Betaine monomer, polymer, composition containing the polymer, and molded article

Abstract

The present invention relates to a betaine monomer which includes a positively charged moiety and a negatively charged moiety that are equivalent to each other, wherein the positively charged moiety and the negatively charged moiety are linked to each other by a branched alkylene group having 2-6 carbon atoms.

Description

[Technical Field]

[0001] The present invention relates to a betaine monomer, a polymer containing structural units derived from said monomer, a composition containing said polymer, and a molded article coated with said polymer. [Background technology]

[0002] Polymers containing structural units derived from betaine monomers are widely used as coating compositions, etc. For example, Patent Document 1 describes a hydrophilic coating agent containing an alkoxysilyl group-containing polymer obtained by polymerizing a monomer component containing a betaine monomer and an alkoxysilyl group-containing compound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 084219 Summary of the Invention [Problem to be solved by the invention]

[0004] Although various polymers capable of functioning as hydrophilic coating agents have been investigated, there is still a demand for polymers having high hydrophilicity, for example, capable of making a surface coated with the polymer hydrophilic for a long period of time. Therefore, an object of the present invention is to provide a polymer having high hydrophilicity, and a monomer that provides the polymer, which can make a surface coated with the polymer hydrophilic for a long period of time. [Means for solving the problem]

[0005] In order to solve the above problems, the present inventors have conducted extensive research into the structure of betaine monomers, and as a result have found that the above problems can be solved by a betaine monomer in which a positively charged moiety and a negatively charged moiety are linked by a branched alkylene group having 2 to 6 carbon atoms, and a polymer containing a structural unit derived from the monomer, thereby completing the present invention.

[0006] That is, the present invention includes the following preferred embodiments. [1] A betaine monomer having a positively charged moiety and a negatively charged moiety that are equivalent to each other, and the positively charged moiety and the negatively charged moiety are linked by a branched alkylene group having 2 to 6 carbon atoms. [2] Formula (1): [ka] [In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear or branched alkylene group having 1 to 4 carbon atoms, and R 3 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, R 4 represents a branched alkylene group having 2 to 6 carbon atoms, X represents -NH- or -O-, and Y represents -SO3 - or -COO - represents] The betaine monomer according to [1] above, represented by the formula: [3] R 4 represents an isobutylene group, and Y represents -SO3 - The betaine monomer according to [2] above, [4] A polymer containing at least a structural unit derived from the betaine monomer according to any one of [1] to [3] above. [5] The polymer according to [4], wherein the amount of the structural units derived from the betaine monomer is 5% by mass or more based on the amount of all structural units contained in the polymer. [6] The polymer according to [4] or [5] above, further comprising at least one type of constitutional unit selected from the group consisting of constitutional units derived from hydrophobic monomers, constitutional units derived from hydrophilic monomers, constitutional units derived from alkoxysilyl group-containing monomers, and constitutional units derived from crosslinkable monomers having a crosslinkable group in the side chain. [7] A composition containing the polymer according to any one of [4] to [6] above. [8] The composition according to [7] above, which is a coating composition. [9] A molded article coated with the polymer according to any one of [4] to [6] above. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a highly hydrophilic polymer and a monomer that provides the polymer, which can hydrophilize a surface coated with the polymer, preferably for a long period of time. [Brief explanation of the drawings]

[0008] [Figure 1] 10 shows phase contrast microscope images showing the state of cell adsorption on each coating piece at 37°C. [Figure 2] These are phase-contrast microscope images showing the state of cell adsorption on each coating piece at 70°C. [Figure 3] 10 shows phase contrast microscope images showing the state of cell adsorption on each coating piece at 37°C. [Figure 4] 10 shows phase contrast microscope images showing the state of cell adsorption on each coating piece at 37°C. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0010] (betaine monomer) The betaine monomer of the present invention is a betaine monomer having a positively charged moiety and a negatively charged moiety that are equivalent to each other, and the positively charged moiety and the negatively charged moiety are linked by a branched alkylene group having 2 to 6 carbon atoms. Generally, betaine has a positively charged moiety and a negatively charged moiety at positions that are not adjacent to each other in the same molecule, and no hydrogen atoms are bonded to the atoms of the positively charged moiety, so that the molecule as a whole has no electric charge. In other words, the betaine monomer of the present invention is one embodiment of a molecule having a zwitterionic structure that has both positive and negative charges in one molecule. In the betaine monomer of the present invention, the positively charged moiety and the negatively charged moiety are linked by a branched alkylene group having 2 to 6 carbon atoms.

[0011] Examples of betaine monomers having equivalent positively and negatively charged moieties include phosphobetaine, carbobetaine, and sulfobetaine, preferably carbobetaine and sulfobetaine.

[0012] Examples of the branched alkylene group having 2 to 6 carbon atoms that connects the positively charged moiety and the negatively charged moiety of the betaine monomer include a methylmethylene group, an ethylmethylene group, a propylmethylene group, a butylmethylene group, a pentylmethylene group, a dimethylmethylene group, a methylethylmethylene group, a diethylmethylene group, a methylethylene group, an ethylethylene group, a propylethylene group, a butylethylene group, a dimethylethylene group, a methylethylethylene group, a diethylethylene group, an isobutylene group (methylpropylene group), an ethylpropylene group, a propylpropylene group, a dimethylpropylene group, a methylethylpropylene group, an isopentylene group (methylbutylene group), an ethylbutylene group, a dimethylbutylene group, and an isohexene group (methylpentylene group).

[0013] The branched alkylene group connecting the positively charged moiety and the negatively charged moiety of the betaine monomer has 2 to 6 carbon atoms, and from the viewpoint of easily forming an intramolecular salt as described below, the number of carbon atoms is preferably 2 to 5, more preferably 2 to 4, and even more preferably 3 to 4.

[0014] Without wishing to be bound by theory, it is believed that the reason why a polymer derived from a betaine monomer having equivalent positively and negatively charged moieties, with the positively and negatively charged moieties linked by a branched alkylene group having 2 to 6 carbon atoms, can impart high hydrophilicity, preferably maintained for a long period of time, to a surface coated with the polymer is as follows: On a surface coated with a polymer containing a structural unit derived from a betaine monomer, the portion derived from the betaine monomer contains a positively and negatively charged moiety. Here, it is believed that the positively and negatively charged moieties can take either an intramolecular salt structure in which a salt is formed within a single structural unit derived from a single betaine monomer molecule, or an intermolecular salt structure in which a salt is formed between a positively and negatively charged moiety between adjacent structural units. In either structure, a certain degree of hydrophilicity is exhibited by forming a salt. However, in the case of an intermolecular salt structure, the interaction between the positively and negatively charged moieties is weaker than in the case of an intramolecular salt structure, resulting in a state in which the positively and negatively charged moieties each exist independently. Therefore, a surface coated with a polymer containing many intermolecular salt structures is susceptible to the influence of polar molecules such as water, as the positively and negatively charged moieties are susceptible to external charges. As a result, it is believed that adhesion of other charged substances, such as proteins, present around the polymer is likely to occur. In contrast, in the betaine monomer of the present invention, the positively and negatively charged moieties are linked by a branched alkylene group having 2 to 6 carbon atoms, thereby shortening the distance between them. Furthermore, the steric hindrance caused by the branched alkyl group is thought to further shorten the distance between them. As a result, the interaction between the positively and negatively charged moieties is thought to be stronger, making it easier for them to form intramolecular salts. From the above, it is believed that the polymer has high hydrophilicity, and the high number of intramolecular salt structures on the surface coated with the polymer makes it easier to maintain the hydrophilic surface for a long period of time, thereby inhibiting the adhesion of proteins, cells, and the like for a long period of time.

[0015] Specific examples of such betaine monomers include those represented by the formula (1): [ka] [In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a linear or branched alkylene group having 1 to 4 carbon atoms, and R 3 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, R 4 represents a branched alkylene group having 2 to 6 carbon atoms, X represents -NH- or -O-, and Y represents -SO3 - or -COO - represents] Examples of the betaine monomer include the betaine monomer represented by the following formula:

[0016] R in formula (1) 1 represents a hydrogen atom or a methyl group. 2 represents a linear or branched alkylene group having 1 to 4 carbon atoms. Examples of the linear or branched alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, a methylmethylene group, a methylethylene group, a dimethylethylene group, and a methylpropylene group. 2 is preferably an alkylene group having 1 to 3 carbon atoms, more preferably an alkylene group having 2 or 3 carbon atoms, and even more preferably an ethylene group, from the viewpoints of easily enhancing the function exerted by the formed intramolecular salt structure, easily increasing the hydrophilicity of the polymer, and easily maintaining the hydrophilicity of the surface coated with the obtained polymer.

[0017] R in formula (1) 3 are each independently a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, and an isopropyl group. 3 From the viewpoint of facilitating the formation of an intramolecular salt structure, is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably a methyl group.

[0018] R in formula (1)4 represents a branched alkylene group having 2 to 6 carbon atoms. Examples of the branched alkylene group having 2 to 6 carbon atoms include the groups described above for the branched alkylene group having 2 to 6 carbon atoms that connects the positively charged portion and the negatively charged portion of the betaine monomer. R in formula (1) 4 is preferably a branched alkylene group having 2 to 5 carbon atoms, more preferably a branched alkylene group having 2 to 4 carbon atoms, even more preferably a branched alkylene group having 3 to 4 carbon atoms, and even more preferably an isobutylene group (methylpropylene group), from the viewpoints of maintaining an intramolecular salt structure, easily increasing the hydrophilicity of the polymer, and easily maintaining the hydrophilicity of the surface coated with the obtained polymer. The betaine monomer represented by the above formula (1) is particularly 4 is a branched alkylene group having 2 to 6 carbon atoms, it is believed that this can enhance the interaction between the positively charged moiety and the negatively charged moiety in one monomer structure represented by formula (1), resulting in high hydrophilicity.

[0019] In formula (1), X represents -NH- or -O-. When X is -O-, the polymerizability during synthesis (polymerization) of the polymer containing the betaine monomer of the present invention can be increased. When X is -NH-, hydrophilicity can be maintained for a longer period of time.

[0020] Y in formula (1) is -SO3 - or -COO - Y represents -SO3 - The compound represented by formula (1) is also called sulfobetaine, and Y is -COO - The compound represented by formula (1) is also called carbobetaine. From the viewpoint of easily maintaining the intramolecular salt structure, Y in formula (1) is -SO3 - On the other hand, from the viewpoint of increasing the variety of solvents in which the betaine monomer of the present invention and the polymer containing the same can be dissolved, it is preferable that Y in formula (1) represents -COO - It is preferred that

[0021] In one preferred embodiment of the present invention, R 4represents an isobutylene group, and Y represents -SO3 - Represents.

[0022] The method for producing a betaine monomer having a positively charged moiety and a negatively charged moiety that are equivalent to each other and that are linked by a branched alkylene group having 2 to 6 carbon atoms is not particularly limited as long as it can produce a betaine monomer having the structure, and the betaine monomer can be produced by any known method. For example, the method for producing a betaine monomer of the present invention will be described using the method for producing a betaine monomer represented by formula (1) as an example.

[0023] First, the following formula (1-1): [ka] [In formula (1-1), R 1 ~R 3 is the same as the above formula (1)] A compound represented by the following formula is prepared.

[0024] In total, Y is -SO3 - When producing a betaine monomer represented by formula (1), a compound represented by formula (1-2A): [ka] [In formula (1-2A), R5~R 14 are each independently a hydrogen atom or a group of formula (1-2a): [ka] [In formula (1-2a), o, p, and q are each independently an integer of 0 to 4.] j, k, l, m, and n are each independently 0 or 1, provided that at least one of j, k, l, m, and n is 1, and R to R bonded to the carbon atom of the moiety where j, k, l, m, and / or n is 1 14 At least one of the symbols j, k, l, m, n, o, p, and q satisfies 2≦j+k+l+m+n+o+p+q≦6. A compound represented by the formula: or a linear alkylsulfonic acid containing a halogen atom is prepared.

[0025] On the other hand, Y is -COO - When producing a betaine monomer represented by formula (1), a compound represented by formula (1-2B): [ka] [In formula (1-2B), Z represents a halogen atom, M represents an alkali metal atom or ammonium, and R 4 is R in equation (1). 4 is the same as A compound represented by the following formula is prepared.

[0026] Furthermore, a solvent in which each of the above compounds is soluble is prepared. The solvent may be either a solvent in which the betaine monomer represented by formula (1) is soluble or a solvent in which it is insoluble. In particular, from the viewpoint of production efficiency, it is preferable to use a solvent in which Y is -SO3 - When producing a betaine monomer represented by the formula: - When producing a betaine monomer represented by the formula (1-1), it is preferable to use a solvent in which the monomer is soluble. Then, a compound represented by formula (1-1) is dissolved in the prepared solvent, and an equimolar amount of the compound represented by formula (1-1) and a compound represented by formula (1-2A), a linear alkylsulfonic acid containing a halogen atom, or a compound represented by formula (1-2B) is added dropwise under ice cooling, whereby the compounds react with each other to synthesize the betaine monomer represented by formula (1). When a solvent insoluble in the betaine monomer represented by formula (1) is used, the betaine monomer represented by formula (1) precipitates in the solvent. The precipitate is recovered and purified as necessary to produce the betaine monomer represented by formula (1). On the other hand, when a solvent soluble in the betaine monomer represented by formula (1) is used, the betaine monomer represented by formula (1) is dissolved in the solvent, and the solvent can be removed as necessary to produce the betaine monomer represented by formula (1).

[0027] Examples of the compound represented by formula (1-1) include N,N-dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, and N,N-dimethylaminopropyl(meth)acrylate.

[0028] Examples of the compound represented by formula (1-2A) include 2,3-propane sultone, 2,4-butane sultone, 3,5-pentane sultone, 2,5-pentane sultone, 3,6-hexane sultone, and 2,6-hexane sultone.

[0029] Examples of the compound represented by formula (1-2B) include sodium 2-chloropropionate, potassium 2-chloropropionate, ammonium 2-chloropropionate, sodium 2-bromopropionate, potassium 2-bromopropionate, ammonium 2-bromopropionate, sodium 3-chloro-2-methylpropionate, potassium 3-chloro-2-methylpropionate, ammonium 3-chloro-2-methylpropionate, sodium 3-bromo-2-methylpropionate, potassium 3-bromo-2-methylpropionate, ammonium 3-bromo-2-methylpropionate, sodium 2-chlorobutyrate, potassium 2-chlorobutyrate, ammonium 2-chlorobutyrate, sodium 2-bromobutyrate, potassium 2-bromobutyrate, ammonium 2-bromobutyrate, sodium 3-chlorobutyrate, potassium 3-chlorobutyrate, ammonium 3-chlorobutyrate, sodium 3-bromobutyrate, 3- Potassium bromobutyrate, Ammonium 3-bromobutyrate, Sodium 3-chloro-2-methylbutyrate, Potassium 3-chloro-2-methylbutyrate, Ammonium 3-chloro-2-methylbutyrate, Sodium 3-bromo-2-methylbutyrate, Potassium 3-bromo-2-methylbutyrate, Ammonium 3-bromo-2-methylbutyrate, Sodium 2-chlorovalerate, Potassium 2-chlorovalerate, Ammonium 2-chlorovalerate, Sodium 2-bromovalerate, 2-bro Examples thereof include potassium chlorovalerate, ammonium 2-bromovalerate, sodium 3-chlorovalerate, potassium 3-chlorovalerate, ammonium 3-chlorovalerate, sodium 3-bromovalerate, potassium 3-bromovalerate, ammonium 3-bromovalerate, sodium 4-chlorovalerate, potassium 4-chlorovalerate, ammonium 4-chlorovalerate, sodium 4-bromovalerate, potassium 4-bromovalerate, and ammonium 4-bromovalerate.

[0030] (polymer) The present invention also provides a polymer containing at least one structural unit derived from the betaine monomer. The polymer of the present invention may be a homopolymer of one of the above betaine monomers, a copolymer of two or more of the above betaine monomers, or a copolymer of one or more of the above betaine monomers with one or more other monomers. To facilitate sufficient hydrophilization by the polymer, the amount of structural units derived from the betaine monomer in the polymer of the present invention is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, even more preferably 35% by mass or more, particularly preferably 40% by mass or more, especially more preferably 45% by mass or more, especially more preferably 50% by mass or more, particularly preferably 55% by mass or more, and especially more preferably 60% by mass or more, based on the total polymer. The amount of structural units derived from the betaine monomer in the polymer may be calculated by analyzing the polymer structure using NMR or the like, or may be calculated from the amount of each monomer during polymer production.

[0031] The structural unit derived from the betaine monomer represented by formula (1) contained in the polymer of the present invention is represented by formula (2): [ka] [In formula (2), R 1 , R 2 , R 3 , R 4 , X and Y are R in formula (1) 1 , R 2 , R 3 , R 4 , X and Y are as defined above, and * represents a bond to an adjacent structural unit. R in formula (2) 1 , R 2 , R 3 , R 4 , X and Y, R in formula (1) 1 , R 2 , R 3 , R 4 , X and Y apply analogously.

[0032] The betaine monomer homopolymer of the present invention preferably has a solubility such that it can be dissolved in 100 parts by mass of water at 25° C., preferably at least 50 parts by mass, more preferably at least 70 parts by mass, and even more preferably at least 100 parts by mass. When the betaine monomer homopolymer of the present invention has the above-mentioned solubility, a composition containing this polymer can be easily applied uniformly to a substrate such as a film, plate, or molded product.

[0033] When the polymer of the present invention is a copolymer of the betaine monomer and another monomer, the polymer may preferably further comprise at least one constituent unit selected from the group consisting of constituent units derived from hydrophobic monomers, constituent units derived from hydrophilic monomers, constituent units derived from alkoxysilyl group-containing monomers, and constituent units derived from crosslinkable monomers having a crosslinkable group in the side chain. By including the constituent units derived from the betaine monomer, the polymer of the present invention has high hydrophilicity, preferably capable of imparting long-lasting hydrophilicity, while by including constituent units derived from other monomers, it is possible to impart properties such as adsorption to various surfaces. Furthermore, when the polymer of the present invention includes the constituent units derived from the betaine monomer and constituent units derived from other monomers that can be used as a fiber raw material, the polymer of the present invention can be used as a fiber raw material, and fibers produced using this fiber raw material are expected to have high hydrophilicity that is preferably maintained for a long period of time.

[0034] (hydrophobic monomer) When the polymer of the present invention has a structural unit derived from a hydrophobic monomer in addition to the structural unit derived from the betaine monomer, it is expected to be able to form a micelle having a structure in which the structural unit derived from the hydrophobic monomer is located inside and the structural unit derived from the betaine monomer is located outside. By having the structural unit derived from the betaine monomer, which has high hydrophilicity, on the outside, the micelle is expected to have high dispersibility in water. Furthermore, the polymer of the present invention can also be used as a polymer constituting a coating agent for coating the surface of a hydrophobic material. The coating agent can impart hydrophilicity to a hydrophobic surface. Examples of hydrophobic monomers include alkyl (meth)acrylates having an alkyl group containing 1 to 18 carbon atoms, cycloalkyl (meth)acrylates having a cycloalkyl group containing 6 to 12 carbon atoms, aryl (meth)acrylates having an aryl group containing 6 to 12 carbon atoms, alkoxyalkyl (meth)acrylates having an alkoxyalkyl group containing 2 to 8 carbon atoms, alkyl(meth)acrylamides having an alkyl group containing 1 to 12 carbon atoms, alkoxy(meth)acrylamides having an alkoxy group containing 1 to 6 carbon atoms, (meth)acryloylmorpholine, diacetone (meth)acrylamide, styrene-based monomers, fatty acid alkyls having an alkyl group containing 1 to 4 carbon atoms other than alkyl (meth)acrylate esters, and nitrogen-containing monofunctional vinyl monomers. In the polymer of the present invention, one of the above hydrophobic monomers may be used, or two or more may be used in combination. In this specification, (meth)acrylic refers to acrylic and / or methacrylic. Furthermore, (meth)acrylate refers to acrylate and / or methacrylate.

[0035] Examples of alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, neopentyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and cetyl (meth)acrylate.

[0036] An example of a cycloalkyl (meth)acrylate having a cycloalkyl group with 6 to 12 carbon atoms is cyclohexyl (meth)acrylate.

[0037] An example of an aryl (meth)acrylate having 6 to 12 carbon atoms in the aryl group is benzyl (meth)acrylate.

[0038] Examples of the alkoxyalkyl (meth)acrylate in which the alkoxyalkyl group has 2 to 8 carbon atoms include methoxyethyl (meth)acrylate and methoxybutyl (meth)acrylate.

[0039] Examples of alkyl(meth)acrylamides in which the alkyl group has 1 to 12 carbon atoms include N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide.

[0040] Examples of alkoxy(meth)acrylamides in which the alkoxy group has 1 to 6 carbon atoms include N-butoxymethyl(meth)acrylamide.

[0041] Examples of the (meth)acryloylmorpholine include acryloylmorpholine and methacryloylmorpholine.

[0042] Examples of diacetone (meth)acrylamides include diacetone acrylamide and diacetone methacrylamide.

[0043] Examples of the styrene-based monomer include styrene and methylstyrene.

[0044] Examples of fatty acid alkyl groups having 1 to 4 carbon atoms in the alkyl group other than (meth)acrylic acid alkyl esters include methyl itaconate and ethyl itaconate.

[0045] Examples of the nitrogen atom-containing monofunctional vinyl monomer include N-vinylpyrrolidone and N-vinylcaprolactam.

[0046] When the polymer of the present invention further comprises a structural unit derived from a hydrophobic monomer, the amount of the structural unit derived from the hydrophobic monomer may be determined arbitrarily based on the balance between hydrophobicity and hydrophilicity in the application in which the polymer of the present invention is used, and is, for example, 1 to 99 mass %, or even 20 to 80 mass %, based on the total polymer. Polymers further comprising a structural unit derived from a hydrophobic monomer are expected to be suitable for use, for example, as a raw material for coating compositions that exhibit even higher hydrophilicity for a long period of time.

[0047] (hydrophilic monomer) The polymer of the present invention may have, in addition to the structural unit derived from the betaine monomer, a structural unit derived from a hydrophilic monomer other than the betaine monomer. Examples of the hydrophilic monomer include (meth)acrylamide, N-vinylpyrrolidone, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, N-(meth)acrylmorpholide, N-methoxymethyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, 2-hydroxyethyl vinyl ether, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-monomethyl (meth)acrylamide, and N-monoethyl (meth)acrylamide, but the present invention is not limited to these examples. In the polymer of the present invention, one type of the above hydrophilic monomer may be used, or two or more types may be used in combination.

[0048] Among the above hydrophilic monomers, (meth)acrylamide, N-vinylpyrrolidone and (meth)acrylonitrile are preferred, and (meth)acrylamide and N-vinylpyrrolidone are more preferred, from the viewpoint of improving the gas permeability of a film containing the polymer of the present invention.

[0049] When the polymer of the present invention further contains a constituent unit derived from a hydrophilic monomer other than the betaine monomer, the amount of the constituent unit derived from the hydrophilic monomer is, for example, 10 to 50 mass %, or even 30 to 40 mass %, based on the entire polymer.

[0050] (Alkoxysilyl group-containing monomer) When the polymer of the present invention has a constituent unit derived from an alkoxysilyl group-containing monomer in addition to the constituent unit derived from the betaine monomer, a composition containing the polymer of the present invention can be applied to the surface of glass or the like to adsorb the polymer of the present invention onto the surface, thereby providing a hydrophilic coating. Examples of the alkoxysilyl group-containing monomer include an alkoxysilane compound having an ethylenically unsaturated double bond.

[0051] Examples of alkoxysilane compounds having an ethylenically unsaturated double bond include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, parastyryltrimethoxysilane, parastyryltriethoxysilane, etc. From the viewpoint of water resistance and abrasion resistance, it is preferable to use an alkoxysilyl group-containing monomer having three alkoxy groups.

[0052] When the polymer of the present invention further contains a structural unit derived from an alkoxysilyl group-containing monomer, the amount of the structural unit derived from the alkoxysilyl group-containing monomer is preferably 10 to 50 mass %, more preferably 30 to 40 mass %, based on the total polymer, from the viewpoint of improving adhesion to substrates and facilitating the formation of a relatively thick coating film when used as a coating material. Polymers further containing a structural unit derived from an alkoxysilyl group-containing monomer can be suitably used as a raw material for coating materials such as paints.

[0053] (Crosslinking monomer) The polymer of the present invention may contain, in addition to the structural unit derived from the betaine monomer, a structural unit derived from a crosslinkable monomer having two or more crosslinkable groups in its side chain. When the polymer of the present invention contains, in addition to the structural unit derived from the betaine monomer, a structural unit derived from a crosslinkable monomer, a hydrogel can be constructed that can maintain hydrophilicity for a long period of time. Such a hydrogel can be used, for example, as a sustained-release material. The crosslinkable group in the crosslinkable monomer is not particularly limited, but examples thereof include at least one group selected from the group consisting of an acrylic group, a methacrylic group, an epoxy group, an oxetane group, a carbonate group, an isocyanate group, a hydroxyl group, a carboxylic acid group, and a carbonyl group. Examples of crosslinkable monomers having such groups include polyfunctional monomers such as (meth)acrylamide compounds having two or more (meth)acryloyl groups, (meth)acrylate compounds having two or more (meth)acryloyl groups, amine compounds having two or more ethylenically unsaturated double bonds, and aromatic compounds having two or more ethylenically unsaturated double bonds, but the present invention is not limited to these examples. One type of crosslinkable monomer may be used, or two or more types may be used in combination.

[0054] Examples of the (meth)acrylamide compound having two or more (preferably two) (meth)acryloyl groups include alkylene bis(meth)acrylamides in which the alkylene group has 1 to 4 carbon atoms, such as methylene bis(meth)acrylamide.

[0055] Examples of the (meth)acrylate compound having two or more (preferably two or three) (meth)acryloyl groups include ethylene di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0056] Examples of the amine compound having two or more (preferably two or three) ethylenically unsaturated double bonds include diallylamine and triallylamine.

[0057] Examples of aromatic compounds having two or more (preferably two or three) ethylenically unsaturated double bonds include divinylbenzene and diallylbenzene.

[0058] Among the crosslinkable monomers, from the viewpoint of enhancing the polymerizability between monomers and the crosslinkability of the crosslinkable monomer, preferred are (meth)acrylamide compounds having two or more (meth)acryloyl groups, (meth)acrylate compounds having two or more (meth)acryloyl groups, amine compounds having two or more carbon-carbon double bonds, and aromatic compounds having two or more carbon-carbon double bonds, and more preferred are (meth)acrylamide compounds having two or more (meth)acryloyl groups, (meth)acrylate compounds having two or more (meth)acryloyl groups, and amine compounds having two or more carbon-carbon double bonds, and more preferred are (meth)acrylamide compounds having two or more (meth)acryloyl groups and (meth) More preferred are (meth)acrylate compounds having two or more acryloyl groups, and even more preferred are ethylene di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate, with ethylene glycol di(meth)acrylate being particularly preferred. These crosslinkable monomers may be used alone or in combination of two or more.

[0059] When the polymer of the present invention further contains a structural unit derived from a crosslinkable monomer, the amount of the structural unit derived from the crosslinkable monomer is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, based on the entire polymer, from the viewpoints of the flexibility, swelling property, water retention, etc. of the hydrogel when the above-mentioned hydrogel is formed. A polymer further containing a structural unit derived from a crosslinkable monomer can form, for example, the above-mentioned hydrogel, and further, such a hydrogel can be suitably used as a sustained-release material for sustained release of proteins, an electrophoresis gel used in the analysis of proteins, etc.

[0060] When polymerizing the betaine monomer of the present invention, optionally together with other monomers, to produce the polymer of the present invention, it is preferable to use at least one polymerization initiator in order to promote the polymerization reaction of the monomer components. Examples of polymerization initiators include azoisobutyronitrile, methyl azoisobutyrate, azobisdimethylvaleronitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, benzophenone derivatives, phosphine oxide derivatives, benzoketone derivatives, phenylthioether derivatives, azide derivatives, diazo derivatives, and disulfide derivatives, but the present invention is not limited to these examples. These polymerization initiators may be used alone or in combination of two or more.

[0061] The amount of the polymerization initiator is not particularly limited, but is usually preferably about 0.01 to 5 parts by mass per 100 parts by mass of the monomer component.

[0062] Examples of polymerization methods for producing the polymer of the present invention by polymerizing the betaine monomer of the present invention, optionally together with other monomers, include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization, but the present invention is not limited to these examples. Among these polymerization methods, solution polymerization is preferred. When polymerizing the monomer components by solution polymerization, for example, the monomer components can be polymerized by dissolving the monomer components in a solvent and adding a polymerization initiator to the resulting solution while stirring it.

[0063] Examples of solvents include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, and propylene glycol, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and tetrahydrofuran, aromatic hydrocarbon compounds such as benzene, toluene, and xylene, aliphatic hydrocarbon compounds such as n-hexane, alicyclic hydrocarbon compounds such as cyclohexane, and acetates such as methyl acetate and ethyl acetate, but the present invention is not limited to these examples. These solvents may be used alone or in combination of two or more.

[0064] The amount of the solvent is preferably adjusted so that the concentration of the monomer component in the solution obtained by dissolving the monomer component in the solvent is generally about 10 to 80% by mass.

[0065] The polymerization conditions, such as the polymerization temperature and polymerization time, when polymerizing the monomer components are preferably adjusted appropriately depending on the type and amount of the monomer used as the monomer component, the type and amount of the polymerization initiator used, etc.

[0066] The atmosphere during polymerization of the monomer components is preferably an inert gas, such as nitrogen gas or argon gas, but the present invention is not limited to these examples.

[0067] The weight-average molecular weight of the polymer of the present invention is preferably 100 or more, more preferably 500 or more, from the viewpoint of easily increasing the hydrophilicity of the polymer and easily increasing hydrophilicity over a long period of time. From the viewpoint of solubility in solvents and ease of coating when used as a coating material, it is preferably 100,000 or less, more preferably 50,000 or less. The weight-average molecular weight of the polymer of the present invention can be determined by gel permeation chromatography. The weight-average molecular weight by GPC may be measured using, for example, trifluoroethanol as an eluent and a column (e.g., Wako Beads G-50). Polyethylene glycol may also be used as a molecular weight standard.

[0068] The viscosity average molecular weight of the polymer of the present invention is preferably 100 or more, more preferably 500 or more, from the viewpoint of facilitating the enhancement of hydrophilicity of the polymer and the enhancement of hydrophilicity over a long period of time, and is preferably 100,000 or less, more preferably 50,000 or less, from the viewpoint of solubility in solvents and the like and ease of coating when used as a coating material. The viscosity average molecular weight of the polymer of the present invention may be measured, for example, using the method described in the Examples.

[0069] For example, the polymer of the present invention may be a copolymer of the betaine monomer of the present invention and a monomer having an alkoxysilyl group, so that it can be stably coated on glass or silica particles, thereby enabling it to be stably fixed to the substrate by chemical bonding. The polymer of the present invention may also be a copolymer of the betaine monomer of the present invention and a benzophenone (meth)acrylamide monomer having a benzophenone group in the side chain. The benzophenone groups of the copolymer can be crosslinked by reacting with each other using ultraviolet light. This can be used to prepare a gel of a zwitterionic polymer. Furthermore, the polymer of the present invention may be a copolymer of the betaine monomer of the present invention and dopamine (meth)acrylamide having a catechol group in the side chain. By using such a copolymer, the polymer of the present invention can be chemically fixed to various surfaces (including plastics that have been treated with ozone) having functional groups such as hydroxyl groups, thereby providing a highly stable coating.

[0070] (composition) The present invention also provides a composition containing the above-mentioned polymer. The amount of the polymer of the present invention contained in the composition of the present invention is not particularly limited, but from the viewpoint of easily imparting long-term hydrophilicity to the composition, and therefore to films and hydrogels obtained from this composition, it is preferably 1% by mass or more, more preferably 10% by mass or more, based on the total amount of the composition of the present invention. Furthermore, the amount of the polymer is not particularly limited, and can be 100% by mass or less, or even 90% by mass or less.

[0071] The composition of the present invention may further contain at least one solvent in addition to at least one of the above polymers. Examples of solvents include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, and propylene glycol; ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether and tetrahydrofuran; aromatic hydrocarbon compounds such as benzene, toluene, and xylene; aliphatic hydrocarbon compounds such as n-hexane; alicyclic hydrocarbon compounds such as cyclohexane; and acetates such as methyl acetate and ethyl acetate. However, the present invention is not limited to these examples. These solvents may be used alone or in combination.

[0072] The amount of the solvent contained in the composition of the present invention is not particularly limited, but is preferably 0.01 to 99.99 mass %, more preferably 0.1 to 99.9 mass %, based on the total amount of the composition of the present invention.

[0073] The composition of the present invention containing the above-mentioned polymer may be, for example, a coating composition, and preferably a coating composition for imparting functions such as biocompatibility, hydrophilicity, antifouling properties, protein adhesion resistance, cell adhesion resistance, and antifogging properties to the surface of a molded article. Biocompatibility refers to the property of having affinity with biological tissues and organs and not causing foreign body reactions or rejection reactions. One factor that contributes to high biocompatibility is high surface hydrophilicity, which can be maintained for a long period of time. More specifically, the body's recognition of an artificial material as a foreign body is due to the binding of proteins in the body to the material surface. Therefore, if the material surface has high water solubility, protein adsorption is prevented, resulting in high biocompatibility.

[0074] The composition of the present invention may contain other components in addition to the above-mentioned polymer and, if necessary, a solvent. The other components may be appropriately selected depending on the intended use of the composition of the present invention, and examples thereof include inorganic particles, organic particles, pigments, dyes, thickeners, surface tension agents, wettability modifiers, thixotropy regulators, surfactants, and antifoaming agents. The amount of the other components may also be appropriately adjusted depending on the intended use of the composition of the present invention and the functions of the other components, and is, for example, 0.01 to 99.99% by mass based on the composition of the present invention.

[0075] the surface of marine materials such as touch panels for liquid crystal displays and the like, and the inner walls of drainage pipes; the surface of marine materials such as the bottom of ships and aquaculture equipment; sensors; medical devices such as catheters, guide wires, endoscopes, artificial hearts, artificial kidneys, and artificial blood vessels; cosmetics used in skin care, makeup, hair care, hair styling, and the like; cosmetic tools and containers such as cosmetic puffs, cosmetic brushes, and compacts; colorants such as inkjet inks, pigment inks, and dye inks; fiber treatment agents for paper, cloth, and the like; polymer flocculants used in sewage treatment; surfactants used in detergents, etc.; hydrophilic primers for electroplating, and the like. In this case, hydrophilicity can be imparted to a substrate coated with the composition of the present invention or to a material mixed with the composition of the present invention, and as a result, functions such as biocompatibility, antifouling properties, protein adhesion prevention properties, cell adhesion prevention properties, antifogging properties, pollen adsorption prevention properties, airborne fine particle adhesion prevention properties, and virus adhesion prevention properties can be imparted to the surface of the substrate.

[0076] The composition of the present invention may be, for example, a composition for producing a film or membrane. From the composition for producing a film or membrane, a film or membrane containing the polymer of the present invention contained in the composition can be produced, and the film or membrane itself can be used as a material. Furthermore, by fixing the film or membrane to an object, for example by attaching it to the object, it is possible to make the object hydrophilic for a long period of time, even if it is difficult to directly apply the above-mentioned coating composition to the object.

[0077] (molded product) The present invention also provides a molded article coated with the polymer of the present invention. The method for coating a molded article with the polymer of the present invention is not particularly limited, but an example thereof is to apply the composition of the present invention to the surface of the molded article. The molded article coated with the polymer of the present invention has high hydrophilicity, and as a result, the molded article can be endowed with the above-mentioned functions.

[0078] Such molded articles include those mentioned above.

[0079] An example of a method for coating a molded article with the polymer of the present invention will be described. The polymer of the present invention can be coated on a molded article by dissolving the polymer of the present invention in any solvent and immersing the molded article in this solution for a certain period of time. For example, when the polymer of the present invention contains a structural unit derived from a hydrophilic monomer, its adsorption to hydrophilic surfaces can be enhanced, and when it contains a structural unit derived from a hydrophobic monomer, its adsorption to hydrophobic surfaces can be enhanced. Furthermore, when the polymer of the present invention further contains a structural unit derived from the betaine monomer of the present invention and at least one structural unit selected from the group consisting of a structural unit derived from a hydrophobic monomer, a structural unit derived from an alkoxysilyl group-containing monomer, and a structural unit derived from a crosslinking monomer having two or more crosslinking groups in its side chain, a strong coating can be formed by chemically or physically interacting with the surface of the substrate, and high hydrophilicity due to the betaine unit can also be imparted.

[0080] The polymer-coated molded article of the present invention may be used after being subjected to a treatment (hereinafter referred to as a priming treatment) in which the coated polymer is brought into contact with water, a phosphate buffer solution, or the like to orient hydrophilic moieties on the polymer surface. By performing a priming treatment before use, it is expected that the molded article will maintain its hydrophilicity for a long period of time from the beginning of use. [Example]

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0082] (Measurement of viscosity average molecular weight of polymer) The betaine polymer in this example is a polymer containing alkoxysilyl groups, so the average molecular weight was determined by viscosity measurement. The viscosity was measured using an Ubbelohte viscometer (Ubbelohte 0.005, manufactured by Shibata Scientific Co., Ltd.) in a viscosity measurement thermostatic bath (VB-3T, manufactured by Shibata Scientific Co., Ltd.) at 37°C. First, the intrinsic viscosity [η] of five betaine homopolymers (Mw = 3400, 7400, 11400, 23600, 32400) with known weight-average molecular weights (weight-average molecular weights obtained by GPC measurement) was measured. The weight-average molecular weight M and intrinsic viscosity [η] of each betaine homopolymer were calculated using the Mark-Houwink-Sakurada equation: [η] = KM α The K value and α value were determined (K = 6.88 × 10 -3 , α=0.627). Next, the intrinsic viscosity of the betaine polymer used in this example was measured, and the viscosity average molecular weight Mv was determined from the intrinsic viscosity obtained using the above K and α.

[0083] (Measurement of the contact angle of the coating film) <Water contact angle> The water contact angle of the coating film was measured by contacting a 1 μL water droplet with a coating piece described below, and after 15 seconds, the water contact angle was measured using the θ / 2 method using a Kyowa Interface Science Co., Ltd. "DMs-401" and image analysis software "FAMAS." <Air bubble contact angle> The bubble contact angle of the coating film was measured by immersing a coating piece described below in water for 1 hour, then contacting 1 μL of air bubbles with the coating piece in water, and measuring the bubble contact angle after 5 seconds using a DMs-401 instrument manufactured by Kyowa Interface Science Co., Ltd. and analysis software FAMAS using the θ / 2 method.

[0084] (Evaluation of protein adsorption) Nine pieces of each type of coated strip described below were prepared, each of which was immersed in water for priming, and then 500 μL of commercially available fetal bovine serum (FBS, 175012 (Chile), Nichirei Corporation) was applied to one side of the coated strip and allowed to stand in an incubator maintained at 37°C for 2 hours. After washing with phosphate buffer, the amount of adsorbed protein was measured using the bicinchoninic acid method (MicroBCA Protein Assay Kit, Thermo Fisher Scientific).

[0085] (Evaluation of cell adhesion) Six pieces of each type of coating described below were prepared, each of which was immersed in water for priming, and then immersed in a cell culture medium containing 10% FBS and left to stand until cells were seeded. Next, 3 × 10 fibroblasts (3T3 cells) that had been previously expanded and cultured were placed on the coated piece. 4 cells / cm 2 The cells were seeded at a density of 100 μg / ml and cultured for 24 hours under 5% CO2. After culture, the coated pieces were observed under an inverted microscope (IX71, Olympus Corporation) and images were taken with a CCD camera. To evaluate the number of cells adhering to the coated pieces, the coated pieces with cells adhering to them were immersed in cell culture medium containing 1 μg / mL of a nuclear stain (Hoechst 33342, Dojindo Laboratories) for 30 minutes, washed with phosphate buffer, and then observed under an inverted fluorescence microscope (IX71-Floro, Olympus Corporation) to count the number of adhered cells.

[0086] (Long-term stability evaluation of betaine polymer) Each coated piece described below was immersed in phosphate buffer at 37°C or 70°C for a predetermined period (1, 2, 4, 6, or 12 weeks). After immersion for the predetermined period, the coated piece was washed successively with phosphate buffer, pure water, and alcohol, and the number of adhered cells was evaluated using the cell adhesion evaluation method described above.

[0087] Example 1: Synthesis of betaine monomer 1 (sulfoisobutylbetaine acrylamide: SBBAm) A solution was prepared by dissolving 60 g of N,N-dimethylaminopropylacrylamide (DMAPAm) in 260 g of acetone. To this solution, 52 g of 2,4-butanesultone (BSu), an equimolar amount to DMAPAm, was added dropwise under ice cooling. After the dropwise addition, the mixture was stirred at room temperature for 24 hours, resulting in the formation of a white precipitate. The white precipitate was collected by filtration, dissolved in a certain amount of methanol, and reprecipitated by adding acetone. This purification process was repeated several times to obtain SBBAm. The yield of SBBAm was 92%, and the purity was over 97%. [ka]

[0088] Synthesis Example 1: Synthesis of Betaine Monomer 2 (Carboxymethyl Betaine: CMB) 116.5 g of sodium monochloroacetate was dissolved in 85 g of purified water and 15 g of isopropyl alcohol, and 0.69 g of 4-methoxyphenol was added and heated to 50°C. 157 g of N,N-dimethylaminoethyl methacrylate was added dropwise to the solution. After the addition was completed, the solution was stirred at 50-60°C for 7 hours. The reaction solution was then filtered, and the precipitated salt (potassium chloride) was removed, yielding 315.5 g of filtrate. This filtrate was diluted with 280 g of purified water, and the diluted solution was electrodialyzed using an electrodialysis apparatus (Yuasa Ionics Co., Ltd., MEDIMA™-220 (10 cell pairs, cation exchange membrane model number CR67, anion exchange membrane model number AR103)) under the following conditions. In the electrodialysis, 500 g of purified water was used as the salt recovery solution, and a 0.1 mol / L aqueous sodium sulfate solution was used as the electrode solution. The electrical conductivity of the sample solution before electrodialysis was 27,000 μS / cm. Electrodialysis was started at a voltage of 15 V, and after 4.5 hours of electrodialysis while maintaining the temperature of the diluted solution at 19-22°C, the electrical conductivity of the diluted solution became 9 μS / cm. The diluted solution after electrodialysis was concentrated under reduced pressure at 50°C, cooled to room temperature, and then 500 g of acetone was added to perform crystallization. The crystallization resulted in a slurry, so the crystals were filtered and separated. The separated product was dried at 40°C for 3 hours, yielding 178.1 g of white crystals of carboxymethyl betaine (CMB) (yield: 82.8%). [ka]

[0089] Example 2: Synthesis of Polymer 1 (PSBBAm) The SBBAm prepared in Example 1 and 3-methacryloxypropyltrimethoxysilane (MPTMS, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in trifluoroethanol (20 mL) together with 0.027 M azobisisobutyronitrile so that the molar ratio was 7:3 and the total monomer concentration was 0.4 M. Dissolved oxygen was then removed by purging with an inert gas, and the mixture was stirred at 80°C for 4 hours. After 4 hours, azobisisobutyronitrile was further added to the mixture to a concentration of 0.014 M, and the mixture was stirred for another 4 hours while maintaining the temperature at 80°C, yielding a polymer solution 1 containing polymer 1 having a structure represented by the following formula (1) [where m = 70, n = 30]. The viscosity-average molecular weight of the resulting polymer 1 was 1.5 x 10 4 It was. [ka]

[0090] Comparative Example 1: Synthesis of Polymer 2 (PCMB) Polymer solution 2 containing polymer 2 having the structure represented by the following formula (2) was obtained in the same manner as in Example 2, except that CMB prepared in Synthesis Example 1 was used instead of SBBAm prepared in Example 1 and the molar ratio of CMB:MPTMS was set to 9:1. The viscosity-average molecular weight of the obtained polymer 2 was 2.0 × 10 4 It was. [ka]

[0091] Comparative Example 2: Synthesis of Polymer 3 (PSPB) Polymer solution 3 containing polymer 3 having the structure represented by the following formula (3) was obtained in the same manner as in Example 2, except that 2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SPB, manufactured by Sigma-Aldrich) was used instead of SBBAm prepared in Example 1, and the molar ratio of SPB:MPTMS was set to 9:1. The viscosity-average molecular weight of the obtained polymer 3 was 2.0 × 10 4 It was. [ka]

[0092] Comparative Example 3: Synthesis of Polymer 4 (PMPC) Polymer solution 4 containing polymer 4 having the structure represented by the following formula (4) was obtained in the same manner as in Example 2, except that methacryloyloxyethyl phosphorylcholine (MPC, manufactured by Sigma-Aldrich) was used instead of SBBAm prepared in Example 1 and the molar ratio of MPC:MPTMS was set to 9:1. The viscosity-average molecular weight of the obtained polymer 4 was 4.6 × 10 4 It was. [ka]

[0093] Comparative Example 4: Synthesis of Polymer 5 Synthesis of SPBAm monomer: A solution of 60 g of N,N-dimethylaminopropylacrylamide (DMAPAm) in 260 g of acetone was prepared, and 47 g of 1,3-propane sultone (PSu), an equimolar amount to DMAPAm, was added dropwise to the solution under ice cooling. After the dropwise addition, the mixture was stirred at room temperature for 24 hours, resulting in the formation of a white precipitate. The white precipitate was collected by filtration, dissolved in a certain amount of methanol, and reprecipitated by adding acetone. This purification process was repeated several times to obtain SPBAm. The yield of SPBAm was 93%, and the purity was over 97%. [ka] Synthesis of Polymer 5: A polymer solution 5 containing polymer 5 having a structure represented by the following formula (5) was obtained in the same manner as in Example 2, except that the SPBAm produced as described above was used instead of the SBBAm produced in Example 1, and the molar ratio of SPBA:MPTMS was set to 7:3. The viscosity-average molecular weight of the obtained polymer 5 was 2.5 × 10 4 It was. [ka]

[0094] (Creating coated pieces) Each of the polymer solutions described above was diluted with trifluoroethanol (TFE) so that the polymer content was 1 wt%. The diluted polymer solution was maintained at 25°C, and a glass substrate measuring 2 cm in length, 2 cm in width, and 0.1 cm in thickness was immersed in the solution and left for 12 hours. The glass substrate surface was then washed with TFE, methanol, and acetone in that order, dried by nitrogen blowing, and then heated at 80°C for 12 hours to prepare a coated piece coated with each polymer.

[0095] The prepared coated pieces were evaluated for the water contact angle, air bubble contact angle, protein adsorption, and cell adhesion as described above. The results are shown in Tables 1 to 3. Microscopic images of each coated piece are shown in Figures 1 and 2. Furthermore, the cell adhesiveness of each coated specimen was evaluated after storage at 37°C for one year, and the results are shown in Table 4. Microscopic images of each coated specimen after one year are shown in Figure 3 (low magnification) and Figure 4 (high magnification).

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4]

[0100] Surfaces coated with the polymers of the present invention, which contain structural units derived from a betaine monomer having equivalent positive and negative charge moieties, with the positive and negative charge moieties linked by a branched alkylene group having 2 to 6 carbon atoms, exhibited low water contact angles, demonstrating the ability to hydrophilize polymer-coated surfaces. As a result, it was confirmed that adhesion of proteins and cells to the surface was easily inhibited. Furthermore, the long-term inhibition of cell adhesion demonstrated the ability to hydrophilize polymer-coated surfaces over a long period of time. In contrast, surfaces coated with polymers 2 to 4, which do not fall under the betaine monomers of the present invention and contain structural units derived from a monomer in which the positive and negative charge moieties are linked by a linear alkylene group, exhibited high water contact angles, demonstrating a low inhibitory effect on protein and cell adhesion. Furthermore, it was confirmed that surfaces coated with the polymers of the present invention were able to inhibit cell adhesion for up to one year.

[0101] Although the surface coated with the polymer of Comparative Example 4 showed a tendency to become hydrophilic over the long term compared to the surfaces coated with the polymers of the other Comparative Examples, it was confirmed that the effect of inhibiting the adhesion of proteins and cells was not sufficient.

[0102] Example 3: Synthesis of Homopolymer 1 (Homopolymer of SBBAm) The SBBAm prepared in Example 1 was dissolved in trifluoroethanol (20 mL) together with 0.027 M azobisisobutyronitrile to a monomer concentration of 0.4 M. Dissolved oxygen was then removed by purging with an inert gas, and the mixture was stirred at 80°C for 4 hours. After 4 hours, azobisisobutyronitrile was further added to a concentration of 0.014 M, and the mixture was stirred for another 4 hours while maintaining the temperature at 80°C, yielding a polymer solution containing SBBAm homopolymer 1. The weight-average molecular weight of the resulting homopolymer 1 was measured at a flow rate of 1.0 mL / min using trifluoroethanol as the eluent, a Wako Beads G-50 column, and a column and differential refractive index detector temperature of 40°C, yielding a value of 31,000. Polyethylene glycol was used as the molecular weight standard.

[0103] Comparative Example 5: Synthesis of Homopolymer 2 (Homopolymer of SPBAm) A polymer solution 6 containing a homopolymer 2 of SBBAm was obtained in the same manner as in Example 3, except that the SPBAm prepared in Comparative Example 4 was used instead of the SBBAm prepared in Example 1. The weight-average molecular weight of the obtained homopolymer 2 was measured in the same manner as for homopolymer 1 and was found to be 28,000.

[0104] The homopolymers 1 and 2 obtained in Example 3 and Comparative Example 5 were each dissolved in pure water at a concentration of 10 mg / mL to evaluate their solubility. As a result, the homopolymer obtained in Example 3 completely dissolved in pure water at the above concentration, forming a clear solution, whereas the homopolymer obtained in Comparative Example 5 did not completely dissolve at the above concentration, resulting in a cloudy solution. This is thought to be because in homopolymer 1, a polymer of the present invention, the positively charged moiety and the negatively charged moiety are linked by a branched alkylene group having 2 to 6 carbon atoms, which is thought to facilitate salt formation within the side chains of the polymer, resulting in increased solubility in water. In contrast, in homopolymer 2, in which the positively charged moiety and the negatively charged moiety are linked by an unbranched propylene group, the homopolymer is thought to be prone to aggregation due to electrostatic interactions between adjacent side chains of the homopolymer, resulting in reduced solubility in water. Therefore, the homopolymer described in Example 3 was also confirmed to have high hydrophilicity.

Claims

1. A betaine monomer having equivalent positively charged and negatively charged moieties, the positively charged and negatively charged moieties being linked by a branched alkylene group having 3 to 6 carbon atoms, Formula (1): 【Chemical 1】 [In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a linear or branched alkylene group having 1 to 4 carbon atoms, R 3 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, R 4 represents a branched alkylene group having 3 to 6 carbon atoms, X represents —NH— or —O—, and Y represents —SO 3 — or —COO — ] A betaine monomer represented by the formula:

2. R ４ represents an isobutylene group, and Y represents —SO ３ － 2. The betaine monomer of claim 1, wherein

3. A polymer comprising at least a constituent unit derived from the betaine monomer according to claim 1 or 2.

4. The polymer according to claim 3 , wherein the amount of constitutional units derived from the betaine monomer is 5% by mass or more based on the amount of all constitutional units contained in the polymer.

5. 5. The polymer according to claim 3 or 4, further comprising at least one type of structural unit selected from the group consisting of structural units derived from hydrophobic monomers, structural units derived from hydrophilic monomers, structural units derived from alkoxysilyl group-containing monomers, and structural units derived from crosslinkable monomers having two or more crosslinkable groups in their side chains.

6. A composition comprising the polymer according to any one of claims 3 to 5.

7. The composition of claim 6, which is a coating composition.

8. A molded article coated with the polymer according to any one of claims 3 to 5.

Images