Bio-based hydrophilic polyamide polymer material and preparation method thereof

Abstract

The application provides a kind of bio-based hydrophilic polyamide macromolecular material and its preparation method, belong to polyamide macromolecular material field, the application is carried out amidation reaction by monomer I and monomer II, introduce hydroxyl group in polyamide main chain, obtain prepolymer, prepolymer carries out polycondensation reaction and improves molecular weight, obtains the following general formula, in formula, m is any integer of 0-8, n is any integer of 150-200.The bio-based hydrophilic polyamide macromolecular material introduces hydroxyl group in polyamide molecular main chain, utilizes the hydrophilic of the characteristic of hydroxyl group, so that bio-based polyamide macromolecular material has hydrophilic.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, specifically to a bio-based hydrophilic polyamide polymer material. Background Technology

[0002] Polyamide polymers are widely used in food packaging, medical consumables, hydrophilic filtration and other fields due to their excellent mechanical strength, chemical corrosion resistance and molding processability. These applications have strict requirements for their hydrophilic properties.

[0003] In related technologies, the main methods for improving the hydrophilicity of polyamides are surface modification and bulk copolymerization. Surface modification introduces hydrophilic groups through coating or grafting, which is a simple process, but the modified layer is prone to peeling off, and the improvement in hydrophilicity lacks durability. Bulk copolymerization, on the other hand, introduces hydrophilic monomers (polyethers, sulfonates, etc.) into the main chain to achieve a fundamental improvement in hydrophilicity, making it a more industrially viable approach. However, most existing hydrophilic monomers are petrochemical-based, and the hydrophilic groups easily disrupt the regularity of the molecular chain, leading to a decline in the basic properties of polyamides such as crystallinity and thermal stability, making it difficult to balance hydrophilic modification with core properties. Bio-based polyamides are becoming an industry development trend, but currently, bio-based hydrophilic modifying monomers are scarce and their modification effects are limited, failing to meet the needs of high-end applications.

[0004] In view of this, it is necessary to design a bio-based hydrophilic polyamide polymer material and its preparation method to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a bio-based hydrophilic polyamide polymer material and its preparation method. The bio-based hydrophilic polyamide polymer material is modified by copolymerizing natural substances (R)-citric acid produced in specific metabolic processes of microorganisms with diamine, introducing hydroxyl groups located at the central chiral carbon atom in the polyamide molecular backbone, and utilizing the intrinsic hydrophilicity of hydroxyl groups to make the bio-based polyamide polymer material hydrophilic.

[0006] To achieve the above objectives, in a first aspect, this application provides a bio-based hydrophilic polyamide polymer material, which contains structural units represented by the following general formula (1): In the formula, m is any integer from 0 to 8, and n is any integer from 150 to 200.

[0007] Furthermore, the intrinsic viscosity of the bio-based hydrophilic polyamide polymer material is 1.8 dL / g-2.8 dL / g.

[0008] Secondly, this application also provides a method for preparing a bio-based hydrophilic polyamide polymer material, including providing a precursor solution, the precursor solution including monomer I and monomer II; wherein, monomer I contains the structure shown in the following general formula (2), and monomer II contains the structure shown in the following general formula (3); In the formula, m is any integer from 0 to 8; The precursor solution was subjected to amidation reaction in an anaerobic environment and then dehydrated to obtain the prepolymer; The prepolymer was subjected to a condensation reaction under vacuum conditions to obtain a bio-based hydrophilic polyamide polymer material.

[0009] Furthermore, the preparation of the precursor solution includes: dissolving monomer I in a first solvent to obtain a monomer I solution; Monomer II is dissolved in a second solvent to obtain a monomer II solution; The precursor solution was obtained by mixing the monomer I solution and the monomer II solution.

[0010] Furthermore, in the preparation of the precursor solution, the mass percentage of monomer I in the monomer I solution is 50%-70%, and the mass percentage of monomer II in the monomer II solution is 50%-70%.

[0011] Furthermore, in the precursor solution, the molar ratio of monomer I to monomer II is (1-1.2):1.

[0012] Furthermore, the amidation reaction is carried out at a pressure of 0.6 MPa–1.8 MPa; and / or, The amidation reaction is carried out at a temperature of 180℃-220℃; and / or, The amidation reaction takes 2-5 hours.

[0013] Furthermore, the pressure of the polycondensation reaction is 90 Pa-110 Pa; and / or, The temperature for polycondensation is 220℃-260℃; and / or, The polycondensation reaction takes 1-4 hours.

[0014] Furthermore, the protective atmosphere for an anaerobic environment includes nitrogen.

[0015] Thirdly, this application also provides a bio-based hydrophilic polyamide polymer fiber, comprising: obtained by melt spinning the above-mentioned bio-based hydrophilic polyamide polymer material; or, The bio-based hydrophilic polyamide polymer material was prepared by melt spinning using the above-mentioned method.

[0016] The beneficial effects of this application are as follows: In the technical solution of this application, (R)-citric acid, a natural substance produced during a specific metabolic process of microorganisms, is selected as one of the reactants. As a biochemical, (R)-citric acid has a unique chiral structure with a hydroxyl group attached to its central chiral carbon atom. By introducing this hydroxyl group into the main chain of the polyamide molecule, the electronegativity of the oxygen atom (O) in the hydroxyl group is higher than that of the hydrogen atom (H). This makes the OH bond in the hydroxyl group a highly polar covalent bond, and the electron cloud is strongly pulled towards the oxygen atom, resulting in the oxygen atom carrying a partial negative charge (denoted as δ). - Hydrogen atoms carry a partial positive charge (denoted as δ). + This creates a tiny positive and negative pole within a single molecule. Furthermore, the water molecule (H₂O) itself is also a polar molecule, carrying a partially positive charge of hydrogen and a partially negative charge of oxygen. When a molecule containing a hydroxyl group encounters water, a precise attraction between opposite charges occurs: the hydroxyl group carries a δ-pole charge... + Hydrogen will be carried by water molecules with δ - The oxygen is strongly attracted; the hydroxyl group carries a δ-type oxygen. - Oxygen will be carried by water molecules with δ + Hydrogen molecules are strongly attracted to each other. This electrostatic attraction forms a special hydrogen bond, where a hydroxyl group can act as both a hydrogen donor (providing hydrogen) and an acceptor (accepting hydrogen), dynamically binding with water molecules. A three-dimensional hydrogen bond network forms between the hydroxyl group and water molecules. This process helps lower the system's energy, making the molecules more soluble.

[0017] In summary, by using bio-based (R)-citric acid as one of the reactants, hydroxyl groups can be introduced into the polyamide backbone through amidation, thereby improving the hydrophilicity of bio-based hydrophilic polyamide polymers.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Detailed Implementation

[0019] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0024] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0025] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are used only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0026] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0027] Polyamide polymers are widely used in food packaging, medical consumables, hydrophilic filtration and other fields due to their excellent mechanical strength, chemical corrosion resistance and molding processability. These applications have strict requirements for their hydrophilic properties.

[0028] In related technologies, the main methods for improving the hydrophilicity of polyamides are surface modification and bulk copolymerization. Surface modification introduces hydrophilic groups through coating or grafting, which is a simple process, but the modified layer is prone to peeling off, and the improvement in hydrophilicity lacks durability. Bulk copolymerization, on the other hand, introduces hydrophilic monomers (polyethers, sulfonates, etc.) into the main chain to achieve a fundamental improvement in hydrophilicity, making it a more industrially viable approach. However, most existing hydrophilic monomers are petrochemical-based, and the hydrophilic groups easily disrupt the regularity of the molecular chain, leading to a decline in the basic properties of polyamides such as crystallinity and thermal stability, making it difficult to balance hydrophilic modification with core properties. Bio-based polyamides are becoming an industry development trend, but currently, bio-based hydrophilic modifying monomers are scarce and their modification effects are limited, failing to meet the needs of high-end applications.

[0029] To address the aforementioned technical problems, in a first aspect, this application provides a bio-based hydrophilic polyamide polymer material, which contains structural units represented by the following general formula (1): In the formula, m is any integer from 0 to 8, and n is any integer from 150 to 200.

[0030] In this application, by introducing this hydroxyl group into the main chain of the polyamide molecule, the electronegativity of the oxygen atom (O) in the hydroxyl group is higher than that of the hydrogen atom (H). This makes the OH bond in the hydroxyl group a highly polar covalent bond, and the electron cloud is strongly pulled towards the oxygen atom end, resulting in the oxygen atom carrying a partial negative charge (denoted as δ). - Hydrogen atoms carry a partial positive charge (denoted as δ). + This creates a tiny positive and negative pole within a single molecule. Furthermore, the water molecule (H₂O) itself is also a polar molecule, carrying a partially positive charge of hydrogen and a partially negative charge of oxygen. When a molecule containing a hydroxyl group encounters water, a precise attraction between opposite charges occurs: the hydroxyl group carries a δ-pole charge... + Hydrogen will be carried by water molecules with δ- The oxygen is strongly attracted; the hydroxyl group carries a δ-type oxygen. - Oxygen will be carried by water molecules with δ + Hydrogen molecules are strongly attracted to water. This electrostatic attraction forms a special hydrogen bond, where a hydroxyl group can simultaneously act as a hydrogen bond donor (providing H) and acceptor (accepting H), dynamically binding with water molecules. A three-dimensional hydrogen bond network is formed between the hydroxyl group and water molecules. This process helps lower the system's energy, making the molecules more soluble. Introducing hydroxyl groups into the polyamide backbone can improve the hydrophilicity of bio-based polyamide polymers.

[0031] In general formula (1), n ​​is any integer from 150 to 200, and n is the degree of polymerization of the bio-based polyamide polymer. The molecular weight of the bio-based polyamide polymer can be controlled within this range. Within this range, the mechanical properties of the bio-based polyamide polymer reach a plateau region, with good strength, toughness, and wear resistance. Furthermore, the melt viscosity of the bio-based polyamide polymer is suitable, and its flowability is good, making it easy to injection mold, extrude, and spin. In addition, within this range, the crystallization rate and crystallinity of the bio-based polyamide polymer are moderate, which can form fine and uniform grains and maintain the strength and toughness of the material.

[0032] In some embodiments, the intrinsic viscosity of the bio-based hydrophilic polyamide polymer is 1.8 dL / g to 2.8 dL / g.

[0033] In this embodiment, intrinsic viscosity is the extrapolated viscosity value of the polymer solution at infinite dilution, used to characterize the molecular weight and chain structure of the polymer. A higher intrinsic viscosity indicates a longer molecular chain and a higher molecular weight. Setting the intrinsic viscosity of the bio-based hydrophilic polyamide to 1.8 dL / g-2.8 dL / g allows for sufficiently long molecular chains to form physical entanglement, resulting in excellent mechanical properties for the bio-based hydrophilic polyamide polymer. Furthermore, within this range, the melt viscosity of the bio-based hydrophilic polyamide polymer is moderate, providing sufficient flowability for injection molding, extrusion, and spinning processes. Additionally, within this range, the bio-based hydrophilic polyamide polymer can slow down the hydrolytic degradation rate in humid environments, extending the material's service life. Therefore, this intrinsic viscosity range represents a good process window for balancing the mechanical properties, processing performance, and resistance to hydrolytic aging of the bio-based hydrophilic polyamide polymer.

[0034] Secondly, this application also provides a method for preparing a bio-based hydrophilic polyamide polymer material, including providing a precursor solution, the precursor solution including monomer I and monomer II, wherein monomer I contains the structure shown in the following general formula (2), and monomer II contains the structure shown in the following general formula (3); In the formula, m is any integer from 0 to 8. The precursor solution is subjected to amidation reaction in an anaerobic environment and then dehydrated to obtain a prepolymer; the prepolymer is subjected to polycondensation reaction under vacuum conditions to obtain a bio-based hydrophilic polyamide polymer material.

[0035] In this embodiment, setting m to any integer from 0 to 8 allows control over the carbon chain length of monomer II, thereby regulating the density of rigid amide groups in the bio-based hydrophilic polyamide molecular chain. A shorter carbon chain results in a higher density of amide groups per unit length, leading to a denser strong hydrogen bond network and stronger intermolecular forces. This increases the material's melting point, rigidity, and mechanical strength, but also enhances hydrophilicity and moisture absorption. Conversely, a longer carbon chain results in a lower density of amide groups per unit length, reducing hydrogen bond density and increasing molecular chain mobility, thus giving the bio-based hydrophilic polyamide polymer better flexibility, impact resistance, and dimensional stability.

[0036] Monomer I and monomer II undergo an amidation reaction followed by a final polycondensation reaction to obtain a bio-based polyamide polymer.

[0037] In some embodiments, the preparation of the precursor solution includes dissolving monomer I in a first solvent to obtain a monomer I solution; dissolving monomer II in a second solvent to obtain a monomer II solution; and mixing the monomer I solution and the monomer II solution to obtain the precursor solution.

[0038] In this embodiment, monomer I and monomer II are dissolved separately before being mixed. Dissolving them separately allows for uniform dispersion of both in their respective solvents, controlling for excessively high local concentrations or uneven reactions when directly mixed. Furthermore, since the amidation reaction is exothermic, dissolving them separately before mixing allows for the dilution and conduction of the heat of reaction in a larger volume of solvent, limiting local overheating that could lead to oxidation, cross-linking, or degradation, thus providing stability for the synthesis of bio-based hydrophilic polyamides.

[0039] In some embodiments, the mass percentage of monomer I in the monomer I solution is 50%-70%, and the mass percentage of monomer II in the monomer II solution is 50%-70%.

[0040] In this embodiment, setting the mass percentage of monomer I to 50%-70% helps control excessively vigorous local reactions. During the amidation and polycondensation reactions, a mass percentage of monomer I within this range helps control the chain growth rate, regulates system viscosity, and promotes forward reaction, thus better obtaining high-molecular-weight bio-based hydrophilic polyamide polymers. Furthermore, a mass percentage of monomer I within this range can prevent the precipitation of oligomers or salt byproducts generated during the reaction, reducing the risk of overall system solidification. Limiting the concentration helps maintain homogeneity of the system at high temperatures, ensuring uniform mass and heat transfer. Setting the mass percentage of monomer II to 50%-70% reduces its residence time at high temperatures, thereby decreasing its volatility and oxidation. Moreover, in polycondensation reactions, monomer II is typically more nucleophilic than monomer I, potentially leading to excessively rapid local reactions or side reactions. Limiting the mass percentage of monomer II helps control the reaction rate, allowing the prepolymer to polymerize gradually. In addition, appropriately limiting the mass percentage helps maintain a homogeneous reaction environment, allowing the molecular chains to grow uniformly and enabling better control of the molecular weight of bio-based hydrophilic polyamides.

[0041] In some embodiments, the molar ratio of monomer I to monomer II in the precursor solution is (1-1.2):1.

[0042] In this embodiment, setting the molar ratio of monomer I to monomer II to (1-1.2):1 enables the bio-based hydrophilic polyamide polymer to achieve a high molecular weight, thereby improving the performance of the bio-based hydrophilic polyamide polymer material. Furthermore, setting the molar ratio of monomer I to monomer II to (1-1.2):1 can limit the over-termination of a certain end group, allowing for stable chain growth and resulting in a high molecular weight bio-based hydrophilic polyamide polymer material. In addition, setting the molar ratio of monomer I to monomer II to (1-1.2):1 allows for control of the color purity of the bio-based hydrophilic polyamide polymer material and improves the repeatability of the process.

[0043] In some embodiments, the pressure of the amidation reaction is 0.6 MPa-1.8 MPa.

[0044] In this embodiment, the pressure of the amidation reaction is set to 0.6 MPa-1.8 MPa. This pressure falls within the low-to-medium pressure range, which, by continuously removing water, disrupts the amidation reaction equilibrium, allowing the degree of polymerization to exceed the equilibrium limit, thereby obtaining a high-strength and high-toughness bio-based hydrophilic polyamide polymer material. Furthermore, this pressure can suppress the volatilization of monomer II, maintain the molar ratio of monomer I to monomer II, and ensure the stable progress of the amidation reaction.

[0045] In some embodiments, the amidation reaction is carried out at a temperature of 180°C-220°C.

[0046] In this embodiment, the amidation reaction temperature is set within the range of 180℃-220℃, which allows the molecules to gain energy, accelerates the reaction rate, and reaches the molecular weight within the specified time. At this specified temperature, the entire amidation reaction system is in a molten state, and the molecular chains can diffuse freely. To generate more amide bonds, the amidation byproducts need to be removed, thereby promoting the reaction to proceed to the right. At this temperature, the byproducts can be removed in a short time, thus breaking the reaction equilibrium and driving the amidation reaction continuously to the right.

[0047] In some embodiments, the amidation reaction takes 2-5 hours.

[0048] In this embodiment, the amidation reaction time is set to 2h-5h. The amidation reaction can be divided into three stages: in the early stage of the reaction, monomers react rapidly to form oligomers; in the middle stage of the reaction, oligomers react with each other to achieve chain growth; and in the later stage of the reaction, chain growth enters a plateau period, requiring continuous dehydration to continue the reaction. Setting the amidation reaction time to 2h-5h can include these three stages, which is a reasonable window and allows the bio-based hydrophilic polyamide to have sufficient molecular weight.

[0049] In some embodiments, the pressure of the polycondensation reaction is 90 Pa to 110 Pa.

[0050] In this embodiment, the pressure of the polycondensation reaction is set to 90Pa-110Pa. This pressure range is high vacuum, and the pressure inside the system is extremely low. In this system, the boiling point of water will drop to (-40℃)-(-20℃), which allows the byproducts in the polycondensation reaction to be removed quickly, promotes the polycondensation reaction to continue to the right, and enables the bio-based hydrophilic polyamide to reach a sufficient molecular weight.

[0051] In some embodiments, the temperature of the polycondensation reaction is 220°C-260°C.

[0052] In this embodiment, setting the temperature of the polycondensation reaction to 220℃-260℃ can keep the polycondensation reaction system in a molten state, enhance the mobility of molecular chains, increase the frequency of end-group collisions, and continuously increase the molecular weight. In addition, water molecules in the polycondensation reaction system diffuse freely and are more easily removed, thereby promoting the polycondensation reaction to continue to the right and improving production efficiency.

[0053] In some embodiments, the polycondensation reaction takes 1-4 hours.

[0054] In this embodiment, setting the polycondensation reaction time to 1-4 hours effectively reduces molecular chain breakage and maintains molecular weight. Performing polycondensation at high temperatures for too long can cause molecular chain breakage, leading to a decrease in the properties of the bio-based hydrophilic polyamide. Furthermore, within this time range, the color of the bio-based hydrophilic polyamide can be improved. Shorter reaction times reduce oxidation of the bio-based hydrophilic polyamide, but too short a time will result in incomplete polycondensation, low molecular weight, and decreased strength of the bio-based hydrophilic polyamide. Therefore, setting the polycondensation reaction time to 1-4 hours ensures that the bio-based hydrophilic polyamide has a sufficient molecular weight.

[0055] In some embodiments, the protective atmosphere of the oxygen-free environment includes nitrogen.

[0056] In this embodiment, nitrogen is chosen as the protective atmosphere. Nitrogen is an inert gas, and the two nitrogen atoms in a nitrogen molecule are bonded by a triple bond, making it very stable. In the polyamide reaction, nitrogen does not participate in any reaction and can control the oxygen content of the reaction system, limiting the oxidation of the bio-based hydrophilic polyamide and helping to maintain its color. Furthermore, nitrogen can protect the activity of the amine and carboxyl groups, making the reaction more stable and allowing the bio-based hydrophilic polyamide to achieve a high molecular weight.

[0057] Thirdly, this application also provides a bio-based hydrophilic polyamide polymer fiber, comprising: obtained by melt spinning the above-mentioned bio-based hydrophilic polyamide polymer material; or, obtained by melt spinning the bio-based hydrophilic polyamide polymer material prepared by the above-mentioned bio-based hydrophilic polyamide polymer material preparation method.

[0058] It can be explained that melt spinning is a method of making fibers from bio-based hydrophilic polyamide polymer materials. Bio-based hydrophilic polyamide is fed into a metering pump and a screw extruder to melt and obtain a melt at a melting temperature of 240℃-280℃. The melt is spun into filaments by a component, and then subjected to slow cooling, monomer suction, side blowing cooling, bundle oiling, secondary cooling in the tunnel, stretching and shaping, and finally wound to obtain bio-based hydrophilic polyamide fibers.

[0059] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0060] I. Preparation Method Example 1 A precursor solution is provided, comprising (R)-citric acid and ethylenediamine. In monomer I, the mass percentage of (R)-citric acid is 50%, and in monomer II, the mass percentage of ethylenediamine is 50%. The molar ratio of (R)-citric acid to ethylenediamine is 1:1. The precursor solution is subjected to an amidation reaction at 200°C and 1.0 MPa for 4 hours under nitrogen protection, followed by dehydration to obtain a prepolymer. The prepolymer is then subjected to a polycondensation reaction at 240°C and 100 Pa for 2 hours under nitrogen protection to obtain a bio-based hydrophilic polyamide polymer. The bio-based hydrophilic polyamide polymer is then melt-spun to obtain bio-based hydrophilic polyamide fibers.

[0061] Example 2 The difference from Example 1 is that the precursor solution includes (R)-citric acid and propylenediamine. The remaining steps are roughly the same as in Example 1 and will not be repeated here. The bio-based hydrophilic polyamide fiber of Example 2 is obtained.

[0062] Example 3 The difference from Example 1 is that the precursor solution includes (R)-citric acid and butanediamine. The remaining steps are roughly the same as in Example 1 and will not be repeated here. The bio-based hydrophilic polyamide fiber of Example 3 is obtained.

[0063] Example 4 The difference from Example 1 is that the precursor solution includes (R)-citric acid and hexamethylenediamine. The remaining steps are roughly the same as in Example 1 and will not be repeated here. The bio-based hydrophilic polyamide fiber of Example 4 is obtained.

[0064] Example 5 The difference from Example 1 is that the precursor solution includes (R)-citric acid and decanediamine. The remaining steps are roughly the same as in Example 1 and will not be repeated here. The bio-based hydrophilic polyamide fiber of Example 5 is obtained.

[0065] Comparative Example 1 The difference from Example 1 is that the precursor solution includes adipic acid and hexamethylenediamine. The remaining steps are roughly the same as in Example 1 and will not be repeated here. The polyamide fiber of Comparative Example 1 is obtained.

[0066] Comparative Example 2 The difference from Example 1 is that caprolactam is provided for polycondensation reaction. The remaining steps are roughly the same as in Example 1 and will not be repeated here, resulting in polyamide fibers of Comparative Example 2.

[0067] II. Testing Methods Material property testing Intrinsic viscosity test: The sample was tested using a VT2 Ubbelohde viscometer. Phenol / 1,1,2,2-tetrachloroethane (mass ratio 1 / 1) was used as the solvent to prepare a 5 g / L solution. The intrinsic viscosity η of the sample was determined according to the national standard GB / T14190-2017 "Test Method for Fiber Grade Polyester (PET) Chips".

[0068] Moisture regain test: The moisture regain of the fiber was tested based on GB / T6503—2017 "Test Method for Moisture Regain of Chemical Fibers". At a temperature of (20±2)℃ and a relative humidity of (65±5)%, the polyester fiber was weighed and placed in a 105℃ oven to remove moisture until a constant weight was achieved. The percentage obtained by dividing the difference between the wet weight and the dry weight of the fiber by the dry weight represents the moisture regain of the fiber.

[0069] III. Analysis of Test Results for Each Embodiment and Comparative Example Table 1. Performance test results of Examples 1-5 and Comparative Examples 1 and 2 As can be seen from Table 1, introducing hydroxyl groups into the main chain of polyamide molecules can effectively improve the moisture regain of bio-based polyamide fibers by utilizing the intrinsic hydrophilicity of hydroxyl groups.

[0070] By comparing Examples 1-5, as the number of hydrocarbon groups increases, the carbon chain length of bio-based polyamides also increases. The density of rigid amide groups in the molecular chain of bio-based hydrophilic polyamides decreases. The shorter the carbon chain, the higher the density of amide groups per unit length, the denser the strong hydrogen bond network formed, and the stronger the intermolecular forces. Therefore, the more hydrocarbon groups there are, the lower the moisture regain of the bio-based hydrophilic polyamide fiber and the lower its hydrophilicity.

[0071] By comparing Examples 1-4 and Comparative Examples 1 and 2, it was found that when hydroxyl groups were introduced into the main chain of bio-based polyamide, the electronegativity of the oxygen atom (O) in the hydroxyl group was higher than that of the hydrogen atom (H), making the OH bond in the hydroxyl group a highly polar covalent bond. The electron cloud was pulled towards one end of the oxygen atom, resulting in the oxygen atom carrying a partial negative charge (denoted as δ). - Hydrogen atoms carry a partial positive charge (denoted as δ). + Within a single molecule, tiny positive and negative poles are formed. Water molecules (H₂O) are also polar molecules, carrying a partially positive charge of hydrogen and a partially negative charge of oxygen. When a molecule containing a hydroxyl group encounters water, opposite charges attract: the hydroxyl group carries a δ-pole charge... + Hydrogen will be carried by water molecules with δ - The oxygen is strongly attracted; the hydroxyl group carries a δ-type oxygen. - Oxygen will be carried by water molecules with δ +Hydrogen molecules are strongly attracted to water. This electrostatic attraction forms a special hydrogen bond, where a hydroxyl group can act as both a hydrogen bond donor (providing H) and an acceptor (accepting H), dynamically binding with water molecules. A three-dimensional hydrogen bond network is formed between the hydroxyl group and water molecules. This process helps lower the system energy and makes the molecules more soluble. Therefore, introducing hydroxyl groups into the polyamide backbone can improve the moisture regain of bio-based polyamide polymers.

[0072] In summary, introducing hydroxyl groups into the polyamide backbone can effectively improve the moisture regain of polyamide fibers and enhance the hydrophilicity of polyamide.

[0073] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A bio-based hydrophilic polyamide polymer material, characterized in that, The bio-based hydrophilic polyamide polymer material contains the structural unit shown in the following general formula (1): In the formula, m is any integer from 0 to 8, and n is any integer from 150 to 200.

2. The bio-based hydrophilic polyamide polymer material according to claim 1, characterized in that, The intrinsic viscosity of the bio-based hydrophilic polyamide polymer material is 1.8 dL / g-2.8 dL / g.

3. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 1, characterized in that, include: A precursor solution is provided, the precursor solution comprising monomer I and monomer II; wherein monomer I contains the structure shown in general formula (2) below, and monomer II contains the structure shown in general formula (3) below; In the formula, m is any integer from 0 to 8; The precursor solution was subjected to an amidation reaction in an anaerobic environment and then dehydrated to obtain a prepolymer. The prepolymer was subjected to a polycondensation reaction under vacuum conditions to obtain a bio-based hydrophilic polyamide polymer material.

4. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, The preparation of the precursor solution includes: dissolving monomer I in a first solvent to obtain a monomer I solution; The monomer II is dissolved in a second solvent to obtain a monomer II solution; The monomer I solution and the monomer II solution are mixed to obtain the precursor solution.

5. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, In the preparation of the precursor solution, the monomer I solution contains 50%-70% by mass; and the monomer II solution contains 50%-70% by mass.

6. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, In the precursor solution, the molar ratio of monomer I to monomer II is (1-1.2):

1.

7. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, The amidation reaction is performed at a pressure of 0.6 MPa–1.8 MPa; and / or, The amidation reaction is performed at a temperature of 180°C-220°C; and / or, The amidation reaction takes 2-5 hours.

8. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, The pressure of the polycondensation reaction is 90 Pa-110 Pa; and / or, The polycondensation reaction is carried out at a temperature of 220℃-260℃; and / or, The polycondensation reaction takes 1-4 hours.

9. The method for preparing the bio-based hydrophilic polyamide polymer material according to claim 3, characterized in that, The protective atmosphere of the oxygen-free environment includes nitrogen.

10. A bio-based hydrophilic polyamide polymer fiber, characterized in that, Obtained by melt spinning of the bio-based hydrophilic polyamide polymer material as described in claim 1 or 2; or, The bio-based hydrophilic polyamide polymer material is prepared by melt spinning according to the preparation method of any one of claims 3-9.

Images