JP4343002B2 - Thermosensitive gel composite - Google Patents

Description

  The present invention relates to a novel thermosensitive gel composite that swells and contracts in response to temperature.

  Since the temperature-sensitive gel changes in volume depending on the temperature, it can be used in various applications. For example, a drug-sustained release medium, or a bacterial culture medium, a temperature-sensitive material that can easily peel off a strain, Printing ink, temperature-sensitive light-shielding sheet, humidity sensor, temperature sensor, soil water retention material, suppression of gas hydrate formation in natural gas extraction, hair setting or hair spray additive, bathing agent, protective coating, temperature-sensitive separation material , Flocculants, sludge dewatering equipment, cryogens, water-based paints, recording media, shape memory materials, stripping and leveling aids for textile dyeing, auxiliaries in the photographic industry, pharmaceutical sustained release carriers, membrane production, water-soluble Applications such as coatings and filters for cigarettes can be mentioned.

  Conventionally, it is known that a thermosensitive gel is obtained by copolymerization with a crosslinking agent. For example, ammonium persulfate (initiated) is added to an aqueous solution of N-isopropylacrylamide and N, N′-methylenebisacrylamide (crosslinking agent). It is known that it can be obtained by a method (Non-Patent Document 1) in which the agent is added and copolymerized in a micropipette or paraffin oil.

However, the temperature responsiveness of the gel obtained by copolymerization with the crosslinking agent is not sufficient, and in order to increase the responsiveness, a method in which a surfactant is present in the gel (Non-patent Document 2), an anionic polymer Attempts have been made, for example, to cause the presence of sucrose in a gel (Non-patent Document 3). However, the response in temperature change is still insufficient, and further improvement in response has been demanded.
"Journal of Chemical Physics", Volume 81, 6379 (1984) "Journal of Polymer Science, Part B: Polymer Physics", Volume 34, 1597 (1996) “Macromolecules”, Volume 31, Page 6878 (1998)

  The subject of this invention is providing the thermosensitive gel composite excellent in the responsiveness with respect to a temperature change.

  The present invention comprises an anionic water-soluble polymer comprising a repeating structure derived from a monomer comprising an acid having an acid dissociation constant (hereinafter referred to as pKa) of 4 or less in an aqueous solution (25 ° C.), and a thermosensitive gel. A temperature-sensitive gel composite and a method for producing the same are provided.

  According to the present invention, a thermosensitive gel composite having a large volume change with temperature can be obtained.

[Thermosensitive gel composite]
The thermosensitive gel composite of the present invention comprises an anionic water-soluble polymer containing a repeating structure derived from a monomer having a pKa of 4 or less and a thermosensitive gel.

  The ratio of the anionic water-soluble polymer to the temperature-sensitive gel in the temperature-sensitive gel composite of the present invention is preferably temperature-sensitive gel / anionic water-soluble polymer (weight ratio) = 0.01-50. 1 to 10 are more preferable.

[Anionic water-soluble polymer]
The anionic water-soluble polymer used in the present invention includes a repeating structure derived from a monomer composed of an acid having a pKa of 4 or less.

  The monomer comprising an acid having a pKa of 4 or less is preferably at least one selected from a partial ester of phosphoric acid, a partial ester of sulfuric acid, phosphonic acid and sulfonic acid, and more preferably a partial ester of phosphoric acid and sulfonic acid.

  Examples of the partial ester of phosphoric acid include acid phosphooxyalkyl (meth) acrylates such as acid phosphooxyethyl (meth) acrylate and acid phosphooxydecyl (meth) acrylate (also referred to as (meth) acryloyloxydecyl phosphoric acid), 3 -Chloro-2-acid phosphooxypropyl (meth) acrylate, acid phosphooxypolyoxyethylene glycol mono (meth) acrylate, acid phosphooxypolyoxypropylene glycol mono (meth) acrylate, and the like, represented by the formula (II) Acid phosphooxyalkyl (meth) acrylates are preferred. These phosphoric acid partial esters all have a pKa of 4 or less.

[Wherein R ³ represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 20. ]
In the present specification, (meth) acrylate means acrylate or methacrylate, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylamide means acrylamide or methacrylamide.

  Examples of the sulfonic acid include styrene sulfonic acid (pKa = −2.8), m-aniline sulfonic acid (pKa = 3.74), p-aniline sulfonic acid (pKa = 3.23), 2- (meta ) A polymerizable unsaturated group such as acrylamido-2-alkyl (1 to 4 carbon atoms) propanesulfonic acid, more specifically 2-acrylamido-2-methylpropanesulfonic acid (pKa = -1.7). Examples thereof include sulfonic acid and / or a salt thereof.

  The anionic water-soluble polymer used in the present invention may be obtained by copolymerizing a monomer copolymerizable with the above monomer in addition to the above monomer.

  The molecular weight of the anionic water-soluble polymer used in the present invention is preferably in the range of 5000 to 300,000.

[Thermosensitive gel]
The temperature-sensitive gel used in the present invention is a gel-like material formed by crosslinking a part of the temperature-sensitive polymer, and has a property of becoming insoluble in water or an aqueous solution containing inorganic salts. It is.

  Examples of such a thermosensitive gel include those having a structure represented by the general formula (I) and partially crosslinked.

[Wherein, R represents a hydrogen atom or a methyl group. R ¹ and R ² are the same or different and each represents a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms, and R ¹ and R ² together form a ring. Also good. ]
In the general formula (I), examples of the substituent of the alkyl group represented by R ¹ and R ² include an alkoxy group having 1 to 10 carbon atoms and a heterocyclic group. The ring formed by combining R ¹ and R ² includes a ring having one nitrogen atom such as a pyrrolidine ring or a piperidine ring, a ring having two nitrogen atoms, a nitrogen atom and an oxygen atom. And the like.

  Specific examples of those having the structure represented by the general formula (I) include, for example, poly (N-ethyl (meth) acrylamide), poly (Nn-propyl (meth) acrylamide), poly (N-isopropyl ( (Meth) acrylamide), poly (N-cyclopropyl (meth) acrylamide), poly (N, N-dimethyl (meth) acrylamide), poly (N-ethyl-N-methyl (meth) acrylamide), poly (N-methyl) -Nn-propyl (meth) acrylamide), poly (N-isopropyl-N-methyl (meth) acrylamide), poly (N, N-diethyl (meth) acrylamide), poly (N- (meth) acryloylpyrrolidine) , Poly (N- (meth) acryloylpiperidine), poly (N-ethoxyethyl (meth) acrylamide), poly ( -Ethyl-N-methoxyethyl (meth) acrylamide), poly (N-methoxypropyl (meth) acrylamide), poly (N-ethoxypropyl (meth) acrylamide), poly (N-isopropoxypropyl (meth) acrylamide), Poly (N-methoxyethoxypropyl (meth) acrylamide), poly (N-tetrahydrofurfuryl (meth) acrylamide), poly (N-1-methyl-2-methoxyethyl (meth) acrylamide), poly (N-1- Methoxymethylpropyl (meth) acrylamide), poly [N- (2,2-dimethoxyethyl) -N-methyl (meth) acrylamide], poly [N- (1,3-dioxolan-2-yl) -N-methyl (Meth) acrylamide], poly [N-8- (meth) acryloyl 1,4-di Hexa-8- Azasupiro (4,5) decane], poly (N, N-dimethoxy (meth) acrylamide), poly (N- (meth) acryloyl morpholine) temperature-sensitive polymer, such as and the like. Among these, poly (N-alkyl (alkyl group having 1 to 10 carbon atoms) (meth) acrylamide) is preferable, and poly (N-isopropyl (meth) acrylamide) is more preferable.

  These temperature-sensitive polymers may be polymerized with a single monomer, but may be copolymerized with another copolymerizable monomer.

[Method for producing thermosensitive gel composite]
It does not specifically limit as a manufacturing method of the thermosensitive gel composite of this invention, A well-known method can be selected. For example, (a) a method of polymerizing a monomer that forms a temperature-sensitive polymer in the presence of an anionic water-soluble polymer and a crosslinking agent, and (b) an anion in the presence of a temperature-sensitive polymer and a crosslinking agent. And a method of polymerizing a monomer that forms a water-soluble water-soluble polymer, and the method (a) is preferred.

  In the method (a), an anionic water-soluble polymer is synthesized in advance by polymerization, and the resulting anionic water-soluble polymer and a monomer that forms a thermosensitive polymer in the presence of a crosslinking agent are polymerized. This is a method for obtaining a thermosensitive gel complex.

  The method for synthesizing the anionic water-soluble polymer is not particularly limited, and a monomer composed of an acid having a pKa of 4 or less and, if necessary, another copolymerizable monomer may be polymerized in the presence of a polymerization initiator. .

  The cross-linking agent used for gelation is not particularly limited, and examples thereof include dialdehydes such as glutaraldehyde, carbodiimides such as WSC (1-ethyl-3- (3-dimethylaminopropyl) carbodiimide), and denacol. Epoxys (manufactured by Nagase Sangyo), isocyanates such as hexamethylene diisocyanate, toluene diisocyanate, chloro-S-triazines such as cyanuric chloride, maleimide derivatives, acid chlorides, cyanogen bromide, excess Iodic acid, alcoholate, SPDP (N-succinimidyl 3- (2-pyridyldithio) propionate), methylenebis (meth) acrylamide, N, N′-diallyl (meth) acrylamide, N, N′-di (meth) acryloylimide , Triallyl formal, diallyl naphthalate, Tylene glycol di (meth) acrylate, various polyethylene glycol di (meth) acrylates, propylene glycol di (meth) acrylate, various polypropylene glycol di (meth) acrylates, 1,3-butylene glycol di (meth) acrylate, 1,4- Butylene glycol di (meth) acrylate, various polybutylene glycol di (meth) acrylate, glycerol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) And divinyl derivatives such as acrylate and divinylbenzene. A preferred cross-linking agent is a compound having a total of two or more (meth) acryloyl groups and / or allyl groups, and particularly preferably methylene bis (meth) acrylamide. The amount of the crosslinking agent used is preferably 0.1 to 10% by weight, more preferably 0.5 to 3% by weight, based on the monomer.

  The initiator used for the polymerization is not limited as long as it has the ability to initiate radical polymerization, but hydrogen peroxide, potassium persulfate, ammonium persulfate, benzoyl peroxide, t-butyl peroxide, t-butyl peroxide. Peroxides such as oxy-2-ethylhexanoate and butyl perbenzoate, 2,2'-azobis (2-methylpropionamidine) and its mineral salts, 2,2'-azobis (2-methylpropiononitrile) ), 4,4′-azobis (4-cyanovaleric acid) and alkali metal salts or ammonium salts thereof, 2,2′-azobis [2-hydroxymethyl (propiononitrile)], 2,2′-azobis [2- Methyl-N- [1,1′-bis (hydroxymethyl) -2-hydroxyethyl] propionamide], 2,2′-azobis [2-methyl-N- [1,1′-bis (hydroxymethyl) ethyl] ]Professional Onamide], 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (2-methylpropionamide) and other azo initiators, benzyl peroxide, Examples thereof include organic peroxides such as lauroyl peroxide. Radicals may be generated by irradiation with light or radiation. The addition amount of the initiator is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, based on the total amount of monomers.

  Further, redox polymerization may be performed by combining an initiator and a reducing agent. Examples of the reducing agent used include sulfites, hydrogen sulfites, salts such as iron, cobalt and copper, organic acids such as ascorbic acid, and organic amines such as tetramethylethylenediamine and aniline.

  Although superposition | polymerization temperature changes with kinds of initiator to be used, it is 4-90 degreeC normally, respectively, Preferably it is 40-80 degreeC. In redox polymerization, the temperature is preferably room temperature or lower, more preferably 10 to 0 ° C.

  In the following examples,% is% by weight unless otherwise specified.

Synthesis Example 1 (Synthesis of polymethacryloyloxydecyl phosphate)
Formula (III)

After completely dissolving 9.2 g of methacryloyloxydecyl phosphate represented by the following formula in 397 g of deionized water, 0.2 g of ammonium persulfate was added. Next, nitrogen gas was allowed to flow for 15 minutes while stirring at room temperature, 24 ml of tetramethylethylenediamine was added, and polymerization was performed while stirring for 1 hour. Thereafter, stirring was stopped and the mixture was allowed to stand at room temperature for 24 hours. The precipitate was filtered by suction, washed with deionized water, and vacuum dried at 60 ° C. to obtain 1.47 g of colorless polymethacryloyloxydecyl phosphate powder.

Example 1 (Synthesis of poly-N-isopropylacrylamide-polymethacryloyloxydecyl phosphate gel composite)
0.044 g of polymethacryloyloxydecyl phosphoric acid obtained in Synthesis Example 1, 0.93 g of 0.1M NaOH, formula (IV)

N-isopropylacrylamide 0.87 g and methylenebisacrylamide 0.014 g were completely dissolved in 8.5 g of deionized water. Thereafter, 0.015 g of ammonium persulfate was added, nitrogen gas was flowed at 4 ° C. for 15 minutes, 24 ml of tetramethylethylenediamine was added, and then injected into a capillary with a diameter of 1.3 mm to perform radical polymerization for 1 hour. A gel composite was obtained. The obtained gel composite was phase-transferred and removed from the capillary, washed thoroughly with deionized water, and cut to a length of about 5 mm.

Example 2 (Synthesis of poly N-isopropylacrylamide-polyaniline sulfonic acid gel composite)
In Example 1, a gel composite was synthesized in the same manner as in Example 1 except that 0.88 g of 5% polyanilinesulfonic acid aqueous solution (Aldrich) was used instead of polymethacryloyloxydecylphosphoric acid.

Comparative Example 1 (Synthesis of poly N-isopropylacrylamide gel)
A gel was prepared in the same manner as in Example 1 except that 0.044 g of polymethacryloyloxydecyl phosphate and 0.93 g of 0.1M NaOH were removed.

Test Example After the gel composite obtained in Examples 1 and 2 and the gel obtained in Comparative Example 1 were put in deionized exchange water and kept at 85 ° C., the volume Vc when the volume stopped changing was obtained. It was measured. Thereafter, the temperature V was changed in deionized water, and the volume V after holding at each temperature for 60 minutes was measured. Table 1 shows the volume change rate V / Vc at each temperature. A plot of volume change rate V / Vc versus temperature is shown in FIG.

It is the figure which plotted volume change rate V / Vc with respect to temperature about the gel composite obtained in Example 1 and 2, and the gel obtained in the comparative example 1. FIG.

Claims (4)

An anionic water-soluble polymer comprising a repeating structure derived from a monomer comprising an acid having an acid dissociation constant (pKa) in the first stage of 4 or less in an aqueous solution (25 ° C.) and a thermosensitive gel composite comprising a thermosensitive gel Because
A monomer composed of an acid having a pKa of 4 or less is a monomer represented by the general formula (II),

[Wherein R ³ represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 20. ]
A temperature-sensitive gel composite in which the temperature-sensitive gel has a structure represented by the general formula (I) and a part thereof is crosslinked .

[Wherein, R represents a hydrogen atom or a methyl group. R ¹ and R ² are the same or different and each represents a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms, and R ¹ and R ² together form a ring. Also good. ] The temperature-sensitive gel composite according to claim 1, which is obtained by synthesizing a temperature-sensitive gel by polymerization in the presence of an anionic water-soluble polymer. The method for producing a thermosensitive gel composite according to claim 1 or 2 , wherein a monomer that forms a thermosensitive polymer is polymerized in the presence of an anionic water-soluble polymer and a crosslinking agent. The ratio of the anionic water-soluble polymer to the temperature-sensitive gel in the temperature-sensitive gel composite is: temperature-sensitive gel / anionic water-soluble polymer (weight ratio) = 0.01-50. The thermosensitive gel composite according to 1 or 2.

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