JP7306252B2 - String-like micelle composition and hydrous gel - Google Patents

Description

The present invention relates to a cord-like micelle composition and a hydrous gel.

String-like micelles, which grow one-dimensionally and behave like macromolecular chains, have the ability to self-repair against chain breakage due to external energy (mechanical force, light, heat), and regulate rheology. From the viewpoint of , washability, foam stability, etc., its use in a wide range of applications, such as detergents, cosmetics, and cement in the civil engineering field, is attracting attention. In addition, the hydrous gel, which is composed of a network structure of string-like micelles, exhibits reversible viscoelastic behavior and other responsiveness to external stimuli such as temperature and pH, so it can be used as a smart material that can be used for various sensors. is also expected. As a system for forming cord-like micelles, a system in which an electrolyte component is added to a cationic surfactant in an aqueous medium has long been known. Non-Patent Document 1 describes, as a system for forming worm-like micelles, a worm-like micelle composition in which potassium bromide is added as an electrolyte to a cationic surfactant cetyltrimethylammonium bromide (CTAB). Document 1 discloses a string-like micelle composition in which sodium salicylate is added as an electrolyte to CTAB. Addition of an electrolyte component to the ionic surfactant reduces the electrostatic repulsion between the hydrophilic groups of the surfactant. Accompanying this, the curvature of the micelles also decreases, resulting in the formation of string-like micelles. On the other hand, it has been reported that worm-like micelles can be formed even in a system in which a surfactant with high hydrophilicity and a surfactant with low hydrophilicity are combined. Non-Patent Document 2 describes a string-like micelle composition in which sodium dodecyl sulfate is combined with polyoxyethylene dodecyl ether, and Non-Patent Document 3 describes a string-like micelle composition in which polyoxyethylene sorbitan monooleate is combined with polyoxyethylene alkyl ether. is described. The mixed system of surfactants has a different mechanism of string-like micelle formation from the electrolyte-added system mentioned above. changes its packing state to form worm-like micelles. However, many of the systems that form these worm-like micelles contain at least two or more compounds as essential components in addition to water. very few. On the other hand, from the viewpoint of avoiding adverse effects on various physical properties and complication of the system, there are many demands for cord-like micelles that do not favor the combined use of electrolyte components and multiple surfactants. Although some sucrose fatty acid esters and fluorosurfactants have been reported to form worm-like micelles in single-component systems, the temperature and concentration conditions for forming worm-like micelles are extremely limited. Therefore, it is difficult to obtain stable worm-like micelles at temperatures near room temperature. In view of the above, there is a demand for the development of a surfactant composition that is a single-component surfactant system and that can easily and stably form string-like micelles at a temperature near normal temperature.

Japanese Unexamined Patent Publication No. 2003-147330

F. Kern, P.; Lemarechal, S.; J. Candau, M.; E. Cates, Langmuir, 8, 437-440 (1992) D. P. Acharya, T.; Sato, M.; Kaneko, Y.; Singh, H. Kunieda, J.; Phys. Chem. B, 110, 754-760 (2006) D. Varade, K.; Ushiyama, L.; K. Shrestha, K.; Aramaki, J.; Colloid Interface Sci, 312, 489-497 (2007)

The problem to be solved by the present invention is that a single-component surfactant system can easily form string-like micelles at a temperature around normal temperature (5 to 35 ° C.), solubilizing oil-soluble substances. It is an object of the present invention to provide a string-like micelle composition that can be used as a reaction field using a string-like micelle as a template.

［一般式（１）中、Ｒは、炭素数１１～１５のアルキル基を表す。］ The present invention contains water and a surfactant (A) represented by the following general formula (1), and the content of the surfactant (A) is 1.2 to 1.2 parts per 100 parts by mass of water. It relates to a cord-like micelle composition that is 20.0 parts by mass.
General formula (1)

[In general formula (1), R represents an alkyl group having 11 to 15 carbon atoms. ]

The present invention also relates to the cord-like micelle composition, wherein the alkyl group of surfactant (A) is any one of dodecyl group, tridecyl group and tetradecyl group.

The present invention also relates to the above-mentioned cord-like micelle composition containing an oil-soluble substance (B) in the cord-like micelle.

The present invention also relates to the cord-like micelle composition, wherein the oil-soluble substance (B) contains a hydrophobic ethylenically unsaturated monomer.

Further, in the dynamic viscoelasticity measurement at 25° C., the storage elastic modulus G′ is smaller than the loss elastic modulus G″ at an angular frequency of 0.01 rad/s, and the storage elastic modulus is less than the loss elastic modulus G″ at an angular frequency of 1 rad/s. It relates to the above cord-like micelle composition, wherein G' is greater than the loss modulus G''.

The present invention also relates to a hydrous gel formed from the cord-like micelle composition.

The present invention also relates to a method for producing a polymer, comprising polymerizing a hydrophobic ethylenically unsaturated monomer in the cord-like micelle composition.

The worm-like micelle composition of the present invention is a single-component system, and can easily form worm-like micelles at a temperature around normal temperature (5 to 35 ° C.). is available. Therefore, by making use of its rheological behavior, it can be expected to be used in various applications such as body cleansing agents, cosmetics, medicines, and stimulation-responsive smart gel materials.

The figure which shows a Maxwell model. Graph showing schematic curves of G′(ω), G″(ω) in the Maxwell model. 4 is a graph showing the G' and G'' curves of the stringy micelle composition of Example 2. FIG. 2 is a graph showing a Cole-Cole plot (G″vsG′) of the cord-like micelle composition of Example 2. FIG.

［一般式（１）中、Ｒは、炭素数１１～１５のアルキル基を表す。］ <Surfactant (A)>
First, the surfactant (A) used in the present invention will be explained.
Surfactant (A) is a surfactant represented by general formula (1).
General formula (1)

[In general formula (1), R represents an alkyl group having 11 to 15 carbon atoms. ]

Examples of alkyl groups having 11 to 15 carbon atoms include linear or branched alkyl groups having 11 to 15 carbon atoms, and specifically, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, 2- Ethyldecyl group and the like can be mentioned.

The substituent R of the surfactant (A) is an alkyl group having 11 to 15 carbon atoms, preferably an alkyl group having 12 to 14 carbon atoms. Since the number of carbon atoms is in the range of 11 to 15, even a single-component system of the surfactant (A) can easily form cord-like micelles in an aqueous medium. Further, the surfactant (A) having 12 to 14 carbon atoms can stably obtain more fully developed worm-like micelles.

［一般式（２）中、Ｒは、炭素数１１～１５のアルキル基を表す。］ <Method for producing surfactant (A)>
Surfactant (A) can be obtained by a Michael addition reaction between an ethylenically unsaturated monomer represented by general formula (2) and pyrrolidine-2-carboxylic acid.
general formula (2)

[In general formula (2), R represents an alkyl group having 11 to 15 carbon atoms. ]

Examples of ethylenically unsaturated monomers represented by general formula (2) include undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate and the like.

Among pyrrolidine-2-carboxylic acids, pyrrolidine-2-carboxylic acid (L form), which is produced from natural raw materials, has excellent moisturizing properties among amino acids and is highly safe, so it is widely used. It is used in many foods and cosmetics.

A specific method for producing the surfactant (A) will be described below. It can be obtained by heating equimolar amounts of the ethylenically unsaturated monomer represented by the general formula (2) and pyrrolidine-2-carboxylic acid in a reaction solvent. The reaction solvent preferably contains an alcohol solvent. The content of the alcohol solvent in 100% by mass of the reaction solvent is preferably 40% by mass or more, more preferably 60% by mass or more. Among alcohol solvents, ethanol is preferred in consideration of the solubility of pyrrolidine-2-carboxylic acid, the safety of the solvent, and the ease of removal. Considering the reactivity, the concentration of the raw material components is preferably in the range of 20 to 70% by mass. The reaction temperature is preferably in the range of 50 to 90° C., and the reaction time is preferably in the range of 5 to 24 hours.

<Method for preparing string-like micelle composition>
The preparation of the cord-like micelle composition of the present invention will now be described. The cord-like micelle composition of the present invention can be obtained by containing water and the surfactant (A) of general formula (1) and mixing them. The content of surfactant (A) is 1.2 to 20.0 parts by mass, more preferably 5 to 20.0 parts by mass, per 100 parts by mass of water. The range of 1.2 to 20.0 parts by mass enables the surfactant (A) to form string-like micelles in water.

<Solubilization of oil-soluble substance (B) in cord-like micelles>
Furthermore, the cord-like micelle composition of the present invention can contain an oil-soluble substance (B). The oil-soluble substance (B) is incorporated into the core of the worm-like micelle or the palisade layer (between the alkyl groups of the surfactant) and solubilized in the worm-like micelle. For example, by adding a functional substance such as a perfume or a drug as an oil-soluble substance (B) to the worm-like micelle composition, it is possible to obtain a worm-like micelle solution or hydrous gel encapsulating the function-imparting component.

The oil-soluble substance (B) used herein refers to a water-insoluble compound having an octanol/water partition coefficient (Log Kow) of 1 or more. Log Kow is represented by the following formula 1, and is used as an index indicating whether a certain compound A is likely to be distributed into the water phase or the oil phase (octanol). Higher Log Kow indicates higher hydrophobicity, and conversely, lower Log Kow indicates higher hydrophilicity. The Log Kow of the oil-soluble substance (B) is preferably in the range of 1 to 16 from the viewpoint of being effectively incorporated into the wormlike micelles and solubilized. Log Kow can be calculated from experiments such as the flask shaking method and HPLC method, and can also be calculated from chemical structure simulations such as the YMB method (physical property estimation function) of the Hansen solubility parameter software HSPiP. Log Kow in the book is calculated by the YMB method of the Hansen solubility parameter software HSPiP.
[Formula 1]
Log Kow = Log (concentration of compound A in octanol phase/concentration of compound A in aqueous phase)

Oil-soluble substances (B) that can be solubilized in wormlike micelles include arachidic acid (Log Kow = 8.66), isostearic acid (Log Kow = 7.78), oleic acid (Log Kow = 7.54), capric acid ( Log Kow = 3.94), stearic acid (Log Kow = 8.01), sorbic acid (Log Kow = 1.33), palmitic acid (Log Kow = 3.72), behenic acid (Log Kow = 9.93), myristic acid ( Log Kow = 6.01), α-linolenic acid (Log Kow = 6.91), linoleic acid (Log Kow = 7.28), ricinoleic acid (Log Kow = 6.11) and other aliphatic carboxylic acids;

isostearyl palmitate (Log Kow = 14.57), hexadecyl isostearate (Log Kow = 15.28), isoamyl isovalerate (Log Kow = 3.58),
Ethyl oleate (Log Kow = 8.49), oleyl oleate (Log Kow = 15.40), diisopropyl sebacate (Log Kow = 5.24), diethyl sebacate (Log Kow = 4.45), isopropyl myristate (Log Kow = 7.35), octyldodecyl myristate (Log Kow = 14.41), cetyl myristate (Log Kow = 13.71), myristyl myristate (Log Kow = 12.63), propylene glycol monostearate (Log Kow = 7.44). ), hexyl laurate (Log Kow = 7.79), isopropyl linoleate (Log Kow = 7.38), ethyl linoleate (Log Kow = 7.01), and other aliphatic carboxylic acid esters;
Aliphatic carboxylic acid amides such as nonylic acid vanillylamide (Log Kow = 3.72);

isostearyl alcohol (Log Kow = 7.52), octyldodecanol (Log Kow = 7.74), oleyl alcohol (Log Kow = 7.67), steraryl alcohol (Log Kow = 6.94), cetanol (Log Kow = 6.94 ), hexyldecanol (Log Kow = 6.94), behenyl alcohol (Log Kow = 9.56), myristyl alcohol (Log Kow = 5.85), lauryl alcohol (Log Kow = 5.01);

campesterol (Log Kow = 9.63), cholesterol (Log Kow = 9.25), β-sitosterol (Log Kow = 10.11), brassicasterol (Log Kow = 9.62), lanosterol (Log Kow = 10.47), etc. sterols;
Monoterpenes such as α-terpineol (Log Kow = 3.03), β-terpineol (Log Kow = 2.97), γ-terpineol (Log Kow = 3.27), δ-terpineol (Log Kow = 3.06) alcohol;
isopimaric acid (Log Kow = 4.17), abitienoic acid (Log Kow = 5.08), parastric acid (Log Kow = 5.10), neoabithienic acid (Log Kow = 5.24), rosin acids;
Saturated hydrocarbons such as squalane (Log Kow = 7.42), eicosane (Log Kow = 10.23), hexahydrocumene (Log Kow = 2.69);
monoterpenes such as cymene (Log Kow = 3.82), limonene (Log Kow = 4.39), l-menthol (Log Kow = 2.89);
triterpenes such as squalene (Log Kow = 13.60);

Phenols such as cresol (Log Kow = 2.13);
Polyphenols such as curcumin (Log Kow = 2.07);
aromatic alcohols such as phenylethyl alcohol (Log Kow = 1.56);
aromatic carboxylic acids such as mefenamic acid (Log Kow = 3.69);
benzyl benzoate (Log Kow = 3.72), ethyl benzoate (Log Kow = 2.52),
Butyl p-oxybenzoate (Log Kow = 3.37), methyl p-oxybenzoate (Log Kow = 1.93), isopropyl p-oxybenzoate (Log Kow = 2.82), ethyl p-oxybenzoate (Log Kow = 2.43), methyl salicylate (Log Kow = 2.29), benzyl nicotinate (Log Kow = 2.94), diethyl phthalate (Log Kow = 3.23), dibutyl phthalate (Log Kow = 4.61), aromatic carboxylic acid esters such as butyl phthalyl butyl glycolate (Log Kow = 4.15) and flurbiprofen (Log Kow = 4.00);

Sulfonylureas such as glibenclamide (Log Kow = 3.31), tolbutamide (Log Kow = 2.08);
Fat-soluble vitamins such as tocopherol (Log Kow = 11.49);
indomethacin (Log Kow = 4.00), ursodeoxycholic acid (Log Kow = 3.74), paclitaxel (Log Kow = 2.24), pranlukast (Log Kow = 4.61), phenytoin (Log Kow = 1.88), Probucol (Log Kow = 11.71), Phenylbutazone (Log Kow = 3.37), Fenofibrate (Log Kow = 6.71), Furosemide (Log Kow = 1.45), Bezafibrate (Log Kow = 4.05), Lauromacro Compounds such as Gall (Log Kow = 4.69), Risperidone (Log Kow = 3.72), Riboflavin butyrate (Log Kow = 2.14), etc., include, but are not limited to.

Further, the cord-like micelle composition of the present invention contains a hydrophobic ethylenically unsaturated monomer as the oil-soluble substance (B), and the hydrophobic ethylenically unsaturated monomer in the cord-like micelle composition It is also possible to polymerize the body to produce a polymer. For example, a hydrophobic ethylenically unsaturated monomer and a photopolymerization initiator are solubilized in a string-like micelle and photopolymerized by light irradiation to obtain a polymer using the string-like micelle as a template. can be done. For the purpose of suppressing the morphological change of the cord-like micelles, the polymerization reaction is preferably carried out at room temperature or below.

Hydrophobic ethylenically unsaturated monomers that can be solubilized in the wormlike micelles include, for example, aromatic ethylenically unsaturated monomers such as styrene (Log Kow = 2.71);
Butyl acrylate (Log Kow = 2.23), butyl methacrylate (Log Kow = 2.79), 2-ethylhexyl acrylate (Log Kow = 4.05), ethyl methacrylate (Log Kow = 1.63), methyl methacrylate (Log Kow = 1 .13), linear or branched alkyl group-containing ethylenically unsaturated monomers such as propyl methacrylate (Log Kow = 2.16), t-butyl acrylate (Log Kow = 1.99);
Alicyclic alkyl group-containing ethylenically unsaturated monomers such as cyclohexyl methacrylate (Log Kow = 3.26);
fluorinated alkyl group-containing ethylenically unsaturated monomers such as trifluoroethyl methacrylate (Log Kow = 1.96) and trifluoroethyl acrylate (Log Kow = 1.41);

1,6-hexanediol diacrylate (Log Kow = 2.93), 1,9-nonanediol diacrylate (Log Kow = 4.62), 1,10-decanediol diacrylate (Log Kow = 4.88), tricyclo Decane dimethanol diacrylate (Log Kow = 4.16), dipentaerythritol hexaacrylate (Log Kow = 3.04), divinylbenzene (Log Kow = 3.52), pentaerythritol tetraacrylate (Log Kow = 1.77), trimethylol Examples include ethylenically unsaturated monomers having two or more ethylenically unsaturated groups such as propane triacrylate (Log Kow = 1.92).

Photoinitiators that can be solubilized in wormlike micelles include, for example, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene (Log Kow=8.02), 1-hydroxycyclohexylphenyl ketone ( Log Kow = 2.56), benzophenone (Log Kow = 3.01), methyl O-benzoylbenzoate (Log Kow = 2.01), dibenzyl ketone (Log Kow = 3.64), fluorenone (Log Kow = 3.42), 2,2'-diethoxyacetophenone (Log Kow = 1.9), 2-hydroxy-2-methylpropiophenone (Log Kow = 1.31), 2,2-dimethoxy-1,2-diphenylethan-1-one (Log Kow = 2.51), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Log Kow = 2.96), 1-hydroxycyclohexylphenyl ketone (Log Kow = 2 .56), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methylpropan-1-one (Log Kow = 2.95), thioxanthone (Log Kow = 3.9), 2-methylthioxanthone (Log Kow = 4.38), 2-isopropylthioxanthone (Log Kow = 5.22), 4-isopropylthioxanthone (Log Kow = 5.22), 2-chlorothioxanthone (Log Kow = 5.22). = 4.5), diethylthioxanthone (Log Kow = 5.82), and the like.

The oil-soluble substance (B) solubilized in the cord-like micelle is preferably contained in the range of 0.5 to 10 parts by mass with respect to 100 parts by mass of the surfactant (A). By containing it in the range of 0.5 to 10 parts by mass, it is possible to obtain a stable string-like micelle composition that does not easily lose its string-like shape even when the oil-soluble substance (B) is solubilized.

<Confirmation method of string-like micelle formation from dynamic viscoelastic behavior>
The viscoelastic behavior of wormlike micelles depends on their degree of entanglement, but well-developed wormlike micelles can be described by the Maxwell model with a single relaxation time. This is represented by a model in which one spring representing the elastic component and one dashpot representing the Newtonian viscous component are connected in series (Fig. 1). A liquid defined by a single Maxwell model has not been reported except for a system of wormlike micelle solution, and is used as a simple determination method for wormlike micelle formation as a behavior peculiar to wormlike micelles. A well-developed string-like micelle solution defined by the Maxwell model exhibits behavior corresponding to Equation 2 below when dynamic viscoelasticity measurements are performed using a stress-controlled rheometer.
[Formula 2]
^G '(ω) ⁼ _G0 ×( ^ω2τ2 )/(1+ ^ω2τ2 )
G"(ω)= _G0 ×(ωτ)/(1+ ^{ω2τ2 )}

Here, G′ (ω) (Pa) is the storage modulus, G″ (ω) (Pa) is the loss modulus, ω (rad/s) is the angular velocity (angular frequency) of the applied shear stress, τ (s) is the relaxation time, where the relaxation time τ (s) represents the time required for the initial value of the applied shear stress to reach 1/e (e is the base of natural logarithm = 2.718). ω) corresponds to the elastic modulus change at the site of energy storage, i.e., the spring portion, when shear stress is applied to the sample, and G″(ω) is the site of energy loss, i.e., the viscosity of the dashpot portion. Responds to rate changes. This behavior is schematically illustrated with ω on the horizontal axis and G′(ω) and G′(ω) on the vertical axis (FIG. 2). G ₀ in Equation 2 is represented by the flat elastic modulus of the plateau region of G′ obtained on the high frequency side. From Equation 1, the G' curve and the G'' curve intersect at ω=1/τ, where G'=G''. When dynamic viscoelastic behavior according to Equation 2 is shown, a Cole-Cole plot (G″vsG′ plot) is taken and the data overlaps in a semicircular shape centered on the G′ axis. That is, the Cole-Cole plot , if the plot can be drawn in the shape of a semicircle, it can be determined that the surfactant forms string-like micelles in water.

In the dynamic viscoelasticity measurement of the string-like micelle composition at 25 ° C., the storage elastic modulus G' is smaller than the loss elastic modulus G'' at an angular frequency of 0.01 rad/s (low frequency region) and at a frequency of 1 rad/s (high It is preferred that the storage modulus G′ is greater than the loss modulus G″ in the frequency domain). Satisfying the above conditions makes it possible to obtain more fully developed cord-like micelles.

Furthermore, when a Cole-Cole plot is created from G' and G'' obtained by dynamic viscoelasticity measurement, it is more preferable that the plot is in a semicircular shape centered on the G' axis. The plot is semicircular. It is possible to stably obtain more well-developed worm-like micelles.

<Confirmation method of string-like micelles by cryo-electron microscope>
If the worm-like micelles are not sufficiently developed, such as the Cole-Cole plot does not appear in a semicircle, and it is difficult to determine the formation of worm-like micelles only by dynamic viscoelasticity measurement, the worm-like micelle composition The presence or absence of cord-like micelles can be determined by directly observing a frozen object using a cryo-transmission electron microscope (cryo-TEM).

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the Examples below do not limit the scope of the present invention. In addition, "parts" in the examples are "mass parts" and "%"
represents "% by mass".

<Production of surfactant (A)>
[Production Example 1]
A reactor equipped with a reflux device and a stirrer was charged with 92.2 parts by mass of decyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 213.4 parts by mass of ethanol. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (3). The product was identified by ¹ H-NMR measurement using ECX-400P (400 MHz) manufactured by JEOL Ltd. (deuterated chloroform was used as a solvent for measurement), and it was confirmed that the product was the intended product.
compound (3)

[Production Example 2]
A reactor equipped with a reflux device and a stirrer was charged with 98.3 parts by mass of undecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 222.5 parts by mass of ethanol. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (4). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
compound (4)

[Production Example 3]
104.4 parts by mass of dodecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 231.6 parts by mass of ethanol were charged into a reactor equipped with a reflux device and a stirrer. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (5). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
Compound (5)

[Production Example 4]
110.5 parts by mass of tridecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 240.8 parts by mass of ethanol were charged into a reactor equipped with a reflux device and a stirrer. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (6). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
compound (6)

[Production Example 5]
116.6 parts by mass of tetradecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 249.6 parts by mass of ethanol were charged into a reactor equipped with a reflux device and a stirrer. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (7). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
compound (7)

[Production Example 6]
122.7 parts by mass of pentadecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 259.1 parts by mass of ethanol were charged into a reactor equipped with a reflux device and a stirrer. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (8). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
compound (8)

[Production Example 7]
A reactor equipped with a reflux device and a stirrer was charged with 128.8 parts by mass of hexadecyl acrylate, 50.0 parts by mass of pyrrolidine-2-carboxylic acid, and 268.2 parts by mass of ethanol. After raising the temperature while stirring, the mixture was reacted at 78° C. for 16 hours. The end point of the reaction was determined by the disappearance of the raw material spot by thin layer chromatography. After the reaction, the solvent was removed by drying under reduced pressure, and recrystallization was performed with acetone to obtain crystals of the surfactant represented by compound (9). The product was identified by ¹ H-NMR measurement in the same manner as in Production Example 1, and confirmed to be the desired product.
compound (9)

<Production of string-like micelle composition>
[Example 1]
18.0 parts of the surfactant produced in Production Example 2 was added to 100.0 parts of water and dissolved with stirring to prepare a string-like micelle composition. The formation of string-like micelles at 25° C. was confirmed by dynamic viscoelasticity measurement and cryo-electron microscope observation (details of the confirmation method are shown below).

[Examples 2 to 15, Comparative Examples 1 to 6]
Compositions were prepared in the same manner as in Example 1, except that the materials and formulations shown in Tables 1 and 2 were changed. However, the oil-soluble substance was added after the surfactant was dissolved in water and solubilized while stirring. In Comparative Examples 2 and 4, the surfactant was not completely dissolved in water and phase transition occurred, so evaluation of string-like micelle formation (dynamic viscoelasticity measurement, cryo-electron microscope observation) was abandoned. The compositions of Examples 14 and 15 and Comparative Example 6 were placed in a transparent glass cell having a size of 1 cm square and 5 cm high. Polymerization was carried out by further light irradiation under the conditions of cm ² and 20 minutes (accumulated light intensity: 57.6 J/cm ² ). The composition after photopolymerization was similarly subjected to dynamic viscoelasticity measurement and cryo-electron microscopy observation. The progress of the photopolymerization reaction was confirmed by FT-IR by the disappearance of the absorption peak (810 cm ^-1 ) derived from the unsaturated group of the ethylenically unsaturated monomer.

<Determination of string-like micelle formation>
In order to confirm the dynamic viscoelastic behavior of the prepared composition, dynamic viscoelasticity measurement by frequency dispersion was performed using a stress-controlled rheometer AR-2000 manufactured by TA Instruments. Regarding the obtained G′ and G″ curves, the storage elastic modulus G′ is smaller than the loss elastic modulus G″ at an angular frequency of 0.01 rad/s (low frequency region), and at an angular frequency of 1 rad/s (high frequency region ) to check whether the storage modulus G' is greater than the loss modulus G'' (conforming) or not (non-conforming), and further create a Cole-Cole plot (G''vsG' plot) to create a semicircular shape It was confirmed whether the plot of can be drawn (conforming) or not (nonconforming). Compositions with semicircular plots were judged to form well-developed worm-like micelles. In addition, in Examples 14 and 15 in which Examples 8 and 9 were photopolymerized, a phenomenon was confirmed in which the storage elastic modulus G' of the composition increased after the polymerization.

As an example, a graph of the G' curve and the G'' curve of the cord-like micelle composition of Example 2 is shown in ^FIG . "E-0m" respectively means "10 ^-m " (where m represents an integer). It can be seen that G″ is larger than G′ in the low frequency region, and as the frequency increases, the G″ curve intersects with the G′ curve, and the G″ shows a maximum value at the intersection point. It can be seen that G' is larger than G'' in the subsequent high-frequency region, indicating a flat region in which G' is constant. A Cole-Cole plot based on these G' and G'' is shown in FIG. 4. It can be seen that the data are distributed in a semicircular shape around G''=0 and G'=26.4. From the above, it was found that the composition of Example 2 followed a typical Maxwell model, and it was confirmed that well-developed cord-like micelles were formed.

In addition, using a cryo-transmission electron microscope (JEM-2100F (G5)) manufactured by JEOL Ltd., direct observation of the string-like micelle composition frozen at -170 ° C. with liquid ethane (abbreviated as "cryo-TEM observation" ) was performed, and the presence or absence of the formation of string-like micelles was confirmed. Cryo-TEM observation is useful for confirming the presence or absence of formation of string-like micelles when it is difficult to make a judgment only by dynamic viscoelasticity measurement.

Based on the above dynamic viscoelasticity measurement and cryo-TEM observation comprehensively, the formation of string-like micelles was determined. Tables 1 and 2 show the results. Comparative Examples 2 and 4, for which the evaluation was abandoned, were evaluated as x in the following evaluation results. Evaluation criteria are as follows. In the table, "Evaluation NG" means that the evaluation was not possible.
A: Formation of sufficiently developed string-like micelles was confirmed by dynamic viscoelasticity measurement and cryo-TEM observation. (Good)
O: Formation of string-like micelles was confirmed by cryo-TEM observation, although it could not be determined by dynamic viscoelasticity measurement. (within practical range)
x: Formation of string-like micelles could not be confirmed in either dynamic viscoelasticity measurement or cryo-TEM observation. (defective)

<Confirmation of formation of hydrous gel>
The composition prepared in a screw bottle was turned upside down and allowed to stand still for one day to check the fluidity of the composition. When the fluidity was poor and the composition did not settle, it was determined that a hydrous gel was formed. Evaluation criteria for photopolymerization are as follows.
O: A hydrous gel was formed.
x: No hydrous gel was formed.

From the above results, the formation of string-like micelles was observed at 25° C. in all of the compositions of Examples 1 to 15. Among them, in Examples 2 to 4 and 6 to 15, sufficiently developed cord-like micelles were formed so that the Cole-Cole plot in dynamic viscoelasticity measurement could be drawn in a semicircular shape, and the surfactant concentration was 5. % or more, transparent hydrous gels that lost fluidity were obtained. On the other hand, in the compositions of Comparative Examples 1 to 6, formation of string-like micelles was not observed. Further, in the compositions of Examples 14 and 15, in which the ethylenically unsaturated monomer and the photoinitiator were solubilized in the string-like micelle and photopolymerized, the transparency of the appearance and the appearance of the string-like micelle were maintained even after the photopolymerization. Since the storage modulus G' increased while maintaining the shape, it was suggested that a string-like polymer was obtained. On the other hand, with the composition of Comparative Example 6, no string-like polymer was obtained. There was no change in the storage modulus G' before and after polymerization, and no cord-like micelles were confirmed by cryo-TEM observation. From the above, the composition of the present invention can easily form worm-like micelles and stably solubilize oil-soluble substances, and can also be used as a reaction field using worm-like micelles as a template. Proven.

Claims (7)

It contains water and a surfactant (A) represented by the following general formula (1), and the content of the surfactant (A) is 1.2 to 20.0 mass parts per 100 mass parts of water. A string-like micelle composition that is part.
General formula (1)

[In general formula (1), R represents an alkyl group having 11 to 15 carbon atoms. ] 2. The cord-like micelle composition according to claim 1, wherein the alkyl group of the surfactant (A) is any one of dodecyl, tridecyl and tetradecyl groups. 3. The cord-like micelle composition according to claim 1, which contains an oil-soluble substance (B) in the cord-like micelle. 4. The cord-like micelle composition according to claim 3, wherein the oil-soluble substance (B) contains a hydrophobic ethylenically unsaturated monomer. In the dynamic viscoelasticity measurement at 25 ° C., the storage elastic modulus G' is smaller than the loss elastic modulus G'' at an angular frequency of 0.01 rad/s, and the storage elastic modulus G' is less than the loss elastic modulus at an angular frequency of 1 rad/s. The string-like micelle composition according to claims 1-4, which is larger than G″. A hydrous gel formed from the cord-like micelle composition according to any one of claims 1 to 5. A method for producing a polymer by polymerizing a hydrophobic ethylenically unsaturated monomer in the cord-like micelle composition according to claim 4.

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