Photodegradable polymer

Abstract

To provide a photodegradable polymer that is easily decomposed upon exposure to light or the like.SOLUTION: The present invention provides a photodegradable polymer comprising a photodegradable monomer for polymerization with a group represented by a formula (1) as a radical-degradable moiety (where R1 and R2 independently represent an alkyl group or an aryl group).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 containing such a monomer, and a method for producing a photodegradable polymer. [Background technology]

[0002] The global plastics (polymer) market is expected to reach US$756.9 billion by the end of 2030, up from a market value of US$599.4 billion in 2022. Synthetic polymers to date have been designed with an emphasis on performance and durability during use, and the decomposability and recyclability of the polymer after use have not been fully considered. Currently, used polymer waste is disposed of by either landfilling, incineration, or mechanical recycling. In the case of landfilling, most polymer waste is difficult to decompose, so there is a possibility that serious environmental pollution problems will occur due to accumulation in the environment and decomposition pollution. In addition, although thermal recycling is applied to incineration, the energy recovery efficiency is insufficient for heat utilization including power generation, and carbon dioxide is also emitted, so it is difficult to call it recycling in essence. On the other hand, mechanical recycling, for example, in the case of PET bottles, is the most efficient processing method, in which contaminants inside the resin are diffused, decontaminated, dried at high temperatures, and then flakes are formed. However, there are problems in that the polymers to which mechanical recycling can be applied are limited, and that the processing of polymer waste such as composite materials, laminated materials, coating materials, and contaminated materials is difficult and expensive.

[0003] On the other hand, from the perspective of environmental conservation such as the microplastic problem and carbon circulation, the market for biodegradable polymers, "green polymers (GPs)," is expected to reach 5.8 billion US dollars in 2020 and 16.8 billion US dollars in 2030. However, the rate at which GPs biodegrade is greatly affected by environmental conditions (soil, water, air, etc.), and not all GPs are always biodegradable under favorable environmental conditions. In addition, GPs made from non-edible biomass such as bagasse and cellulose are still expensive, so it has taken time to put them into practical use. Therefore, most biodegradable polymers are made from edible crops such as corn and sugarcane, and it is said that the large-scale production of biodegradable polymers may cause serious food shortages. In other words, if the production of biodegradable polymers relies on plant-derived raw materials, there is a possibility that we will face a trade-off relationship in which the environmental conservation problem is solved, but the food problem will be aggravated. Therefore, it is still necessary to address the recycling and microplastic problems by imparting decomposition functions to inexpensive petroleum-derived plastics.

[0004] Photolysis technology as a polymer decomposition technology 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 enzyme decomposition and photocatalysts such as titanium oxide has also been reported (Non-Patent Document 2). Recently, a technology for decomposing polymers having a special cyclic structure by cleaving carbon-oxygen bonds using an organic photocatalyst system has been reported (Non-Patent Document 3), but the target is limited to polymers having a specific structure. In addition, Patent Document 1 describes a photodegradable polymer compound that uses a group containing nitro-substituted benzyl as a photodegradable site, but since the polymer chain is linked via the photodegradable site and the photodegradable site is not used as a monomer, the degree of freedom in designing the photodegradable polymer compound is low. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-233137 A [Non-patent literature]

[0006] [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 TransferMechanism, ACS Cent Sci. 2020, 6. 266-273 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a photodegradable polymer by using a monomer having a radical decomposition site. [Means for solving the problem]

[0008] The present inventors have been researching alkyl radicals for many years, and in the course of their research, they have discovered that the carbon-oxygen bond of an ester can be cleaved by photocatalysis to easily generate alkyl radicals. Since carbon-oxygen bonds are often found in polymers such as polyethylene terephthalate (PET), they have applied this knowledge to polymers and discovered that a photodegradable polymer incorporating a radically decomposable site can be obtained by polymerizing a monomer containing a monomer having a radically decomposable site, thus completing the present invention.

[0009] That is, the present invention is specified by the following items. (1) A monomer for photodegradable polymer polymerization having a group represented by formula (1) as a radically decomposable site. [ka] (In the formula, R1 and R2 independently represent an alkyl group or an aryl group.) (2) The photodegradable polymer polymerization monomer according to the above (1), which has a group represented by formula (2) as a radically decomposable site. [ka] (In the formula, R1 and R2 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring.) (3) The photodegradable polymer polymerization monomer according to (1) or (2) above, wherein R1 and R2 are both alkyl groups. (4) A photodegradable polymer obtained by polymerizing a monomer containing the monomer for polymerization of a photodegradable polymer according to (1) or (2) above. (5) The photodegradable polymer according to (4) above, which is a polyester-based polymer, a polyamide-based polymer, a polyurethane-based polymer, or an epoxy resin. (6) A method for producing a photodegradable polymer by polymerizing a monomer containing a monomer having a group represented by formula (1) as the radically decomposable site described in (1) above, or by polymerizing a monomer containing a monomer having a group represented by formula (2) as the radically decomposable site described in (2) above. Effect of the Invention

[0010] Since the monomer for polymerization of a photodegradable polymer of the present invention has a radically decomposable site, a polymer obtained by polymerizing a monomer containing such a monomer has photodegradability. In addition, since the monomer for polymerization of a photodegradable polymer of the present invention has a site for cleaving a carbon-oxygen bond, it can be widely applied to polymers having a carbon-oxygen bond. The photodegradable polymer of the present invention is a polymer in which a radically decomposable site has been incorporated into the main chain of the polymer by polymerizing a monomer including a monomer having a radically decomposable site, and the radically decomposable site is cleaved by a photocatalytic reaction or the like, thereby preventing the polymer from becoming microplastic, and the polymer can be used as a polymer with a long life that is easily decomposable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to a monomer having, as a radically decomposable site, a group represented by formula (1) which is cleaved by light or the like, a polymer containing such a monomer, and a method for producing a photodecomposable polymer. [ka] In the formula, R1 and R2 independently represent an alkyl group or an aryl group. R1 and R2 in the group represented by formula (1) are alkyl groups such as methyl, ethyl, n-propyl, n-butyl, and other linear alkyl groups, isopropyl, isobutyl, and other branched alkyl groups, and cyclopentyl, cyclohexyl, and other cycloalkyl groups. Aryl groups include phenyl, and the like. R1 and R2 may be the same or different. Furthermore, the group represented by formula (1) can link Y to a carbonyl group (C(O) group) in order to introduce a polymerization initiation site or as a polymerization initiation site. Y represents a chlorine atom or OR3, and R3 represents a hydrogen atom; an alkyl group such as a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, or an n-butyl group, or a branched alkyl group such as an isopropyl group or an isobutyl group; a terminal alkylene group such as a vinyl group, a propylene group, or a 1-butene group; a carboxylic acid group represented by -(CH2)nCOOH; a hydroxyl group represented by -(CH2)nOH; or a hydroxyl group containing an aromatic ring such as a parahydroxybenzene group or bisphenol A. In addition, when R3 represents a carboxylic acid group represented by -(CH2)nCOOH, a hydroxyl group represented by -(CH2)nOH, or a hydroxyl group containing an aromatic ring such as a parahydroxybenzene group or bisphenol A, the hydrogen atom of the carboxylic acid group or the hydroxyl group may be dissociated. Examples of monomers having a group represented by formula (1) include monomers represented by formula (3) in [Chemical formula 5] described later.

[0012] The present invention also relates to a monomer having, as a radically decomposable site, a group represented by formula (2) which is cleaved by light or the like, a polymer containing such a monomer, and a method for producing a photodecomposable polymer. [ka] In the formula, R1 and R2 independently represent an alkyl group or an aryl group, and Ar represents an aromatic ring. R1 and R2 in the group represented by formula (2) are alkyl groups such as methyl, ethyl, n-propyl, n-butyl, and other linear alkyl groups, isopropyl, isobutyl, and other branched alkyl groups, and cyclopentyl, cyclohexyl, and other cycloalkyl groups. Aryl groups include phenyl groups. R1 and R2 may be the same or different. An example of an aromatic ring is a phenyl group. Furthermore, in the group represented by formula (2), similarly to the group represented by formula (1), Y can be linked to a carbonyl group (C(O) group) in order to introduce a polymerization initiation site or as a polymerization initiation site. Y is the same as the Y linked to the group represented by formula (1) described above. As described below, examples of monomers having a group represented by formula (2) as a radically decomposable site include those having a phenyl group as an aromatic ring represented by formula (4) in [Chemical formula 6] and having hydroxyl groups at both ends, those having the same group substituted at the para position on the aromatic ring as Ar represented by formula (5) in [Chemical formula 7] and formula (6) in [Chemical formula 8], those having a para-hydroxybenzene group as R3 represented by formula (6) in [Chemical formula 8], and those having a terminal alkylene group as R3 represented by formula (7) in [Chemical formula 9].

[0013] The group represented by formula (1) or formula (2) is incorporated into a monomer unit through a carbon-oxygen bond, for example, between the monomer unit and a carboxyl group of terephthalic acid through a carbon-oxygen bond. A specific example of a monomer for polymerization of a photodegradable polymer having a group represented by formula (1) as a radically decomposable site is a compound represented by formula (3). The compound of formula (3) is a compound in which, in the group represented by formula (1), R1 and R2 are both methyl groups, the carbon atoms substituted by R1 and R2 are further substituted with hydroxyl groups, Y is OR3, and R3 is a hydrogen atom. [ka] Similarly, specific examples of the photodegradable polymer polymerization monomer having a group represented by formula (2) as a radically decomposable site include the compounds represented by formulas (4) to (7). [ka] [ka] [ka] [ka]

[0014] A synthesis example of the monomer represented by formula (5) is as follows. Terephthalic acid is dissolved in an organic solvent, and the organic solvent is treated with an acid chloride synthesis reagent to obtain terephthalic acid chloride. As the organic solvent, one solvent selected from dichloromethane, toluene, DMF, THF, chloroform, etc. can be used. As the acid chloride synthesis reagent, one reagent selected from thionyl chloride, sulfuryl chloride, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, oxalyl chloride, etc. can be used. 2-hydroxy-2-methylpropanoic acid represented by formula (3) and a base are added to the obtained terephthalic acid chloride, and the monomer represented by formula (5) can be obtained by reacting the mixture in an organic solvent. As the base, pyridine or triethylamine is used, and as the organic solvent, one solvent or a mixed solvent of two or more solvents selected from the above-mentioned solvents and acetonitrile is used.

[0015] A synthesis example of the monomer represented by formula (7) is as follows. The monomer represented by formula (5) is reacted with an allyl halide in an organic solvent in the presence of a base to obtain the monomer represented by formula (7). The allyl halide may be any one of allyl bromide, allyl iodide, etc., and the base may be any one of potassium carbonate, cesium carbonate, sodium hydroxide, N,N-diisopropylethylamine, etc., and the organic solvent may be one or a mixture of two or more selected from DMF, toluene, ether, acetone, THF, dichloromethane, etc.

[0016] The polymer into which the monomer having a group represented by formula (1) or formula (2) is incorporated as a radically decomposable site is not particularly limited, and examples thereof include polyester-based polymers, polyamide-based polymers, polyetheramide-based polymers, polyether-based polymers, polyurethane-based polymers, and other polycondensation / polyaddition-based polymers, polyethylene-based polymers, polypropylene-based polymers, polyvinyl chloride-based polymers, and other addition polymerization-based polymers, phenolic resins, and epoxy resins. Among these, polyester-based polymers, polyamide-based polymers, polyurethane-based polymers, and epoxy resins are preferred from the viewpoint of ease of synthesis. Specifically, the photodecomposable polymer polymerization monomer of the present invention can be appropriately combined with terephthalic acid, hexamethylenediamine, adipic acid, ethylene glycol, 1,4-butanediol, metaphenylenediamine, 4,4'-diphenylmethane diisocyanate, bisphenol A, epichlorohydrin-terminated diene compounds, and the like to polymerize, thereby obtaining a polymer into which a radically decomposable site is incorporated.

[0017] A synthesis example of obtaining polybutylene terephthalate (PBT) having a radically decomposable site using formula (3) as a monomer having a group represented by formula (1) is as follows. A mixture of 1,4-butanediol with a molar ratio of 1 / 1 to terephthalic acid is mixed with the monomer represented by formula (3) in an arbitrary ratio. Then, by carrying out dehydration condensation, polybutylene terephthalate (PBT) in which the monomer represented by formula (3) is incorporated as a radically decomposable site can be obtained.

[0018] An example of synthesis for obtaining a polymer of formula (8) using a monomer of formula (7) having a group represented by formula (2) is as follows. [ka] The monomer represented by formula (7) is dissolved in an organic solvent under an inert gas atmosphere, and a catalyst for polymerization is added to carry out metathesis polymerization to obtain a photodegradable polymer represented by formula (8). As the organic solvent, one solvent or a mixed solvent of two or more solvents selected from chloroform, chlorobenzene, toluene, hexane, ethanol, etc. can be used, and as the catalyst for polymerization, any one of the first generation Grubbs catalyst, the second generation Grubbs catalyst, the third generation Grubbs catalyst, etc. can be used. The temperature and time during polymerization are preferably 70 to 90°C and 12 to 48 hours, respectively.

[0019] In addition, examples of synthesis for obtaining a polymer using the monomers of formulae (5) and (6) having a group represented by formula (2) include the following synthesis examples.

[0020] A synthesis example in which a polyethylene terephthalate (PET) 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 methanol to form a dimethyl ester, and the obtained 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 to be 1 / 1. By carrying out an ester exchange reaction of this mixture, a polyethylene terephthalate (PET) in which the monomer represented by formula (5) is incorporated as a radically decomposable site can be obtained.

[0021] A synthesis example of obtaining polyethylene naphthalate (PEN) having a radically decomposable site using a monomer represented by formula (5) is as follows. The monomer represented by formula (5) is reacted with thionyl chloride to obtain an acid chloride, and 2,6-naphthalenedicarboxylic acid chloride and ethylene glycol are mixed with the obtained acid chloride. 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 to be 1 / 1. By carrying out a dehydrochlorination reaction of this mixture, polyethylene naphthalate (PEN) in which the monomer represented by formula (5) is incorporated as a radically decomposable site can be obtained.

[0022] Furthermore, a synthesis example in which nylon 6,6 having a radically decomposable site is obtained 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, they are mixed so that the total molar ratio of adipic acid and hexamethylenediamine to the monomer represented by formula (5) is 1 / 1. Then, by carrying out dehydration condensation, nylon 6,6 in which the monomer represented by formula (5) is incorporated as a radically decomposable site can be obtained.

[0023] A synthesis example in which a polyurethane having a radically decomposable site is obtained using a monomer represented by formula (6) is as follows. 1,4-butanediol and 4,4'-diphenylmethane diisocyanate are mixed with the monomer represented by formula (6). In this case, they are mixed so that the molar ratio of 4,4'-diphenylmethane diisocyanate to the total of the monomer represented by formula (6) and 1,4-butanediol is 1 / 1. Then, a polyaddition reaction is carried out to obtain a polyurethane in which the monomer represented by formula (6) is incorporated as a radically decomposable site.

[0024] Furthermore, a synthesis example in which an epoxy resin having a radically decomposable site is obtained using a monomer represented by formula (6) is as follows. Bisphenol A and epichlorohydrin are mixed with the monomer represented by formula (6). In this case, they are mixed so that the molar ratio of epichlorohydrin to the total of the monomer represented by formula (6) and bisphenol A is 1 / 1. After that, when a prepolymer is obtained, a curing agent is added to this polymer and the polymer is heat-treated, thereby obtaining an epoxy resin in which the monomer represented by formula (6) is incorporated as a radically decomposable site.

[0025] Furthermore, a synthesis example of obtaining a polyethylene-based polymer having a radically decomposable site using the monomer represented by formula (6) is as follows: A polyethylene-based polymer in which the monomer represented by formula (6) is incorporated as a radically decomposable site can be obtained by mixing the monomer represented by formula (6) and 1,5-hexadiene, which is a terminal diene compound, in any ratio and carrying out metathesis polymerization.

[0026] The monomers having a group represented by formula (1) or formula (2) are arranged in the polymer as radically decomposable sites at any interval based on the content ratio in the polymer. A homopolymer can be obtained by polymerizing only the monomers having a group represented by formula (1) or formula (2), or a copolymer can be obtained by polymerizing a monomer having a group represented by formula (1) or formula (2) and a monomer not having the group represented by formula (1) or formula (2) in any ratio, in which the monomers are arranged in any ratio, and photodecomposition can be controlled. The photodegradable polymer of the present invention can be decomposed by irradiation with artificial light, which is light of a specific wavelength, in the presence of a photocatalyst, and can also be decomposed by irradiation with sunlight in the presence of a photocatalyst. Furthermore, the photodegradable polymer of the present invention can be decomposed in a natural environment in which air or the like is present when exposed to sunlight in the presence of a photocatalyst. 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 the case of decomposition using sunlight. That is, the photodegradable polymer of the present invention is photodecomposed by radical decomposition of the group represented by formula (1) or formula (2) by a photocatalytic reaction and cleavage of the carbon-oxygen bond.

[0027] The artificial light, which is light of a specific wavelength, is light of a wavelength necessary for exciting the photocatalyst to be used, such as light of 365 nm or 405 nm. In addition, the photocatalyst is light 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 type of material having such a reduction potential, but taking into consideration the interaction with the substrate, examples of suitable materials include BDB (bisdiphenylaminobenzene), NPB, BBDB, and HPTPN. The chemical structural formulas of BDB, NPB, BBDB, and HPTPN are shown below. [ka] [ka] [ka] [ka]

[0028] Furthermore, the photodegradable polymer of the present invention allows time control of radical decomposition of the polymer by selecting the content ratio of the monomer having a radically decomposable group represented by formula (1) or formula (2) in the polymer and the decomposition conditions (e.g., exposure to light of a specific wavelength or exposure to sunlight). The amount of the photocatalyst used is preferably about 1 mol% relative to the photodegradable polymer when it is desired to decompose to a certain extent within several days under irradiation of light of a specific wavelength. The photocatalyst can be added to the photodegradable polymer at the time of decomposition, but can also be kneaded into or coated on the polymer before the photodegradable polymer is used for a certain purpose. In addition, an organic or inorganic third component may be added to the photodegradable polymer together with the photocatalyst as a component that makes it easier for the photocatalyst to be fixed to the polymer. The photodegradable polymer of the present invention is decomposed by adding a photocatalyst to the photodegradable polymer and irradiating it with artificial light or sunlight. Other decomposition conditions in the photodegradable polymer decomposition method are not particularly limited, but when promoting decomposition, a Lewis acid such as water can be added as a co-catalyst for the photocatalyst. Other conditions for promoting decomposition include dissolving the photodegradable polymer in a solvent and setting the decomposition temperature higher than room temperature. As a solvent for dissolving the photodegradable polymer, one organic solvent or a mixed organic solvent of two or more selected from DMF, toluene, ether, acetone, THF, dichloromethane, etc. is preferred. EXAMPLES

[0029] The present invention will be specifically described below by way of examples of the present invention, but the technical scope of the present invention is not limited to these examples.

[0030] [Test Example 1] A tertiary alkyl group (-C(CH3)(CH3)C(O)-O-) was incorporated into a terephthalic acid methyl ester compound as a radical decomposable site to produce the compound of the following formula (9), which was then irradiated with 405 nm visible LED light in the presence of 1 mol% of a photocatalyst (BDB). The generation of radicals was confirmed, and decomposition proceeded with a conversion rate of 18%. [ka]

[0031] [Test Example 2] The experiment was carried out under the same conditions as in Test Example 1, except that NPB was used instead of BDB as the photocatalyst in Test Example 1. The generation of radicals was confirmed in the same manner, and the reaction proceeded with a conversion rate of 90%. Furthermore, the generated radicals were captured by 1,1-diphenylethene, and the corresponding lactone was obtained in a yield of 71%.

[0032] These results suggest that the monomers for PET-related polymers were decomposed at radically decomposable sites when irradiated with light of a specific wavelength under photocatalysis, suggesting that the PET-related polymers are decomposed into monomers. In addition, it was confirmed that the tertiary alkyl groups used as radically decomposable sites can be converted to lactones, indicating the possibility of further utilization of the photodecomposed polymers. EXAMPLES

[0033] A PET-like polymer was synthesized using the monomer having a tertiary alkyl group used in Test Example 1 as a radically decomposable site, and subjected to photodecomposition. (1) Synthesis of Monomer Terephthalic acid (10mmol, 1.0 equiv.) and dichloromethane (10mL, 1.0M) were mixed, and thionyl chloride (30mmol, 3.0 equiv.) was added while stirring and refluxing. Stirring was continued as it was, and after 3.5 hours, the pressure was reduced and the acid was removed to obtain reaction mixture A. Then, a mixed solution of 2-hydroxy-2-methylpropanoic acid (22mmol, 2.1 equiv.) and pyridine (20mmol, 2.0 equiv.) dissolved in acetonitrile (20mL, 0.5M) was added to reaction mixture A cooled to 0°C while stirring. Then, the temperature was raised to room temperature and stirring was continued to obtain reaction mixture B. After one night, reaction mixture B was separated with 1M aqueous hydrochloric acid, exposed to magnesium sulfate, and purified by recrystallization from Et2O / Hexane to obtain the compound of formula (5) in a yield of 56% (1.90g, 5.63mmol). IR; 2999, 2918, 2695, 2570, 1708, 1506, 1467, 1422, 1372, 1281, 1188,1153, 1107, 1017, 923, 850, 781, 728. 1HNMR(CD3OD); 8.08 (s, 4H), 1.68 (s, 12H). 13CNMR(CD3OD); 174.5, 164.6, 134.2129.4, 79.2, 23.7. [ka]

[0034] The compound of formula (5) (1.0 mmol, 1.0 equiv.), allyl bromide (4.0 mmol, 4.0 equiv.), and potassium carbonate (2.0 mmol, 2.0 equiv.) were dissolved in DMF (2 mL, 0.5 M) and stirred at room temperature overnight to obtain reaction mixture C. Then, reaction mixture C was extracted with an organic layer of hexane / ethyl acetate = 1 / 4 (volume ratio), concentrated with a rotary evaporator, and purified by flash column chromatography (Hex:AcOEt = 10:1) to obtain the compound of formula (7) in a yield of 76% (318.8 mg, 0.76 mmol). IR; 2994, 2945, 2119, 1741, 1722, 1466, 1410, 1368, 1305, 1275, 1230,1217, 1183, 1140, 1103, 1020, 988, 963, 934, 877, 852, 819, 760, 728. 1HNMR(CDCl3); 8.07 (s, 4H), 5.91-5.83 (m, 2H), 5.30 (d, J = 17.1 Hz, 2H), 5.21 (d, J= 10.8 Hz, 2H), 4.65 (d, J = 5.7Hz, 4H), 1.72 (s, 12H). 13CNMR(CDCl3); 172.1, 164.7, 134.1, 131.8, 129.8, 118.5, 79.4, 66.1, 24.8. [ka]

[0035] (2) Polymer synthesis The compound of formula (7) (5.0 mmol, 1.0 equiv.) was added with the second generation Grubbs catalyst (1.0 mol%) and CHCl3 (2.0 M) in a glove box and stirred at 80°C for 20 h to obtain reaction mixture D. After that, reaction mixture D was reprecipitated with CHCl3 / hexane = 1 / 10 (volume ratio) to obtain the polymer of formula (8) in a yield of 50% (1056.4 mg, 2.5 mmol). [ka]

[0036] (3) Photodecomposition of polymers In a screw vial containing a rotor, the polymer of formula (8) (0.1 mmol, 1.0 equiv.), DPE (0.4 mmol, 4.0 equiv.), and the photocatalyst BNPB (0.001 mmol, 1 mol%) and THF / H2O (volume ratio: 0.38 mL / 0.02 mL, 0.25 M) were placed, dissolved, and substituted with nitrogen to obtain a reaction solution. The reaction solution was placed in a photoreactor and stirred at room temperature for 24 hours under 365 nm LED light, then dissolved in THF, filtered with cotton, and the solvent was removed using an evaporator. The obtained sample was then analyzed by GPC (THF). The molecular weight peak before irradiation was 7905 (number average molecular weight 8162), while the molecular weight peak after irradiation was 2748 (number average molecular weight 3638), confirming the decomposition of the polymer. In addition, when 4 equivalents of 1,1-diphenylethene was used as a radical scavenger in the reaction, the corresponding lactone was obtained in a yield of over 30%. [Industrial Applicability]

[0037] The photodegradable polymer of the present invention, which contains a monomer having a tertiary alkyl group as a radically decomposable site, was decomposed in 24 hours under irradiation with a 365 nm LED, and since its easy decomposition was confirmed, it can be used as a photodecomposition control polymer, which decomposes slowly over time in the natural environment and rapidly decomposes by irradiation with ultraviolet light in a factory. In addition, since the life of the polymer can be controlled by the application timing of the photodecomposition means, it is also possible to design and synthesize polymers according to the period of use.

Claims

1. A photodegradable polymer polymerization monomer having a group represented by formula (1) as a radical decomposition site. 【Chemistry 1】 (In the formula, R1 and R2 independently represent an alkyl group, Y represents a chlorine atom or OR3, and R3 represents a hydrogen atom; an alkyl group; a terminal alkylene group; a carboxylic acid group represented by (CH2)nCOOH; a hydroxyl group represented by -(CH2)nOH; or a hydroxyl group containing a parahydroxybenzene group or an aromatic ring containing bisphenol A.)

2. A photodegradable polymer polymerization monomer according to claim 1, having a group represented by formula (2) as a radical decomposable site. 【Chemistry 2】 (In the formula, R1 and R2 are the same as in formula (1), Ar represents an aromatic ring, and Y is the same as in formula (1).)

3. The monomer for photodegradable polymer polymerization according to claim 2, wherein Ar is a phenyl group.

4. The monomer for photodegradable polymer polymerization according to claim 1, wherein R1 and R2 are independently a methyl group or an ethyl group.

5. The monomer for photodegradable polymer polymerization according to claim 1, wherein R1 and R2 are both methyl groups.

6. The photodegradable polymer polymerization monomer according to claim 1, having a group represented by any one of formulas (3) to (7) as a radical decomposable site. 【Transformation 3】 【Chemistry 4】 【Transformation 5】 【Transformation 6】 【Transformation 7】

7. A photodegradable polymer characterized by being obtained by polymerizing a monomer containing the photodegradable polymer polymerization monomer described in any one of Claims 1 to 6.

8. The photodegradable polymer according to claim 7, wherein the photodegradable polymer is selected from polycondensation polymers, polyaddition polymers, or addition polymerization polymers.

9. The photodegradable polymer according to claim 7, wherein the photodegradable polymer is a polyester polymer, a polyamide polymer, a polyetheramide polymer, a polyether polymer, a polyurethane polymer, a polyethylene polymer, a polypropylene polymer, a polyvinyl chloride polymer, a phenolic resin, or an epoxy resin.

10. The photodegradable polymer according to claim 9, wherein the photodegradable polymer is selected from: polybutylene terephthalate incorporating a photodegradable monomer represented by formula (3); polyethylene terephthalate, polyethylene naphthalate, or nylon 6,6 incorporating a photodegradable monomer represented by formula (5); or polyurethane, epoxy resin, or polyethylene-based polymer incorporating a photodegradable monomer represented by formula (6).

11. A method for producing a photodegradable polymer, comprising polymerizing a monomer containing a monomer having a group represented by formula (1) as a radical degradable site as described in claim 1, or polymerizing a monomer containing a monomer having a group represented by formula (2) as a radical degradable site as described in claim 2.

12. A method for decomposing a photodegradable polymer by adding a photocatalyst to the photodegradable polymer described in Claim 7 and irradiating it with artificial light or sunlight.

13. The method for decomposing a photodegradable polymer according to claim 12, further comprising adding a radical scavenger that captures the generated radicals.

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