Water-soluble tetrahydropyrrole lactamide acrylate bio-based monomers and polymers thereof

Abstract

This invention relates to a water-soluble tetrahydropyrrole lactamide acrylate bio-based monomer and its polymer, belonging to the field of bio-based polymer technology. The invention utilizes lactate and tetrahydropyrrole to synthesize the precursor tetrahydropyrrole lactate under solvent-free and mild conditions. Then, the corresponding polymerizable monomer containing double bonds is synthesized via acylation. The polymer is then synthesized through conventional thermally initiated polymerization and reversible addition-fragmentation chain transfer polymerization. Research has found that, compared to most reported bio-based monomers, the tetrahydropyrrole lactamide acrylate bio-based monomer developed in this invention can be polymerized in an environmentally friendly aqueous solution system, yielding a water-soluble polymer with high glass transition temperature and thermal decomposition temperature. This high-temperature resistant thermosetting water-soluble polymer can improve the strength of other polymer materials through copolymerization with other polymer materials, thus showing promising applications in composite materials and engineering plastics.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polymer technology, specifically relating to a water-soluble tetrahydropyrrole lactamide acrylate bio-based monomer and its polymer. Background Technology

[0002] In recent years, the importance of environmental protection and sustainable development has been increasing, and the need to develop alternatives to traditional petrochemical materials using renewable resources has become increasingly urgent. Therefore, renewable bio-based polymers have received widespread attention. Currently, the synthesis of bio-based polymers faces many unresolved issues, including developing a wider variety of environmentally friendly bio-based monomers, effectively controlling the properties of polymer materials, and achieving high performance. Scientists have prepared various polymerizable monomers using various biomass raw materials such as terpenes, lactic acid, and lignin, and synthesized bio-based polymers through various polymerization methods. However, most lactic acid-based monomers reported in the literature are insoluble in water, requiring the use of environmentally unfriendly organic solvents during polymerization, which does not conform to the concept of green chemistry. Therefore, it is necessary to develop water-soluble bio-based monomers for polymerization in aqueous solutions. Summary of the Invention

[0003] In order to obtain more renewable bio-based monomers that can be polymerized in environmentally friendly solutions, the present invention aims to provide a water-soluble tetrahydropyrrole lactamide acrylate bio-based monomer and its polymer.

[0004] To achieve the above-mentioned objectives of this invention, the following technical solution is provided:

[0005] The structural formula of the water-soluble tetrahydropyrrole lactamide acrylate bio-based monomer described in this invention is shown in (I), and its polymers are shown in (II) and (III):

[0006]

[0007] In the compound of formula (Ⅲ), X is an N, P, O, or S atom;

[0008] R1 is a C1-C12 cyano, C1-C12 alkyl, C1-C12 ester, or C6-C30 aryl;

[0009] R2 is a C1-C12 alkyl, C1-C12 ester, C6-C30 aryl, or C5-C24 heteroaryl (the heteroatom in the heteroaryl group is at least one of N, O, or S);

[0010] R3 is a C1-C12 alkyl, C1-C12 ester, C6-C30 aryl, or C5-C24 heteroaryl (the heteroatom in the heteroaryl group is at least one of N, O, or S);

[0011] n is a positive integer representing the number of aggregation units;

[0012] Synthesis of compound with structural formula (I): A 1 molar amount of lactic acid ester (methyl lactate, ethyl lactate, propyl lactate, butyl lactate, etc.) is directly mixed with 1.1–1.3 molar amounts of tetrahydropyrrole, and the mixture is stirred at 25–40 °C for 60–80 hours. After the reaction, the product is concentrated by rotary evaporation. The resulting liquid is purified by column chromatography using ethyl acetate as eluent, and the eluent is removed by rotary evaporation to obtain the precursor tetrahydropyrrole lactate. A 1 molar amount of the precursor tetrahydropyrrole lactate is then mixed with 1–1.5 molar amounts of triethylamine. The product is dissolved in ultra-dry dichloromethane under argon positive flow, then mixed evenly at 0-10℃ under anaerobic conditions and stirred for 10-40 minutes. Then, 1-1.5 times the molar amount of acryloyl chloride is slowly added dropwise, and the reaction is carried out at room temperature for 10-20 hours. The product is filtered, washed, and dried. The desiccant is removed by filtration and the solvent is removed by rotary evaporation. The resulting liquid is purified by column chromatography using ethyl acetate and n-hexane in a volume ratio of 6:1. The eluent is then removed by rotary evaporation to obtain the tetrahydropyrrole lactamide acrylate monomer shown in structural formula (I).

[0013] Synthesis method of compound (II): 1 molar amount of tetrahydropyrrole lactamide acrylate monomer and 0.0025 to 0.05 molar amount of oil-soluble free radical initiator (such as azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, azobisisobutyronitrile, dimethyl azobisisobutyrate, etc., oil-soluble thermal initiator, photoinitiator, or redox initiator) are mixed evenly in dimethyl sulfoxide. The mixture is deoxygenated by argon displacement for 20 to 60 minutes, and then reacted in an oil bath at 60 to 80°C for 5 to 10 hours. After the reaction is completed, the reaction solution is exposed to air to quench the reaction, yielding polytetrahydropyrrole lactamide acrylate as shown in structural formula (II).

[0014] Synthesis method of compound with structural formula (III): A chain transfer reagent (one of dithioesters, trithiocarbonates, dithiocarbamates, and xanthate esters), tetrahydropyrrole lactamide acrylate monomer, and water-soluble free radical initiators (such as 4,4'-azobis(4-cyanopentanoic acid), azobisisobutyramidine hydrochloride, azobisisobutyramidine hydrochloride, etc., water-soluble thermal initiators, photoinitiators, and redox initiators) are mixed evenly with water to prepare a reaction solution. Argon gas is then used to place the solution in the reaction chamber. The solution is deoxygenated for 20-60 minutes, then placed in an oil bath at 60-80℃ for 10-24 hours. After the reaction is completed, the reaction solution is exposed to air to quench the reaction, thereby obtaining polytetrahydropyrrole lactamide acrylate with controllable dispersion as shown in structural formula (Ⅲ); wherein, the solid content of the polymerization solution is 10%-100%, and the molar ratio of chain transfer reagent to tetrahydropyrrole lactamide acrylate monomer and free radical initiator is 1:10-2000:0.01-0.5.

[0015] The reaction formula is shown below:

[0016]

[0017] The tetrahydropyrrole lactamide acrylate water-soluble bio-based monomer developed in this invention can be polymerized in an environmentally friendly system, yielding a water-soluble polymer with a high glass transition temperature and a high thermal decomposition temperature. This water-soluble polymer with a high glass transition temperature and a high thermal decomposition temperature (e.g.) Figure 6 and Figure 7 (As shown) can improve the strength of other polymer materials by copolymerization with other polymer materials, thus it has the potential to be developed for applications in composite materials and engineering plastics. Attached Figure Description

[0018] Figure 1 The monomer PMLA of Embodiment 1 of the present invention 1 H NMR spectrum;

[0019] Figure 2 The monomer PMLA of Embodiment 1 of the present invention 13 C NMR spectrum;

[0020] Figure 3 This is the mass spectrum of the monomer PMLA in Example 1 of the present invention; Figures 1-3 This demonstrates the successful synthesis and purification of PMLA;

[0021] Figure 4 The image shows the GPC diagram of PPMLA, the product of Example 2 of this invention. From the diagram, we obtained the molecular weight and dispersion of polytetrahydropyrrole lactamide acrylate obtained by conventional free radical polymerization.

[0022] Figure 5 The purified PPMLA product from Example 2 of this invention 1 The 1H NMR spectrum confirmed that the polytetrahydropyrrole lactamide acrylate was completely purified.

[0023] Figure 6 The figure shows the DSC curve of PPMLA, the product of Example 2 of the present invention. From the figure, we obtained the glass transition temperature of polytetrahydropyrrole lactamide acrylate.

[0024] Figure 7 The TGA curve of PPMLA, the product of Example 2 of the present invention, shows the thermal decomposition temperature of polytetrahydropyrrole lactamide acrylate.

[0025] Figure 8 PPMLA, the product of Example 3 of this invention 50 The GPC plot shows the molecular weight and dispersion of polytetrahydropyrrole lactamide acrylate obtained by RAFT polymerization with controllable dispersion. Detailed Implementation

[0026] To make the objectives and technical solutions of this invention clearer, the substantive content of this invention will be described below in conjunction with specific embodiments; the embodiments listed in this invention are only used to illustrate this invention and are not intended to limit the scope of this invention.

[0027] Example 1:

[0028] Synthesis of tetrahydropyrrole lactamide acrylate

[0029] First, the precursor tetrahydropyrrole lactate (PML) was synthesized. Tetrahydropyrrole (11.73 g, 0.165 mol) and methyl lactate (15.62 g, 0.15 mol) were mixed thoroughly in a flask and stirred at 30 °C for 3 days. After the reaction was complete, the product was concentrated by rotary evaporation, and the resulting liquid was purified by column chromatography (ethyl acetate). The eluent was then removed by rotary evaporation, finally yielding 19.29 g of a pale yellow liquid, PML, with a yield of 89.9%. The structural formula is as follows:

[0030]

[0031] Subsequently, the monomer tetrahydropyrrole lactamide acrylate PMLA was synthesized. PML (11.45 g, 0.08 mol) and triethylamine (9.71 g, 0.096 mol) were dissolved in 50 mL of ultra-dry dichloromethane under argon positive flow. The mixture was stirred thoroughly at 5 °C under anaerobic conditions for 30 minutes, followed by slow dropwise addition of acryloyl chloride (8.69 g, 0.096 mol). After the addition was complete, the reaction solution was brought to room temperature and stirred overnight. The solid was removed by filtration. The filtrate was washed with 1 M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated sodium chloride solution, respectively. After washing, the solution was dried over anhydrous magnesium sulfate, filtered to remove magnesium sulfate, and then the solvent was removed by rotary evaporation. The resulting liquid was purified by column chromatography (ethyl acetate: n-hexane 6:1, v / v), and the eluent was removed by rotary evaporation, finally yielding 10.34 g of a pale yellow liquid PMLA, with a yield of 70.6%. The structural formula is as follows:

[0032]

[0033] In this embodiment, the product characterization results are shown in [reference needed]. Figure 1 , Figure 2 , Figure 3 This indicates that the product with the target structure was obtained.

[0034] Example 2:

[0035] a) Synthesis of polytetrahydropyrrole lactamide acrylate (PPMLA)

[0036] Tetrahydropyrrole lactamide acrylate PMLA (0.2994 g, 1.5 mmol), azobisisobutyronitrile (AIBN) (0.62 mg, 3.8 μmol), and dimethyl sulfoxide (DMSO) (700 mL) were added to a 4 mL dry glass bottle. After sealing the bottle, oxygen was removed by argon purging for 30 minutes. After deoxygenation, the bottle was placed in a 70 °C oil bath and reacted for 10 hours. The reaction was then quenched by opening the bottle cap to obtain polytetrahydropyrrole lactamide acrylate. NMR testing showed that the monomer conversion rate was greater than 99%.

[0037] Experimental test analysis:

[0038] The PPMLA prepared in this embodiment was tested. Nuclear magnetic resonance (NMR) analysis showed that the signal peak integrated area corresponding to the double bond hydrogens on the tetrahydropyrrole lactamide monomer indicated a monomer conversion rate greater than 99%. Gel permeation chromatography (GPC) analysis showed that the M... n,GPC = 47.35 kg / mol See Figure 4 .

[0039] b) Thermal property testing of polytetrahydropyrrole lactamide acrylate

[0040] The PPMLA polymer sample was dried overnight in a 60°C vacuum drying oven to remove the solvent. NMR analysis revealed the absence of monomer and solvent peaks in the purified sample. Thermal performance testing was then performed. The NMR spectrum of the purified polymer is shown below. Figure 5 .

[0041] Differential scanning calorimetry (DSC) was performed on the dried and purified polymer sample of this embodiment. 5.77 mg of PPMLA was weighed, and the test temperature range was set to -50 to 200 °C with a heating rate of 10 °C / min. The test was conducted under a nitrogen atmosphere for two cycles, with a holding time of 2 minutes after each temperature change. Analysis of the data after the test showed that the glass transition temperature of PPMLA was 75 °C. (See also...) Figure 6 This indicates that the product has a high glass transition temperature.

[0042] Thermogravimetric analysis was performed on the dried and purified polymer sample of this embodiment. 5.86 mg of PPMLA was weighed, and the test temperature range was set to room temperature to 200°C, with a heating rate of 10°C / min. Analysis of the data after the test showed that the thermal decomposition temperature of PPMLA was 316°C. (See [link to relevant documentation]). Figure 7 This indicates that the product has good thermal stability.

[0043] Example 3:

[0044] Polytetrahydropyrrole lactamide acrylate (PPMLA) 50(MMLA is the English name of the monomer, PMMLA is the polymer, and the subscript 50 indicates the target degree of polymerization of the polymer, which is determined by the ratio of monomer to chain transfer agent. In this example, the target degree of polymerization is 50) RAFT polymerization

[0045] Polytetrahydropyrrole lactamide acrylate (PMLA) (0.3857 g, 1.96 mmol), chain transfer reagent 4-((((2-carboxyethyl)thio)thiocarbonyl)thio)-4-cyanopentanoic acid (CTPA) (0.0120 g, 39.03 μmol), 4,4'-azobis(4-cyanopentanoic acid) ACVC (2.194 mg, 7.83 μmol), and water (H2O) (600 mL) were added to a 4 mL dry glass bottle to prepare a polymerization solution with a solid content of 40%. The glass bottle was sealed and deoxygenated by argon purging for 30 minutes. After deoxygenation, the solution was placed in a 70°C oil bath and reacted for 20 hours. The reaction was then quenched by opening the bottle cap to obtain polytetrahydropyrrole lactamide acrylate (PPMLA) with controllable dispersion. 50 NMR spectroscopy showed that the monomer conversion rate was greater than 99%. The polymer structure is as follows:

[0046]

[0047] The PPMLA prepared in this embodiment 50 Testing was conducted, and the integrated area of ​​the signal peak corresponding to the double bond hydrogen on the tetrahydropyrrolidone lactamide acrylate monomer, measured by NMR, showed that the monomer conversion rate was greater than 99%. Gel permeation chromatography (GPC) analysis indicated that the polymer PPMLA... 50 M n,GPC =2.37 kg / mol, See Figure 8 .

[0048] Using chain transfer reagents with other structures, RAFT polymers containing different substituents, as shown in structural formula (Ⅲ), can also be obtained.

Claims

1. A water-soluble tetrahydropyrrole lactamide acrylate bio-based polymer, the structural formula of which is shown in one of the following figures. (II) n is a positive integer representing the number of aggregation units; (IV)。 2. The method for preparing the water-soluble tetrahydropyrrole lactamide acrylate bio-based polymer according to claim 1, characterized in that: One molar amount of tetrahydropyrrolidinyl lactamide acrylate monomer as shown in structural formula (I) was mixed with 0.0025~0.05 molar amount of oil-soluble free radical initiator in dimethyl sulfoxide. The mixture was deoxygenated by argon displacement for 20~60 minutes, and then placed in an oil bath at 60~80℃ for 5~10 hours. After the reaction was completed, the reaction solution was exposed to air to quench the reaction, and polytetrahydropyrrolidinyl lactamide acrylate as shown in structural formula (II) was obtained. （I）。 3. The method for preparing a water-soluble tetrahydropyrrole lactamide acrylate bio-based polymer as described in claim 2, characterized in that: Oil-soluble free radical initiators include azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, azobiscyclohexylformitrile, or dimethyl azobisisobutyrate.

4. The method for preparing a water-soluble tetrahydropyrrole lactamide acrylate bio-based polymer according to claim 1, characterized in that: A reaction solution was prepared by uniformly mixing a chain transfer reagent, tetrahydropyrrolidinyl acrylate monomer with structural formula (I), a water-soluble free radical initiator, and water. The solution was deoxygenated by argon displacement for 20-60 minutes and then placed in an oil bath at 60-80°C for 10-24 hours. After the reaction was completed, the reaction solution was exposed to air to quench the reaction, thereby obtaining polytetrahydropyrrolidinyl acrylate with controllable dispersion as shown in structural formula (IV). The solid content of the polymerization solution was 10%-100%, the molar ratio of chain transfer reagent, monomer, and free radical initiator was 1:10-2000:0.01-0.5, and the chain transfer reagent was 4-((((2-carboxyethyl)thio)thiocarbonyl)thio)-4-cyanopentanoic acid. （I）。 5. The method for preparing a water-soluble tetrahydropyrrole lactamide acrylate bio-based polymer as described in claim 4, characterized in that: The water-soluble free radical initiator is one of 4,4'-azobis(4-cyanopentanoic acid), azobisisobutyramidine hydrochloride, or azobisisobutyramidine hydrochloride.

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