JPH0443096B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention focuses on polymers into which anion exchange groups can be introduced.
This paper relates to a new method for producing an amphoteric ion exchanger from an original block copolymer consisting partly or entirely of polyA and polyB, a polymer with an aromatic ring. In recent years, materials with a multiphase structure have attracted attention as medical materials and materials for separation membranes because they can exhibit specific functions that homogeneous materials do not have. Among these, amphoteric ion exchangers, in which a micro-region with a cation exchange group and a micro-region with an anion exchange group exist simultaneously, have antithrombotic and cellular properties as medical materials due to the effects of both fixed charges. It is expected to have high affinity and high ion permeability as a separation membrane, and is expected to have a variety of uses in these fields. Production of an amphoteric ion exchanger having such a microscopic multiphase structure becomes possible by utilizing the microphase separation phenomenon in block copolymers. (for example,
In this case, after molding the original block copolymer whose component blocks are a polymer capable of introducing an anion exchange group and a polymer capable of introducing a cation exchange group, microphase separation is performed. This is done by introducing negative and positive ion exchange into each domain. Among these, the introduction of cation exchange groups is
This is done by sulfonating polymers with aromatic rings (e.g. polystyrene) or hydrolyzing polymers with ester groups (e.g. polymethyl methacrylate), but it is usually done using concentrated sulfuric acid, chlorosulfonic acid or fuming sulfuric acid. The reaction of sulfonation is radical, and there is a risk of deforming the material or disturbing the microstructure during the reaction.On the other hand, when monomers with polar groups such as ester groups are used, block copolymers with narrow molecular weight distributions may be formed. becomes difficult to obtain. The present invention was made with the aim of solving this problem and obtaining an amphoteric ion exchanger with excellent performance. In other words, after extensive research, the present inventors have developed an original block copolymer containing a part or all of the components of a polymer polyA into which an anion exchange group can be introduced and a polymer polyB having an aromatic ring. In order to obtain an amphoteric ion exchanger, two or more acid halide groups or one acid anhydride group are introduced into the polyA moiety in the presence of a Friedel-Crafts catalyst.
It has been found that an amphoteric ion exchanger in which the initial microstructure is maintained can be obtained by performing a step in which a polyfunctional compound having at least one or both of these or phosgene is applied. The present invention will be explained in detail below. Among the polymers constituting the original block copolymer used in the present invention, polymers into which an anion exchange membrane can be introduced
polyA is a polymer having a nitrogen-containing heterocycle or a tertiary amino group, for example, the following monomer group A
It is a polymer of monomers selected from. Monomer group A: vinylpyridines such as 2-vinylpyridine, 4-vinylpyridine, and 2-methyl-5-vinylpyridine, vinylpyrimidines, vinylquinolines, vinylcarbazoles, vinylimidazoles, o,m,p-vinylphenylalkylenedialkylamines represented by dialkylaminoalkyl acrylates represented by _{Dialkyl acrylamides represented} by is 2
Or 3. ) PolyA may also be a halomethylated polymer having an aromatic ring, such as polystyrene or poly(α-methylstyrene). In addition, among the polymers constituting the original block copolymer used in the present invention, the polymer polyB having an aromatic ring is used.
is, for example, a polymer of the following monomer group B. Monomer group B: Monomers represented by general formulas [1] to [3] (However, R ₄ is hydrogen, a methyl group or a vinyl group, R ₅ is hydrogen or an alkyl group having 1 to 12 carbon atoms, x is a halogen, and Ar is an aromatic ring.) The original block copolymer used in the present invention is ,above
In addition to polyA and polyB, the component block may include a polymer polyC that does not have an ion exchange functional group. The monomer constituting this polyC may be a diene monomer such as butadiene, isobrene, pentadiene, cyclohexadiene, or the like. Polymers composed of such diene monomers can be easily crosslinked by known methods, so if they are included in the component block of a block copolymer, the mechanical strength of the resulting amphoteric ion exchanger can be increased, and the micro- The phase structure can be stabilized. The Friedel-Crafts catalyst used in the present invention includes AlCl ₃ , SbCl ₅ , FeCl ₃ , TeCl ₂ , SnCl ₄ ,
_TiCl4 , _{BiCl3 , ZnCl2} , _BF3 , HF, _H2SO4 , _P2
These are compounds represented by chemical formulas such as O ₅ and H ₃ PO ₄ , and these are known as Lewis acids. The polyfunctional compound used in the present invention has an aromatic, saturated aliphatic, unsaturated aliphatic, or heterocyclic structure having 3 to 20 carbon atoms,
It is necessary to have two or more acid halide groups or one or more acid halide groups and one or more acid anhydride groups. The acid halide group mentioned here is
For example, carbonyl halide group (-COX) and sulfonyl halide group (SO ₂

【Formula】Ya Sulfonic anhydride group

[Formula]. However, X means a halogen atom, and is particularly preferably chlorine or bromine. In order to introduce a high density of cation exchange groups into a membrane, a polyfunctional compound having many of the above-mentioned functional groups is effective. Among the polyfunctional compounds described above, representative examples of those having no acid anhydride group are listed below.

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(However, R ₆ is -CH ₂ -, -O-, -SO ₂ -,

It is a bonding unit represented by [Formula]. ) Further, representative examples of polyfunctional compounds having an acid anhydride group used in the present invention are listed below.

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[Formula] In the present invention, an original block copolymer is used, in which a part or all of the components are a polymer polyA into which an anion exchange group can be introduced and a polymer polyB having an aromatic ring. A step of introducing an anion exchange group into the part to make this part a polymer polyA~ ⁺ having an anion exchange group, a step of crosslinking the molded product if necessary, in the presence of a Friedel-Crafts catalyst,
The desired amphoteric ion exchanger can be obtained by performing the step of converting the polyB moiety into a polymer ^polyB-- having a cation exchange group by applying the above-mentioned polyfunctional compound. However, the molding step needs to be performed before the crosslinking step and the step of introducing at least one of the ion exchange groups. As is well known, a block copolymer is composed of individual component blocks, forming a microphase-separated structure consisting of domains with a size defined by the length of the blocks. Typical forms of the phase formed at this time are lamellar, spherical, and rod-like, but this is determined by the composition of the block copolymer, the type of solvent used for molding, the temperature during molding, etc. . Therefore, the above method makes it possible to produce a material that simultaneously has a region with cation exchange groups and a region with anion exchange groups. Since this method does not involve a vigorous sulfonation reaction using concentrated sulfuric acid, chlorosulfonic acid, or fuming flowing acid, there is little risk of deforming the material or disturbing the initial microphase-separated structure. Examples of block copolymers used in the present invention include:
A polymer polyA that can introduce an anion exchange group and a polymer polyB that can introduce a cation exchange group are
(polyA−polyB) _o , (polyA−polyB)) − _o polyA,
polyB (-polyA-polyB) _o (n is an integer of 1 or more), or both of these polymers and a polymer polyC that does not introduce an ion exchange group are polyA-polyB-polyC , polyB−
polyA−polyC, polyA−polyC−polyB, polyA
−polyB−polyC−polyB, polyB−polyA−
polyC−polyA, polyA−polyB−polyC−
polyA, polyB−polyA−polyC−polyB, polyC
−polyA−polyB−polyC, polyC−polyA−
polyC−polyB, polyC−polyB−polyC−polyA,
polyA−polyB−polyC−polyB−polyA, polyA
−polyC−polyB−polyC−polyA, polyB−
polyA−polyC−polyA−polyB, polyB−polyC
−polyA−polyC−polyB, polyC−polyA−
polyC−polyB−polyC, (polyA−polyC−
polyB) _l , (polyA−polyB−polyC) _l , (polyB−
polyA−polyC) _l , (polyA−polyC−polyB−
PolyC) _l (polyB-polyC-polyA-polyC) _l (in each case, l is an integer of 2 or more). In addition, polyB, polyB-polyC type binary block copolymer grafted with polyA-polyC type binary block copolymer and polyA, polyC grafted with polyA-polyC type binary block copolymer.
PolyB grafted with a -polyA-polyC type ternary block copolymer, polyA grafted with a polyC-polyB-polyC type ternary block copolymer, etc. can also be used as the original block copolymer in the present invention. The original block copolymer used in the present invention must contain at least 5% by weight of a polymer polyB into which a cation exchange group can be introduced and a polymer polyA into which an anion exchange group can be introduced. If the content of each is less than this, the effect of the presence of both ion exchange regions will be significantly reduced in the final membrane. More preferably, the weight ratio of polyA and polyB is 20
% or more of the original block copolymer is preferably used. Furthermore, in order to increase the strength of the membrane after introducing ion-exchange groups, it is sufficient to contain 10% to 90% by weight of polymer polyC, which does not introduce ion-exchange groups, and more preferably 25% or more. Good. The molecular weights of the component polymers polyA, polyB and polyC constituting the block copolymer used in the present invention are preferably 10 ³ to ^{10 6} g/mol.
More preferably, it is 10 ⁴ to 5×10 ⁵ g/mol. As is generally well known, in a block copolymer, as the molecular weight decreases, the volume fraction of the compatible interface region generated at the boundary between two adjacent domains formed by microphase separation increases.
For this reason, in a sample with a low molecular weight, polyion complexes are likely to be formed, and the effect of having cation domains and anion domains simultaneously exist due to microphase separation is weakened. According to experimental facts published so far, it is clear that when the molecular weight of each block is less than 10 ³ g/mol, a clear phase-separated structure is hardly formed. On the other hand, if the molecular weight exceeds 10 ⁶ g/mol, the viscosity in the solid or solution state will be high, making molding difficult. Such a block copolymer can be produced, for example, by a living anionic polymerization method. In this case, the initiator may be known butyllithium (n, sec, tert, etc.), 2-methylbutyllithium, or sodium naphthalene,
Metal organic compounds such as sodium anthracene, α-methylstyrene tetramer sodium, α-methylstyrene tetramer sodium, and sodium biphenyl are used, and aromatic hydrocarbons, cyclic ethers, aliphatic hydrocarbons (generally benzene ,
Toluene, tetrahydrofuran, n-hexane,
Polymerization is carried out in a vacuum or an inert gas atmosphere such as nitrogen gas or argon gas. Furthermore, the above-mentioned graft block copolymer can be obtained by adding halomethylstyrene to a solution of a polymer having carbanion propagating terminals. In order to introduce an anion exchange group into a polymer block having a nitrogen-containing heterocycle or a tertiary amino group among the component blocks constituting the block copolymer, the block copolymer is treated with vapor of an alkyl halogen compound or in a container. Then, the nitrogen atom may be quaternized. This quaternization reaction is desirably carried out after the original block copolymer is molded and before the introduction of a cation exchange group into the polyB portion and the crosslinking reaction of the polyC portion. The alkyl halogen compound used here is C _P H _2p+1 X or X(CH ₂ ) _q X (p is 1
to 12, q is an integer from 2 to 12, and X is a bromine or iodine atom). In order to introduce an anion exchange group into a polymer block having a halomethyl group, dialkylamine or trialkylamine may be applied thereto. Cross-linking of the polydiene part (polyC part) is performed using peroxide, sulfur, sulfur monochloride, ultraviolet light, or AlCl ₃ ,
SbCl ₅ , FeCl ₃ , TeCl ₂ , SnCl ₄ , TiCl ₄ , BF ₃ , H ₂
This can be easily accomplished using a Friedel-Crafts catalyst such as SO ₄ . In the reaction for introducing the cation exchange group used in the present invention, a crosslinking reaction occurs in parallel. The density of the ion exchange group introduced and the crosslinking density are closely related to the type and concentration of the Friedel-Crafts catalyst used, the type and concentration of the polyfunctional compound, the type of solvent, the reaction temperature, and the reaction time. In order to suppress the crosslinking reaction and increase the density of the introduced cation exchange groups, the polyfunctional compound may be used in a sufficient excess amount relative to the active aromatic ring. In particular, in order to introduce high-density cation exchange groups into molded products such as films, the concentration of the polyfunctional compound in the reaction solution is preferably high, usually 1 to 30 g/dl, more preferably 5 to 30 g/dl.
It is 20g/dl. Furthermore, the greater the number of functional groups in the polyfunctional compound used, the easier it is for a high density of cation exchange groups to be incorporated. The amphoteric ion exchanger obtained by the above method is expected to be applied to the fields of separation membranes and medical materials that have high ion selectivity, as described above. For example, if used as a separation membrane, in addition to separating acids and salts,
Ion permeability can be controlled by adjusting pH. In addition, as a medical material, by creating a surface with a microstructure consisting of a weak electrolyte type cation exchange region and a strong electrolyte type anion exchange region, the adhesion between the material and cells can be improved. It is expected to be applied to culture and bioreactors. Hereinafter, the present invention will be explained with reference to Examples. In the examples, the amount of cation exchange groups introduced into the membrane was determined by immersing the film treated with 1N hydrochloric acid and washing with water in a 1 mol/aqueous sodium acetate solution, and adjusting the pH to approximately 8.0 with sodium hydroxide.
After leaving it for an hour, it was washed with water and then soaked in 1N hydrochloric acid for 24 hours.
This was done by quantifying sodium ions released from the membrane by immersion for a period of time using atomic absorption spectrometry. To measure the anion exchange group, the counter ion of the anion exchange group was converted to Cl ^- by immersing the film in a 1 mol/concentration potassium chloride aqueous solution for 24 hours, followed by washing with water and then dipping it in 1 mol/containing sodium nitrate solution. This was done by soaking the film for 24 hours and quantifying chloride ions released from the film using the known Holhardt method. Example 1 In benzene 1 purified through a sodium mirror, styrene, 4-vinylbenzyldimethylamine (hereinafter abbreviated as 4-VBDMA) and isoprene were mixed with 8 g of isoprene using 3.5 x 10 ^-4 mol of sec-butyllithium as an initiator. , 15 g of styrene, 8 g of isoprene, 25 g of 4-VBDM, and 8 g of isoprene were added in the order of 5 steps every 20 hours to perform polymerization, resulting in polyC-polyA-polyC-
A polyB-polyC type original block copolymer was obtained. A film with a thickness of about 60 μm was prepared by solvent evaporation on a mercury surface using a 5% by weight benzene solution of the obtained original block copolymer, stained with an osmic acid aqueous solution, and observed with a transmission electron microscope. , polystyrene layer (S), poly(4-
VBDMA) layer (A), and polyisoprene layer (I)
However, a three-phase lamellar structure in which repeating units of -I-S-I-A- were regularly arranged was confirmed. A film similarly prepared from the original block copolymer was quaternized in the A portion by treatment in methyl iodide vapor for 10 hours at room temperature, and then in a nitromethane solution of 20 volume percent sulfur monochloride at room temperature. The I part is crosslinked by soaking in for 3 hours,
Further, this film was treated under reflux for 10 hours using a mixture consisting of 10 g of benzenetricarboxylic acid chloride, an equimolar amount of aluminum chloride, and 100 ml of carbon disulfide to introduce a carboxylic acid group into the S part. After sequentially washing the obtained film with methanol, dilute aqueous sodium hydroxide solution, and dilute hydrochloric acid, the number of moles of carboxylic acid groups introduced into the film was measured by a titration method.
It was determined that 0.75 milliequivalents of carboxylic acid groups were present per g. Further, the anion exchange capacity was 0.77 milliequivalent per gram of dry membrane. Furthermore, when the film subjected to the above chemical treatment was stained with osmium tetroxide and observed under a transmission electron microscope, it was found that the initial lamellar structure was basically maintained. Example 2 A 60 μm thick film obtained by casting the original block copolymer obtained in Example 1 from a benzene solution was subjected to quaternization of the A part and crosslinking of the I part in the same manner as in Example 1. After that, the mixture was treated under reflux for 5 hours using a mixture consisting of 4 g of anhydrous trimellitic acid chloride, anhydrous aluminum chloride in a molar amount 1.5 times that amount, and 100 ml of carbon disulfide. Furthermore, after washing with methanol, the film was treated with dilute aqueous sodium hydroxide solution and dilute hydrochloric acid, and the amount of carboxylic acid groups in the film was determined, and it was found that 1.1 milliequivalents were present per gram of dry film. Further, the anion exchange capacity was 0.76 milliequivalent per gram of dry membrane. Example 3 A film with a thickness of 60 μm obtained by casting the original block copolymer obtained in Example 1 from a benzene solution was subjected to quaternization of the A part and crosslinking of the I part in the same manner as in Example 1. . The obtained film was immersed in 100 ml of carbon disulfide, 13 g of anhydrous aluminum chloride was added thereto, the temperature was maintained at 4° C., about 20 g of phosgene was gradually introduced over 3 hours, and the film was left to stand for 4 days. After cleaning the film with carbon disulfide and acetone,
When the film was treated with a dilute aqueous sodium hydroxide solution and the amount of carboxylic acid groups introduced into the film was quantified, it was found that 0.26 milliequivalents were present per gram of dry film. Further, the anion exchange capacity of this membrane was 0.81 milliequivalent per gram of dry membrane. Example 4 In addition to changing benzenetricarboxylic acid chloride to 5-sulfonylisophthalic acid chloride in Example 1, an amphoteric ion exchange membrane was prepared in the same manner as in Example 1, and the cation exchange capacity and The anion exchange capacities were 0.76 meq and 0.73 meq per gram of dry membrane, respectively. Example 5 Benzene 1 purified through sodium mirror
After adding 4.5×10 ^-4 mol of n-butyllithium, 30 g of p-tert-butoxystyrene and butadiene were added.
By adding 42 g and 28 g of 4-VBDMA in this order every 20 hours, a polyA-polyC-polyB type original block copolymer was obtained. A film with a thickness of approximately 60 μm prepared from a 5% by weight benzene solution of the resulting original block copolymer on a mercury surface by solvent evaporation was stained with an aqueous osmic acid solution and observed with a transmission electron microscope. layer
(B), poly(4-VBDMA) layer (A), and poly(para-tert-butoxystyrene) layer (S′)
A three-phase lamellar structure arranged by repeating units of BS'BA- was confirmed. Poly(( 4-VBDMA) after quaternization, 1% by weight
4 in n-hexane solution of stannic chloride at room temperature.
The film was immersed in acetone and concentrated hydrobromic acid was added dropwise to crosslink the polybutadiene portion by immersion for a period of time, and then to remove the tert-butyl group from the poly(p-tert-butoxystyrene) portion. 20
Reflux was performed for an hour. Furthermore, 13 g of anhydrous aluminum chloride and 100 ml of carbon disulfide were used to introduce a carboxylic acid group into the hydroxystyrene portion.
The temperature was maintained at 4°C, and about 20g of phosgene was gradually introduced into the mixture over a period of 3 hours.
It was left at that temperature for 20 hours. This film was immersed in a dilute aqueous sodium hydroxide solution for several hours, then washed with acetone and water, and the amount of carboxylic acid groups introduced into the film was quantified. The amount of carboxylic acid groups present was 0.85 milliequivalent per gram of dry film. I understood. In addition, the anion exchange capacity is per gram of dry membrane.
It was 1.3 milliequivalent. Example 6 In the same manner as in Example 5, 0.3 g of a 60 μm thick film obtained by casting the original block copolymer obtained in Example 5 from a benzene solution was coated with poly(4-
VBDMA) moiety was quaternized, the polybutadiene moiety was crosslinked, and the tert-butyl group was eliminated. The film was then treated with 150 ml of carbon disulfide, 5 g of citric acid chloride, and citric acid chloride.
It was immersed in a mixture consisting of 1.2 times the molar amount of anhydrous aluminum chloride and reacted at 30°C for 3 hours to introduce a carboxylic acid group into the poly(p-hydroxystyrene) portion. After soaking the film in a dilute aqueous sodium hydroxide solution for several hours, the film was washed with acetone and water, and the amount of carboxylic acid groups introduced into the film was quantified, and it was found that 1.5 milliequivalents of carboxylic acid groups were present per gram of dry film. I understood. Further, the anion exchange capacity was 1.1 milliequivalent per gram of dry membrane. Example 7 In the same manner as in Example 5, 0.3 g of a 60 μm thick film obtained by casting the original block copolymer obtained in Example 5 from a benzene solution was coated with poly(4-
VBDMA) moiety was quaternized, the polybutadiene moiety was crosslinked, and the tert-butyl group was eliminated. Subsequently, the film was immersed in a mixture consisting of 150 ml of carbon disulfide, 10 g of succinic anhydride, and 25 g of anhydrous aluminum chloride, and a reaction was carried out at 30°C for 12 hours to add carboxylic acid groups to the poly(p-hydroxystyrene) moiety. introduced. The film was washed with a dilute aqueous sodium hydroxide solution and acetone, then washed with acetone and water, and the amount of carboxylic acid groups introduced into the film was determined.
It was found that 0.65 milliequivalents were present per day. Further, the anion exchange capacity was 1.3 milliequivalents per gram of dry membrane.

Claims (1)

[Scope of Claims] 1 Introduction of an anion exchange group into an original block copolymer whose components include a polymer polyA into which an anion exchange group can be introduced and a polymer polyB having an aromatic ring as part or all of the components. reaction and cation exchange in the presence of a Friedel-Crafts catalyst by the action of a polyfunctional compound having two or more acid halide groups, one or more acid anhydride groups, or one or more of both, or phosgene. A method for producing an amphoteric ion exchanger, which comprises performing a group introduction reaction. 2. The method for producing an amphoteric ion exchanger according to claim 1, wherein the original block copolymer contains 30% or more by weight of a polymer polyC made of a diene monomer. 3. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the polymeric polyC portion made of a diene monomer is crosslinked before introducing the cation exchange group. 4. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the Friedel-Crafts catalyst is selected from Lewis acids. 5 Lewis acids include AlCl ₃ , SbCl ₅ , FeCl ₃ , TeCl ₂ ,
_SnCl4 , _TiCl4 , _BiCl3 , _ZnCl2 , _BF3 , HF, _H2
Claim 4 which is SO ₄ , P ₂ O ₅ , H ₃ PO ₄
The method for producing the amphoteric ion exchanger described in Section 1. 6. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the acid halide group is a carbonyl halide group. 7. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the acid halide group is a sulfonyl halide group. 8. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the acid anhydride group is a carboxylic acid anhydride group. 9. The method for producing an amphoteric ion exchanger according to claim 1 or 2, wherein the acid anhydride group is a sulfonic acid anhydride group.