (1):

[0011]

[0012] R １ represents a hydrogen atom or a methyl group, and X １ represents an oxygen atom or an NH group, R ２ and R ３ each independently represents a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, and R ２ and R ３ are bonded to form a five- or six-membered ring, and L １ and L ２ each independently represents a linear or branched alkylene group having 2 to 10 carbon atoms.

[0013] Preferably, the monomer containing a glycol ether in a side chain is represented by the following formula (2):

[0014]

[0015] R ４ represents a hydrogen atom or a methyl group, and X ２ represents an oxygen atom or an NH group, L ３ represents a methylene group or an ethylene group, R ５ represents a hydrogen atom, a methyl group or an ethyl group, and n represents an integer of 1 to 90.

[0016] Preferably, the monomer containing an alkyl chain in a side chain is represented by the following formula (3):

[0017]

[0018] X ３ represents an oxygen atom or an NH group, R ６ represents a hydrogen atom or a methyl group, R ７ represents a linear or branched alkyl group having 1 to 10 carbon atoms.

[0019] The molar ratio of the repeating units derived from a monomer containing sulfobetaine in the side chain / the repeating units derived from a monomer containing a glycol ether in the side chain / the repeating units derived from a monomer containing an alkyl chain in the side chain is preferably in the range of 1 / 0.1 to 5 / 0.1 to 10. The copolymer may further contain a repeating unit derived from a monomer containing at least one group selected from the group consisting of a methoxysilyl group and an ethoxysilyl group in the side chain. The copolymer may further contain a repeating unit derived from a monomer containing an azide group in the side chain. The copolymer is preferably soluble in an alcohol-based solvent.

[0020] The present invention relates to a resin composition containing the copolymer, and a hydrophilizing agent containing the copolymer and an alcohol-based solvent.

[0021] The present invention further relates to an article treated with the hydrophilizing agent.

[0022] The copolymer of the present invention provides a polymer that is hydrophilic, soluble in an alcohol-based solvent, and hydrophobic enough to be adsorbed to a substrate. The hydrophilizing agent of the present invention provides a hydrophilizing agent containing the copolymer and an alcohol-based solvent. The article of the present invention provides an article treated with the hydrophilizing agent.

[0023] FIG. 1 shows the results of a fibrinogen adsorption test.

[0024] The present invention will be described in more detail. Unless otherwise specified, the "to" symbol in a numerical range indicates a range from above to below, and both endpoints are included. Furthermore, when a numerical range is indicated, the upper and lower limits can be combined as appropriate, and the resulting numerical range is also considered to be disclosed. In this specification, the term "compound" (e.g., when referring to a compound with "compound" at the end) refers to the compound itself, as well as its salts and ions. This term also includes derivatives in which a portion of the structure has been modified, such as by introducing a substituent, to the extent that the desired effect is achieved. In this specification, when a substituent has a dissociable hydrogen atom (a group in which the hydrogen atom dissociates under the action of a base), this substituent includes ionic or salt forms. In this specification, when a substituent, linking group, etc. (hereinafter referred to as "substituent, etc.") is not specified as substituted or unsubstituted, this means that the group may have an appropriate substituent. Therefore, even when a term "group" (e.g., "alkyl group") is used herein, this "group" (e.g., "alkyl group") encompasses not only an unsubstituted group (e.g., an "unsubstituted alkyl group") but also a substituted group (e.g., a "substituted alkyl group"). This also applies to compounds where substituted or unsubstituted is not specified. Preferred substituents include the substituent T described below. When simply referring to a "substituent" in this specification, a substituent selected from the substituents T described below is preferably used. In this specification, when there are multiple substituents, etc., designated by a specific symbol, or when multiple substituents, etc., are specified simultaneously or alternatively, this means that the respective substituents, etc., may be the same or different from each other. Furthermore, unless otherwise specified, when multiple substituents, etc., are adjacent, they may be linked to each other or fused to form a ring. In this specification, when a polymer has multiple constituents of the same designation (represented by the same general formula), the constituents may be the same or different from each other.

[0025] [Copolymer] <Repeating unit derived from monomer containing sulfobetaine in the side chain> The copolymer of the present invention contains a repeating unit derived from a monomer containing sulfobetaine in the side chain (hereinafter, sometimes referred to as SB unit). The SB unit is thought to impart hydrophilicity to the copolymer of the present invention. The monomer containing sulfobetaine in the side chain is not limited to a specific monomer. The monomer containing sulfobetaine in the side chain is preferably represented by the following formula (1). Note that the "betaine structure" refers to a structure in which a positive charge and a negative charge are present at non-adjacent positions within the same molecule, no dissociable hydrogen atom is bonded to the positively charged atom, and the molecule as a whole is uncharged.

[0026]

[0027] In the formula (1), R １ represents a hydrogen atom or a methyl group, and X １ represents an oxygen atom or an NH group, R ２ and R ３ each independently represents a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, and R ２ and R ３ are bonded to form a five- or six-membered ring, and L １ and L ２ each independently represents a linear or branched alkylene group having 2 to 10 carbon atoms.

[0028] Specific examples of the monomer represented by formula (1) include compounds represented by the following formula:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] Conventional cations or anions can be used as counter ions for forming a salt structure. Examples of cations used as counter ions include metal cations, such as sodium ions, lithium ions, potassium ions, calcium ions, magnesium ions, and zinc ions. It is also preferable to have a cation derived from an amine. Examples of such amines that can be used preferably include polyvalent amines such as polyethyleneimine, monoalkylamines such as hexylamine, dialkylamines such as dibutylamine, trialkylamines such as triethylamine, alcohol amines such as ethanolamine, aromatic ring-containing amines such as benzylamine and dimethylaminopyridine, and polycyclic amines such as diazabicycloundecene. Examples of anions used as counter ions include halogen anions. Two or more types of counter ions may be used to form a salt structure. For example, it is also preferable to use a metal cation and an amine-derived cation (preferably a cation derived from a polyvalent amine such as polyethyleneimine) in combination.

[0038] <Monomer containing glycol ether in the side chain> The copolymer of the present invention contains a repeating unit (hereinafter, sometimes referred to as glycol ether unit) derived from a monomer containing glycol ether in the side chain. The glycol ether unit is thought to impart solubility in alcohol-based solvents to the copolymer of the present invention. The monomer containing glycol ether in the side chain is not limited to a specific monomer. The monomer containing glycol ether in the side chain is preferably represented by the following formula (2):

[0039]

[0040] In the formula (2), R ４ represents a hydrogen atom or a methyl group, and X ２ represents an oxygen atom or an NH group, L ３ represents a methylene group or an ethylene group, R ５ represents a hydrogen atom, a methyl group or an ethyl group; n represents an integer of 1 to 90, more preferably an integer of 1 to 20, and even more preferably an integer of 1 to 10.

[0041] Specific examples of the monomer represented by formula (2) include compounds represented by the following formula:

[0042]

[0043]

[0044] <Monomer Having an Alkyl Chain in the Side Chain> The copolymer of the present invention contains a repeating unit (hereinafter, sometimes referred to as an alkyl unit) derived from a monomer having an alkyl chain in the side chain. The alkyl unit is considered to impart hydrophobicity to the copolymer of the present invention. The monomer having an alkyl chain in the side chain is not limited to a specific monomer. The monomer having an alkyl chain in the side chain is preferably represented by the following formula (3):

[0045]

[0046] In the formula (3), X ３ represents an oxygen atom or an NH group, R ６ represents a hydrogen atom or a methyl group, R ７ represents a linear or branched alkyl group having 1 to 10 carbon atoms.

[0047] Specific examples of the monomer represented by formula (3) include compounds represented by the following formula:

[0048]

[0049]

[0050]

[0051]

[0052]

[0053] The molar ratio of the repeating units derived from the monomer containing sulfobetaine in the side chain / the repeating units derived from the monomer containing glycol ether in the side chain / the repeating units derived from the monomer containing alkyl chain in the side chain is not limited to a specific range. The ratio is preferably in the range of 1 / 0.1 to 5 / 0.1 to 10, and more preferably 1 / 0.3 to 1.5 / 1.5 to 4. When the ratio is in the above range, the copolymer of the present invention has a better balance of hydrophilicity, solubility in alcohol-based solvents, and hydrophobicity capable of being adsorbed to a substrate.

[0054] <Other Monomers> The copolymer of the present invention may further contain a repeating unit derived from a monomer containing at least one group selected from the group consisting of a methoxysilyl group and an ethoxysilyl group in its side chain. The monomer containing at least one group selected from the group consisting of a methoxysilyl group and an ethoxysilyl group in its side chain is not limited to a specific monomer. Examples of the monomer containing at least one group selected from the group consisting of a methoxysilyl group and an ethoxysilyl group in its side chain include compounds represented by the following formula (4):

[0055]

[0056] The copolymer of the present invention may further contain a repeating unit derived from a monomer containing an azide group in a side chain. The monomer containing an azide group in a side chain is not limited to a specific monomer. Examples of the monomer containing an azide group in a side chain include a compound represented by the following formula (5):

[0057]

[0058] The weight-average molecular weight of the copolymer of the present invention is not limited to a specific range. The weight-average molecular weight is preferably in the range of 50,000 to 500,000. When the weight-average molecular weight is in the above range, the hydrophilicity, solubility in alcohol-based solvents, and hydrophobicity of the copolymer of the present invention are enhanced. The weight-average molecular weight may be a weight-average molecular weight calculated as sodium polyacrylate by gel permeation chromatography (GPC). When the weight-average molecular weight cannot be measured under the above measurement conditions, for example, because the copolymer is crosslinked, the weight-average molecular weight is measured by static light scattering.

[0059] Examples of the substituent T include the following: an alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), an alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl, etc.), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, For example, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably 5- or 6-membered heterocyclic groups having at least one oxygen atom, sulfur atom, or nitrogen atom. Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups. For example, tetrahydropyran ring group, tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (a group in which an -O- group is bonded to the above heterocyclic group), Alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 6 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), amino groups (preferably amino groups having 0 to 20 carbon atoms, alkylamino groups, and arylamino groups, for example, amino (—NH ２), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfamoyl groups having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl groups (including alkylcarbonyl groups, alkenylcarbonyl groups, alkynylcarbonyl groups, arylcarbonyl groups, and heterocyclic carbonyl groups, preferably acyl groups having 1 to 20 carbon atoms, for example, acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotinoyl, etc.), acyloxy groups (alkylcarbonyl Examples of such a group include an acyloxy group, an alkenylcarbonyloxy group, an alkynylcarbonyloxy group, an arylcarbonyloxy group, and a heterocyclic carbonyloxy group, and are preferably acyloxy groups having 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, benzoyloxy, naphthoyloxy, and nicotinoyloxy; an aryloyloxy group (preferably an aryloyloxy group having 7 to 23 carbon atoms, such as benzoyloxy); a carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, such as N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms, for example, acetylamino, benzoylamino, etc.), alkylthio groups (preferably alkylthio groups having 1 to 20 carbon atoms, for example, methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), heterocyclic thio groups (groups in which an -S- group is bonded to the above heterocyclic groups), alkylsulfonyl groups (preferably or alkylsulfonyl groups having 1 to 20 carbon atoms, for example, methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl groups (preferably arylsulfonyl groups having 6 to 22 carbon atoms, for example, benzenesulfonyl, etc.), alkylsilyl groups (preferably alkylsilyl groups having 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), arylsilyl groups (preferably arylsilyl groups having 6 to 42 carbon atoms, for example, triphenylsilyl, etc.), phosphoryl groups (preferably phosphate groups having 0 to 20 carbon atoms, for example, —OP(═O)(R, Ｐ ) ２ ), a phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, —P(═O)(R Ｐ ) ２ ), a phosphinyl group (preferably a phosphinyl group having 0 to 20 carbon atoms, for example, —P(R Ｐ ) ２ ), sulfo group (sulfonic acid group), carboxy group, hydroxy group, sulfanyl group, cyano group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). Ｐ is a hydrogen atom or a substituent (preferably a group selected from the above-mentioned substituents T). Each of these groups exemplified as the above-mentioned substituent T may further have the above-mentioned substituent T as a substituent.

[0060] The copolymer of the present invention may be soluble or insoluble in an alcohol-based solvent, but is preferably soluble in an alcohol-based solvent.

[0061] The copolymer can be synthesized by combining the monomers according to the purpose and, if necessary, by radical polymerization in the presence of a catalyst (including a polymerization initiator, a chain transfer agent, etc.) The method and conditions for radical polymerization are not particularly limited, and conventional methods and conditions can be appropriately selected.

[0062] [Resin Composition and Hydrophilizing Agent] The resin composition and hydrophilizing agent of the present invention contain the copolymer. The content of the copolymer in the resin composition and hydrophilizing agent of the present invention is not limited to a specific range. The content is preferably in the range of 0.05 to 5.00 mass%. When the content is in the above range, the copolymer of the present invention has a better balance of hydrophilicity, solubility in alcohol-based solvents, and hydrophobicity capable of being adsorbed to a substrate.

[0063] The resin composition and hydrophilizing agent of the present invention may contain general additives that are added to resin compositions. Examples of such additives include compatibilizers, nucleating agents, UV absorbers, weathering agents, heat stabilizers, light stabilizers, binders, antiblocking agents, lubricants, neutralizing agents, crystallization accelerators, colorants, foaming agents, waterproofing agents, water repellents, antibacterial agents, antifogging agents, and impact resistance modifiers. The additives contain at least one of the additives described above, and are preferably at least one of the additives described above.

[0064] The form of the resin composition and hydrophilizing agent of the present invention is not limited to a specific form. The resin composition and hydrophilizing agent of the present invention may be any of a liquid, a gel, and a solid. The resin composition and hydrophilizing agent of the present invention are preferably liquid.

[0065] The use of the resin composition of the present invention is not limited to a specific use, and the use is preferably as a hydrophilizing agent.

[0066] The hydrophilizing agent of the present invention contains an alcohol-based solvent. The content of the alcohol-based solvent in the hydrophilizing agent of the present invention is not limited to a specific range. The content is preferably in the range of 0.05 to 5.00 mass%. When the content is in the above range, the hydrophilicity of the hydrophilizing agent of the present invention, solubility in the alcohol-based solvent, and hydrophobicity capable of being adsorbed to a substrate are better balanced.

[0067] The alcohol-based solvent is not limited to a specific alcohol, and preferably includes at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, and butanol, more preferably at least one selected from the group consisting of ethanol, n-propanol, and isopropanol, and even more preferably ethanol.

[0068] [Application of Resin Composition and Hydrophilizing Agent] The resin composition and hydrophilizing agent of the present invention are used to treat a substrate. The substrate is not limited to a specific substrate. The portion of the substrate to be treated with the resin composition and hydrophilizing agent of the present invention preferably comprises a hydrophobic material such as rubber, resin, glass, ceramic, or metal. The resin composition and hydrophilizing agent of the present invention may be applied to at least a portion of the substrate. Treatment with the resin composition and hydrophilizing agent of the present invention can impart hydrophilicity to a substrate that has not been subjected to pretreatment such as plasma discharge. The coating film formed by applying the resin composition and hydrophilizing agent of the present invention to the substrate has high salt water resistance and low affinity for proteins.

[0069] The present invention relates to the use of the resin composition, namely, the use of the resin composition as a hydrophilizing agent.

[0070] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0071] In the examples and comparative examples, various physical properties were measured or calculated as follows. (1) Solubility of copolymers: 2 to 3 mg of each copolymer was added to a 1.5 mL microtube. 1 mL of ion-exchanged water, a water-ethanol mixed solvent (50% by mass ethanol aqueous solution), or ethanol was added to each microtube, and the mixture was stirred for approximately 30 seconds using a vortex mixer. Each sample was heated in an oven at 80°C for 1 hour, and the state of dissolution was visually confirmed. The solubility was evaluated according to the following criteria: -Solubility Evaluation Criteria- 5: The copolymer was completely dissolved to form a transparent solution. 4: The solution did not become transparent, but the dispersion remained stably dispersed for 24 hours or more. 3: The copolymer was dispersed, but settled within a short period of time. 2: Some of the copolymer was dispersed, but some of the copolymer remained settled. 1: The copolymer was not dispersed and settled.

[0072] (2) Bubble Contact Angle Test Each copolymer was dispersed or dissolved in ethanol to a concentration of 1% by mass. An untreated polystyrene plate (Hikari Corporation, t1mm) was dipped and dried with an air blower. The plate was heated at 50°C for 1 hour in an oven and washed with ion-exchanged water three times. The surface-treated polystyrene plate was immersed in ion-exchanged water and exposed to 2.0 μL of air. The bubble contact angle was measured from an image taken 30 seconds after contact using a contact angle meter (DropMaster, Kyowa Interface Science Co., Ltd.). After measurement, the surface-treated polystyrene plate was immersed in phosphate-buffered saline (Nacalai Tesque, Inc., 10x concentrated PBS diluted 10x) and left at room temperature for one week. After one week, the bubble contact angle was measured again using the contact angle meter.

[0073] (3) Fibrinogen Adsorption Test Fibrinogen (manufactured by Fujifilm Corporation, derived from human plasma) was dissolved in the phosphate-buffered saline (PBS) at pH 7.0 to prepare a 2000 μg / mL fibrinogen aqueous solution. Two mL of the fibrinogen aqueous solution was added to polystyrene dishes (AGC Techno Glass Corporation, φ35 mm) coated with the SB homopolymer (described below), the ternary heteropolymer obtained in Example 9, and MPC polymer (NOF Corporation, a polymer containing both phosphate and ammonium ions), as well as to an unpretreated polystyrene dish (hereinafter sometimes referred to as a blank). The dishes were then left in a refrigerator overnight to allow fibrinogen to adsorb to the surface of each polystyrene dish. The fibrinogen aqueous solution was removed from each dish, and the dishes were washed three times with 3 mL of ion-exchanged water. Two mL of a 5% by weight aqueous solution of sodium dodecyl sulfate was added, and each washed dish was subjected to ultrasonic irradiation for one hour to obtain sample solutions in which fibrinogen had been removed from the substrate surface. Two mL of working solution (20 mL of Reagent A and 400 μL of Reagent B) prepared using a Protein Assay BCA kit (Fujifilm Corporation) was placed in a cuvette, and 1 mL of each fibrinogen-containing sample solution was added. The samples were allowed to stand at room temperature for one hour to allow color development, and the absorbance was measured using the BCA mode on a NanoDrop microspectrophotometer (Thermo Fisher Scientific).

[0074] (Synthesis of Monomer) 42.51 g of N-(3-dimethylaminopropyl)methacrylamide (Tokyo Chemical Industry Co., Ltd.), 30.58 g of 1,3-propane sultone (Tokyo Chemical Industry Co., Ltd.), and 400 mL of acetone (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 1 L beaker. The resulting solution was stirred at room temperature at 340 rpm for 24 hours. Stirring was stopped and the mixture was allowed to stand for 10 minutes to allow the solid product to settle. The supernatant was removed by natural filtration. Approximately 200 mL of acetone was added to the white solid remaining in the beaker and stirred with a glass rod. The supernatant was again removed by natural filtration. This washing procedure was repeated three times. The white solid remaining on the filter paper and the white solid remaining in the beaker were vacuum-dried at 60°C overnight to obtain a monomer represented by formula (1) (C3SB monomer). Additionally, 1.19 g of N-(3-dimethylaminopropyl)methacrylamide (Tokyo Chemical Industry Co., Ltd.), 0.95 g of 1,4-butanesultone (Tokyo Chemical Industry Co., Ltd.), 0.0008 g of tert-butylhydroquinone (Tokyo Chemical Industry Co., Ltd.), and 5 mL of acetonitrile (Tokyo Chemical Industry Co., Ltd.) were added to a 100 mL beaker. The resulting solution was stirred at 80°C and 340 rpm for 24 hours. Stirring was stopped and the mixture was left to stand overnight to allow the solid product to settle. The supernatant was removed by natural filtration. Approximately 50 mL of acetone was added to the white solid remaining in the beaker and stirred with a glass rod. The supernatant was again removed by natural filtration. This washing procedure was repeated three times. The white solid remaining on the filter paper and the white solid remaining in the beaker were vacuum-dried overnight at 60°C to obtain a monomer (C4SB monomer).

[0075] (Synthesis of Homopolymer Having C3SB Monomer as Repeating Unit) 22.74 g of C3SB monomer was added to a 100 mL eggplant-shaped flask, and 80 mL of ion-exchanged water was added to dissolve the C3SB monomer. Then, 200 mg of ammonium persulfate (Tokyo Chemical Industry Co., Ltd.), a polymerization initiator, was added and the flask was covered with aluminum foil. The eggplant-shaped flask was heated to 60°C and allowed to stand for 20 hours. The reaction solution was colorless and transparent. After the reaction was completed, the eggplant-shaped flask was removed from the oil bath, and 80 mL of ion-exchanged water was added. The temperature of the reaction solution dropped rapidly, and the reaction solution became cloudy. 800 mL of the reaction solution was poured into ethanol (Fujifilm Wako Pure Chemical Industries, Ltd.) to allow reprecipitation. The precipitated white gel-like substance was collected with a spatula and washed three times with ethanol. The mixture was then dried in vacuo overnight to obtain the homopolymer (SB homopolymer) as a white solid.

[0076] Examples 1 to 27 and Comparative Examples 1 to 4: C3SB monomer and the monomers shown in Table 1 were added to a 9 mL / 1 mL mixed solvent of ethanol and water, and the mixture was stirred for 30 minutes while bubbling with nitrogen gas. 15 mg of 2,2-azobis(isobutylnitrile) (Tokyo Chemical Industry Co., Ltd.), a radical polymerization initiator, was added, and the mixture was heated and stirred overnight at 60°C while continuing to flow nitrogen. After the reaction was completed, the white precipitate and solution in the flask were transferred to a sample vial and dried in vacuum at 60°C overnight to obtain a copolymer. The results are shown in Table 1.

[0077]

[0078] The copolymers of Comparative Examples 1, 2, and 4, which did not contain alkyl units, and the copolymer of Comparative Example 3, which did not contain glycol ether units, did not disperse in ethanol and instead precipitated. Furthermore, the absolute values ​​of the rate of change in bubble contact angle for these copolymers were large. In other words, the saltwater resistance of the coating films formed by applying these copolymers to the polystyrene plates was low. On the other hand, the copolymers of Examples 1 to 27, which contained the three units, were dissolved or stably dispersed in ethanol. Furthermore, the absolute values ​​of the rate of change in bubble contact angle for these copolymers were small. In other words, the saltwater resistance of the coating films formed by applying these copolymers to the polystyrene plates was high.

[0079] A 1% by mass SB homopolymer aqueous solution was heated in an oven at 80°C for 30 minutes to completely dissolve the solution. Meanwhile, the polystyrene dish was subjected to vacuum plasma treatment (300 W, 10 minutes). After the vacuum plasma treatment, 3 mL of a 1% by mass SB homopolymer aqueous solution was added to the dish, which was then heat-treated in an oven at 80°C for 10 minutes. After the heat treatment, the SB aqueous solution was removed from the dish, which was then washed three times with 3 mL of ion-exchanged water and dried with an air blower to prepare a dish coated with SB homopolymer. A fibrinogen adsorption test was then performed. The results are shown in Figure 1.

[0080] The ternary heteropolymer obtained in Example 9 was dispersed in isopropyl alcohol to a concentration of 1% by mass and dissolved by ultrasonic irradiation for 1 hour. 3 mL of the isopropyl alcohol solution of the ternary heteropolymer was added to the dish, immediately removed, and dried by air blowing. The dried dish was then heated in an oven at 50°C for 1 hour, washed three times with 3 mL of ion-exchanged water, and dried by air blowing to prepare the dish coated with the ternary heteropolymer, and a fibrinogen adsorption test was performed. The results are shown in Figure 1.

[0081] The peak at 562 nm is due to fibrinogen. The absorbance at 562 nm was highest for the sample solution peeled from the blank, followed by the sample solution peeled from the dish coated with the SB homopolymer, the sample solution peeled from the dish coated with the MPC polymer, and the sample solution peeled from the dish coated with the ternary heteropolymer. This indicates that the affinity for proteins decreases in the order of the ternary heteropolymer obtained in Example 9, the MPC polymer, and the SB homopolymer.

Claims

1. A copolymer containing repeating units derived from a monomer containing sulfobetaine in the side chain, repeating units derived from a monomer containing glycol ether in the side chain, and repeating units derived from a monomer containing an alkyl chain in the side chain.

2. The copolymer described in claim 1, wherein the monomer containing sulfobetaine in the side chain is represented by the following formula (1): R １ represents a hydrogen atom or a methyl group, and X １ represents an oxygen atom or an NH group, R ２ and R ３ each independently represents a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, and R ２ and R ３ are bonded to form a five- or six-membered ring, and L １ and L ２ each independently represents a linear or branched alkylene group having 2 to 10 carbon atoms.

3. In the copolymer described in claim 1, the monomer containing a glycol ether in the side chain is represented by the following formula (2): R ４ represents a hydrogen atom or a methyl group, and X ２ represents an oxygen atom or an NH group, L ３ represents a methylene group or an ethylene group, R ５ represents a hydrogen atom, a methyl group, or an ethyl group, and n represents an integer of 1 to 90.

4. The copolymer according to claim 1, wherein the monomer containing an alkyl chain in the side chain is represented by the following formula (3): X ３ represents an oxygen atom or an NH group, R ６ represents a hydrogen atom or a methyl group, R ７ represents a linear or branched alkyl group having 1 to 10 carbon atoms, and is a copolymer.

5. The copolymer described in claim 1, wherein the molar ratio of the repeating units derived from a monomer containing sulfobetaine in the side chain / the repeating units derived from a monomer containing glycol ether in the side chain / the repeating units derived from a monomer containing an alkyl chain in the side chain is in the range of 1 / 0.1-5 / 0.1-10.

6. The copolymer according to claim 1, further comprising a repeating unit derived from a monomer containing at least one group selected from the group consisting of a methoxysilyl group and an ethoxysilyl group in the side chain.

7. The copolymer according to claim 1, further comprising a repeating unit derived from a monomer containing an azide group in the side chain.

8. The copolymer according to claim 1, which is soluble in an alcohol-based solvent.

9. A resin composition comprising the copolymer according to any one of claims 1 to 8.

10. A hydrophilizing agent comprising the copolymer according to any one of claims 1 to 8 and an alcohol-based solvent.

11. An article treated with the hydrophilizing agent according to claim 10.

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