JP2007332309A - Photoresponsive composition, method and system for controlling photoviscoelasticity and use of photoresponsive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoresponsive composition which exhibits a large variation of viscoelasticity through irradiation with light, and has such advantages as capability of reducing a cost since constituted of few components; and to provide a method and system of controlling photoviscoelasticity with use of the composition. <P>SOLUTION: The composition contains at least either cinnamic acid or its salt, and a quaternary ammonium salt. The method and system of controlling photoviscoelasticity involves a photoirradiation process of irradiating the composition with light having a wavelength to cause photoresponse of cinnamic acid or its salt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photoresponsive composition, a photoviscoelasticity control method using the composition, a photoviscoelasticity control system, and use of the photoresponsive composition.

  Surfactants form various molecular aggregates such as micelles and vesicles in water under conditions such as concentration, temperature, and salt addition. Among them, when string-like micelles are formed, it is known that high viscoelasticity is exhibited due to the three-dimensional entanglement between the string-like micelles. If solution viscoelasticity can be controlled by reversibly controlling the formation / disintegration of string-like micelles by an external stimulus, application to the release control of fragrances, drugs and the like is expected.

  For example, it is known that when sodium salicylate is added to an aqueous solution of cetyltrimethylammonium bromide (CTAB), which is a cationic surfactant, the viscosity of the solution increases, resulting in an aqueous solution exhibiting viscoelastic behavior. This is because CTAB and sodium salicylate form string micelles in an aqueous solution, and these string micelles have viscoelasticity.

  Regarding the formation of this string-like micelle structure, studies on its structural analysis and solution properties have been advanced, and many reports have been made. Practical examinations that take advantage of this property have been reported to the extent that there are thermal fluids in district cooling and heating systems that make use of the pipe resistance reduction, but only for their use. This is because an aqueous solution having an increased viscosity is difficult to handle and is often used for a limited time. On the other hand, if the breakage and re-formation of the string-like micelle structure can be freely controlled, it has been expected that various applications using the aqueous solution can be expected.

  As a method for controlling the string micelle structure in the solution, a method for controlling by adding a new substance to the solution system, a method for controlling by adding heat to the solution, an oxidation / reduction reaction by an electrochemical reaction A method of controlling by the above (Patent Document 2 below) and the like are known.

  However, the method of adding a new substance to the solution may affect the properties other than the viscoelasticity of the solution and may not be preferable, and there may be a problem that the change is not reversible. Further, the method of applying heat to the solution may affect the characteristics of the substance or the entire solution when a substance that is weak against heat exists in the solution system. Moreover, since it is specified that the temperature of the solution must be increased by applying heat, the application may be limited. Furthermore, it may be difficult to heat the solution depending on the environment in which it is used, such as a test in outer space or a test in the deep sea. In the method of controlling by oxidation / reduction reaction by electrochemical reaction, it may be difficult to perform oxidation / reduction by electrochemical reaction depending on the environment used, such as a test in outer space and a test in deep sea. In addition, when a substance that easily undergoes a redox reaction exists in the solution system, it may affect the characteristics of the substance or the entire solution. Moreover, since it will be specified, such as having to make it the conditions for causing an electrochemical reaction, the use may also be limited.

  In Patent Document 1 below, the viscoelastic behavior of an aqueous solution in which such a cord-like micelle structure is formed is controlled more easily and reversibly than means such as addition of a third component, heating, and oxidation-reduction by an electrochemical reaction. Technology that can freely control the disassembly and re-formation of the string-like micelle structure formed in the solution by irradiating light, and a photoresponsive aqueous solution corresponding to this Have been reported.

  In the following Patent Document 1, a technique for freely controlling the disassembly and re-formation of the string-like micelle structure formed in the solution by irradiating light and a photoresponsive composition corresponding thereto are disclosed. .

  The photoresponsive composition described in Patent Document 1 is a photoresponsive composition prepared by mixing a quaternary ammonium salt, a micelle formation inducing substance, and a quaternary ammonium salt of an azobenzene-based compound in water. is there. As a specific example, a cationic surfactant known to exhibit high viscoelasticity due to the formation of string micelles: a photoresponsive substance (trans / cis photoisomerism) in an aqueous solution of cetyltrimethylammonium bromide (CTAB) / sodium salicylate (NaSal). For example, reversible viscosity control by light of a solution to which an azobenzene-modified surfactant (4-alkylbenzene-4 ′-(oxyethyl) trimethylammonium bromide (AZTMA)) is added as a chemical reaction substance is disclosed.

  According to the technique described in Patent Document 1, the viscosity of a solution can be reduced by a very simple operation of light irradiation without taking the steps of adding a third component, heating, and oxidation-reduction by an electrochemical reaction as in the prior art. It has been reported that elastic behavior and the like can be freely controlled.

JP 2003-147330 A JP-A-2005-290203

  However, in Patent Document 1, a system that forms a string-like micelle containing a quaternary ammonium salt and a micelle formation inducing substance is used as a photoresponsive substance (trans / cis photoisomerization reactive substance). A photo-responsive composition is formed by adding a quaternary ammonium salt, and a string-like micelle is formed by utilizing the trans / cis photoisomerization reaction of the photo-responsive substance by irradiating the photo-responsive composition with light. Viscosity is controlled by reducing the viscoelasticity by forming and increasing the viscosity, but quaternary ammonium salts of azobenzene compounds as photoresponsive substances are usually expensive. There is no market distribution so much. Further, since no photoresponsive substance is employed as the quaternary ammonium salt or micelle formation inducing substance, the viscosity change is often small.

  The present invention has been made in view of the above-mentioned problems and the like, and is a photoresponsive composition having advantages such as a higher viscoelasticity change rate due to light irradiation, less components and reduced cost, The main purpose is to provide a photoviscoelasticity control method, a photoviscoelasticity control system and a photoresponsive composition using the same.

  The present invention is a photoresponsive composition containing at least one of cinnamic acid and cinnamic acid salt and a quaternary ammonium salt.

  The photoresponsive composition, wherein the quaternary ammonium salt is at least from the group consisting of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetylpyridinium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride and octadecylpyridinium chloride. It is preferable that one or more are selected.

  In the photoresponsive composition, it is preferable that the cinnamate contains sodium cinnamate.

  The photoresponsive composition may further contain a quaternary ammonium salt of an azobenzene compound.

  It is preferable that the photoresponsive composition contains an emission that is released due to a decrease in viscoelasticity due to photoresponse.

  Further, the present invention is a photoviscoelasticity control method, comprising a light irradiation step of irradiating the light-responsive composition with light having a wavelength that causes a photoresponse of cinnamic acid or cinnamic acid salt. Features.

  In the photoviscoelasticity control method, it is preferable that the wavelength light causing the photoresponse is wavelength light corresponding to a photoisomerization reaction.

  In the photoviscoelasticity control method, it is preferable that the light irradiation step includes a photoviscoelasticity reduction step of reducing viscoelasticity by light irradiation. Furthermore, it is preferable to include a photo-viscoelasticity increasing step of increasing viscoelasticity by light irradiation after the viscoelasticity reduction.

  In the photoviscoelasticity control method, it is preferable that an external substance is taken in by the photoviscoelasticity increasing step.

  In the photoviscoelasticity control method, the external substance is preferably a harmful substance.

  In addition, the present invention is a photoviscoelasticity control system, and includes a light control device that performs photoviscoelasticity control by the photoviscoelasticity control method described above. That is, the photoresponsive composition includes a light irradiation device that irradiates the photoresponsive composition with light having a wavelength that causes a photoresponse of cinnamic acid or cinnamic acid salt.

  In the photoviscoelasticity control system, it is preferable that the wavelength light that causes the photoresponse is wavelength light corresponding to a photoisomerization reaction.

  The light viscoelasticity control system, wherein the light irradiation device includes a light viscoelasticity reduction device that decreases viscoelasticity by light irradiation, and a photoviscoelasticity increase device that increases viscoelasticity by light irradiation after the viscoelasticity decrease. It is preferable to include

  In the photoviscoelasticity control system, the photoresponsive composition includes an emission that is released by a decrease in viscoelasticity due to an optical response, and the emission is released by a decrease in viscoelasticity by the photoviscoelasticity reduction device. It is preferable to take in again the discharge | released discharge | released by the viscosity increase by a photoviscoelasticity increase apparatus.

  The present invention is also characterized by the use of a photoresponsive composition comprising at least one of cinnamic acid and cinnamic acid salt and quaternary ammonium salt for photoviscoelastic control.

  The present invention provides a photoresponsive composition having advantages such as a higher rate of change in viscoelasticity due to light irradiation, fewer constituent components, and reduced cost, a photoviscoelasticity control method using the same, a photoviscoelasticity control system, Use of the photoresponsive composition can be provided.

  The present inventor obtained the knowledge that if the added salt (micelle formation-inducing substance) necessary for the formation of string-like micelles is changed to one that undergoes photoisomerization, an even greater change in viscosity can be expected. As a result, the structure is surprisingly similar to NaSal and functions as a micelle formation-inducing substance. In addition, it responds to light in solution (in this specification, a reaction related to the disassembly and control of micelles, which is cis-trans If viscosity control by light irradiation is performed on a composition containing cinnamic acid or cinnamate, which includes a photoisomerization reaction and a photodimerization reaction), a large viscoelastic change rate can be expected. Thus, the present inventors have found that control by viscosity change can be performed without using a quaternary ammonium salt of an azobenzene-based compound, which is a photoresponsive substance that cannot be said to have great market distribution. Cinnamic acid or cinnamate basically has a large market distribution and is often inexpensive, and the price of the photoresponsive composition can be reduced.

  The photoresponsive composition according to this embodiment will be described below. In addition, this embodiment is only one form for implementing this invention, and this invention is not limited by this embodiment.

"Photoresponsive composition"
The photoresponsive composition according to this embodiment is prepared by mixing quaternary ammonium salt and cinnamic acid or cinnamic acid salt as a micelle formation inducing substance in a liquid.

  The quaternary ammonium salt used in the present invention is not particularly limited as long as it forms a string-like micelle structure together with a micelle formation inducing substance such as a cationic surfactant. For example, the quaternary ammonium salt is represented by the following formula (I). And quaternary ammonium salts.

  Preferred examples of the quaternary ammonium salt include alkyl quaternary ammonium salts and long-chain alkyltrimethylammonium bromide quaternary ammonium salts. Specifically, cetyltrimethylammonium bromide (CTAB), cetyltrimethyl Ammonium chloride, cetylpyridinium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecylpyridinium chloride and the like can be mentioned.

  The micelle formation-inducing substance used in the present embodiment is cinnamic acid or cinnamic acid that can form a string-like micelle structure or the like in an aqueous solution together with the quaternary ammonium salt and can at least reduce viscoelasticity by a photoresponsive reaction. There is no particular limitation as long as it is a salt. The micelles to be formed are preferably cord-like micelles from the viewpoint of viscoelasticity control, and will be described below as examples. However, the micelles are not particularly limited as long as the micelles give a change in viscoelasticity to the solution.

  Specific examples of micelle formation inducing substances include cinnamic acid, sodium cinnamate, potassium cinnamate, trans-cinnamic acid, α-methylcinnamic acid, 2-methylcinnamic acid ( 2-methylcinnamic acid), 2-fluorocinnamic acid, 2- (trifluoromethyl) cinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid, 2-chlorocinnamic acid -Methoxycinnamic acid (2-methoxycinnamic acid), 2-hydroxycinnamic acid (2-hydroxycinnamic acid), 2-nitrocinnamic acid (2-nit ocinamic acid), 2-carboxycinnamic acid, trans-3-fluorocinnamic acid, 3- (trifluoromethyl) cinnamic acid (3- (trifluoromethyl) cinnamic acid 3-chlorocinnamic acid, 3-bromocinnamic acid, 3-methoxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3-hydroxycinnamic acid, 3 -Nitrocinnamic acid, 4-methylcinnamic acid (4-methylcinnamic acid) cid), 4-fluorocinnamic acid, trans-4- (trifluoromethyl) -cinnamic acid (trans-4- (trifluoromethyl) -cinnamic acid), 4-chlorocinnamic acid (4-chlorocinnamic acid) ), 4-bromocinnamic acid, 4-methoxycinnamic acid, 4-hydroxycinnamic acid, 4-nitrocinnamic acid, 3,3-dimethoxycinnamic acid, ethyl paramethoxycinnamate, isopropyl paramethoxycinnamate, Examples thereof include methoxycinnamic acid derivatives such as octyl lamethoxycinnamate, 2-methoxyethyl paramethoxycinnamate, sodium paramethoxycinnamate, potassium paramethoxycinnamate, and glyceryl para-2-methoxycinnamate mono-2-ethylhexanoate.

  The photoresponsive composition according to the present embodiment uses the quaternary ammonium salt, cinnamic acid or cinnamic acid salt as a micelle formation inducing substance, and these can be a photoresponsive composition such as an aqueous solution. Prepared by mixing in liquid.

  As the liquid used for the preparation, any quaternary ammonium salt, cinnamic acid or cinnamate as a micelle formation inducing substance can be used without particular limitation as long as it can form a string-like micelle as much as possible, Hereinafter, an aqueous solution will be exemplified and described.

  The concentration of each component in the aqueous solution in the preparation of the photoresponsive composition according to the present embodiment varies depending on the intended viscoelastic behavior, responsiveness to light irradiation, and the like, but as the quaternary ammonium salt, 10 mmol In many cases, cinnamic acid or cinnamic acid salt as a micelle formation inducing substance is preferably about 50% with respect to quaternary ammonium salt.

  Since the aqueous solution in which these components are blended contains a photoresponsive composition that forms string micelles or the like, it exhibits viscoelastic behavior.

  This viscoelastic behavior is maintained until the light-responsive composition has a large contribution to the photoisomerization reaction until it is irradiated with light of a wavelength corresponding to the disassembly of the string-like micelles. On the other hand, when irradiated with light of a wavelength corresponding to the disassembly of the string-like micelles, among the components forming the string-like micelles, the micelle formation inducing substance causes deformation from a trans type to a cis type as described later, The string-like micelles are disassembled and show a decrease in viscoelasticity. After that, when the irradiation with the wavelength light corresponding to the dissociation of the string-like micelle is stopped, and further the irradiation with the wavelength light corresponding to the formation of the string-like micelle is performed, the micelle formation inducing substance is changed from the cis form to the trans form. Since it returns and reforms the string micelle, it becomes a reversible reaction in which the viscoelasticity increases again.

  This viscoelastic behavior is maintained until the light-responsive composition has a large contribution to exhibit a photodimerization reaction until it is irradiated with light having a wavelength corresponding to the disassembly of the string-like micelles by the photodimerization reaction. . On the other hand, when irradiated with light of a wavelength corresponding to the disassembly of the string micelle, among the components forming the string micelle, the micelle formation inducing substance causes a photodimerization reaction, the string micelle is disassembled, and viscoelastic Decrease. In this case, the photo-dimerization reaction often fails to return to the original micellar organic material and tends to be an irreversible reaction.

  Since the change in the viscoelastic behavior of the liquid containing the photoresponsive composition according to the present embodiment depends exclusively on the deformation of cinnamic acid or cinnamic acid salt as a micelle formation inducing substance, light with a wavelength at which this compound changes. It becomes possible to control viscoelasticity. That is, by selecting light of each deformation wavelength for cinnamic acid or cinnamate as a micelle formation inducing substance, an aqueous solution whose viscoelastic behavior changes with ultraviolet light, or visible light other than the ultraviolet light, etc. It can also be prepared in an aqueous solution whose viscoelastic behavior changes. Corresponding wavelengths can be adopted by appropriately selecting the wavelength at which photoresponsiveness of cinnamic acid or cinnamic acid as a micelle formation inducing substance is selected from known literatures. For example, in the case of sodium cinnamate, the wavelength light corresponding to the disassembly of the ultraviolet light by the string-like micelle is about 260 to 400 nm (corresponding to the first ultraviolet light in the system 100 described later), and the string-like micelle is formed. The wavelength light corresponding to is about 230 to 255 nm (corresponding to the second ultraviolet light in the system 100 described later).

  The photoresponsive composition according to this embodiment prepared in an aqueous solution has viscoelasticity reduction due to disassembly of string-like micelles, viscoelasticity increase due to regeneration, and viscoelasticity and other physical properties greatly change. At the same time, the quaternary ammonium salt contained as a constituent component thereof is a compound that usually acts as a surfactant, so that it can be used for use. For example, a quaternary ammonium salt is used as a cationic surfactant, and as a preservative and bactericidal agent for cosmetics. The photoresponsive composition according to this embodiment containing the quaternary ammonium salt is a cosmetic product. It can be used for applications such as preservatives and bactericides. In addition, it can be used as a sunscreen using the ultraviolet absorbing action of cinnamic acid and cinnamic acid salt, and is also useful as a cosmetic.

  Examples of the use of the photoresponsive composition according to the present embodiment include components such as fragrances, drugs, pigments, and other hydrophobic substances, particularly oil-based components, and photoresponsive release that releases these upon light irradiation. It can be advantageously used as a composition. This photoresponsive release composition is produced, for example, by the following method. These releases are not limited to perfumes and drugs, but can be included in micelles and released into solution by controlled release.

  That is, first, the light-responsive composition according to the present embodiment is irradiated with light having a wavelength corresponding to the optical response that the string-like micelles disassemble, and the string-like micelles are sufficiently agitated in a state where the string-like micelles are disassembled. Add ingredients. Next, after stopping irradiation with light having a wavelength corresponding to the optical response of the string-like micelles being disassembled, the string-like micelles are re-formed by irradiating with light having a wavelength corresponding to the optical response formed by the string-like micelles. Then, the above-mentioned components are held or adsorbed on the string-like micelles, and a photoresponsive release composition is obtained.

  The photoresponsive release composition obtained in this way is irradiated with light having a wavelength corresponding to the optical response that the string-like micelles disassemble, so that the string-like micelles are disassembled again and held or adsorbed thereto. The components etc. that have been released are released into the aqueous solution. In addition, if the cord-like micelle is re-formed by irradiating light of the wavelength corresponding to the photo-response formed by the string-like micelle, such as stopping the irradiation of light having a wavelength corresponding to the photo-response that the string-like micelle is disassembled The above-mentioned components are held or adsorbed on the string micelles, and a photoresponsive release composition is obtained.

  In this way, it is possible to control to hold or adsorb or release external substances.

  The reason why the liquid containing the photoresponsive composition according to the present embodiment changes the viscoelastic behavior by light irradiation is considered as follows. FIG. 17 is a schematic diagram showing the disassembly and formation of string-like micelles related to the viscoelastic behavior.

  Cinnamic acid or cinnamate as a micelle formation-inducing substance in string-like micelles is irradiated with light of a wavelength corresponding to the disassembly of string-like micelles, such as natural light or artificial light, and then transformed from a trans form to a cis form. It has a property that can be changed. Furthermore, the light irradiation is stopped and the light irradiation with the wavelength corresponding to the formation of string-like micelles such as natural light or artificial ultraviolet light is changed from the cis body to the trans body, and the change from the cis body to the trans body is promoted. In some cases, it can have the property of

  When a quaternary ammonium salt and a micelle formation inducing substance are mixed in a liquid, these components are considered to be aligned to form a string-like micelle, but this is irradiated with light having a corresponding wavelength such as ultraviolet light. As a result, cinnamic acid or cinnamate as a micelle formation inducing substance undergoes the above reaction to form a cis form. As a result, string-like micelles cannot be maintained and disassembled.

  On the other hand, when the corresponding wavelength light is irradiated, cinnamic acid or cinnamate as a micelle formation inducing substance becomes trans-type and can be aligned again, and as a result, the original string micelle is formed.

  Thus, it is considered that the viscoelastic behavior of the solution can be greatly changed because the string-like micelles are disassembled by irradiation with ultraviolet light or the like and are re-formed.

  In the present embodiment, cinnamic acid or cinnamate as a micelle formation inducing substance undergoes trans / cis photoisomerization reaction as a photoresponsive substance, and therefore, other than being involved in forming string micelles as a photoresponsive substance. The viscoelastic behavior can be greatly changed as compared with the case where the third object is added.

  The photoresponsive composition according to this embodiment is preferable because it can change the viscoelastic behavior without using a means such as addition of a third component, heating, or oxidation-reduction by an electrochemical reaction. However, if it is determined that it is possible to use means such as addition of the third component, heating, and oxidation-reduction by an electrochemical reaction, these means are not prevented from being used in addition to the light control method of the present embodiment. Absent.

  In the present embodiment, the quaternary ammonium salt of the azobenzene compound is preferably not used because it increases the components and increases the cost, but is used when it is suitable from the viewpoint of further improving the rate of change in viscoelasticity. May be. The quaternary ammonium salt of the azobenzene compound to be used is a compound in which a quaternary ammonium salt is bonded to a part of the compound having an azobenzene skeleton, and examples thereof include compounds represented by the following formula (II). Can do.

  Specific examples of the quaternary ammonium salt of the azobenzene compound include 4-butylazobenzene-4′-oxyethyltrimethylammonium bromide (AZTAB), 4-hexylazobenzene-4′-oxyethyltrimethylammonium bromide, 4-octylazobenzene. -4'-oxyethyltrimethylammonium bromide and their chlorides.

  Moreover, you may take out a photoresponsive composition from aqueous solution. In this case, a liquid such as an aqueous solution other than the photoresponsive composition may be removed. The viscoelasticity of the liquid added as the photoresponsive composition can be changed by adding a liquid such as water again after removing the liquid after removing the liquid.

"Photoviscoelastic control method, photoviscoelastic control system"
Hereinafter, a photoviscoelasticity control method and a photoviscoelasticity control system using the photoresponsive composition according to the present embodiment will be described.

  In the photoviscoelasticity control method according to the present embodiment, the photoresponsive composition is irradiated with light having a wavelength that causes a photoresponse of cinnamic acid or cinnamate (light irradiation step). FIG. 18 shows a photoviscoelasticity control system 100 using the photoviscoelasticity control method according to the present embodiment. Here, the photoviscoelasticity control system 100 is described by exemplifying an embodiment of a reversible viscoelasticity control method of a photoresponsive composition for a photoisomerization reaction.

  The photoviscoelasticity control system 100 includes a solution 10 containing a photoresponsive composition, a container 20 in which the solution 10 is stored, a light source 30 that irradiates the solution 10 with light 40, and a computer 50 that controls light irradiation of the light source 30. A photo-viscoelastic control system.

  As an example of the photoresponsive composition, CTAB and sodium cinnamate solution are used.

  The light source 30 is a light source that can selectively irradiate ultraviolet light having a wavelength at which cinnamate ions of sodium cinnamate are cis isomerized from trans or visible light having a wavelength at which cis is trans isomerized. The light source 30 is connected to the computer 50, and changes the wavelength of the light 40 based on an instruction from the computer 50, irradiates the light 40, or stops the irradiation. An appropriately selected method can be employed to change the wavelength. For example, a method such as attaching a filter such as an ultraviolet light filter to the light source 30 to selectively pass the wavelength thereby changing the wavelength of the light 40, etc. Can be mentioned.

  The computer 50 includes a storage device and a computing device (CPU) (not shown) as components. The storage device stores the wavelength of the first ultraviolet light having a wavelength at which cinnamate ions are cis-isomerized from trans and the wavelength of the second ultraviolet light having a wavelength at which cis is trans-isomerized. The storage device is not particularly limited, but is not particularly limited as long as it is a device capable of storing wavelengths such as a read-only storage device (ROM or the like) or a readable / writable storage device (RAM or the like). The CPU reads a desired wavelength from the storage device when controlling the light source 30, and instructs the control of the irradiation light 40 of the light source 30 based on this.

  FIG. 19 shows an example of a processing flow of the photoviscoelasticity control system 100.

  The CPU of the computer 50 determines to reduce the viscoelasticity of the solution 10 based on a request input from the outside (S1). When the CPU determines that the viscoelasticity is to be reduced, the CPU reads the wavelength of the first ultraviolet light having a wavelength at which the cinnamate ions are cis-isomerized from the trans from the storage device. Next, the CPU instructs the light source 30 to irradiate the read wavelength of the first ultraviolet light as the light 40. In response to this instruction, the light source 30 irradiates the solution 10 with the wavelength of the first ultraviolet light at which the cinnamate ions undergo cis isomerization from trans as light 40 (S2).

  Even if the CPU of the computer 50 determines that the viscoelasticity has been lowered until the string-like micelles are disassembled to a desired state, the first ultraviolet light is used to maintain the string-like micelles being disassembled. The light source 30 is continuously instructed to continue irradiation as light 40 (S3).

  It is determined to increase the viscoelasticity of the solution 10 based on a request input from the outside (S4). When determining that the viscoelasticity is to be increased, the CPU stops the irradiation of the first ultraviolet light that has been instructed to the light source 30 to continue the irradiation as the light 40 (S5).

  Next, the CPU of the computer 50 reads the wavelength of the second ultraviolet light at a wavelength at which the cinnamate ions are isomerized from cis to trans from the storage device. Next, the CPU instructs the light source 30 to irradiate the read wavelength of ultraviolet light as the light 40. The light source 30 receives this instruction and irradiates the solution 10 with the wavelength of ultraviolet light, which is the wavelength at which cinnamate ions undergo trans-isomerization from cis, as light 40 (S6).

  The CPU of the computer 50 continues to instruct the light source 30 to continue irradiating the second ultraviolet light as the light 40 until the viscoelasticity is increased until the string-like micelle is formed and the desired state is obtained (S7).

  As described above, according to the photoviscoelasticity control system 100, the lowering and increasing of the viscoelasticity of the solution 10 containing the photoresponsive composition can be controlled by disassembling and forming the string micelles.

  The photo-viscoelasticity control system 100 includes a photoviscoelasticity reduction step for reducing viscoelasticity by light irradiation under the control of the light source 30 and the computer 50, and a photoviscoelasticity increase step for increasing viscoelasticity by light irradiation after the viscoelasticity reduction. Both are implemented, enabling reversible control. However, only one of the photoviscoelasticity reduction process and the photoviscoelasticity increase process may be performed in the photoviscoelasticity control system 100 as desired.

  The photoviscoelasticity control system 100 can also implement a method in which an external substance is placed in the solution 10 and the external substance is retained or adsorbed by a photoviscoelasticity increasing process.

  The external substance is not particularly limited, but it is preferable to use a harmful substance (especially an organic harmful substance) or the like to be collected by the photoviscoelasticity control system 100. That is, this is a method of using the photoviscoelasticity control system 100 as a hazardous substance recovery system.

  A method of using the photoviscoelasticity control system 100 as a hazardous substance recovery system will be described. The CPU of the computer 50 determines to reduce the viscoelasticity of the solution 10 (S1). When the CPU determines that the viscoelasticity is to be reduced, the CPU reads the wavelength of the first ultraviolet light having a wavelength at which the cinnamate ions are cis-isomerized from the trans from the storage device. Next, the CPU instructs the light source 30 to irradiate the read wavelength of the first ultraviolet light as the light 40. In response to this instruction, the light source 30 irradiates the solution 10 with the wavelength of the first ultraviolet light at which the cinnamate ions undergo cis isomerization from trans as light 40 (S2).

  Even if the CPU of the computer 50 determines that the viscoelasticity has been lowered until the string-like micelles are disassembled to a desired state, the first ultraviolet light is used to maintain the string-like micelles being disassembled. The light source 30 is continuously instructed to continue irradiation as light 40 (S3).

  Next, a harmful substance-containing liquid containing harmful substances as external substances is added to the solution 10. When the harmful substance-containing liquid is added to the solution 10, it is determined that the viscoelasticity of the solution 10 is increased (S4). When determining that the viscoelasticity is to be increased, the CPU stops the irradiation of the first ultraviolet light that has been instructed to the light source 30 to continue the irradiation as the light 40 (S5).

  Next, the CPU of the computer 50 reads the wavelength of the second ultraviolet light at a wavelength at which the cinnamate ions are isomerized from cis to trans from the storage device. Next, the CPU instructs the light source 30 to irradiate the read wavelength of the second ultraviolet light as the light 40. The light source 30 receives this instruction and irradiates the solution 10 with the wavelength of the second ultraviolet light having a wavelength at which the cinnamate ion undergoes trans-isomerization from cis as light 40 (S6).

  The CPU of the computer 50 continues to instruct the light source 30 to continue irradiating ultraviolet light as the light 40 until the viscoelasticity increases until a string-like micelle is formed and a desired state is obtained (S7). The harmful substances are removed from the solution 10 by being held or adsorbed in the process of forming the string micelles. In this way, external substances such as harmful substances can be removed.

  As for the photoviscoelasticity control method and the method of using the photoviscoelasticity control system according to the present embodiment, the wavelength light that causes photoresponse is wavelength light corresponding to the photoisomerization reaction of cinnamic acid or cinnamic acid salt. Viscoelasticity can be reversibly controlled, which is suitable, but is not limited to this, and it may be an irreversible reaction in which micelles are disintegrated by the photodimerization reaction of cinnamic acid or cinnamic acid salt, and viscoelasticity only decreases. It may be suitable depending on the use in which stability by irreversible reaction is important.

  Hereinafter, the present embodiment will be described more specifically by way of examples. However, the present invention is not limited to these examples.

"reagent"
As the cationic surfactant, cetyltrimethylammonium bromide (CTAB) (manufactured by Aldrich Chemical Company, Inc.) was used. In addition, cinnamic acid (HCin) (manufactured by Wako Pure Chemical Industries, Ltd.), which exhibits a reversible trans / cis photoresponsiveness reaction by light irradiation in an aqueous solution, and HCin in a 5 mol / l sodium hydroxide aqueous solution (Wako Pure Chemical Industries, Ltd.) Sodium cinnamate (NaCin) converted to Na salt as cinnamate by Kogyo Co., Ltd. was used as an inducer of string-like micelle formation.

  HCin and NaCin were added to CTAB to visually observe whether or not the viscosity was developed, and the optimum conditions for comparing the two systems were examined. The optimum condition was the one with the highest viscosity, and this was used.

  The sample was prepared by adding trans HCin and NaCin to a 50 mM CTAB aqueous solution so that the concentration was 20, 40, 50 mM, followed by thorough stirring and standing at 25 ° C. for 2 days or longer. The sample was irradiated with light and the change in viscosity was measured.

"experimental method"
<Photoisomerization method>
For the photoisomerization of NaCin, a 200 W mercury / xenon lamp (SAN-EISUPERCURE-203S) was used as a light source. At the time of ultraviolet light irradiation, an ultraviolet light filter (Kenko U-340, transmission wavelength region 260-390 nm) was attached, and light irradiation was performed at room temperature. Note that the intensity of light upon light irradiation was 10 mW / cm ² .

<Ultraviolet / visible absorption spectrum measurement method>
Confirmation of trans / cis photoisomerization by UV irradiation of HCin and NaCin added to the CTAB aqueous solution was performed by ultraviolet / visible absorption spectrum measurement. An ultraviolet / visible spectrophotometer (manufactured by Hitachi, Ltd .: U-3310) was used for the measurement, and the measurement wavelength range was 190 to 550 nm. A quartz cell having an optical path length of 1 cm was used as the measurement cell.

<Rheological measurement>
The stress control type rheometer CSL100 (manufactured by Carri-Med Ltd) was used at 25 ° C., the flow curve was measured using a coaxial double cylinder, and the dynamic viscoelasticity was measured using a cone plate geometry.

"Example 1"
<Examination of optimum concentration ratio>
The CTAB concentration was fixed at 50 mM, and visual observation was performed on the solutions to which various concentrations of HCin and NaCin were added. Visual observation of the HCin / CTAB aqueous solution is shown in FIG. 1, and visual observation of the NaCin / CTAB aqueous solution is shown in FIG.

  As a result, in both HCin / CTAB and NaCin / CTAB systems, as HCin and NaCin were added, it was observed that the inclination of the liquid level increased in FIG. 1 and FIG. I understood. In particular, in the solution to which NaCin was added, it was observed that the inclination of the liquid surface was larger than that of HCin / CTAB, and thus a marked improvement in viscosity was observed.

  In the HCin-added solution, precipitation was observed when the concentration of HCin exceeded 40 mM. Therefore, in the following examples, mixed aqueous solutions in which the concentration of HCin and NaCin was 40 mM were examined.

"Example 2"
<Measurement of flow curve of HCin / CTAB aqueous solution>
The rheological evaluation of the HCin / CTAB aqueous solution was performed by flow curve measurement and viscosity curve measurement. The obtained flow curve and viscosity curve are shown in FIGS. 3 and 4, respectively. In the flow curve measurement, we measured two types of processes: increasing the shear stress and decreasing it.

  Hereinafter, a curve obtained in the process of increasing the shear stress is referred to as an up curve, and a curve obtained in the process of decreasing the shear stress is referred to as a down curve.

  In FIG. 3, the up curve and the down curve do not match, and a hysteresis curve is drawn. Therefore, it was found that the fluid was not a Newtonian behavior but a non-Newtonian fluid, and the viscosity (corresponding to the slope of the flow curve) changed with the change of the shear rate.

Although the viscosity could not be numerically determined, the viscosity was in the range of 9.0 × 10 ^{−1 to} 1.5 × 10 ⁻¹ Pa · s from FIG. 4 and was a low value. From this, it is considered that a small molecular assembly is formed.

"Example 3"
<Dynamic viscoelasticity measurement of NaCin / CTAB aqueous solution>
Since the NaCin / CTAB (40 mM / 50 mM) aqueous solution had high viscosity and it was difficult to evaluate the viscosity from the flow curve, dynamic viscoelasticity measurement was attempted. The dynamic viscoelasticity measurement was performed in the linear viscoelasticity region. The linear viscoelastic region refers to a region where a proportional relationship is established between stress (stress) and strain (strain).

<Measurement of linear viscoelastic region>
The linear viscoelastic region was determined by changing the shear stress from 0.01 Pa to 10 Pa under a constant frequency of 6.28 rad · s ⁻¹ (1.0 Hz).

  The result of having calculated | required the linear viscoelastic area | region about NaCin / CTAB (40 mM / 50 mM) aqueous solution is shown in FIG. In the linear viscoelastic region, a linear relationship is established between stress (stress) and strain (strain), and the viscoelastic parameters (G ′ (storage elastic modulus), G ″ (loss elastic modulus)) remain constant. .

  When the linear viscoelastic region was obtained from FIG. 5, it was found to be approximately 2% strain to 8% strain. Therefore, the dynamic viscoelasticity measurement was performed with a 5% strain in the linear viscoelastic region for the NaCin / CTAB (40 mM / 50 mM) aqueous solution system.

<Frequency dependence of G ′ and G ″>
The frequency dependence (25 ° C.) of G ′ (storage elastic modulus) and G ″ (loss elastic modulus) measured for an aqueous solution of NaCin / CTAB (40 mM / 50 mM) is shown in FIG. Yes, G ″ is a parameter related to viscosity. The measurement frequency was 3.14 × 10 ^{−2 to} 12.56 rad · s ⁻¹ (0.005 to 2.00 HZ).

  Here, the relaxation behavior of the Maxwell model type will be described. The Maxwell model type relaxation behavior is a behavior having a single relaxation time with no relaxation time distribution.

  In the results of frequency dependence of G ′ and G ″ obtained in an aqueous solution of NaCin / CTAB (40 mM / 50 mM) (FIG. 6), viscosity is dominant on the low frequency side (G ′ <G ″), and elasticity on the high frequency side. It showed a dominant (G ′> G ″) behavior. G ′ had a flat region on the high frequency side, and G ″ showed a maximum. This behavior is similar to that of the Maxwell model. Therefore, when G ″ was plotted against G ′ (Cole-Cole plot), a beautiful semicircle was obtained (FIG. 7).

  This shows that Maxwell's behavior with a single relaxation time with no relaxation time distribution is shown.

  Many relaxation behaviors of the Maxwell model type have been observed so far for cord-like micelle systems represented by NaSal / CTAB, suggesting that cord-like micelles are formed in the NaCin / CTAB aqueous solution. Become. Shikata, T .; Hirata, H .; Kotaka, T. Langmuir have shown that the relaxation behavior of this Maxwell model type is observed in the string-like micelle system, and this can confirm the formation of the string-like micelle qualitatively. 1987, 3, 1081.

  As a factor in which the relaxation mechanism peculiar to such string-like micelles becomes the relaxation behavior of the Maxwell model type, for example, a ghost network model has been proposed (refers to Shikata, T .; Hirata, H .; Kotaka, T. Langmuir 1988, 4, 354.). The relaxation mechanism of this model is based on the phenomenon that when a time equal to or greater than the entanglement lifetime elapses, the entangled cross-linking points disappear and the string-like micelles slip through each other. Such behavior is considered to be impossible in the case of a polymer having a structure in which a molecular chain is constructed by covalent bonds and is not cleaved, but a string-like micelle system that is a thermodynamic equilibrium system. Is a phenomenon that can be considered because it can be cleaved or recombined by relatively weak intermolecular forces, and is considered a suitable model for describing the viscoelastic behavior of string-like micelles.

<Calculation of zero shear viscosity>
Since the NaCin / CTAB (40 mM / 50 mM) aqueous solution has a Maxwell model type behavior, the viscosity of the solution was evaluated based on the _zero shear viscosity η ₀ .

Η ₀ was determined based on the following formula (1). (Τ: relaxation time)

As shown in the above equation (1), η ₀ seen on the very low frequency side of η ′ (ω≈0) corresponds to η of static measurement (FIG. 9).

As a result, the zero shear viscosity was 4.1 × 10 ¹ Pa · s.

Example 4
<Observation results of molecular assembly by low-temperature transmission electron microscope (cryo-TEM)>
From Example 3, it was suggested that string-like micelles were formed in the NaCin / CTAB (40 mM / 50 mM) aqueous solution. Therefore, observation with cryo-TEM was performed to confirm the formation of string-like micelles (FIG. 10). As a result, rod-like string micelles extending in all directions could be confirmed.

This indicates that a number of string-like micelles overlap each other and are closely entangled to form a three-dimensional network, and the entanglement of the molecular assembly is considered to make the aqueous solution highly viscous. (The black spots observed in FIG. 10 are considered to be water droplets, frost, or impurities attached at the time of sample preparation. Since the sample to be observed is observed at an extremely low temperature of −170 ° C. or less, the sample prepared was May be attached when moving to the transmission electron microscope body.)
"Example 5"
<Visual observation of viscosity change before and after UV irradiation>
Viscosity change by UV irradiation of HCin / CTAB (40 mM / 50 mM) aqueous solution and NaCin / CTAB (50 mM / 40 mM) aqueous solution was tried.

  As a result, the HCin / CTAB aqueous solution did not show a large change in viscosity, but a decrease in viscosity was observed (FIG. 11).

  On the other hand, the viscosity of the aqueous NaCin / CTAB solution significantly decreased after UV irradiation (FIG. 12). After that, focusing on the NaCin / CTAB system in which the viscosity was remarkably reduced, changes in solution viscosity due to UV irradiation were studied.

"Example 6"
<Confirmation of trans / cis photoisomerization of NaCin>
Cin has only a thermodynamically stable trans isomer, but undergoes geometric isomerization to a cis isomer by light irradiation. Therefore, confirmation of trans / cis photoisomerization of NaCin by UV light irradiation was first performed by ultraviolet / visible absorption spectrum measurement. UV light irradiation was performed under the conditions of a liquid volume: 3 ml and a light intensity: 10 mW / cm ² .

FIG. 13 shows the results of ultraviolet / visible absorption spectrum measurement of the NaCin / CTAB aqueous solution. From the figure, the trans body before irradiation with ultraviolet light has a maximum absorption wavelength λ _max at about 269 nm. When UV (260-390 nm) was irradiated to the CTAB aqueous solution to which this trans-form NaCin was added, the absorbance decreased and the maximum absorption wavelength also changed to the short wavelength side (about 255 nm).

  Since this is considered to be due to a change in the three-dimensional structure, it is considered that the NaCin molecule was photoisomerized from the trans form to the cis form by irradiation with ultraviolet light.

  The reason why NaCin is isomerized is that the C═C group becomes π-π * excited by irradiation with ultraviolet light, and becomes unstable in energy due to the antibonding property of π * orbit. At this time, it is stabilized by isomerization from the trans form to the cis form. It took about 3 hours until this spectral change was not recognized.

Even after the change in the spectrum is no longer observed, the photoisomerization does not proceed completely. The isomerization from the trans form to the cis form and the isomerization from the cis form to the trans form are not performed. It is thought that conversion is happening at the same time. That is, it is considered that the change in the spectrum is not observed because the trans body and the cis body have a constant ratio (light steady state). It can be considered that λ _max became a short wavelength and the absorbance decreased due to UV irradiation because, in the cis isomer, the steric strain hindered the good overlap of the orbits conjugated with the cis isomer.

  Next, the presence or absence of reversibility was confirmed by measuring the ultraviolet / visible absorption spectrum after standing in the dark. However, after standing in a dark place for 5 days, no change occurred that the spectrum returned to the value before the light irradiation.

  HCin is known to have light dimerization in addition to isomerization. Although dimerization occurs mainly in the crystalline state, it has also been reported that it occurs due to the condensation effect of solubilization in micelles even in aqueous HCin / CTAB solutions. Therefore, in order to determine which is occurring in the NaCin / CTAB aqueous solution, ultraviolet / visible absorption spectrum measurement during dimerization (HCin / CTAB aqueous solution) was also performed (FIG. 14).

  When the HCin / CTAB aqueous solution was irradiated with UV, the peak absorbance continued to decrease with the irradiation time of the UV light, and this indicates that the C = C double bond of cinnamic acid disappeared. It is presumed that the heavy bond is crosslinked. Therefore, the HCin / CTAB aqueous solution is highly likely to have dimerized by UV irradiation.

  In addition, it has been reported that the aqueous solution of NaCin only undergoes photoisomerization. When the ultraviolet / visible absorption spectrum measurement of this system was performed, the spectrum change was the same as the result of FIG. For this reason, it was found that photoisomerization occurred in the NaCin / CTAB aqueous solution.

"Example 6"
<Viscosity after UV irradiation of NaCin / CTAB aqueous solution>
From Example 5, it was visually confirmed that the viscosity of the aqueous NaCin / CTAB solution was significantly reduced by irradiation with UV light. Therefore, the viscosity of the NaCin / CTAB aqueous solution after UV irradiation was determined from the flow curve, and the change in viscosity due to UV irradiation was confirmed. Since the viscosity was remarkably reduced after UV irradiation and could not be measured by dynamic viscoelasticity measurement, the viscosity was determined from the flow curve. The obtained flow curve and viscosity curve are shown in FIGS. 15 and 16, respectively.

  As a result, the flow curve of the Newtonian fluid is a straight line passing through the origin, and the viscosity is constant. From the flow curve (FIG. 15) showing the behavior, it was found that the fluid was Newtonian after UV irradiation.

Moreover, when the viscosity of this solution was calculated | required from the viscosity curve, it was 1.8 * 10 < ^-3 > Pa * s, and it turned out that it reduces to about 1/23000 before UV irradiation (4.1 * 10 Pa * s). . This decrease in viscoelasticity was much larger than the change in the system (1/1000) of the usual CTAB / NaSal / AZTMA mixed aqueous solution.

  From the above results, it is considered that NaCin in string-like micelles formed before UV irradiation caused a photoisomerization reaction by UV irradiation, changed to a small molecular aggregate without entanglement, and the solution viscosity was lowered.

  HCin / CTAB (40 mM / 50 mM) aqueous solution is a non-Newtonian fluid, and it is considered that a small molecular assembly is formed. Moreover, although the viscosity was originally low, a viscoelasticity drop was observed by visual observation although a large change in viscosity was not observed before and after UV irradiation.

“Results and Discussion”
The results are shown below and a discussion as an example.

<Result>
The NaCin / CTAB (40 mM / 50 mM) aqueous solution showed high viscoelasticity, and formation of string-like micelles could be confirmed from dynamic viscoelasticity measurement and observation with a low-temperature transmission electron microscope (cryo-TEM).

  Further, the viscosity was remarkably lowered by UV irradiation (about 1/23000 before UV irradiation). This change in viscosity was much larger than in the case of the CTAB / NaSal / AZTMA mixed aqueous solution (1/1000).

<Discussion>
Consider as an example. The viscosity reduction of the NaCin / CTAB aqueous solution due to UV irradiation is considered to be caused by the following. Before UV irradiation, NaCin is a linear trans body with a benzene ring buried on the CTAB micelle surface, and the negative charge of cinnamate ions shields the charge repulsion between CTAB molecules, and the relationship between critical packing parameters. As a result, a string-like micelle is formed. After UV irradiation, the critical packing parameters are reduced by isomerization into bulky cis bodies, the cinnamate ions are desorbed from the micelle surface by increasing the distance between hydrophilic groups of CTAB molecules, and string micelles are It is thought that the viscosity decreased due to the formation of spherical micelles or small rod-like micelles that collapsed and were not entangled (FIG. 17). Therefore, according to this theory, the same tendency can be seen for all cinnamates having cinnamate ions.

It is a photograph which shows HCin / CTAB aqueous solution visual observation. It is a photograph which shows NaCin / CTAB aqueous solution visual observation. It is a figure which shows the flow curve of HCin / CTAB aqueous solution. It is a figure which shows the viscosity curve of HCin / CTAB aqueous solution. It is a figure which shows the result of the linear viscoelastic area | region of NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a figure which shows the result of the frequency dependence of G'orG "of NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a figure which shows the Cole-Cole plot of NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a schematic diagram explaining the entanglement of a string-like micelle (ghost network model). It is a figure for obtaining the zero shear viscosity of HCin / CTAB (40 mM / 50 mM) aqueous solution. It is a photograph of a cryo-TEM image of a NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a photograph which shows the visual observation before and behind UV irradiation of HCin / CTAB (40 mM / 50 mM) aqueous solution. It is a photograph which shows the visual observation before and behind UV irradiation of NaCin / CTAB aqueous solution. It is a figure which shows the ultraviolet and visible absorption spectrum before and behind UV irradiation of NaCin / CTAB aqueous solution. It is a figure which shows the ultraviolet and visible absorption spectrum before and behind UV irradiation of NaCin / CTAB aqueous solution. It is a figure which shows the flow curve of NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a figure which shows the viscosity curve of NaCin / CTAB (40 mM / 50 mM) aqueous solution. It is a schematic diagram explaining the mechanism of the viscoelasticity fall by UV irradiation. It is a schematic diagram which concerns on the photoviscoelasticity control system which concerns on this embodiment. It is a processing flow figure concerning the photoviscoelasticity control system concerning this embodiment.

Claims (13)

  A photoresponsive composition comprising at least one of cinnamic acid and cinnamic acid salt and a quaternary ammonium salt. The photoresponsive composition according to claim 1,
The quaternary ammonium salt is at least one selected from the group consisting of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetylpyridinium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride and octadecylpyridinium chloride. Responsive composition. The photoresponsive composition according to claim 1 or 2,
The cinnamate is a photoresponsive composition containing sodium cinnamate. The photoresponsive composition according to any one of claims 1 to 3,
Furthermore, the photoresponsive composition containing the quaternary ammonium salt of an azobenzene type compound. The photoresponsive composition according to any one of claims 1 to 4, comprising:
A photoresponsive composition comprising an emission that is released by a decrease in viscoelasticity due to photoresponse. A photo-viscoelastic control method,
The photoviscoelasticity control method including the light irradiation process which irradiates the photoresponsive composition as described in any one of Claim 1 to 5 including the wavelength light which raises the photoresponse of a cinnamic acid or a cinnamate. . The photoviscoelasticity control method according to claim 6,
A photoviscoelasticity control method, wherein the wavelength light causing the photoresponse is wavelength light corresponding to a photoisomerization reaction. The photoviscoelasticity control method according to claim 6 or 7,
The light irradiation step includes
A photoviscoelasticity control method including a photoviscoelasticity reduction step of reducing viscoelasticity by light irradiation. The photoviscoelasticity control method according to any one of claims 6 to 8,
An optical viscoelasticity control method including an optical viscoelasticity increasing step of increasing viscoelasticity by light irradiation after the optical viscoelasticity decrease. The photoviscoelasticity control method according to claim 9,
A photoviscoelasticity control method for taking in an external substance by the photoviscoelasticity increasing step. The photoviscoelasticity control method according to claim 10,
The photoviscoelasticity control method, wherein the external substance is a harmful substance.   An optical viscoelasticity control system, comprising an optical control device that performs optical viscoelasticity control by the optical viscoelasticity control method according to any one of claims 6 to 11.   Use of a photoresponsive composition comprising at least one of cinnamic acid and cinnamic acid salt and a quaternary ammonium salt in a method for controlling photoviscoelasticity.