Monomer for polymerization of photodegradable polymer, photodegradable polymer, production method and decomposition method thereof, and method for recovering lactone

Abstract

To provide a monomer for polymerization of a photodegradable polymer having a radical-decomposable site which is easily decomposed by light in the main chain of the polymer, a highly versatile photodegradable polymer containing the monomer in the main chain of the polymer, a method for producing the polymer, a method for decomposing the polymer, and a method for recovering an organic compound (lactone) by the decomposition of the polymer.SOLUTION: The monomer for polymerization of a photodegradable polymer has a group represented by formula (1) as a radical-decomposable site. Wherein R1, R2, R3 and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring. ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a monomer for polymerization of a photodegradable polymer having a radically decomposable site, a photodegradable polymer obtained by polymerizing a monomer containing such a monomer, a method for producing the photodegradable polymer, a method for decomposing the photodegradable polymer by irradiating it with light, and a method for decomposing the photodegradable polymer by irradiating it with light and recovering the corresponding lactone. [Background technology]

[0002] The global plastics (polymer) market is expected to reach US$756.9 billion by the end of 2030, up from US$599.4 billion in 2022. Synthetic polymers have traditionally been designed with an emphasis on performance and durability, without sufficient consideration of the degradability and recyclability of the polymers after use. Currently, post-consumer polymer waste is disposed of by landfilling, incineration, or mechanical recycling. Landfilling, however, poses the risk of serious environmental pollution due to the persistence of most polymer waste, resulting in environmental accumulation and degradation. While thermal recycling is used for incineration, it is difficult to call it recycling in its truest sense, due to the insufficient energy recovery efficiency for heat utilization, including power generation, and the resulting carbon dioxide emissions. On the other hand, mechanical recycling, for example, in the case of PET bottles, involves sorting, crushing, and cleaning, followed by high-temperature diffusion of contaminants from the resin, decontamination, and drying to produce flakes. This is the most efficient method. However, there are problems in that the polymers to which mechanical recycling can be applied are limited, and processing polymer waste such as composite materials, laminated materials, coating materials, and contaminated materials is difficult and expensive.

[0003] Meanwhile, from the perspectives of environmental conservation, including the microplastics issue, and carbon cycle, the market for biodegradable polymers, or "green polymers" (GPs), is expected to reach US$5.8 billion in 2020 and US$16.8 billion in 2030. However, the biodegradation rate of GPs is greatly affected by environmental conditions (e.g., soil, water, air), and not all GPs are always biodegradable under favorable environmental conditions. Furthermore, GPs derived from nonedible biomass such as bagasse and cellulose remain expensive, slowing their practical application. Therefore, most biodegradable polymers are derived from food crops such as corn and sugarcane. Mass production of biodegradable polymers is feared to cause serious food shortages. Therefore, relying on plant-based raw materials for biodegradable polymer production could lead to a trade-off between solving environmental conservation issues and worsening food shortages. Therefore, there is still a need to address the recycling and microplastics issues by endowing inexpensive petroleum-based plastics with biodegradable properties.

[0004] Photolysis technology as a polymer decomposition technique is relatively old, having been known since the 1960s, and some photolysis systems for polystyrene and ketone polymers have been put to practical use (Non-Patent Document 1). Furthermore, since the 1970s, photolysis of polymers using enzymes and photocatalysts such as titanium oxide has also been reported (Non-Patent Document 2). Recently, a technology for decomposing polymers with special cyclic structures by cleaving carbon-oxygen bonds using an organic photocatalyst system has been reported (Non-Patent Document 3), but the target is limited to polymers with specific structures. It has also been reported that introducing a small amount of vinyl ether into a (meth)acrylic polymer decomposes the polymer through a hydrogen atom transfer reaction upon irradiation with light (Non-Patent Document 4), but the vinyl ether is present in the side chain, not in the main chain of the polymer. Furthermore, Patent Document 1 describes a photodegradable polymer compound that uses a group containing a nitro-substituted benzyl as the photodegradable moiety, but because the polymer chain is linked via the photodegradable moiety and the photodegradable moiety is not used as a monomer, the degree of freedom in designing the photodegradable polymer compound is limited.

[0005] The present inventors have been engaged in research into alkyl radicals for many years, and in the course of their research, have discovered that alkyl radicals can be easily produced by cleaving the carbon-oxygen bond of an ester through photocatalysis. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-233137 [Non-patent literature]

[0007] [Non-Patent Document 1] N. Grassie, et al., Journal of Applied Polymer Science, The Photooxidation of Polymers II. Photolysis of Polystyrene,Vol.9,pp.975-986 (1965) [Non-patent document 2] Masao Kato, Polymers, Easily Degradable Polymers, Vol.5, No.7·8, pp.409-411(1972) [Non-patent document 3] Adam M. Freiberg et al., Triggered Transience of Plastic Materials by a Single Electron Transfer Mechanism, ACS Cent Sci.2020, 6. 266-273 [Non-patent document 4] Taichi Kimura, Makoto Ouchi, Angewandte Chemie InternationalEdition, Photocatalyzed HAT-Degradation of Vinyl Polymers: Cleavage of CC Bondin Backbone Triggered by Radical Activation of CH Bond in Pendant,10.1002 / anie.202305252(DOI), 26 June 2023 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide a monomer for photodegradable polymer polymerization having a radically decomposable structure in the main chain of the polymer that is easily decomposed by light, a highly versatile photodegradable polymer that contains such a monomer in the main chain of the polymer, a method for producing the same, a method for decomposing the same, and a method for recovering an organic compound (lactone) by decomposing the polymer. [Means for solving the problem]

[0009] The inventors have conducted research into alkyl radicals for many years and have identified radically decomposable sites that are easily decomposed by light. Based on this, they have applied this knowledge to polymers and discovered that versatile photodecomposable polymers incorporating radically decomposable sites can be produced by polymerizing monomers containing monomers having radically decomposable sites. Furthermore, they have discovered an efficient method for decomposing such photodecomposable polymers and a method for recovering the organic compound (lactone) obtained by decomposition, thereby completing the present invention.

[0010] That is, the present invention is specified by the following items. [1] A photodegradable polymer polymerization monomer having a group represented by the following formula (1) as a radically decomposable site: [ka] (In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.) [2] The photodegradable polymer polymerization monomer according to [1], wherein the photodegradable polymer polymerization monomer is selected from the following formulae (2) to (7): [ka] TIFF2026038490000003.tif3576 (wherein X represents Cl, Br, or I.) TIFF2026038490000004.tif39100TIFF2026038490000005.tif42100TIFF2026038490000006.tif46121TIFF2026038490000007.tif35140[3] A photodegradable polymer obtained by polymerizing a monomer containing the monomer for photodegradable polymer polymerization according to [1] or [2]. [4] The photodegradable polymer according to [3], characterized in that a monomer other than the photodegradable polymer polymerization monomer according to [1] or [2] is a base monomer constituting the main chain. [5] The photodegradable polymer according to [3], which is a polyester-based polymer, a polyamide-based polymer, a polyurethane-based polymer, an epoxy-based resin, or a polyether ether ketone-based polymer. [6] The photodegradable polymer according to [4], wherein the base monomer is a polyester-based monomer, a polyamide-based monomer, a polyurethane-based monomer, an epoxy-based resin monomer, or a polyether ether ketone-based monomer. [7] A method for producing a photodegradable polymer, comprising polymerizing a monomer containing a monomer having a group represented by the following formula (1) as a radically decomposable site: [ka] (In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.) [8] A method for decomposing a photodegradable polymer, comprising irradiating a photodegradable polymer having a group represented by the following formula (1) as a radically decomposable site with light: [ka] (In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.) [9] The method for decomposing a photodegradable polymer according to [8], further comprising using a photocatalyst.

[10] The method for decomposing a photodegradable polymer according to [9], further comprising using a co-catalyst.

[11] A method for recovering the corresponding lactone, comprising decomposing a photodegradable polymer having a group represented by the following formula (1) as a radically decomposable site by irradiating it with light in the presence of a photocatalyst and a cocatalyst: [ka] (In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.) [Effects of the Invention]

[0011] Since the monomer for polymerization into a photodegradable polymer of the present invention has a radically decomposable moiety, a polymer obtained by polymerizing a monomer containing such a monomer has photodegradability. Furthermore, since the monomer for polymerization into a photodegradable polymer of the present invention has a moiety that cleaves a carbon-oxygen bond, it can be widely applied to polymers having a carbon-oxygen bond. Therefore, as the photodegradable polymer of the present invention, a highly versatile photodegradable polymer can be produced. Furthermore, the photodegradable polymer of the present invention is a polymer in which a radically decomposable moiety is incorporated into the main chain of the polymer, and can be decomposed by cleavage of the radically decomposable moiety upon irradiation with light, etc. Furthermore, the substance obtained during decomposition can be recovered as a lactone. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a monomer for polymerization of a photodegradable polymer having a group represented by formula (1) as a radically decomposable site, a photodegradable polymer obtained by polymerizing such a monomer, a method for producing the same, a method for decomposing the same, and a method for recovering the organic compound (lactone) obtained by decomposition. [ka] (In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.)

[0013] The photodegradable polymer polymerization monomer of the present invention has a group that is cleaved by light, that is, a radically decomposable site, represented by the following formula (1). [ka] In the formula, R1, R2, R3, and R4 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring. R1, R2, R3, and R4 in the group represented by formula (1) are alkyl groups such as methyl, ethyl, n-propyl, and n-butyl, branched alkyl groups such as isopropyl and isobutyl, and cycloalkyl groups such as cyclopentyl and cyclohexyl. Aryl groups include phenyl. R1, R2, R3, and R4 may be the same or different. Furthermore, the group represented by formula (1) can be converted into a polymerization monomer having the group represented by formula (1) by linking Y to a carbonyl group (C(O) group) to introduce or serve as a polymerization initiation site. Y represents a chlorine atom, boron atom, iodine atom, or OR5, and R5 represents a hydrogen atom; an alkyl group such as a linear alkyl group (e.g., methyl, ethyl, n-propyl, or n-butyl), or a branched alkyl group (e.g., isopropyl or isobutyl); a terminal alkylene group (e.g., vinyl, propylene, or 1-butene); a carboxylic acid group represented by -(CH2)nCOOH; a hydroxyl group represented by -(CH2)nOH; or a hydroxyl group containing an aromatic ring (e.g., parahydroxybenzene, bisphenol A). When R5 represents a carboxylic acid group represented by -(CH2)nCOOH, a hydroxyl group represented by -(CH2)nOH, or a hydroxyl group containing an aromatic ring (e.g., parahydroxybenzene, bisphenol A), the hydrogen atom of the carboxylic acid group or hydroxyl group may be dissociated. Note that n is an integer.

[0014] Specific examples of the monomer for polymerization of a photodegradable polymer having a group represented by formula (1) as the radically decomposable site of the present invention include those represented by formulas (2) to (7). [ka] TIFF2026038490000014.tif3576 (wherein X represents Cl, Br, or I.) TIFF2026038490000015.tif39100TIFF2026038490000016.tif42100TIFF2026038490000017.tif46121TIFF2026038490000018.tif35140

[0015] The monomer for polymerization of a photodegradable polymer represented by formula (2) of the present invention is a monomer for polymerization of a photodegradable polymer, in which in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, Y is OR5, and R5 is a propyl group. The photodegradable polymer polymerization monomer of the present invention represented by formula (3) is a photodegradable polymer polymerization monomer in which, in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, and Y is a chlorine atom, a boron atom, or an iodine atom. The photodegradable polymer polymerization monomer of the present invention represented by formula (4) is a photodegradable polymer polymerization monomer in which, in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, Y is OR5, and R5 is -(CH2)2OH. The monomer for photodegradable polymer polymerization represented by formula (5) of the present invention is a monomer for photodegradable polymer polymerization in which, in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, Y is OR5, and R5 is a hydrogen atom. The monomer for photodegradable polymer polymerization represented by formula (6) of the present invention is a monomer for photodegradable polymer polymerization in which, in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, Y is OR5, and R5 is hydroxybenzene. The monomer for polymerization of a photodegradable polymer represented by formula (7) of the present invention is a monomer for polymerization of a photodegradable polymer, in which in formula (1), R1 to R4 are all methyl groups, Ar is a phenyl group, Y is OR5, and R5 is a propyl oxide group.

[0016] The monomer for polymerization of the photodegradable polymer of the present invention can be synthesized by a conventional method. For example, a synthesis example of the monomer represented by formula (5) is as follows. Terephthalic acid chloride can be obtained by dissolving terephthalic acid in an organic solvent and treating it with an acid chloride synthesis reagent. The organic solvent can be one selected from dichloromethane, toluene, DMF, THF, chloroform, etc. The acid chloride synthesis reagent can be one selected from thionyl chloride, sulfuryl chloride, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, oxalyl chloride, etc. The resulting terephthalic acid chloride can be reacted with 2-hydroxy-2-methylpropanoic acid and a base in an organic solvent to obtain a monomer represented by formula (5). Examples of the base include pyridine and triethylamine, and examples of the organic solvent include the above-mentioned solvents plus acetonitrile, or a mixture of two or more solvents.

[0017] The photodegradable polymer of the present invention can be produced by polymerizing monomers including a monomer for polymerization of a photodegradable polymer. The photodegradable polymer of the present invention can be produced as a homopolymer by polymerizing only the monomer for photodegradable polymer polymerization having the group represented by formula (1), and can also be produced as a copolymer in which the monomer for photodegradable polymer polymerization of the present invention is arranged in any ratio by polymerizing the monomer for photodegradable polymer polymerization having the group represented by formula (1) with other monomers in any ratio.

[0018] The copolymer may be a polymer in which a monomer other than the monomer having a radically decomposable moiety serves as a base monomer to form the polymer main chain, and a monomer having a group represented by formula (1) is incorporated as a radically decomposable moiety into the main chain formed by the base monomer. The polymer formed by the base monomer is not particularly limited, and examples thereof include polycondensation / polyaddition polymers such as polyester polymers including polyarylene, polyamide polymers, polyetheramide polymers, polyether polymers, and polyurethane polymers, addition polymerization polymers such as polyethylene polymers, polypropylene polymers, and polyvinyl chloride polymers, phenolic resins, and epoxy resins. Among these, polyester polymers, polyamide polymers, polyurethane polymers, and epoxy resins are preferred from the viewpoint of ease of synthesis. Specifically, the photodegradable polymer polymerization monomer of the present invention can be polymerized in appropriate combination with terephthalic acid, hexamethylenediamine, adipic acid, ethylene glycol, 1,4-butanediol, metaphenylenediamine, 4,4'-diphenylmethane diisocyanate, bisphenol A, epichlorohydrin-terminated diene compounds, etc. to obtain a polymer incorporating a radically decomposable site.

[0019] Examples of base monomers for polyester-based polymers include base monomers represented by the following formulas (8) and (9) or base monomers represented by the following formulas (8) and (10), and polyester-based base polymers can be produced by polymerization of such base monomers. [ka] In the formula, n represents an integer of 2 to 4. TIFF2026038490000020.tif4881TIFF2026038490000021.tif57100

[0020] Examples of base monomers for polyamide-based polymers include base monomers represented by the following formulas (11) and (12) or base monomers represented by the following formulas (13) and (14), and polyamide-based base polymers can be produced by polymerization of such base monomers. [ka] In the formula, n represents an integer of 6 to 9. TIFF2026038490000023.tif3581In the formula, n represents an integer of 4 to 8. TIFF2026038490000024.tif3470In the formula, the amino group is substituted at the meta or para position. TIFF2026038490000025.tif4481In the formula, the carboxyl group is substituted at the meta or para position.

[0021] Examples of base monomers for polyurethane-based polymers include base monomers represented by the following formulas (15) and (16), and polyurethane-based base polymers can be produced by polymerization of such base monomers. [ka] TIFF2026038490000027.tif2876In the formula, n represents an integer of 2 to 6.

[0022] Examples of base monomers for epoxy resins include base monomers represented by the following formulas (17) and (18), and epoxy resins (base polymers) can be produced by polymerization of such base monomers. [ka] TIFF2026038490000029.tif2266

[0023] Examples of base monomers for polyether ether ketone-based polymers include base monomers represented by the following formulas (19) and (20), and polyether ether ketone-based base polymers can be produced by polymerization of such base monomers. [ka] TIFF2026038490000031.tif2770In the formula, M means sodium or potassium.

[0024] The polymer of the present invention can be produced by a conventional method using the monomer for polymerization of the photodegradable polymer of the present invention. For example, a photodegradable polymer as a polyester polymer can be obtained by dissolving the monomer represented by formula (2) in an organic solvent under an inert gas atmosphere, adding a polymerization catalyst, and carrying out metathesis polymerization. The organic solvent can be one solvent or a mixed solvent of two or more solvents selected from chloroform, chlorobenzene, toluene, hexane, ethanol, etc., and the polymerization catalyst can be any one of a first-generation Grubbs catalyst, a second-generation Grubbs catalyst, a third-generation Grubbs catalyst, etc. The polymerization temperature and time are preferably 70 to 90°C and 12 to 48 hours, respectively.

[0025] Furthermore, a synthesis example in which polyethylene terephthalate (PET) having a radically decomposable moiety is obtained using a monomer represented by formula (5) is as follows: The monomer represented by formula (5) is reacted with methanol to form a dimethyl ester, and the resulting dimethyl ester is mixed with dimethyl terephthalate and ethylene glycol. In this case, the molar ratio of ethylene glycol to the total of the dimethyl ester and dimethyl terephthalate is mixed so that it is 1 / 1. By subjecting this mixture to a transesterification reaction, polyethylene terephthalate (PET) in which the monomer represented by formula (5) has been incorporated as a radically decomposable moiety can be obtained.

[0026] Furthermore, a synthesis example in which polyethylene naphthalate (PEN) having a radically decomposable site is obtained using a monomer represented by formula (5) is as follows: The monomer represented by formula (5) is reacted with thionyl chloride to form an acid chloride, and the resulting acid chloride is mixed with 2,6-naphthalenedicarboxylic acid chloride and ethylene glycol. In this case, the molar ratio of ethylene glycol to the total of the acid chloride represented by formula (5) and 2,6-naphthalenedicarboxylic acid chloride is mixed at 1 / 1. By subjecting this mixture to a dehydrochlorination reaction, polyethylene naphthalate (PEN) in which the monomer represented by formula (5) has been incorporated as a radically decomposable site can be obtained.

[0027] Furthermore, a synthesis example of obtaining nylon 6,6 having a radically decomposable moiety using a monomer represented by formula (5) is as follows: The monomer represented by formula (5) is mixed with adipic acid and hexamethylenediamine. In this case, the mixture is mixed so that the molar ratio of the total of adipic acid and hexamethylenediamine to the monomer represented by formula (5) is 1 / 1. Then, dehydration condensation is carried out to obtain nylon 6,6 incorporating the monomer represented by formula (5) as a radically decomposable moiety.

[0028] The photodegradable polymer of the present invention can be decomposed by light irradiation; specifically, it can be decomposed by irradiation with artificial light, which is light of a specific wavelength, and can also be decomposed by irradiation with sunlight. Furthermore, when exposed to sunlight, the photodegradable polymer of the present invention can be decomposed in a natural environment, such as in the presence of air. When artificial light is used, the decomposition rate of the photodegradable polymer is easier to control and the decomposition rate can be increased compared to when sunlight is used for decomposition. As the artificial light, which is light of a specific wavelength, light of 365 nm or 405 nm is used. That is, the photodegradable polymer of the present invention is photodecomposed by radical decomposition of the group represented by formula (1) and cleavage of the carbon-oxygen bond.

[0029] In the method for decomposing a photodegradable polymer of the present invention, a photocatalyst can be used when irradiating with light. The photocatalyst can be a catalyst having a reduction potential (E 0 Red ) is sufficient as long as it has a reduction potential lower than -1.29 V. There are no particular limitations on the substance as long as it has such a reduction potential, but taking into consideration the interaction with the substrate, BDB (bisdiphenylaminobenzene), NPB, BNPB, HPTPN, etc. are suitable examples. The chemical structural formulas of BDB, NPB, BNPB, and HPTPN are shown below. [ka] TIFF2026038490000033.tif3460TIFF2026038490000034.tif43100TIFF2026038490000035.tif4360

[0030] The photodegradable polymer of the present invention allows for time-dependent control of the radical decomposition of the polymer by selecting the content ratio of the monomer having a radically decomposable moiety, a group represented by formula (1), in the polymer and the decomposition conditions (e.g., irradiation with light of a specific wavelength or exposure to sunlight). The amount of photocatalyst used is preferably about 1 mol% relative to the photodegradable polymer when decomposition to a certain extent is desired within a few days under irradiation with light of a specific wavelength. The photocatalyst can be added to the photodegradable polymer during decomposition, or it can be kneaded into or coated on the polymer before the photodegradable polymer is used for a specific purpose. Additionally, an organic or inorganic third component may be added to the photodegradable polymer together with the photocatalyst to facilitate fixation of the photocatalyst to the polymer.

[0031] Furthermore, in the method for decomposing a photodegradable polymer of the present invention, a co-catalyst for the photocatalyst can be used to promote decomposition. Examples of the co-catalyst include, but are not limited to, water, Bronsted acid, Lewis acid, sulfuric acid, hydrochloric acid, PTSA (p-toluenesulfonic acid) / HO, and CSA.

[0032] The environment in which the method for decomposing a photodegradable polymer of the present invention is carried out is not particularly limited, but the method can be carried out in a solvent. The solvent for carrying out the method for decomposing a photodegradable polymer of the present invention is not particularly limited, but is preferably one organic solvent or a mixed organic solvent of two or more selected from N,N'-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), N,N-diacetylacetamide (DMA), dioxane, toluene, ether, acetone, THF, dichloromethane, etc., and particularly preferably a mixed solvent of THF (tetrahydrofuran) and water.

[0033] The photodegradable polymer of the present invention is decomposed by adding a photocatalyst and a co-catalyst, if necessary, to the photodegradable polymer and irradiating the polymer with artificial light or sunlight. The other decomposition conditions in the method for decomposing the photodegradable polymer are not particularly limited, but it is preferable that the decomposition temperature be higher than room temperature.

[0034] The photodegradable polymer of the present invention contains a monomer for photodegradable polymer polymerization having a group represented by formula (1) as a radically decomposable site, and therefore, when decomposed by light irradiation, compounds derived from -C(O)-C(R3)(R4)-O- and -OC(R1)(R2)-C(O)- are generated. Products derived from such structures can be recovered as lactones by allowing diphenylethane (DPE) or the like to coexist during the decomposition of the photodegradable polymer. The method for recovering lactones of the present invention can be carried out simultaneously with the method for decomposing a photodegradable polymer of the present invention.

[0035] The present invention will be specifically described below with reference to examples of the present invention, but the technical scope of the present invention is not limited to these examples. [Example]

[0036] [Production of photodegradable polyester polymer] The photodegradable polyester polymer of the present invention was produced according to the following chemical reaction formula. [ka] Bis(1-(allyloxy)-2-methyl-1-oxopropan-2-yl) terephthalate (5 mmol: the compound of formula (2)) and 2nd-Hoveyda-Grubbs catalyst (1 mol%) were placed in a flask equipped with a rotor. Dichlorobenzene (5 mL) was added and the mixture was stirred at 80°C for 20 hours while reducing the pressure (600 Pa) using a vacuum pump. After the reaction, the product was obtained in a 34% yield by cotton filtration and reprecipitation (methanol). The resulting product had the following molecular weight: Mn=20,110, Mp=31,299, Mw=37,561, Mw / Mn=1.87 [Example]

[0037] [Production of photodegradable polyester polymer (polyarylate)] The photodegradable polyarylate of the present invention was produced according to the following chemical reaction formula. [ka] Bis(1-chloro-2-methyl-1-oxopropan-2-yl)terephthalate (1 mmol: compound of formula (3)) and bisphenol A (1 mmol) were placed in a screw vial equipped with a rotor and the atmosphere was replaced with nitrogen. Dichloromethane (1 mL) was then added and stirred. Triethylamine (5 mmol) was then slowly added and the mixture was stirred at 70°C for 20 hours. After the reaction, the product was obtained in 46% yield by cotton filtration and reprecipitation (methanol). The resulting product had the following molecular weight: Mn =16,494, Mw = 26,921, Mp = 25,171, Mw / Mn = 1.63 [Example]

[0038] [Production of photodegradable polyurethane polymer] The photodegradable polyurethane polymer of the present invention was produced according to the following chemical reaction formula. [ka] Bis(1-(2-hydroxyethoxy)-2-methyl-1-oxopropan-2-yl)terephthalate (2 mmol: compound of formula (4)) and 1,4-diisocyanatobenzene (2 mmol)) were placed in a flask equipped with a stirrer and the atmosphere was replaced with nitrogen. Tetrahydrofuran (50 mL) was then added and stirred. Triethylamine (6 mmol) was then added and the mixture was stirred at 70°C for 24 hours under reflux. After the reaction, the product was obtained in 49% yield by cotton filtration and reprecipitation (acetone). The resulting product had the following molecular weight: Mn =78,359, Mw = 223,234, Mp = 51,040, Mw / Mn = 2.85 [Example]

[0039] [Production of photodegradable epoxy resin] A reaction vessel was charged with 135 g (0.4 mol) of the compound of formula (5) and 260 g (0.6 mol) of a 10% aqueous solution of caustic soda, and the mixture was heated to 45°C with stirring to homogenize. Then, 46 g (0.5 mol) of epichlorohydrin was added, and the reaction temperature was maintained at approximately 100°C for 80 minutes. The stirring was then stopped, the mixture was allowed to separate into two phases, and the aqueous layer was removed. The reaction product was repeatedly washed with hot water, and after confirming its neutrality, it was dehydrated by heating, yielding 150 g of a low molecular weight epoxy resin with a molecular weight of 2,000. 82 g of this low molecular weight epoxy resin was mixed with 14 g (0.04 mol) of the compound of formula (5), and the mixture was heated at 200°C for 90 minutes to react, yielding 80 g of a resin with a molecular weight of 13,000. [ka] [Example]

[0040] [Production of photodegradable polyether ether ketone polymers] The photodegradable polyether ether ketone polymer (PEEK) of the present invention was produced according to the following chemical reaction formula. [ka] A 50 mL flask equipped with a stir bar was charged with 4 (1.0 equiv., 2.0 mmol, 796.8 mg) and 5 (1.0 equiv., 2.0 mmol, 750.4 mg: compound of formula (3)). Dichloromethane (DCM (0.25 M, 8 mL)) and EtN (4.0 equiv., 8.0 mmol, 1.1 mL) were added in a glove box, sealed, and vented. The mixture was stirred under reflux under a nitrogen atmosphere for 24 h. After the reaction, the mixture was filtered through cotton with DCM. The solvent was removed using a rotary evaporator, and the reaction mixture was added dropwise to a beaker containing 200 mL of methanol. The resulting precipitate was collected by suction filtration to obtain a polymer. The molecular weight of the polymer was as follows: Mp: 19,261, Mn: 12,095, Mw: 20,616, Mw / Mn: 1.7. [Example]

[0041] [Decomposition of photodegradable polyester polymers] The photodegradable polyester polymer of the present invention produced in Example 1 (represented as 1 in the following chemical reaction formula) was decomposed according to the following chemical reaction formula. [ka] Polymer 1 (0.1 mmol, 1.0 equiv.), DPE (1,1 diphenylethene, 0.2 mmol, 2.0 equiv.), cocatalyst p-toluenesulfonic acid monohydrate (PTSA·HO 10 mol%, 0.01 equiv.), photocatalyst BNPB (0.005 mmol, 5 mol%), and solvent tetrahydrofuran (THF) / HO (volume ratio: 0.38 mL / 0.02 mL, 0.25 M) were placed in a screw vial containing a rotor and dissolved. The atmosphere was then purged with nitrogen to obtain a reaction solution. The reaction solution was placed in a photoreactor and stirred at room temperature under 365 nm LED light for 24 hours. The solution was then dissolved in THF, filtered with cotton, and the solvent was removed using an evaporator. The resulting sample was analyzed by GPC (THF). The results are shown in Table 1 below. [Table 1] From the above results, it was confirmed that the molecular weight of the photodegradable polyester polymer of the present invention decreased upon irradiation with light in the presence of a photocatalyst and a co-catalyst, thereby causing decomposition of the polymer. In addition, since DPE was present in the decomposition reaction system, it was confirmed that lactone (shown as 2 in the above chemical reaction formula and in the table) was recovered as a product. [Example]

[0042] [Decomposition of photodegradable polyester polymer (polyarylate)] The photodegradable polyarylate of the present invention produced in Example 2 was decomposed according to the following chemical reaction formula. [ka] Polymer 1 (0.1 mmol, 1.0 equiv.), DPE (1,1 diphenylethene, 0.4 mmol, 4.0 equiv.), p-toluenesulfonic acid monohydrate (0.01 mmol, 0.01 equiv.), photocatalyst BNPB (0.005 mmol, 5 mol%), and solvent tetrahydrofuran (THF) / HO (volume ratio: 0.38 mL / 0.02 mL, 0.25 M) were placed in a screw vial containing a rotor and dissolved. The atmosphere was then purged with nitrogen to obtain a reaction solution. The reaction solution was placed in a photoreactor and stirred at room temperature under 365 nm LED light for 24 hours. The solution was then dissolved in THF, filtered with cotton, and the solvent was removed using an evaporator. The resulting sample was analyzed by GPC (THF). The results are shown in Table 2 below. [Table 2] The above results confirm that the molecular weight of the photodegradable polyester polymer (polyarylate) of the present invention decreased when p-toluenesulfonic acid (PTSA) / HO was used as a co-catalyst (represented as Additive in the above chemical reaction formula and table) under light irradiation in the presence of a photocatalyst, thereby confirming that decomposition of the polymer occurred. Furthermore, it was confirmed that p-toluenesulfonic acid (PTSA) / HO is a preferable co-catalyst from the viewpoints of polymer decomposition and lactone recovery (represented as 2 in the above table). [Example]

[0043] [Decomposition of photodegradable polyurethane polymers] The photodegradable polyurethane polymer of the present invention produced in Example 3 was decomposed according to the following chemical reaction formula. [ka] Polymer 1 (0.1 mmol, 1.0 equiv.), DPE (1,1-diphenylethene, 0.4 mmol, 4.0 equiv.), and the photocatalyst BNPB (0.005 mmol, 5 mol%) were dissolved in the solvent tetrahydrofuran (THF) / HO (volume ratio: 0.38 mL / 0.02 mL, 0.25 M) and purged with nitrogen to obtain a reaction solution. The reaction solution was placed in a photoreactor and stirred at room temperature under 365 nm LED light for 24 hours. The solution was then dissolved in THF, filtered through cotton, and the solvent was removed using an evaporator. The resulting sample was analyzed by GPC (THF). The results are shown in Table 3 below. [Table 3] From the above results, it was confirmed that the photodegradable polymer of the present invention decomposes (7%) by light irradiation alone. The decomposition rate increased to 60% by light irradiation in the presence of a photocatalyst, and further increased to 99% by using a co-catalyst. Meanwhile, the recovery of lactone (represented as 2 in the above table) from the photodegradable polymer of the present invention was confirmed by light irradiation in the presence of a photocatalyst. [Example]

[0044] [Decomposition of photodegradable epoxy resin] The photodegradable epoxy resin of the present invention produced in Example 4 was decomposed in accordance with the following chemical reaction formula. [ka] Polymer 1 (0.1 mmol, 1.0 equiv.), DPE (1,1 diphenylethene, 0.4 mmol, 4.0 equiv.), cocatalyst p-toluenesulfonic acid monohydrate (PTSA·HO 10 mol%, or 1.0 equiv.), photocatalyst BNPB (0.005 mmol, 5 mol%), and solvent tetrahydrofuran (THF) / HO (volume ratio: 0.38 mL / 0.02 mL, 0.25 M) were placed in a screw vial containing a rotor and dissolved. The atmosphere was then purged with nitrogen to obtain a reaction solution. The reaction solution was placed in a photoreactor and stirred at room temperature under 365 nm LED light for 24 hours. The solution was then dissolved in THF, filtered with cotton, and the solvent was removed using an evaporator. The resulting sample was analyzed by GPC (THF). The results are shown in Table 4 below. [Table 4] From the above results, it was confirmed that the photodegradable epoxy resin of the present invention can decompose the polymer by irradiating it with light in the presence of a photocatalyst and using p-toluenesulfonic acid monohydrate (PTSA / HO) as a co-catalyst, and that lactone (represented as 2 in the above chemical reaction formula and table) can also be recovered. [Example]

[0045] [Decomposition of photodegradable polyether ether ketone polymers] The photodegradable polyether ether ketone polymer of the present invention produced in Example 5 was decomposed according to the following chemical reaction formula. [ka] A screw-cap vial containing a stir bar was charged with polyether ether ketone polymer (1.0 equiv., 0.5 mmol, 350.4 mg), DPE (1,1 diphenylethene, 4.0 equiv., 2.0 mmol, 0.35 mL), BNPB (5 mol%, 12.8 mg), PTSA (p-toluenesulfonic acid)·HO (10 mol%, 9.5 mg), and THF (tetrahydrofuran) / HO (95 / 5, 0.25 M, 1.9 mL / 0.1 mL). After purging with nitrogen for 5 minutes, the reaction solution was irradiated with 365 nm LED light in a photoreactor and stirred at room temperature for 24 hours. After the reaction, the product was dissolved in THF and filtered through cotton. The filtrate was analyzed by GPC (THF). The results are shown in Table 5. [Table 5] As can be seen from the table above, the molecular weight peak before irradiation was 19,707 (number average molecular weight 12,139), while the molecular weight peak after irradiation was 6,559 (number average molecular weight 5,946), confirming the decomposition of the polymer. The recovery of lactone (represented as 2 in the chemical reaction formula and Table 5) was 7% by NMR yield. [Industrial Applicability]

[0046] The photodegradable polymer of the present invention, which contains a monomer having a tertiary alkyl group as a radically decomposable moiety, was decomposed in 24 hours under irradiation with a 365 nm LED, confirming its rapid decomposition. This demonstrates its potential for application as a photodegradation-controlled polymer, capable of slow decomposition over time in the natural environment and rapid decomposition under UV irradiation in factories. Furthermore, because the polymer's lifespan can be controlled by the timing of application of the photodegradation method, it is possible to design and synthesize polymers tailored to the intended use period. Furthermore, because lactones can be recovered as a result of decomposition, the recovered lactones can be widely recycled.

Claims

1. A monomer for photodegradable polymer polymerization, having a group represented by the following formula (1) as a radically decomposable site: 【Chemistry 1】 (In the formula, R １ , R ２ , R ３ and R ４ are independently an alkyl group or an aryl group, and Ar is an aromatic ring.

2. The photodegradable polymer polymerization monomer according to claim 1, wherein the photodegradable polymer polymerization monomer is selected from the following formulas (2) to (7): 【Chemistry 2】 【change】 (In the formula, X represents Cl, Br, or I.) 【change】 【change】 【change】 【change】

3. A photodegradable polymer obtained by polymerizing a monomer containing the monomer for polymerization of a photodegradable polymer according to claim 1 or 2.

4. 4. The photodegradable polymer according to claim 3, wherein a monomer other than the monomer for polymerization of the photodegradable polymer according to claim 1 or 2 is a base monomer constituting the main chain.

5. The photodegradable polymer according to claim 3 , wherein the photodegradable polymer is a polyester-based polymer, a polyamide-based polymer, a polyurethane-based polymer, an epoxy-based resin, or a polyether ether ketone-based polymer.

6. The photodegradable polymer according to claim 4, wherein the base monomer is a polyester-based monomer, a polyamide-based monomer, a polyurethane-based monomer, an epoxy-based resin monomer, or a polyether ether ketone-based monomer.

7. A method for producing a photodegradable polymer, comprising polymerizing a monomer containing a monomer having a group represented by the following formula (1) as a radically decomposable site: 【Transformation 3】 (In the formula, R １ , R ２ , R ３ and R ４ are independently an alkyl group or an aryl group, and Ar is an aromatic ring.

8. A method for decomposing a photodegradable polymer, comprising irradiating a photodegradable polymer having a group represented by the following formula (1) as a radically decomposable site with light: 【Chemistry 4】 (In the formula, R １ , R ２ , R ３ and R ４ are independently an alkyl group or an aryl group, and Ar is an aromatic ring.

9. The method for decomposing a photodegradable polymer according to claim 8, further comprising using a photocatalyst.

10. The method for decomposing a photodegradable polymer according to claim 9, further comprising using a co-catalyst.

11. A method for recovering the corresponding lactone, comprising decomposing a photodegradable polymer having a group represented by the following formula (1) as a radically decomposable site by irradiating the polymer with light in the presence of a photocatalyst and a cocatalyst: 【Transformation 5】 (In the formula, R １ , R ２ , R ３ and R ４ are independently an alkyl group or an aryl group, and Ar is an aromatic ring.

Images