Eugenol-based non-isocyanate polyurethane and method for its preparation

Abstract

The application relates to a preparation method of eugenol-based non-isocyanate polyurethane, and belongs to the polyurethane field.The method comprises the following steps: firstly, eugenol glyceryl ether is obtained through etherification reaction by taking bio-based monomer eugenol as raw material; then, a double-functionality eugenol cyclic carbonate is prepared through ester exchange reaction, epoxidation reaction and a carbon dioxide route; finally, a non-isocyanate polyurethane is obtained through one-pot reaction with diamine. The non-isocyanate polyurethane avoids the use of toxic isocyanate, takes renewable resources eugenol and greenhouse gas CO2 as raw materials, has a green and environment-friendly preparation process, is low in cost, conforms to the green chemistry concept, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to an eugenol-based non-isocyanate polyurethane and its preparation method. Background Technology

[0002] Polyurethane is widely used in the automotive, furniture, construction, and electrical appliance industries due to its lightweight nature and excellent impact resistance and insulation properties. Traditionally, polyurethane is prepared through a stepwise polymerization reaction of polyols and isocyanates. While this route is simple and produces high-performance PU, the raw materials used in its synthesis highlight its sustainability drawbacks. Polyols can be produced from renewable feedstocks such as vegetable oils or their derivatives. However, isocyanates are petroleum-derived products derived from phosgene, which are unstable and toxic.

[0003] In recent years, non-isocyanate routes have become a focus of research. Among all synthetic routes for non-isocyanate-based polyurethanes (NIPUs), the most studied and promising is the reaction route between cyclic carbonates and amines. This route has several advantages. First, from an economic and environmental perspective, using CO2 as an inert gas, which can be used as both a solvent and a reagent, is relatively safe, inexpensive, and reduces the pressure of carbon emissions. Second, the reaction can achieve very high yields in the presence of a suitable catalyst, resulting in extremely high atom economy. Furthermore, the NIPU structure prepared by this route contains primary or secondary alcohols, also known as polyhydroxycarbamates (PHUs), which not only gives it superior resistance to hydrolysis, permeation, and chemical corrosion, but also provides a basis for crosslinking or further functionalization.

[0004] With the depletion of fossil resources, there is a growing interest in bio-based precursors. Indeed, biomass, including vegetable oils, lignin, and polysaccharides, presents promising pathways for polymer production. Currently, a growing number of research groups are dedicated to synthesizing bio-based cyclic carbonates to replace petroleum-based PHUs.

[0005] Eugenol, the main component of clove oil, has always attracted attention. It can be extracted from nature at a relatively low cost and exhibits antibacterial properties against a wide range of Gram-negative and Gram-positive bacteria. Furthermore, eugenol contains active phenolic hydroxyl and allyl groups. The phenolic group provides possibilities for modification through etherification and esterification, while the allyl group provides a pathway for the oxidative synthesis of epoxides. The structure of eugenol allows for the production of materials with excellent thermal and mechanical properties to meet demanding applications.

[0006] Therefore, there is an urgent need in this field to develop a non-isocyanate polyurethane that utilizes renewable resources and avoids the use of isocyanates. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing an eugenol-based non-isocyanate polyurethane and its preparation method.

[0008] To solve the above problems, the present invention adopts the following technical solution: a method for preparing non-isocyanate polyurethane, characterized in that the method includes the following steps: (1) Synthesis of eugenol glycerol ether Eugenol, solvent A, glycerol and catalyst A are mixed and reacted at 100-120℃ for 8-18 h. After post-treatment, eugenol glycerol ether is obtained. (2) Synthesis of eugenol monocyclic carbonate The eugenol glycerol ether synthesized in step (1) was mixed with dimethyl carbonate and catalyst A, and reacted at 70-90°C for 6-10 h. After post-treatment, eugenol monocyclic carbonate was obtained. 3) Synthesis of epoxyeugenol The eugenol monocyclic carbonate synthesized in step (2) was mixed with m-chloroperoxybenzoic acid and an appropriate amount of solvent B and reacted at 15℃~30℃ for 24~72 h. After post-treatment, epoxy eugenol was obtained. (4) Synthesis of eugenol cyclic carbonates The epoxy eugenol synthesized in step (3) was added to a high-pressure reactor along with carbon dioxide and catalyst B. The reaction temperature was 100-160 °C, the carbon dioxide pressure was 1-3 MPa, and the reaction time was 8-12 h to obtain a double-tube eugenol cyclic carbonate. (5) Preparation of eugenol-based non-isocyanate polyurethane The eugenol cyclic carbonate synthesized in step (4) and diamine compounds were added to a reaction flask at different molar ratios. An appropriate amount of solvent C was added, and nitrogen gas was introduced as a protective gas. The reaction temperature was 70-150 °C and the reaction time was 10-12 h to prepare non-isocyanate polyurethane.

[0009] The solvent A is at least one of diethyl carbonate or dimethyl carbonate, and the molar ratio of eugenol to solvent A is 1:1 to 1.5; the catalyst A is potassium carbonate, and the molar ratio of eugenol to catalyst A is 1:0.05 to 0.3; the molar ratio of eugenol to glycerol is 1:1.5 to 3.

[0010] The molar ratio of eugenol glycerol ether to dimethyl carbonate is 1:5 to 20; the catalyst A is potassium carbonate, and the molar ratio of eugenol glycerol ether to catalyst A is 1:0.01 to 0.05.

[0011] Solvent B is one or more of dichloromethane and trichloromethane.

[0012] The catalyst B is one or more of quaternary ammonium salts such as tetrabutylammonium bromide, organic alkali metals or metal halides, and the molar ratio of epoxy eugenol to the catalyst B is 1:0.01 to 0.05.

[0013] The solvent C is one or more of N,N-dimethylformamide and dimethyl sulfoxide; the diamine compound is at least one of 1,6-hexanediamine (HDA), 1,10-decanediamine (DDA), 4,7,10-trioxo-1,13-tetanediamine (TTD), and polyetheramine (Mn=D400).

[0014] The molar ratio of the eugenol cyclic carbonate to the diamine compound is one or more of 1:0.8, 1:1.2, and 1:1.

[0015] Due to the adoption of the above technical solutions, the beneficial effects of this invention compared with the prior art are as follows: The method for preparing eugenol-based non-isocyanate polyurethane provided by this invention does not use isocyanate compounds that are harmful to the human body during the polyurethane preparation process. It uses eugenol, a renewable resource, as a raw material and utilizes the greenhouse gas CO2 to reduce the pressure of carbon emissions. The production process is green and environmentally friendly and harmless to human health. It is a new type of green and environmentally friendly polyurethane preparation method.

[0016] This invention is green and environmentally friendly, conforms to the concept of sustainable development, and has good application prospects. Attached Figure Description

[0017] Figure 1 The images show the 1H NMR spectra of the raw materials, synthesized eugenol-based cyclic carbonates, and intermediate products in Example 1, from top to bottom corresponding to the 1H NMR spectra of eugenol, eugenol glycerol ether, eugenol monocyclic carbonate, epoxy eugenol, and eugenol cyclic carbonate.

[0018] Figure 2 The infrared spectra of eugenol-based non-isocyanate polyurethanes in Examples 2-5 of this invention are shown.

[0019] Figure 3 The mechanical properties of eugenol-based non-isocyanate polyurethanes in Examples 2-5 of this invention are shown. Detailed Implementation

[0020] Unless otherwise stated, implied from the context, or as is customary in the art, all parts and percentages in this application are based on weight, and all testing and characterization methods used are concurrent with the filing date of this application. Where applicable, any patent, patent application, or disclosure relating to this application is incorporated herein by reference in its entirety, and its equivalent patent families are also incorporated herein by reference, particularly the definitions disclosed in these documents concerning synthetic techniques, product and processing design, polymers, comonomers, initiators, or catalysts in the art. If any definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition provided in this application shall prevail.

[0021] The numerical ranges in this application are approximate values ​​and therefore may include values ​​outside the range unless otherwise stated. A numerical range includes all values ​​from the lower limit to the upper limit, increasing by one unit, provided there is an interval of at least two units between any lower and any higher value. For example, if the stated composition, physical, or other property (such as molecular weight, melt index, etc.) is 100 to 1000, it means that all individual values, such as 100, 101, 102, etc., are explicitly listed, as well as all subranges, such as 100 to 166, 155 to 170, 198 to 200, etc. For ranges containing values ​​less than 1 or fractions greater than 1 (e.g., 1.1, 1.5, etc.), one unit is appropriately considered as 0.0001, 0.001, 0.01, or 0.1. For ranges containing single digits less than 10 (e.g., 1 to 5), one unit is generally considered as 0.1. These are merely specific examples of what is intended to be expressed, and all possible combinations of values ​​between the listed minimum and maximum values ​​are considered to be clearly stated in this application. It should also be noted that the terms "first," "second," etc., used herein are not intended to specify a particular order, but are merely used to distinguish substances with different structures.

[0022] When referring to chemical compounds, unless explicitly stated otherwise, the singular includes all isomers and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively). Additionally, unless explicitly stated otherwise, nouns described with "an," "a," or "the" also include their plural forms.

[0023] The terms “comprising,” “including,” “having,” and their derivatives do not exclude the presence of any other components, steps, or processes, regardless of whether such other components, steps, or processes are disclosed in this application. To eliminate any doubt, unless expressly stated otherwise, all compositions using the terms “comprising,” “including,” or “having” in this application may contain any additional additives, excipients, or compounds. Conversely, except for those necessary for operational performance, the term “substantially constitutes…” excludes any other components, steps, or processes described below with respect to that term. The term “consisting of…” does not include any components, steps, or processes not specifically described or listed. Unless expressly stated otherwise, the term “or” refers to the individual members listed or any combination thereof.

[0024] Example The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Unless otherwise specified, the reagents and raw materials used can be purchased commercially. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or according to the product instructions.

[0025] Example 1 This embodiment provides a method for preparing eugenol-based non-isocyanate polyurethane, comprising the following steps: (1) Synthesis of eugenol glycerol ether 32.84 g of eugenol, 55.25 g of glycerol (3 eq), 33.08 g of diethyl carbonate (1.4 eq), and 2.76 g of potassium carbonate (0.1 eq) were placed in a 250 mL three-necked flask and refluxed at 110 °C for 16 h under a nitrogen atmosphere. After the reaction was complete, the mixture was extracted three times with saturated sodium chloride solution and ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and concentrated. After adding ethanol, the mixture was placed in a -4 °C freezer to allow crystals to precipitate. The crystals were then filtered and dried under vacuum to obtain 28.52 g of white powdered eugenol glycerol ether. 1 H NMR(DMSO-d6): δ (ppm)= 3.29 (d, 2H, CH2), 3.43 (m, 2H, CH2), 3.73 (s, 3H, CH3), 3.78~3.91 (m, 3H, CH+CH2), 4.63 (t, 1H, OH), 4.89 (d, 1H, OH), 5.02~5.06 (m,2H, CH2), 5.94 (m, 1H, CH), 6.67~6.87 (m, 3H, PhH).

[0026] (2) Synthesis of eugenol monocyclic carbonate 23.83 g of eugenol glycerol ether, 90.08 g of dimethyl carbonate (10 eq), and 0.55 g of potassium carbonate (0.04 eq) were placed in a three-necked flask and refluxed at 90 °C for 8 h. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filtrate was concentrated and recrystallized from ethanol, then dried under vacuum to obtain 21.70 g of white needle-like eugenol monocyclic carbonate. 1H NMR (DMSO-d6): δ(ppm)= 3.31 (d, 2H, CH2), 3.75 (s, 3H,CH3), 4.14~4.22 (m, 2H,CH2), 4.40~4.62(m, 2H, CH2), 5.05 (m, 2H, CH2), 5.10 (m, 1H, CH), 5.95 (m, 1H, CH), 6.71~6.93 (m, 3H, PhH).

[0027] (3) Synthesis of epoxyeugenol Dissolve 26.42 g of eugenol monocyclic carbonate in an appropriate amount of dichloromethane and place the solution in a three-necked flask. Add 25.89 g of m-chloroperoxybenzoic acid (1.5 eq) in portions under an ice-water bath, stir for 1 h, and then react at room temperature for 2 days. After the reaction was completed, the precipitated m-chlorobenzoic acid was filtered out. The filtrate was quenched with sodium sulfite aqueous solution, washed three times with sodium bicarbonate aqueous solution, washed three times with saturated sodium chloride aqueous solution, dried with anhydrous sodium sulfate, concentrated, recrystallized with ethanol, and dried under vacuum to obtain 21.02 g of pale yellow needle-like crystals of epoxyeugenol. 1H NMR (DMSO-d6): δ (ppm) = 2.55~2.78 (m, 4H, CH2+CH2), 3.10 (m, CH), 3.76 (s, 3H, CH3), 4.15~4.23 (m, 2H, CH2), 4.40~4.62 (m, 2H, CH2), 5.09~5.16 (m, 1H, CH), 6.79~6.96 (m, 3H, PhH).

[0028] (4) Synthesis of eugenol cyclic carbonates 6 g of epoxy eugenol and 0.07 g of tetrabutylammonium bromide (0.01 eq) were added to a high-pressure reactor, and 2 MPa CO2 was introduced. The reaction was carried out at 120 °C for 9 h. After the reaction was completed, the reactor was removed and cooled to room temperature. The gas inside the reactor was then purged to obtain 6.94 g of brown solid eugenol cyclic carbonate. 1H NMR (DMSO-d6): δ (ppm) = 2.98 (d, 2H, CH2), 3.76 (s, 1H, CH3), 4.16~4.62 (m, 6H, CH2+CH2+CH2), 5.05 (m, 1H, CH), 5.13 (m, 1H, CH), 6.81~6.97 (m, 3H, PhH).

[0029] Example 2 Eugenol cyclic carbonate and 1,6-hexanediamine (HDA) were added in a 1:1 molar ratio to a three-necked flask containing nitrogen and a condenser. Then, a certain amount of dimethyl sulfoxide was added, and the mixture was heated to 100 °C and stirred for 12 hours. After the reaction was complete, the water-washed reaction solution was poured into a mold, which was then dried in an oven at 60 °C for 24 hours, followed by drying in a vacuum oven at 100 °C for 24 hours to obtain eugenol-based non-isocyanate polyurethane.

[0030] Example 3 Eugenol cyclic carbonate and 1,10-decanediamine (DDA) were added in a 1:1 molar ratio to a three-necked flask containing nitrogen and a condenser. Then, a certain amount of dimethyl sulfoxide was added, the temperature was raised to 100 °C, and the reaction was stirred for 12 hours. After the reaction was complete, the water-washed reaction solution was poured into a mold, which was then dried in an oven at 60 °C for 24 hours, followed by drying in a vacuum oven at 100 °C for 24 hours to obtain eugenol-based non-isocyanate polyurethane.

[0031] Example 4 Eugenol cyclic carbonate and 4,7,10-trioxo-1,13-tetanediamine (TTD) were added in a 1:1 molar ratio to a three-necked flask containing nitrogen and a condenser. Then, a certain amount of dimethyl sulfoxide was added, and the mixture was heated to 100 °C and stirred for 12 hours. After the reaction was complete, the reaction solution was poured into a mold, which was then dried in an oven at 60 °C for 24 hours, followed by drying in a vacuum oven at 100 °C for 24 hours to obtain eugenol-based non-isocyanate polyurethane.

[0032] Example 5 Eugenol cyclic carbonate and polyetheramine D400 were added in a 1:1 molar ratio to a three-necked flask containing nitrogen and a condenser. Then, a certain amount of dimethyl sulfoxide was added, the temperature was raised to 100 °C, and the reaction was stirred for 12 hours. After the reaction was complete, the reaction solution was poured into a mold, which was then dried in an oven at 60 °C for 24 hours, followed by drying in a vacuum oven at 100 °C for 24 hours to obtain eugenol-based non-isocyanate polyurethane.

[0033] Performance Characterization The raw material eugenol and the synthetic intermediates in Example 1 were characterized using 1H NMR spectroscopy. The results are shown in [reference needed]. Figure 1 The NMR peak positions correspond to the structures, proving the synthesis of each intermediate product and the eugenol-based cyclic carbonate.

[0034] The eugenol-based non-isocyanate polyurethanes in Examples 2-5 were characterized using infrared spectroscopy. The results are shown below. Figure 2 At 1693 cm -1 A new absorption peak appears at 3315 cm⁻¹, which is attributed to the C=O stretching vibration peak of the urethane group in PHU. -1 The absorption peaks at the specified locations correspond to the stretching vibrations of OH and NH, which sufficiently demonstrates the preparation of eugenol-based non-isocyanate polyurethane.

[0035] The tensile properties of eugenol-based PHU in Examples 2-4 were tested using an electronic tensile testing machine. Figure 3 As shown, the structure of diamines significantly affects the mechanical properties of PHU. PHU prepared with decanediamine exhibits the highest tensile strength (2.08 MPa) and a good elongation at break (185.33%). This is because the structure of decanediamine is relatively rigid, increasing tensile strength. In contrast, PHU prepared with hexamethylenediamine has a tensile strength of only 0.76 MPa and an elongation at break of 150.95%. This is because the test temperature is below its glass transition temperature, and PHU is in a glassy state, resulting in poor mechanical properties. PHU prepared with TTD has the worst tensile strength (0.05 MPa), but its elongation at break is 1400%. This is because TTD has good flexibility, increasing the segmental flexibility of PHU, improving elongation at break, and reducing Young's modulus.

[0036] All raw materials used in this application are commercially available and widely sourced, allowing for large-scale production.

[0037] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A method for preparing eugenol-based non-isocyanate polyurethane, characterized in that, The method includes the following steps: (1) Synthesis of eugenol glycerol ether Eugenol, solvent A, glycerol and catalyst A are mixed and reacted at 100-120℃ for 8-18 h. After post-treatment, eugenol glycerol ether is obtained. (2) Synthesis of eugenol monocyclic carbonate The eugenol glycerol ether synthesized in step (1) was mixed with dimethyl carbonate and catalyst A and reacted at 70-90°C for 6-10 h. After post-treatment, eugenol monocyclic carbonate was obtained. (3) Synthesis of epoxyeugenol The eugenol monocyclic carbonate synthesized in step (2) was mixed with m-chloroperoxybenzoic acid and an appropriate amount of solvent B and reacted at 15℃~30℃ for 24~72 h. After post-treatment, epoxy eugenol was obtained. (4) Synthesis of eugenol cyclic carbonates The epoxy eugenol synthesized in step (3) was added to a high-pressure reactor along with carbon dioxide and catalyst B. The reaction temperature was 100-160 °C, the carbon dioxide pressure was 1-3 MPa, and the reaction time was 8-12 h to obtain bifunctional eugenol cyclic carbonate. (5) Preparation of eugenol-based non-isocyanate polyurethane The eugenol cyclic carbonate synthesized in step (4) and diamine compounds were added to a reaction flask at different molar ratios. An appropriate amount of solvent C was added, and nitrogen gas was introduced as a protective gas. The reaction temperature was 70-150 °C and the reaction time was 10-12 h to prepare non-isocyanate polyurethane. In step (1), solvent A is at least one of diethyl carbonate or dimethyl carbonate, and the molar ratio of eugenol to solvent A is 1:1 to 1.5; catalyst A is potassium carbonate, and the molar ratio of eugenol to catalyst A is 1:0.05 to 0.3; the molar ratio of eugenol to glycerol is 1:1.5 to 3. In step (2), the molar ratio of eugenol glycerol ether to dimethyl carbonate is 1:5 to 20; the catalyst A is potassium carbonate, and the molar ratio of eugenol glycerol ether to catalyst A is 1:0.01 to 0.05; In step (3), solvent B is one or more of dichloromethane and trichloromethane; In step (4), the catalyst B is one or more of quaternary ammonium salts, organic alkali metals or metal halides, and the molar ratio of epoxy eugenol to the catalyst B is 1:0.01 to 0.

05. In step (5), the diamine compound is at least one of 1,10-decanediamine and 4,7,10-trioxo-1,13-tetanediamine; the molar ratio of the eugenol cyclic carbonate to the diamine compound is one of 1:0.8, 1:1.2, and 1:1; and the solvent C is one or more of N,N-dimethylformamide and dimethyl sulfoxide.

2. An eugenol-based non-isocyanate polyurethane, prepared by the method of claim 1.

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