Mechanochromic compound and method for producing mechanochromic polymer compound

Abstract

To provide a solid material exhibiting coloration and / or fluorescence emission that is usable under a variety of conditions.SOLUTION: A mechanochromic compound is represented by the following formula (1), wherein X is an oxygen atom or a sulfur atom, Y is an oxygen atom, a sulfur atom, or a nitrogen atom, the number of R2 in each phenyl group is any one of 1 to 5, and R1 and R2 are each independently a hydrocarbon group having 1 to 100000 carbon atoms that may have a substituent and may contain a heteroatom.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a mechanochromic compound and a mechanochromic polymer compound. According to the present invention, a mechanochromic polymer compound can be easily obtained by radical polymerization or the like. [Background technology]

[0002] In recent years, compounds have been discovered that generate stable radical structures in response to mechanical stimuli (mechanical stress) such as compression, stretching, impact, shear, crushing, bending, or friction. These compounds have attracted attention as compounds that visually change color and can visualize the degree of mechanical stress or the location of damage (Patent Document 1). Compounds that have the property of developing color or emitting light in response to such mechanical stimuli are called mechanochromic compounds (mechanochromic materials). The material described in Patent Document 1 generates a stable radical structure in response to mechanical stimuli and develops a blue color specific to that structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-58606 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-210991 Summary of the Invention [Problem to be solved by the invention]

[0004] Furthermore, some compounds with radical structures exhibit fluorescence. However, these compounds mainly exhibit radical structures when exposed to visible light or lasers such as gamma rays, and have not been provided as stable radical solid materials. The present inventors have developed mechanochromic compounds that generate stable radical structures when subjected to mechanical stimulation (grinding) and are capable of color development and / or fluorescence emission (Patent Document 2). However, the mechanochromic compounds are not sufficiently stable depending on the conditions of use, and their applications are limited. Therefore, an object of the present invention is to provide a color-developing and / or fluorescent solid material that can be used under various conditions. [Means for solving the problem]

[0005] The present inventors have conducted extensive research into color-developing and / or fluorescent mechanochromic compounds that can be used under various conditions, and have surprisingly found that mechanochromic compounds having a specific structure containing a diarylacetonitrile skeleton exhibit properties that make them usable under various conditions. The present invention is based on this finding. Therefore, the present invention provides [1] The following formula [1]: [ka] (wherein X is an oxygen atom or a sulfur atom, Y is an oxygen atom, a sulfur atom, or a nitrogen atom, and R 2 The number of R is 1 to 5 in each phenyl group. 1 and R 2 each independently represents a hydrocarbon group having 1 to 100,000 carbon atoms which may have a substituent and which may contain a heteroatom, and the substituent is a halogen atom, an alkyl group, an alkoxy group, an alkynyl group, an alkenyl group, a hydroxyl group, a thiol group, a sulfinyl group, a sulfonyl group, a carboxy group, a silyl group, an alkoxysilyl group, an epoxy group, an amino group, an aldehyde group (formyl group), a carbonyl group, an alkoxycarbonyl group, an amide group, or an isocyanate group; [2] The mechanochromic compound according to [1], wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, comprises a polymer chain selected from the group consisting of polyurethane, polyester, polyamide, polylactone, polystyrene, polyacrylic acid or its ester or amide, polymethacrylic acid or its ester or amide, polyalkylene oxide, polysiloxane, polydimethylsiloxane, polycarbonate, polylactide, polyolefin, polyisobutylene, polyamideimide, polybutadiene, epoxy resin, phenolic resin, polyacetylene, polyvinyl, and a combination of two or more thereof. [3] The mechanochromic compound according to [1], wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, contains a vinyl group, an ethynyl group, or an azide group at its terminal. [4] A crosslinking agent containing the mechanochromic compound according to [3]. [5] A method for producing a mechanochromic polymer compound by radical polymerization, characterized by mixing a monomer having a vinyl group and the crosslinking agent according to [4] (excluding crosslinking agents in which the terminal group of the hydrocarbon group is an ethynyl group or an azide group). [6] The mechanochromic compound according to [1], wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, contains a halogen atom at its terminal. [7] A polymerization initiator containing the mechanochromic compound according to [6]. [8] A method for producing a mechanochromic polymer compound by radical polymerization, comprising mixing a monomer having a vinyl group and the polymerization initiator according to [7]. [9] The mechanochromic compound according to [1] or [2], which develops color and / or emits fluorescence in response to a mechanical stimulus.

[10] The mechanochromic compound according to [9], wherein the mechanical stimulus is selected from the group consisting of compression, stretching, impact, shear, crushing, bending, friction, ultrasound, and a combination of two or more thereof.

[11] A mechanochromic material containing the mechanochromic compound according to [1] or [2].

[12] The mechanochromic material according to

[11] , which is a laminate or a molded body.

[13] A method for detecting a mechanical stimulus, comprising a step of detecting a mechanical stimulus applied to the mechanochromic material according to

[11] by measuring a change in color and / or fluorescence emission; and

[14] The method for detecting a mechanical stimulus according to

[13] , wherein the mechanical stimulus is selected from the group consisting of compression, stretching, impact, shear, crushing, bending, friction, ultrasound, and a combination of two or more thereof. Regarding. [Effects of the Invention]

[0006] According to the mechanochromic compound and the method for producing a mechanochromic polymer compound of the present invention, a mechanochromic polymer compound can be easily obtained by radical polymerization. That is, the mechanochromic compound of the present invention has sufficient temperature stability compared to, for example, the mechanochromic compound having a tetraarylsuccinonitrile basic skeleton described in Patent Document 2, and can be used in radical polymerization with good operability. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 shows the results of a grinding test of the α-CN-DAAE-diPS obtained in Example 2, confirming the fluorescence emission of the DAAN radical. [Figure 2] FIG. 1 shows the results of a grinding test of α-CN-DAAE-diPS-H obtained in Example 4, confirming the fluorescence emission of DAAN radical. [Figure 3] FIG. 1 is a diagram showing stress-strain curves in tensile tests of the polymer compounds of Example 7 and Comparative Example 2. [Figure 4] FIG. 1 shows the results of ESR and fluorescence spectrum measurements of the polymer compounds of Example 7 and Comparative Example 2. [Figure 5] 1 is a graph showing (a) the fluorescence spectrum of the polymer compound of Example 7 and (b) the activation rate calculated from ESR measurement. [Figure 6] 1 is a photograph showing the luminescence behavior during a tensile test of the polymer compound of Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0008] [1] Mechanochromic compounds The mechanochromic compound of the present invention is represented by the following formula [1]: [ka] (In the formula, X is an oxygen atom or a sulfur atom, Y is an oxygen atom, a sulfur atom, or a nitrogen atom; R 2 is 1 to 5 in each phenyl group, R 1 and R 2 are each independently a hydrocarbon group having 1 to 100,000 carbon atoms which may have a substituent and which may contain a heteroatom, and the substituent is a halogen atom, an alkyl group, an alkoxy group, an alkynyl group, an alkenyl group, a hydroxyl group, a thiol group, a sulfinyl group, a sulfonyl group, a carboxy group, a silyl group, an alkoxysilyl group, an epoxy group, an amino group, an aldehyde group (formyl group), a carbonyl group, an alkoxycarbonyl group, an amide group, or an isocyanate group. It is expressed as:

[0009] X is an oxygen atom or a sulfur atom. Y is an oxygen atom, a sulfur atom, or a nitrogen atom. Therefore, the combinations of X and Y are oxygen and oxygen atoms, oxygen and sulfur atoms, oxygen and nitrogen atoms, sulfur and oxygen atoms, sulfur and sulfur atoms, or sulfur and nitrogen atoms, respectively, and the effects of the present invention can be obtained with any combination. For example, when the combination of X and Y is oxygen and oxygen atoms, the mechanochromic compound of the present invention has the following a-CN-diarylacetic acid ester (α-CN-DAAE) skeleton. [ka]

[0010] R 2 The number of R is independently 1 to 5 in each phenyl group. For example, 2 The number of R is 1, 2, 3, 4, or 5, preferably 4 or less, more preferably 3 or less, even more preferably 2 or less, and most preferably 1. 2 The position of R is not particularly limited, and may be any of the ortho, meta, or para positions. 2 is preferably the meta or para position, most preferably the para position, from the viewpoint of not affecting the cleavage of the mechanochromic compound of the present invention. Also, from the viewpoint of production of the mechanochromic compound of the present invention, it is preferably the meta or para position, most preferably the para position.

[0011] R 1 and R 2 are each independently a hydrocarbon group having 1 to 100,000 carbon atoms which may have a substituent and which may contain a heteroatom. R 1 and R 2 The heteroatom that may be contained in is not particularly limited as long as the effects of the present invention can be obtained, but examples thereof include a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom, a fluorine atom, a boron atom, a sodium atom, an aluminum atom, a selenium atom, a chlorine atom, an iodine atom, and a bromine atom.

[0012] R 1 and R 2 The substituent that may be possessed by is not particularly limited as long as the effects of the present invention can be obtained, but examples thereof include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group, an alkoxy group, an alkynyl group, an alkenyl group, a hydroxyl group, a thiol group, a sulfinyl group, a sulfonyl group, a carboxy group, a silyl group, an alkoxysilyl group, an epoxy group, an amino group, an aldehyde group (formyl group), a carbonyl group, an alkoxycarbonyl group, an amide group, or an isocyanate group. The substituent is a group that replaces a hydrogen atom of a hydrocarbon group. 1 and R 2 When R has a polymer chain, the substituent may be present at the end of the main chain or at the end of a side chain of the polymer repeat unit. 1 and R 2 When the compound does not have a polymer chain, the hydrogen atoms of the hydrocarbon group are substituted.

[0013] <Mechanochromic compounds containing polymer chains> The hydrocarbon group which may contain a heteroatom can contain a polymer chain. The polymer chain is a polymer chain containing repeating units, and the number of repeating units is not limited, but is, for example, 1 to 10,000, in some embodiments 1 to 5,000, in some embodiments 1 to 3,000, in some embodiments 1 to 1,000, in some embodiments 1 to 800, in some embodiments 1 to 500, in some embodiments 1 to 400, in some embodiments 1 to 300, in some embodiments 1 to 200, in some embodiments 1 to 100, in some embodiments 1 to 80, in some embodiments 1 to 60, in some embodiments 1 to 40, in some embodiments 1 to 30, in some embodiments 1 to 20, and in some embodiments 1 to 10. Examples of polymer chains include, but are not limited to, polymer chains selected from the group consisting of polyurethane, polyester, polyamide, polylactone, polystyrene, polyacrylic acid or its ester or amide, polymethacrylic acid or its ester or amide, polyalkylene oxide, polysiloxane, polydimethylsiloxane, polycarbonate, polylactide, polyolefin, polyisobutylene, polyamideimide, polybutadiene, epoxy resin, phenolic resin, polyacetylene, polyvinyl, and combinations of two or more thereof. The polymer chain may be a linear polymer chain, a branched polymer chain, a grafted polymer chain, or a cyclic polymer chain. Furthermore, the polymer chain may be a polymer chain in which two or more repeating units (monomers) are alternately bonded, or a polymer chain in which two or more repeating units (monomers) are randomly bonded. R 1 The polymer chains that may be included in R 1or a divalent group may be present between the oxygen atom, sulfur atom, or nitrogen atom and the polymer chain. Examples of the divalent group include divalent hydrocarbon groups having 1 to 40 carbon atoms that may contain a heteroatom (e.g., alkylene group, alkenylene group, ether group, or ester group). R 2 The polymer chains that may be included in R 2 The carbon atom may be bonded to the carbon atom to which the aryl group is bonded by a single bond, or a divalent group may be present between the carbon atom and the polymer chain. Examples of the divalent group include divalent hydrocarbon groups having 1 to 40 carbon atoms that may contain a heteroatom (for example, an alkylene group, an alkenylene group, an ether group, or an ester group).

[0014] The mechanochromic compound of the present invention may be a mechanochromic compound containing a polymer chain, or may be a mechanochromic compound not containing a polymer chain. A mechanochromic material containing a mechanochromic compound containing a polymer chain can be molded into a laminate or a molded article as the mechanochromic material described below. When the mechanochromic compound is used in the obtained laminate or molded article, the laminate or molded article develops color and / or emits fluorescence when a mechanical stimulus is applied to the laminate or molded article.

[0015] <Mechanochromic compounds without polymer chains> R in mechanochromic compounds without polymer chains 1 and R 2 is not particularly limited, and may be, for example, a hydrocarbon group having 1 to 50 carbon atoms which may contain a hetero atom and which may have a substituent. R 1 and R 2The terminal of R is not limited, and examples thereof include a hydroxyl group, an alkoxy group (e.g., a methoxy group), an alkynyl group, an alkenyl group, a thiol group, a sulfinyl group, a sulfonyl group, a carboxy group, an ester group, a silyl group, an alkoxysilyl group, an epoxy group, an amino group, an aldehyde group, a carbonyl group, an alkoxycarbonyl group, an amide group, a halogenated alkyl group, or an isocyanate group. 1 and R 2 Examples of the group include the following groups: [ka] Furthermore, mechanochromic compounds that do not contain polymer chains can also be used as, but are not limited to, the following crosslinking agents or polymerization initiators, and mechanochromic compounds that contain polymer chains can be prepared by radical polymerization or the like.

[0016] Cross-linking agent The mechanochromic compound of the present invention may have a substituted hydrocarbon group having 1 to 100,000 carbon atoms, which may contain a heteroatom, and may contain a vinyl group, an ethynyl group, or an azide group at the end. The "end" is not particularly limited as long as the mechanochromic compound functions as a crosslinking agent in radical polymerization. For example, the end of the hydrocarbon group may be the end of the main chain or the end of the side chain of the hydrocarbon group. A mechanochromic compound containing a vinyl group at its terminal can be used as a crosslinking agent in radical polymerization. Also, a mechanochromic compound containing an ethynyl group or an azide group at its terminal can be used as a crosslinking agent.

[0017] <Polymerization initiator> The mechanochromic compound of the present invention may have a hydrocarbon group having 1 to 100,000 carbon atoms, which may have a substituent and may contain a heteroatom, and which may contain a halogen atom at the end. The "end" is not particularly limited as long as the mechanochromic compound functions as a polymerization initiator in radical polymerization. For example, it may be the end of the hydrocarbon group, such as the end of the main chain or the end of the side chain of the hydrocarbon group. The mechanochromic compound containing a halogen atom at its terminal can be used as a polymerization initiator in radical polymerization.

[0018] Diarylacetonitrile (DAAN) skeleton The mechanochromic compound of the present invention is a compound having the following diarylacetonitrile skeleton (hereinafter, sometimes referred to as DAAN skeleton). [ka] The mechanochromic compound of the present invention represented by formula (1) has the following basic skeleton. [ka] Furthermore, when the combination of X and Y is an oxygen atom and an oxygen atom, which is one embodiment of the mechanochromic compound represented by formula (1) of the present invention, the mechanochromic compound of the present invention has the following α-CN-diarylacetic acid ester (α-CN-DAAE) skeleton. [ka]

[0019] The mechanochromic compound of the present invention undergoes cleavage between the carbon atom to which -CN is bonded and the carbon atom to which -XY is bonded upon mechanical stimulation. This cleavage produces the DAAN skeleton. The resulting DAAN skeleton exhibits fluorescence. The DAAN skeleton is generated by cleavage of the bond between the DAAN skeleton and the -CXY structure when a mechanical stimulus is applied to the mechanochromic compound of formula (1). That is, the generation of fluorescence reflects the application of a mechanical stimulus to the mechanochromic compound of the present invention.

[0020] For example, when the mechanochromic compound of the present invention includes a polymer chain, from the viewpoint of detecting a mechanical stimulus, the polymer chain is 1 is included in, and R 2 It is preferable that the polymer chain is included in at least one of R 1 is included in, and R 2 If the compound is included in at least one of the following formulas, then R 1 and the polymer chain contained in R 2 When a mechanical stimulus is applied to the polymer chain contained in the polymer chain, the bond between the DAAN skeleton and the -CXY structure becomes more likely to be cleaved, and the DAAN skeleton becomes more likely to be generated by the mechanical stimulus. [ka] On the other hand, if the polymer chain is R 1 Not included in one R 2 or two R's 2 When the compound is included in the -CXY structure, the mechanical stimulus applied to the bond between the DAAN skeleton and the -CXY structure is weak, resulting in a decrease in the production of the DAAN skeleton. Therefore, the mechanical stimulus applied to the mechanochromic compound of the present invention is not sufficiently reflected, i.e., it is not optimal from the viewpoint of detecting the mechanical stimulus. The polymer chain is R 1 is included in, and R 2 It is believed that mechanical stimuli can be transmitted most efficiently by being included in at least one of the above.

[0021] As used herein, the term "mechanical stimulus" refers to a mechanical stimulus applied to the bond between the DAAN backbone and the -CXY structure, but is not limited thereto. Examples include compression, stretching, impact, shear, crushing, bending, friction, ultrasound, or a combination of two or more thereof. The strength of the mechanical stimulus is not limited as long as it produces a DAAN backbone, but the fluorescence emission and the magnitude of the mechanical stimulus can be easily measured. The molecular weight of the mechanochromic compound of the present invention is not limited as long as a DAAN skeleton is generated by mechanical stimulation, but a relatively high molecular weight is preferred. For example, the molecular weight is preferably 400 or more, more preferably 1000 or more, even more preferably 5000 or more, and most preferably 10000 or more. The upper limit of the molecular weight is not limited, but is, for example, 2,000,000 or less, for example, 1,000,000 or less.

[0022] Coloring The mechanochromic compound of the present invention develops color when subjected to a mechanical stimulus. The color that develops is not particularly limited, but it develops a pink color.

[0023] 《Fluorescence》 The mechanochromic compound of the present invention emits fluorescence when subjected to a mechanical stimulus. To detect the fluorescence, it is preferable to irradiate it with ultraviolet light. The wavelength is not limited, but it can be detected by irradiating it with a wavelength of, for example, 330 nm to 390 nm, preferably 365 nm.

[0024] [2] Mechanochromic materials The mechanochromic material of the present invention includes the mechanochromic compound. The mechanochromic material may consist essentially of the mechanochromic compound, or may contain other compounds and the mechanochromic compound. The mechanochromic material can be molded into a laminate or a molded body.

[0025] Examples of mechanochromic materials made of mechanochromic compounds include materials made of compounds prepared by introducing the structure represented by formula (1) into a compound suitable for the application in which the material is to be used. Specifically, examples include mechanochromic materials made of polymers into which the structure represented by formula (1) has been introduced into the main chain or crosslinking points of the polymer.

[0026] On the other hand, materials containing other compounds and the mechanochromic compound of the present invention can be produced by mixing the mechanochromic compound described in the section “[1] Mechanochromic compound” above with a compound suitable for the application in which the material is to be used. The content of the mechanochromic compound in the mechanochromic material is not particularly limited as long as color development or fluorescence emission in response to mechanical stimuli can be detected, but is, for example, 0.1 to 99%, more preferably 1 to 95%, and even more preferably 2 to 90%. In particular, the mechanochromic compound containing the polymer chain of the present invention has high sensitivity to color development or fluorescence emission in response to mechanical stimuli. Therefore, a mechanochromic material with sufficient sensitivity can be obtained by adding a small amount of the compound.

[0027] The mechanochromic material of the present invention is preferably in the form of a solid, but is not limited thereto, and may be in the form of a liquid, gel, sol, or the like, as long as it develops color or emits fluorescence in response to a mechanical stimulus.

[0028] [3] Manufacturing method for mechanochromic polymer compounds The method for producing a mechanochromic polymer compound by radical polymerization of the present invention is characterized by mixing a monomer having a vinyl group with the crosslinking agent or the polymerization initiator. A mechanochromic polymer compound having a chain structure can be obtained by polymerizing the monomer having a vinyl group using the polymerization initiator. Furthermore, a mechanochromic polymer compound having a crosslinked structure can be obtained by performing radical polymerization in the presence of the crosslinking agent. Examples of monomers having a vinyl group include, but are not limited to, isocyanate group-containing vinyls, aromatic vinyls, amide group-containing vinyls, vinyl esters, unsaturated sulfonic acids, unsaturated phosphoric acids, aliphatic vinyls, and alicyclic vinyls. Examples of the isocyanate group-containing vinyl compounds include vinyl isocyanate and isopropenyl isocyanate. Examples of aromatic vinyls include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, t-butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene, and vinylnaphthalene. Examples of amide group-containing vinyls include acrylamide, methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic acid amide, and N,N-dialkyl acrylamide (for example, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, etc.). Examples of vinyl esters include vinyl acetate and vinyl propionate. Examples of unsaturated sulfonic acids include styrene sulfonic acid, sodium styrene sulfonate, and 2-acrylamido-2-methylpropane sulfonic acid. Examples of unsaturated phosphoric acids include mono(2-methacryloyloxyethyl) acid phosphate and mono(2-acryloyloxyethyl) acid phosphate. Aliphatic vinyls include alkenes (e.g., propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, or α-olefins) and alkadienes (e.g., butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene, or 1,7-octadiene). Examples of alicyclic vinyls include cyclohexene, (di)cyclopentadiene, vinylcyclohexene, ethylidenebicycloheptene, and terpenes (for example, pinene, limonene, or indene). In the method for producing the mechanochromic compound of the present invention, one or more of the above-mentioned monomers may be used, and these monomers become repeating units in the polymer chain of the mechanochromic compound of the present invention.

[0029] The radical polymerization conditions can be appropriately selected from those commonly used in this field depending on the type of monomer and the like. The reaction temperature is not particularly limited as long as each monomer undergoes radical polymerization, but is, for example, 0° C. to 150° C., in one embodiment 20 to 120° C., and in another embodiment 50 to 100° C. The above upper and lower limits can be combined as appropriate. The reaction time is not particularly limited as long as each monomer undergoes radical polymerization, but is, for example, 5 minutes to 200 hours, in one embodiment 10 minutes to 100 hours, in another embodiment 30 minutes to 50 hours, and in another embodiment 1 hour to 10 hours. The above upper and lower limits can be combined as appropriate. The reaction may be carried out in the absence of a solvent or in a solvent. The solvent is not particularly limited as long as each monomer is radically polymerized, and examples thereof include alcohols, ethers, glycol ethers, ethylene glycol alkyl ether acetates, diethylene glycol alkyl ethers, propylene glycol monoalkyl ethers, propylene glycol alkyl ether acetates, propylene glycol alkyl ether propionates, aromatic hydrocarbons, halogenated hydrocarbons, amides, ketones, and esters.

[0030] [4]Method for detecting mechanical stimuli The method for detecting a mechanical stimulus of the present invention includes a step of detecting a mechanical stimulus applied to the mechanochromic material by measuring a change in color or fluorescence emission. The mechanical stimulus is not particularly limited, but examples thereof include compression, stretching, impact, shearing, crushing, bending, friction, and a combination of two or more thereof. The strength of the mechanical stimulus can be measured by the amount of change in color or fluorescence. For example, by measuring the relationship between the strength of the mechanical stimulus and the amount of color or fluorescence in advance, the strength of the mechanical stimulus applied to the mechanochromic material can be quantified.

[0031] Color development can be measured by a UV-visible spectrophotometer, and fluorescence emission can be measured by a spectrofluorometer.

[0032] 《Effect》 The reason why the mechanochromic compound of the present invention has sufficient temperature stability and can be used with good operability in radical polymerization has not been analyzed in detail, but can be assumed as follows, although the present invention is not limited by the assumption below. The mechanochromic compound described in Patent Document 2 is a compound having a tetraarylsuccinonitrile basic skeleton (TASN skeleton), which generates two DAAN skeletons when a mechanical stimulus is applied, thereby emitting fluorescence. [ka] The two DAAN skeletons generated from the TASN skeleton described in Patent Document 2 are in a state of dissociation-recombination equilibrium around room temperature and can respond sensitively to temperature changes. Therefore, two DAAN skeletons can be generated from the TASN skeleton under the temperature conditions of radical polymerization. On the other hand, the mechanochromic compound of the present invention is formed from a DAAN skeleton and a -CXY structure. When a mechanical stimulus is applied to the mechanochromic compound of the present invention, the DAAN skeleton and the -CXY structure are generated, as shown below. However, the mechanochromic compound of the present invention formed from a DAAN skeleton and a -CXY structure is stable to temperature changes and does not react sensitively to temperature changes, generating the DAAN skeleton and the -CXY structure. [ka] In the -CXY structure, X is an oxygen atom or a sulfur atom, and Y is an oxygen atom, a sulfur atom, or a nitrogen atom. The fact that the structure bonded to the DAAN skeleton is a -CXY structure, and that X is an oxygen atom or a sulfur atom and Y is an oxygen atom, a sulfur atom, or a nitrogen atom, is presumed to reduce the sensitivity of the bond between the DAAN skeleton and the -CXY structure to temperature changes. In other words, the mechanochromic compound of the present invention is considered to be a mechanochromic compound that generates a DAAN skeleton and emits fluorescence in response to mechanical stimuli, but is stable with respect to temperature changes. Therefore, the mechanochromic compound of the present invention is presumed to exhibit applicable thermal stability during radical polymerization. [Example]

[0033] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0034] Example 1 In this example, α-CN-DAAE having a hydroxy group was synthesized according to the following formula: [ka]

[0035] (Synthesis of Me-ACA-OMe) [ka] Me-ACA-OMe was synthesized by reacting 4-methoxyphenylacetonitrile with dimethyl carbonate in the presence of sodium hydride. A pale yellow viscous liquid was obtained in 88% yield. 1 H NMR spectrum, and 13 The formation of Me-ACA-OMe was confirmed by C NMR spectroscopy.

[0036] (Synthesis of HO-ACA-OMe) [ka] HO-ACA-OMe was synthesized by transesterification of Me-ACA-OMe with ethylene glycol. Colorless crystals were obtained in 71% yield. 1 H NMR spectrum and 13 The formation of HO-ACA-OMe was confirmed by C NMR spectroscopy.

[0037] (Synthesis of TBSO-ACA-OMe) [ka] HO-ACA-OMe was protected with a tert-butyldimethylsilyl (TBS) group to synthesize TBSO-ACA-OMe. A colorless, transparent, viscous liquid was obtained in 95% yield. 1 H NMR spectrum and 13 The formation of TBSO-ACA-OMe was confirmed by C NMR spectroscopy.

[0038] (Synthesis of (2-(4-bromophenoxy)ethoxy)(tert-butyl)dimethylsilane) [ka] 2-(p-Bromophenoxy)ethanol was protected with a TBS group to synthesize (2-(4-Bromophenoxy)ethoxy)(tert-butyl)dimethylsilane. A colorless, transparent, viscous liquid was obtained in 97% yield. 1 H NMR spectrum and 13The formation of (2-(4-bromophenoxy)ethoxy)(tert-butyl)dimethylsilane was confirmed by C NMR spectrum.

[0039] (Synthesis of α-CN-DAAE-diOTBS) [ka] α-CN-DAAE-diOTBS was synthesized by a coupling reaction using a palladium catalyst. A pale yellow viscous liquid was obtained in 80% yield. 1 H NMR spectrum and 13 The formation of α-CN-DAAE-diOTBS was confirmed by C NMR spectroscopy.

[0040] (Synthesis of α-CN-DAAE-diOH) [ka] α-CN-DAAE-diOTBS was treated with hydrochloric acid to deprotect the TBS group and convert it to α-CN-DAAE-diOH. A pale yellow viscous liquid was obtained in 73% yield. 1 H NMR spectrum and 13 The formation of α-CN-DAAE-diOH was confirmed by C NMR spectroscopy, and the peak of the sodium adduct ion of the target compound was obtained by electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS).

[0041] Example 2 In this example, α-CN-DAAE-diOH obtained in Example 1 was introduced into the polystyrene main chain. Specifically, α-CN-DAAE-introduced polystyrene (PS) was synthesized by copper-catalyzed azide-alkyne click reaction (CuAAC) according to the following scheme: [ka]

[0042] (Synthesis of α-CN-DAAE-dialkyne) [ka] α-CN-DAAE-dialkyne was synthesized by esterification of α-CN-DAAE-diOH with 5-hexynoic acid using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI·HCl) as a condensing agent. A pale yellow viscous liquid was obtained in 64% yield. 1 The formation of α-CN-DAAE-dialkyne was confirmed by 1 H NMR spectroscopy.

[0043] (Synthesis of PS-Br) [ka] PS-Br was synthesized by ATRP of styrene using ethyl 2-bromoisobutyrate as an initiator. A white powder was obtained in 18% yield. The GPC elution curve of the product showed a single peak with a narrow molecular weight distribution. 1 The formation of PS-Br was confirmed by 1 H NMR spectroscopy.

[0044] (Synthesis of PS-N3) [ka] By reacting PS-Br with sodium azide, PS (PS-N3) bearing an azide group at one end was synthesized. A white powder was obtained in 99% yield. The GPC elution curve of the product showed a single peak with a narrow molecular weight distribution, which was consistent with that of PS-Br. 1 The positions of all signals in the H NMR spectrum indicate the desired structure. 1 H NMR spectrum was obtained. Furthermore, FT-IR revealed a stretching vibration at 2093 cm resulting from azide, which was not observed in PS-Br. -1 From the above, PS-N3 was obtained.

[0045] (Synthesis of α-CN-DAAE-diPS) [ka] Using CuAAC, PS with one α-CN-DAAE in the center of the molecular chain was synthesized. After the reaction, excess PS-N3 was removed by fractional precipitation using cyclohexane / hexane, and a white powder was obtained in a yield of 58%. The GPC elution curve of the product showed a single peak with a narrow molecular weight distribution, confirming that the molecular weight was approximately twice that of PS-N3. 1 In the H NMR spectrum, all signals were assigned without any contradiction. Furthermore, FT-IR revealed a peak at 2093 cm due to the stretching vibration of azide. -1 The disappearance of the peak indicated the progress of the reaction and the removal of PS-N3. From the above, α-CN-DAAE-diPS was obtained.

[0046] Example 3 In this example, a grinding test was carried out on the α-CN-DAAE-diPS obtained in Example 2, and fluorescence emission was confirmed. 100 mg of the synthesized α-CN-DAAE-diPS was ground in a ball mill (30 Hz, 30 min) and the mechanical response was evaluated by ESR and fluorescence spectroscopy. The ESR spectrum is shown in Figure 1. Fluorescence spectroscopy confirmed fluorescence emission after grinding, and the fluorescence spectrum matched that of the DAAN-diOMe radical (Figure 1). In other words, grinding generated DAAN radicals.

[0047] Example 4 In this example, to demonstrate that an α-CN-DAAE-containing polymer can be synthesized by radical polymerization, PS having α-CN-DAAE at the center of the molecular chain was synthesized by ATRP according to the following formula: [ka]

[0048] (Synthesis of α-CN-DAAE-diBr) [ka] α-CN-DAAE-diBr was synthesized by reacting α-CN-DAAE-diOH with 2-bromoisobutyryl bromide in the presence of triethylamine (TEA). A pale yellow viscous liquid was obtained in 86% yield. 1 H NMR spectrum and 13 The formation of α-CN-DAAE-diBr was confirmed by C NMR spectroscopy.

[0049] (Synthesis of α-CN-DAAE-diPS-Br) [ka] α-CN-DAAE-diPS-Br was synthesized by ATRP of styrene using α-CN-DAAE-diBr as an initiator, and a white powder was obtained in 10% yield. 1 All signals were consistently assigned in the H NMR spectrum. The GPC elution curve of the product showed a narrow peak with a molecular weight distribution. Although some high molecular weight products were observed, which are thought to have been generated by coupling of the growing ends, it was determined that the polymerization proceeded without side reactions. From the above, α-CN-DAAE did not inhibit radical polymerization and was introduced into the polymer by ATRP.

[0050] (Synthesis of α-CN-DAAE-diPS-H) [ka] After deactivation of the terminals with tributyltin hydride, α-CN-DAAE-diPS-H was synthesized, yielding a white powder in 79% yield. 1 The progress of the reaction was confirmed by H NMR spectroscopy. The peak top molecular weight of the product in the GPC elution curve did not change, but an increase in the proportion of high molecular weight compounds was confirmed. This is thought to be because low molecular weight compounds were preferentially removed by precipitation purification, resulting in a relative increase in high molecular weight compounds.

[0051] Example 5 In this example, a grinding test was carried out on α-CN-DAAE-diPS-H obtained in Example 4, and fluorescence emission was confirmed. The PS with α-CN-DAAE at the center of the molecular chain obtained by ATRP was ground in a ball mill (30 Hz, 30 min) to investigate its mechanical response. ESR measurements revealed that trace amounts of radicals were generated only after grinding (Figure 2a). Fluorescence spectroscopy measurements also confirmed weak fluorescence emission (Figure 2b). Therefore, α-CN-DAAE is a mechanochromophore that can be introduced into polymers by radical polymerization.

[0052] Example 6 and Comparative Example 1 In this example, crosslinked polymers incorporating α-CN-DAAE at the crosslinking points were synthesized by free radical polymerization. Specifically, a dimethacrylate crosslinker with an α-CN-DAAE skeleton (α-CN-DAAE-diMA: Example 6) and a control crosslinker without an α-CN-DAAE skeleton (benzene-diMA: Comparative Example 1) were synthesized. [ka]

[0053] (Synthesis of α-CN-DAAE-diMA) [ka] α-CN-DAAE-diMA was synthesized by reacting α-CN-DAAE-diOH with methacryloyl chloride. A pale yellow viscous liquid was obtained in 64% yield. 1 H NMR spectrum and 13 The formation of α-CN-DAAE-diMA was confirmed by C NMR spectroscopy.

[0054] (Synthesis of Crosslinking Agent of Comparative Example 1) [ka] Benzene-diMA was synthesized by reacting 1,4-benzenedimethanol with methacryloyl chloride. Colorless crystals were obtained in 45% yield. 1 H NMR spectrum and 13 The formation of benzene-diMA was confirmed by C NMR spectroscopy.

[0055] Example 7 and Comparative Example 2 In this example and comparative example, polymer compounds were obtained by radical copolymerization using the crosslinking agents obtained in Example 6 and Comparative Example 1. (Synthesis of cross-linked polymethyl acrylate) Crosslinked poly(methyl acrylate) (CP) bearing α-CN-DAAE at the crosslinking points was prepared by free radical copolymerization of methyl acrylate and crosslinker (α-CN-DAAE-diMA or benzene-diMA) using 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70) as an initiator in dehydrated dimethylacetamide (DMAc). α-CN-DAAE ) and cross-linked polymers without RMC (CP benzene ) was synthesized. The yield of each crosslinked polymer and the degree of swelling calculated from the swelling test are shown in Table 1. Since the yields were similar and high for the two types of crosslinking agents, it was determined that the polymerization proceeded normally. The degree of swelling was calculated from the change in weight before and after immersion in anisole for 24 hours using Eq. 4.1. [Table 1]

[0056] Tensile test To evaluate the mechanical properties of the synthesized crosslinked polymers, each sample was punched into a dumbbell shape (ISO 37-4) and subjected to a tensile test at room temperature (21.8-23.2°C) at a tensile speed of 10 mm / min. Each sample was measured four times, and a representative stress-strain curve is shown in Figure 3. Table 2 shows various mechanical properties determined from the tensile tests. CP of Comparative Example 2 benzene Compared to CP α-CN-DAAE showed roughly the same mechanical properties. Unlike conventional RMCs, α-CN-DAAE is thought to have a bond strength closer to that of a normal covalent bond. In other words, α-CN-DAAE is an RMC that can be introduced into polymers without impairing the mechanical properties of the material. [Table 2]

[0057] <ESR and fluorescence spectrum measurements> ESR and fluorescence spectrum measurements were performed on the test specimen after fracture. benzene In Example 7 (CP), no radical generation or fluorescence emission was observed before or after tension (Fig. 4). α-CN-DAAE ), only after tension, an ESR signal at g = 2.003 corresponding to carbon radicals and yellow fluorescence (λ em,max The fluorescence spectrum was confirmed to be consistent with that of the DAAN-diOMe radical, confirming the generation of the DAAN radical (Figure 5a). The activation rate calculated from ESR measurements was approximately 0.01% (Figure 5b). Considering that the introduction rate of α-CN-DAAE was approximately 5.5 wt%, it became clear that stress could be visualized even though the amount of activated α-CN-DAAE was extremely small.

[0058] <Luminescence behavior during tensile test> CP of Example 7 α-CN-DAAE During the tensile test, ultraviolet light with a wavelength of 365 nm was irradiated onto the specimen. As shown in Figure 6, yellow fluorescence was observed from a strain of approximately 550%. [Industrial Applicability]

[0059] The mechanochromic compound of the present invention has sufficient temperature stability and can be used in radical polymerization with good operability.

Claims

1. The following formula [1]: 【Chemistry 1】 (In the formula, X is an oxygen atom or a sulfur atom, Y is an oxygen atom, a sulfur atom, or a nitrogen atom; R ２ is 1 to 5 in each phenyl group, R １ and R ２ are each independently a hydrocarbon group having 1 to 100,000 carbon atoms which may have a substituent and which may contain a heteroatom, and the substituent is a halogen atom, an alkyl group, an alkoxy group, an alkynyl group, an alkenyl group, a hydroxyl group, a thiol group, a sulfinyl group, a sulfonyl group, a carboxy group, a silyl group, an alkoxysilyl group, an epoxy group, an amino group, an aldehyde group (formyl group), a carbonyl group, an alkoxycarbonyl group, an amide group, or an isocyanate group. A mechanochromic compound represented by the formula:

2. 2. The mechanochromic compound according to claim 1, wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, comprises a polymer chain selected from the group consisting of polyurethane, polyester, polyamide, polylactone, polystyrene, polyacrylic acid or its ester or amide, polymethacrylic acid or its ester or amide, polyalkylene oxide, polysiloxane, polydimethylsiloxane, polycarbonate, polylactide, polyolefin, polyisobutylene, polyamideimide, polybutadiene, epoxy resin, phenolic resin, polyacetylene, polyvinyl, and combinations of two or more thereof.

3. 2. The mechanochromic compound according to claim 1, wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, contains a vinyl group, an ethynyl group, or an azide group at its terminal.

4. A crosslinking agent comprising the mechanochromic compound according to claim 3 .

5. A method for producing a mechanochromic polymer compound by radical polymerization, comprising mixing a monomer having a vinyl group and the crosslinking agent according to claim 4 (excluding crosslinking agents in which the terminal group of the hydrocarbon group is an ethynyl group or an azide group).

6. 2. The mechanochromic compound according to claim 1, wherein the hydrocarbon group having 1 to 100,000 carbon atoms and optionally containing a heteroatom, which may have a substituent, contains a halogen atom at its terminal.

7. A polymerization initiator comprising the mechanochromic compound according to claim 6 .

8. A method for producing a mechanochromic polymer compound by radical polymerization, comprising mixing a monomer having a vinyl group and the polymerization initiator according to claim 7.

9. The mechanochromic compound according to claim 1 or 2, which develops color and / or emits fluorescence in response to a mechanical stimulus.

10. 10. The mechanochromic compound of claim 9, wherein the mechanical stimulus is selected from the group consisting of compression, stretching, impact, shear, crushing, bending, friction, ultrasound, and combinations of two or more thereof.

11. A mechanochromic material comprising the mechanochromic compound according to claim 1 or 2.

12. The mechanochromic material according to claim 11, which is a laminate or a molded body.

13. A method for detecting a mechanical stimulus, comprising the step of detecting a mechanical stimulus applied to the mechanochromic material according to claim 11 by measuring a change in color development and / or fluorescence emission.

14. The method for detecting a mechanical stimulus according to claim 13, wherein the mechanical stimulus is selected from the group consisting of compression, extension, impact, shear, crushing, bending, friction, ultrasound, and combinations of two or more thereof.

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