Polyesteramide copolymer as well as preparation method and application thereof

Abstract

The invention relates to a polyesteramide copolymer as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The polyesteramide copolymer is prepared by the following preparation method: heating hydroxy acid, amino acid and caprolactam in the presence of a catalyst, and carrying out ring opening-condensation cascade polymerization to obtain the polyesteramide copolymer. The preparation method disclosed by the invention can be used for synthesizing the polyesteramide copolymer with high molecular weight and high performance in one step, and the polyesteramide copolymer has higher strength, toughness, elongation at break and good biodegradability, and has wide application prospects in the fields of engineering plastics, drug delivery, automobile accessories and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polyesteramide copolymer, its preparation method, and its application. Background Technology

[0002] Polyesteramide copolymers are a class of copolymer materials with polyamide as the hard segment and polyester as the soft segment. They combine the high mechanical properties of polyamide (such as tensile strength and modulus) with the biodegradability of polyester, while also possessing good processing performance. Their properties can be flexibly controlled by adjusting the structure and content of polyester and polyamide. Therefore, these materials have wide applications in automotive parts, sporting goods, machine tools, pipes, toys, medical supplies, and home appliances.

[0003] Currently, the main methods for synthesizing polyesteramides are ring-opening polymerization and condensation polymerization. Industrially, condensation polymerization is the primary method for synthesizing polyesteramides, directly preparing polyesteramide copolymers by directly feeding diacids and their derivatives with diols, diamines / amino alcohols / amino acids, etc., in a one-step process. Due to the significant difference in reactivity between esterification and amidation reactions, stepwise vacuum polymerization is required. First, the polyester segment is synthesized at a low temperature, and then the polyamide segment is synthesized at a higher temperature. This process is time-consuming, and the polyester segment is prone to decomposition under the synthesis conditions of the polyamide segment, leading to numerous side reactions and ultimately resulting in a low molecular weight copolymer (typically only a few thousand). To increase the molecular weight, Bayer's BAK series polyamide copolymers (US005644020A) and Arkema's PEBAX series polyamide copolymers (US4230838) employ the method of adding polyfunctional compounds or chain extenders in the later stages of condensation copolymerization. However, the addition of polyfunctional compounds or chain extenders makes the polymerization process prone to crosslinking or branching, making the final copolymer structure difficult to control and resulting in unstable product performance.

[0004] Ring-opening polymerization can also be used to synthesize polyesteramide copolymers. Komoto et al. used caprolactam and caprolactone for ring-opening copolymerization to prepare polyesteramide copolymers. However, due to the exchange of carboxyl anions with lactam anions in the system, a large amount of anionic initiator is required to accelerate the reaction rate, and the monomer conversion rate is low. The resulting polyesteramide copolymers have low molecular weights, generally only a few thousand, and poor performance [H. Komoto. Macromol. Chem. 1968, 115, 33-42]. Polyesteramides can also be prepared by direct ring-opening polymerization of morpholine-2,5-dione containing ester and amide bonds in the cyclic structure. However, the monomer synthesis required for this type of reaction is relatively complex, which limits its application in the synthesis of polyesteramide copolymers [Helder. J. Macromol. Rapid Commun. 1986, 7(4), 193-198]. Therefore, current polyesteramide synthesis technology has the problem of difficulty in rapidly and efficiently synthesizing high-performance polyesteramide copolymers.

[0005] Patent CN 201911244454.2 discloses a polyesteramide and its preparation method. The method uses a macrolide-based diacid glycol ester as a monomer and a diamine or amino alcohol as an initiator to perform a ring-opening-condensation cascade polymerization to synthesize the polyesteramide. The obtained polyesteramide exhibits excellent mechanical properties as well as good biodegradability and biocompatibility. However, this method requires the use of cyclic diacid glycol esters as monomers, and currently, there are few commercially available diacid glycol ester monomers, which are relatively expensive.

[0006] Patent CN202310209914.8 discloses a polyamide copolymer and its preparation method and application, using amino acids or amino acid esters and cyclic esters as monomers to prepare polyesteramide through ring-opening-condensation cascade polymerization. This method can synthesize high molecular weight and high-performance polyesteramide copolymers in one step. However, the introduction of the polyamide segment mainly uses linear amino acids or amino acid esters as monomers, which are relatively expensive, and does not involve relatively inexpensive cyclic monomers such as caprolactam, thus limiting the use of raw materials. This is because the synthesis of nylon 6 from caprolactam usually requires ring-opening polymerization under high temperature and pressure, followed by slow pressure release to shift the polymerization equilibrium towards higher molecular weight.

[0007] In order to meet the needs of social development, there is an urgent need to develop a low-cost, high-performance, and simple-to-prepare polyesteramide copolymer to meet the growing market demand. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a polyesteramide copolymer, its preparation method, and its applications. This invention uses hydroxy acids, amino acids, and caprolactam as monomers to prepare polyesteramide copolymers via ring-opening-condensation cascade polymerization (PROP). Specifically, by ring-opening caprolactam with amino acids, α-amino-ω-carboxyl polyamide or copolyamide intermediates are obtained. Hydroxy acids can also self-polymerize to form α-hydroxy-ω-carboxyl oligomers. The polyamide / copolyamide intermediates then undergo condensation polymerization with the hydroxy acids or their oligomers to obtain the corresponding polyesteramide copolymer. During the polymerization reaction, monomers can be fed in one step, and ring-opening polymerization and condensation polymerization can proceed in the same system in a cascade manner, resulting in the efficient synthesis of polyesteramide copolymers. This invention solves the problem that the preparation of polyamides from lactams usually requires high temperature and high pressure through the ring-opening polymerization of lactams with amino acids under normal pressure, thus enabling the preparation of polyesteramide copolymers from inexpensive lactams such as caprolactam.

[0009] The polyesteramide copolymers synthesized in this invention all have high molecular weights, with intrinsic viscosity [η] reaching over 1.00 dL / g, and exhibit excellent mechanical properties. The composition and properties of the polyesteramide materials can be flexibly controlled by adjusting factors such as the monomer feed ratio, polymerization time, polymerization temperature, and the types of amino acids and hydroxy acids.

[0010] This invention is achieved through the following technical solution:

[0011] The first objective of this invention is a polyesteramide copolymer, characterized in that the polyesteramide copolymer comprises two block components: polyester and polyamide; the structural formula of the polyesteramide is as follows:

[0012] ,

[0013] In this context, R1 comes from amino acids, R2 comes from hydroxy acids, and a, b, and c are determined by the molar ratio of the reactants caprolactam, amino acids, and hydroxy acids, respectively. a is any integer from 1 to 40, b is any integer from 1 to 10, c is any integer from 1 to 40, and m is any integer from 10 to 200.

[0014] In one embodiment of the present invention, the polyesteramide copolymer has a high molecular weight and its intrinsic viscosity [η] can reach above 1.00 dL / g.

[0015] A second objective of this invention is to provide a method for preparing the aforementioned polyesteramide copolymer, comprising the following steps: using caprolactam, amino acids, and hydroxy acids as monomers, and in the presence of a catalyst, preparing the polyesteramide copolymer through a ring-opening-condensation cascade polymerization reaction. The polyesteramide copolymer is formed by the random copolymerization of caprolactam, hydroxy acids, and amino acid monomers, and contains alternating ester and amide bond structural units.

[0016] By ring-opening caprolactam with amino acids, α-amino-ω-carboxyl polyamide or copolyamide intermediates are obtained. Hydroxy acids can also self-polymerize to form α-hydroxy-ω-carboxyl oligomers. The polyamide / copolyamide intermediates undergo condensation polymerization with the hydroxy acids or their oligomers to obtain the corresponding polyesteramide copolymers. The reaction products do not require separation and purification. This invention allows for the control of the amide bond content in the resulting polyesteramide copolymer by adjusting the ratio of amino acids, caprolactam, and hydroxy acids, thereby enabling the adjustment of the properties of the resulting polyesteramide copolymers over a wide range. The ring-opening polymerization of caprolactam with amino acids under normal pressure solves the problem that the preparation of polyamides from caprolactams usually requires high temperature and high pressure, thus allowing the preparation of polyesteramide copolymers from inexpensive caprolactams such as caprolactam. The polyesteramide copolymers of this invention exhibit good thermal stability and excellent mechanical properties. Polyesteramide copolymers containing aliphatic polyester segments also possess good biocompatibility and biodegradability.

[0017] In one embodiment of the present invention, the general chemical formula of the amino acid is:

[0018] ,

[0019] Where R1 is (CH2) n When n is an ω-amino acid, the amino acid is an ω-amino acid and n is any integer from 1 to 15.

[0020] When R1 is [(CH2)R3], the amino acid is an α-amino acid.

[0021] In one embodiment of the present invention, the amino acids used are one or more compounds containing both amino and carboxyl groups, such as glycine, aminocaproic acid, aminobutyric acid, aminoheptanoic acid, aminodecanoic acid, aminoundecanoic acid, tranexamic acid, histidine, L-valine, L-alanine, L-leucine, L-methionine, L-cysteine, L-tert-leucine, and L-glutamic acid.

[0022] In one embodiment of the present invention, the general chemical formula of the hydroxy acid is:

[0023] ,

[0024] Where R2 is (CH2). n When n is an ω-hydroxy acid, the hydroxy acid is an ω-hydroxy acid and n is any integer from 1 to 15;

[0025] When R2 is (CH2)(CH3)2, the hydroxy acid is a β-hydroxy acid.

[0026] In one embodiment of the present invention, the hydroxy acid is one or more of the following compounds containing both hydroxy and carboxyl groups: 2,2-dimethyl-3-hydroxypropionic acid, 2-hydroxyacetic acid, 6-hydroxyhexanoic acid, 7-hydroxyheptanoic acid, 8-hydroxyoctanoic acid, 9-hydroxynonanoic acid, 10-hydroxydecanoic acid, 12-hydroxylauric acid, 15-hydroxypentadecanoic acid, and 16-hydroxyhexadecanoic acid.

[0027] In one embodiment of the present invention, the catalyst is a titanate compound; the titanate compound is n-butyl titanate and / or isopropyl titanate;

[0028] And / or, the amount of the catalyst used is 0.01% to 1% of the total feed mass.

[0029] In one embodiment of the present invention, the molar ratio of caprolactam to hydroxy acid is 0.3:1 to 4:1.

[0030] In one embodiment of the present invention, the molar ratio of caprolactam to amino acid is 0.5:1 to 20:1.

[0031] In one embodiment of the present invention, the ring-opening-condensation cascade polymerization reaction is carried out under normal pressure protective gas or vacuum conditions; after the reaction, the polymer is obtained directly without any further processing.

[0032] In one embodiment of the present invention, the protective gas is nitrogen and / or argon.

[0033] In one embodiment of the present invention, the temperature of the ring-opening-condensation cascade polymerization reaction is 190 ℃ to 260 ℃, and the reaction time is 120 minutes to 600 minutes.

[0034] In one embodiment of the present invention, the polyamide (caprolactam and amino acid) and polyester (hydroxy acid) exhibit elastomer properties when the molar ratio is 1:1 to 4:1.

[0035] A third object of the present invention is to provide the application of the aforementioned polyesteramide copolymer in biodegradable polyesteramide copolymers.

[0036] The polyesteramide copolymer prepared by this invention has good biodegradability and excellent mechanical properties. By controlling the ratio of ester bonds to amide bonds, the polymer molecular weight, and the molecular weight distribution, it has broad potential value in daily life, such as high-end shoe materials, medical devices, and automotive parts.

[0037] The technical solution of the present invention has the following advantages compared with the prior art:

[0038] This invention provides a polyesteramide copolymer and its preparation method. The main monomer used, caprolactam, is relatively inexpensive, significantly reducing the production cost of the polyesteramide copolymer and solving the problem of existing technologies' difficulty in rapidly and efficiently producing low-cost, high-performance polyesteramide copolymer materials.

[0039] The polyesteramide copolymer synthesized in this invention has a high molecular weight, which can be controlled by adjusting the reaction time. The content of polyamide and polyester segments in the copolymer can be flexibly adjusted by changing the monomer feed ratio, thereby controlling its mechanical properties and biodegradability. When the polyamide to polyester ratio is 1:1 to 4:1, it exhibits elastomer properties. The polyesteramide copolymer of this invention has excellent mechanical properties, with an elongation at break of 1000% to 3000% and a tensile strength of 20 MPa to 60 MPa. Compared with commercially available polyamide copolymers such as the PEBAX series (tensile strength 30 MPa to 60 MPa; elongation at break 300% to 700%), it has comparable mechanical properties and a superior elongation at break, but at a significantly lower cost.

[0040] The polyesteramide copolymer of this invention exhibits excellent biodegradability, and the degradation rate is controlled by conditions such as temperature and enzymes. In a phosphate buffer solution at 37°C (pH 7.2-7.4), its mass and molecular weight remain essentially unchanged. However, in a phosphate buffer solution containing lipase at 37°C (pH 7.2-7.4), its mass and molecular weight decrease significantly, while under refrigeration conditions at 4°C, its mass and molecular weight remain essentially unchanged.

[0041] The ring-opening-condensation cascade polymerization method of this invention aims to cascade ring-opening polymerization and condensation polymerization reactions in the same system to prepare high molecular weight polyesteramide copolymers. This method has advantages such as simple steps, controllable molecular weight, no need for post-processing, and the ability to synthesize in large quantities. Furthermore, the synthesized polyesteramide copolymers exhibit excellent biodegradability, and the degradation rate can be adjusted by temperature, enzyme content, etc.

[0042] This invention synthesizes polyesteramide copolymers by a ring-opening-condensation cascade polymerization method involving hydroxy acids, amino acids, and caprolactam, thus solving the problem of developing low-cost, high-molecular-weight polyesteramide copolymers. The polyesteramide copolymers synthesized using this method possess both excellent mechanical properties and biodegradability, making them an environmentally friendly material with significant application value. Attached Figure Description

[0043] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0044] Figure 1This is a synthetic route diagram of the polyesteramide of the present invention; wherein, R1 is derived from an amino acid, R2 is derived from a hydroxy acid, a is any integer from 1 to 40, b is any integer from 1 to 10, c is any integer from 1 to 40, m is any integer from 10 to 200; p is the number of repeating units of aminocaproic acid in the reaction intermediate structure, which is any integer from 1 to 40; u is the number of repeating units of amino acid in the reaction intermediate structure, which is any integer from 1 to 10; r is the number of repeating units of hydroxy acid in the reaction intermediate structure, which is any integer from 1 to 40.

[0045] Figure 2 The 1H NMR spectrum of the polyesteramide copolymer PEA-1 obtained in Example 1 by ring-opening-condensation cascade polymerization of 10-hydroxydecanoic acid, caprolactam and aminocaproic acid under nitrogen at 190 °C and vacuum at 240 °C.

[0046] Figure 3 The intrinsic viscosity of the polyesteramide copolymer (PEA-2) in Example 2 is shown in the graph obtained by sampling at different times during the vacuum polycondensation stage.

[0047] Figure 4 Thermogravimetric curve of polyesteramide copolymer (PEA-1) in Test Example 1 (heating rate: 10 °C per minute, atmosphere: nitrogen);

[0048] Figure 5 Stress-strain curve of polyesteramide copolymer (PEA-4) in test example 2 (tensile rate: 40 mm / min, temperature: 26 °C);

[0049] Figure 6 Stress-strain curve of polyesteramide copolymer (PEA-8) in test example 3 (tensile rate: 40 mm / min, temperature: 26 °C);

[0050] Figure 7 The graph shows the degradation curves of the polyesteramide copolymer (PEA-1) in Test Example 4 in a phosphate buffer solution at 37 °C, under conditions without lipase and with lipase, as a function of time. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0052] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0053] The CAS numbers of the organic reagents used in this invention are listed below:

[0054] Table 1

[0055]

[0056] The preparation method of the polyesteramide copolymer of the present invention is as follows: Figure 1 As shown, polyesteramide copolymers are prepared by ring-opening-condensation cascade polymerization, resulting in a series of high molecular weight polyesteramide copolymers.

[0057] Example 1

[0058] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0059] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 10-hydroxydecanoic acid (33.84 g) were added to a reaction flask, nitrogen gas was introduced, and tetrabutyl titanate (48 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-1.

[0060] Viscosity tests on PEA-1 showed an intrinsic viscosity [η] of 1.35 dL / g, demonstrating that the synthesized polyesteramide copolymer has a high molecular weight.

[0061] The 1H NMR spectrum of PEA-1 is as follows: Figure 2 As shown in the figure, the monomer peaks disappeared, and the integrated intensities of the methylene proton peaks attached to the ester carbonyl group and the methylene proton peaks attached to the amide carbonyl group in the polymer were basically consistent with the feed ratio, proving the successful synthesis of the target product.

[0062] Example 2

[0063] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0064] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 10-hydroxydecanoic acid (22.56 g) were added to a reaction flask, nitrogen gas was introduced, and tetrabutyl titanate (37 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 60 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-2.

[0065] Viscosity testing of PEA-2 revealed an intrinsic viscosity [η] of 1.38 dL / g, confirming the successful synthesis of the target product.

[0066] Viscosity tests were conducted on samples taken at different time points during the PEA-2 polymerization process. The viscosity changes of PEA-2 during the vacuum polycondensation stage are shown below. Figure 3As shown, the polymer viscosity gradually increases over time.

[0067] Example 3

[0068] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0069] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 10-hydroxydecanoic acid (22.56 g) were added to a reaction flask, nitrogen gas was introduced, and tetrabutyl titanate (37 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 260 °C, and the mixture was vacuum polymerized for 60 minutes to obtain the polyesteramide copolymer PEA-3.

[0070] Viscosity testing of PEA-3 revealed an intrinsic viscosity [η] of 1.68 dL / g, confirming the successful synthesis of the target product.

[0071] Example 4

[0072] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0073] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 10-hydroxydecanoic acid (5.64 g) were added to a reaction flask, nitrogen gas was introduced, and 20 μL of tetrabutyl titanate was added. The mixture was mechanically stirred and heated to 180 °C. After reacting for 90 minutes, the temperature was raised to 240 °C, and the mixture was vacuum polymerized for 180 minutes to obtain the polyesteramide copolymer PEA-4.

[0074] Viscosity testing of PEA-4 revealed an intrinsic viscosity [η] of 1.54 dL / g, confirming the successful synthesis of the target product.

[0075] Example 5

[0076] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0077] Caprolactam (11.32 g), aminocaproic acid (1.32 g), and 10-hydroxydecanoic acid (5.64 g) were added to a reaction flask, nitrogen gas was introduced, and tetrabutyl titanate (19 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-5.

[0078] Viscosity testing of PEA-5 revealed an intrinsic viscosity [η] of 1.45 dL / g, confirming the successful synthesis of the target product.

[0079] Example 6

[0080] This embodiment provides a method for synthesizing a polyesteramide copolymer, as follows: caprolactam (5.28 g), aminocaproic acid (10.56 g), and 10-hydroxydecanoic acid (22.56 g) are added to a reaction flask, nitrogen gas is introduced, and tetrabutyl titanate (19 μL) is added. The mixture is mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature is raised to 240 °C, and the mixture is subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-6.

[0081] Viscosity testing of PEA-6 revealed an intrinsic viscosity [η] of 1.25 dL / g, confirming the successful synthesis of the target product.

[0082] Example 7

[0083] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0084] Caprolactam (11.32 g), aminoundecanoic acid (4.02 g), and 10-hydroxydecanoic acid (5.64 g) were added to a reaction flask, nitrogen gas was introduced, and 21 μL of tetrabutyl titanate was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-7.

[0085] Viscosity testing of PEA-7 revealed an intrinsic viscosity [η] of 1.67 dL / g, confirming the successful synthesis of the target product.

[0086] Example 8

[0087] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0088] Caprolactam (11.32 g), L-valine (2.34 g), and 10-hydroxydecanoic acid (5.64 g) were added to a reaction flask, nitrogen gas was introduced, and isopropyl titanate (19 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 250 °C, and the mixture was subjected to vacuum polymerization for 90 minutes to obtain the polyesteramide copolymer PEA-8.

[0089] Viscosity testing of PEA-8 revealed an intrinsic viscosity [η] of 1.35 dL / g, confirming the successful synthesis of the target product.

[0090] Example 9

[0091] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0092] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 8-hydroxyoctanoic acid (6.41 g) were added to a reaction flask, nitrogen gas was introduced, and 20 μL of tetrabutyl titanate was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 120 minutes, the temperature was raised to 240 °C, and then vacuum polymerization was carried out for 180 minutes to obtain the polyesteramide copolymer PEA-9.

[0093] Viscosity testing of PEA-9 revealed an intrinsic viscosity [η] of 1.65 dL / g, confirming the successful synthesis of the target product.

[0094] Example 10

[0095] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0096] Caprolactam (11.32 g), aminododecanic acid (2.72 g), and 16-hydroxyhexadecanoic acid (10.88 g) were added to a reaction flask, nitrogen gas was introduced, and isopropyl titanate (25 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 60 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 180 minutes to obtain the polyesteramide copolymer PEA-10.

[0097] Viscosity testing of PEA-10 revealed an intrinsic viscosity [η] of 1.44 dL / g, confirming the successful synthesis of the target product.

[0098] Example 11

[0099] This embodiment provides a method for synthesizing a polyesteramide copolymer, as detailed below:

[0100] Caprolactam (11.32 g), aminocaproic acid (2.62 g), and 2,2-dimethyl-3-hydroxypropionic acid (4.72 g) were added to a reaction flask. Nitrogen gas was introduced, and tetrabutyl titanate (19 μL) was added. The mixture was mechanically stirred and heated to 190 °C. After reacting for 150 minutes, the temperature was raised to 240 °C, and the mixture was subjected to vacuum polymerization for 60 minutes to obtain the polyesteramide copolymer PEA-11.

[0101] Viscosity testing of PEA-11 showed an intrinsic viscosity [η] of 1.14 dL / g, confirming the successful synthesis of the target product.

[0102] Comparative Example 1

[0103] This comparative example provides a method for synthesizing a polyesteramide copolymer, which is similar to Example 4, except that the amino acid component is not introduced, while the other steps are the same as in Example 4.

[0104] Due to the lack of amino acid components, the ring-opening polymerization of caprolactam is very slow in this process, the monomer conversion rate is low, and the monomer is easily carried out by nitrogen gas or evaporated under vacuum when heated, clogging the device and making it difficult for the reaction to continue.

[0105] Comparative Example 2

[0106] This comparative example provides a method for synthesizing a polyesteramide copolymer, similar to Example 4, except that caprolactam is missing, while the other steps are consistent with Example 4, to obtain the polyesteramide copolymer PEA-12.

[0107] Due to the lack of a ring-opening reaction, the entire reaction proceeds relatively slowly. Viscosity testing of PEA-12 revealed an intrinsic viscosity [η] of 0.58 dL / g, lower than that of copolymers containing caprolactam monomers.

[0108] Test Example 1: Thermal stability test of polyamide copolymer PEA-1.

[0109] Approximately 5 mg of the PEA-1 polyamide copolymer sample prepared in Example 1 was weighed and subjected to thermogravimetric analysis (TGA) at a temperature increased to 700 °C per minute under a nitrogen atmosphere. The thermogravimetric curve of PEA-1 is shown below. Figure 4 The initial (5%) thermal decomposition temperature of the polymer was 329 °C, indicating that the synthesized polyamide copolymer has good thermal stability.

[0110] Test Example 2: Tensile test of polyamide copolymer PEA-4.

[0111] The PEA-4 polyamide copolymer sample prepared in Example 4 was pressed into a 0.2 mm thick sheet, cut into dumbbell-shaped strips, and subjected to tensile testing at a tensile rate of 40 mm / min. The stress-strain curve of PEA-4 is shown in [Figure number missing]. Figure 5 The polymer has a Young's modulus of 180 MPa, a tensile strength of about 60 MPa, and an elongation at break of more than 1000%, indicating that the polymer has excellent mechanical properties and that the copolymer under these conditions exhibits the properties of an elastomer.

[0112] Test Example 3: Tensile test of polyamide copolymer PEA-8.

[0113] The PEA-8 polyamide copolymer sample prepared in Example 8 was pressed into a 0.2 mm thick sheet, cut into dumbbell-shaped strips, and subjected to tensile testing at a tensile rate of 40 mm / min. The stress-strain curve of PEA-8 is shown in [Figure number missing]. Figure 6 The polymer has a Young's modulus of 160 MPa, a tensile strength of about 50 MPa, and an elongation at break of more than 1100%, indicating that the polymer has excellent mechanical properties and that the copolymer under these conditions exhibits the properties of an elastomer.

[0114] Test Example 4

[0115] Degradation test of polyesteramide copolymer PEA-1 in 37 °C phosphate buffer solution under lipase-free and lipase-containing conditions.

[0116] The phosphate buffer solution has a pH of 7.2–7.4 and contains sodium chloride at a concentration of 80.0 g / L, potassium chloride at 2.00 g / L, disodium hydrogen phosphate dodecahydrate at 36.3 g / L, and potassium dihydrogen phosphate at 2.40 g / L. The phosphate buffer solution is divided into a lipase-free group and a lipase-containing group (lipase name: *Pseudomonas cepacia* lipase, enzyme activity: 30.0 × 10⁻⁶). 3 Unit: per gram; Manufacturer: Sigma-Aldrich; Product No.: 534641-10G.

[0117] The PEA-1 polyamide copolymer prepared in Example 1 was pressed into a 0.2 mm film and cut into small circular pieces of approximately 5.0 mg each. These pieces were then immersed in approximately 1.00 mL of a phosphate buffer solution containing lipase (concentration: 1.00 mg / mL). The samples were placed at 37°C for degradation experiments. A control experiment was also conducted in a phosphate buffer solution without lipase, with all other conditions unchanged. After the predetermined number of days had elapsed, the samples were removed, rinsed with distilled water, filtered, and dried. The mass change was then measured using an electronic balance.

[0118] The degradation curve of polyamide copolymer PEA-1 as a function of time is shown in the figure. Figure 7 As shown in the figure, the polyamide copolymer PEA-1 showed little change in mass in a phosphate buffer solution at 37 °C without lipase; however, its mass decreased rapidly under the action of lipase, and it degraded by 56% after 30 days, indicating that the polyamide copolymer PEA-1 has good degradability.

[0119] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polyesteramide copolymer, characterized in that, The polyesteramide copolymer comprises two block components: polyester and polyamide; the structural formula of the polyesteramide is as follows: ， In this context, R1 comes from amino acids, R2 comes from hydroxy acids, and a, b, and c are determined by the molar ratio of the reactants caprolactam, amino acids, and hydroxy acids, respectively. a is any integer from 1 to 40, b is any integer from 1 to 10, c is any integer from 1 to 40, and m is any integer from 10 to 200.

2. The polyesteramide copolymer according to claim 1, characterized in that, The intrinsic viscosity of the polyesteramide copolymer is greater than or equal to 1.00 dL / g.

3. The method for preparing the polyesteramide copolymer according to claim 1 or 2, characterized in that, Includes the following steps: Polyesteramide copolymers were prepared by ring-opening-condensation cascade polymerization using caprolactam, amino acids and hydroxy acids as monomers under the action of a catalyst.

4. The preparation method according to claim 3, characterized in that, The general chemical formula of the amino acid is: ， Where R1 is (CH2) n When n is an ω-amino acid, the amino acid is an ω-amino acid and n is any integer from 1 to 15. When R1 is [(CH2)R3], the amino acid is an α-amino acid.

5. The preparation method according to claim 3, characterized in that, The general chemical formula of the hydroxy acid is: ， Where R2 is (CH2) n When n is an ω-hydroxy acid, the hydroxy acid is an ω-hydroxy acid and n is any integer from 1 to 15; When R2 is (CH2)(CH3)2, the hydroxy acid is a β-hydroxy acid.

6. The preparation method according to claim 3, characterized in that, The catalyst is a titanate compound; And / or, the amount of the catalyst used is 0.01% to 1% of the total feed mass.

7. The preparation method according to claim 3, characterized in that, The molar ratio of caprolactam to amino acids is 0.5:1 to 20:

1. And / or, the molar ratio of caprolactam to hydroxy acid is 0.3:1 to 4:

1.

8. The preparation method according to claim 3, characterized in that, The ring-opening-condensation cascade polymerization reaction is carried out under normal pressure protective gas or vacuum conditions; after the reaction, the polymer is obtained directly without any further processing.

9. The preparation method according to claim 3, characterized in that, The ring-opening-condensation cascade polymerization reaction is carried out at a temperature of 190 ℃ to 260 ℃ for a time of 120 minutes to 600 minutes.

10. The use of the polyesteramide copolymer according to claim 1 or 2 in biodegradable polyesteramide copolymers.

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