Pet / pcl composite hollow fiber for small-bore artificial blood vessel skeleton and preparation method thereof

Abstract

This invention belongs to the field of textile fibers and fiber material preparation, specifically relating to PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons and their preparation method. The hollow fibers have a diameter of 3–6 mm and a wall thickness of 0.5–2 mm. The spinning solution is a mixed solution of PET and PCL, exhibiting excellent mechanical properties and certain separation performance. This invention employs a dry-jet wet spinning method based on the principle of non-solvent-induced phase separation. By controlling conditions such as shell liquid composition, coagulation bath, and air gaps, the precise design of fiber morphology and properties is achieved. This invention improves the toughness and functional properties of hollow fibers prepared from PET materials through the introduction of polycaprolactone (PCL), and also achieves gradient control of its pore structure from finger-like pores to sponge-like pores.

Description

Technical Field

[0001] This invention belongs to the field of textile fibers and fiber material preparation, specifically relating to PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons and their preparation method. Background Technology

[0002] Currently, hollow fiber or hollow fiber membranes are mostly used for filtration, purification, or interception. The fabrication methods for artificial blood vessels also focus on electrospinning, weaving, and tissue engineering. Furthermore, the fabrication of small-diameter blood vessels presents corresponding technical challenges. Given the current demand for blood vessels, hollow fiber, as a self-supporting hollow structure and a polymer material with inherent biocompatibility, has a natural advantage in manufacturing artificial blood vessels. Polyethylene terephthalate (PET) is widely used due to its excellent chemical stability, low cost, and wide availability. However, due to the strong rigidity of its molecular chains and the predominantly finger-like pore structure resulting from traditional wet spinning, hollow fibers prepared from PET exhibit defects in mechanical properties such as high brittleness, low strength, and poor tensile properties, limiting their application under dynamic loads and complex environments. Polycaprolactone (PCL), an aliphatic polyester and a semi-crystalline polymer, possesses excellent flexibility, biocompatibility, and controllable degradation. It is often used in composite materials to toughen and modify rigid polymers. However, its inherent degradability presents certain limitations in the field of artificial blood vessels.

[0003] There are two methods for producing hollow fibers: dry spinning and wet spinning. In wet spinning, the instantaneous phase separation in the coagulation bath results in a finger-like pore structure. Although the porosity is relatively high, it is unevenly distributed, and the axial tensile strength is low, making it prone to cracking along the pores under dynamic stress. Hollow fibers prepared by dry spinning have a dense, non-porous structure with very low porosity. Although they have high toughness, their separation performance is poor. As for the blending and modification of PET and PCL, the interfacial compatibility between PET and PCL is poor. At the same time, the low melting point of PCL (60℃) limits the application of composite materials. Traditional PET and PCL blending and spinning conditions are complex, difficult to control, and generally inefficient, and cannot effectively improve or control the performance and structure of composite fibers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a PET / PCL composite hollow fiber for use in small-diameter artificial blood vessel skeletons, which exhibits excellent mechanical properties and certain separation performance.

[0005] The present invention also provides a preparation method, which uses dry-jet wet spinning based on the principle of non-solvent phase separation, and achieves precise design of fiber morphology and properties by adjusting conditions such as shell liquid composition, coagulation bath, and air gap.

[0006] The PET / PCL composite hollow fiber for small-diameter artificial blood vessel skeleton described in this invention has a diameter of 3-6 mm, a wall thickness of 0.5-2 mm, and the spinning solution is a mixed solution of PET and PCL.

[0007] The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to the present invention includes the following steps:

[0008] (1) Dissolve PET and PCL in a solvent to prepare a spinning solution, then prepare a spinning core solution and let it stand to remove bubbles;

[0009] (2) The spinning solution and spinning core solution are placed into the syringe, the coaxial needle is connected in the structural order, and the syringe is placed into the spinning equipment. The coagulation tank is placed directly below the coaxial needle. The coagulation tank is filled with a coagulation bath, and an air gap is set between the end of the needle and the coagulation bath.

[0010] (3) Start the spinning equipment so that the spinning solution and the spinning core solution enter the coagulation bath of the coagulation tank through the air gap, and then the nascent fiber is drawn. After standing in a water bath, the solvent is completely removed. Water is introduced into the cavity through a syringe to remove the core solution, and PET / PCL composite hollow fiber is obtained.

[0011] A schematic diagram of the hollow fiber spinning process in this invention is shown below. Figure 1 As shown in the diagram, the hollow fiber forming principle of this invention is as follows: Figure 2 As shown.

[0012] The molecular weight of PET in step (1) is 30,000 to 40,000, more preferably 35,000 to 40,000, and the molecular weight of PCL is 40,000 to 60,000, more preferably 40,000 to 50,000.

[0013] Step (1) The mass ratio of PET to PCL is (4.05~6.75):(0.45~1.75), more preferably (4.05~5.4):(0.45~1.4). PCL is a key additive for improving the performance and structure of composite hollow fibers. If the amount of PCL added is too low, the viscosity of the spinning solution will be insufficient, the fiber-forming property will be poor, and the structural performance of the composite fiber will change little. If the amount of PCL added is too high, it will reach the upper limit of solubility and affect the stability of the spinning solution. The mass-volume ratio of PET to solvent is (4.05~6.75) g:20 mL.

[0014] The present invention does not have any particular limitation on the type of solvent, as long as it can dissolve PET and PCL powder well at room temperature. According to a preferred embodiment of the present invention, the solvent is preferably hexafluoroisopropanol. Hexafluoroisopropanol is one of the few common solvents that can dissolve PET and PCL at room temperature, with a concentration of ≥99%.

[0015] The specific method for preparing the spinning solution in step (1) is as follows: PET is added to a solvent, stirred and dissolved to obtain a PET solution, and then PCL is added and stirred and dissolved to obtain the spinning solution.

[0016] Furthermore, the solution stirring temperature is 18℃~26℃, more preferably 22℃~26℃, the stirring speed after adding PET is 60~80 rpm, the initial dissolution stirring time is 10~15 min, the stirring speed after adding PCL is 140~180 rpm, and the stirring time is 10~16 h, more preferably 12~16 h.

[0017] The spinning core solution in step (1) is an aqueous solution of sodium alginate. Further, the spinning core solution is prepared by adding sodium alginate to deionized water and stirring. The stirring speed is preferably 180-200 rpm, the stirring temperature is preferably 22-26℃, and the stirring time is preferably 6-10 h.

[0018] The amount of sodium alginate added to the spinning core solution in step (1) is 4~6 g / 100 mL. More preferably, it is 5~5.5 g / 100 mL. Sodium alginate, as a water-soluble material with good fluidity and support, and whose viscosity can be adjusted according to the amount added, can play a good supporting role for the outer fiber and the viscosity matching effect between the core solution and the layer solution when used as the core layer solution.

[0019] The preferred temperature for degassing in step (1) is 20~26℃, the preferred time for degassing is 10~16h, and more preferably 12~16h. The syringe is 20mL.

[0020] The bottom of the coagulation tank is first laid with 20-40 mL of sodium alginate solution in an "S" shape as a fiber coagulation and stretching buffer layer. After standing, the bottom buffer layer is allowed to spread completely before the coagulation bath is added.

[0021] The coagulation bath is a mixture of water and ethanol, with the ethanol / water volume ratio preferably being 50-80%, more preferably 60-80%, and even more preferably 65-75%. The ethanol is preferably one or more types of ethanol with different concentrations, such as 95% ethanol or anhydrous ethanol.

[0022] The diameter of the coaxial needle core hole in step (2) is preferably 3~6mm, more preferably 4~6mm, and the interlayer spacing is 0.5~2mm. More preferably 1~1.5mm. The core hole diameter determines the size of the hollow fiber diameter, and the interlayer spacing affects the appropriate propulsion speed of the spinning solution, as well as the thickness and coating uniformity of the hollow fiber.

[0023] The air gap in step (2) is 0.5~1.5cm. More preferably, it is 0.5~1cm.

[0024] The flow rate ratio of the spinning solution to the spinning core solution in step (3) is 4~5.5 mL / min: 4~5 mL / min.

[0025] The width of the coagulation bath in step (3) is preferably 3-5cm, the depth is preferably 3-7cm, more preferably 4-7cm, the length is preferably 60-100cm, more preferably 80-100cm, the water bath settling time is preferably 4-8h, more preferably 6-8h, and the number of times water is introduced through the syringe is preferably 3-8 times, more preferably 5-8 times.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The present invention improves the toughness and functional properties of hollow fibers prepared from PET material by introducing polycaprolactone (PCL), and modulates its pore structure from finger pores to sponge pores.

[0028] (2) This invention uses dry-jet wet spinning technology to prepare PET / PCL composite hollow fibers with different PCL contents based on the principle of non-solvent phase separation. This preparation method can physically dissolve PET and PCL at room temperature by selecting a suitable solvent, combining the advantages of dry spinning and wet spinning. The fiber is formed quickly, and the forming speed and structural gradient are controllable. At the same time, the pore size and wall thickness of the hollow fiber can be well controlled by setting the ratio of coaxial needle and coagulation bath. Through the synergy of solvent evaporation in the air gap section and phase separation in the coagulation bath, gradient delayed phase separation is achieved. The PCL material is uniformly phased in the PET matrix. The special pore network structure and the "bridging" effect of PCL can significantly improve the fiber toughness.

[0029] (3) This invention systematically explored the effect of PCL addition on the fiber structure-performance relationship. At the same time, since PET and PCL are both materials with good biocompatibility, coupled with excellent mechanical and flux properties and uniform and unique sponge pore structure, they have high application value and application potential in the textile and medical fields such as artificial blood vessel skeleton construction. Attached Figure Description

[0030] The accompanying drawings, which are provided to further illustrate the invention and form part of the invention, are included here. In the drawings:

[0031] Figure 1 This is a schematic diagram of the hollow fiber spinning process in this invention;

[0032] Figure 2 This is a schematic diagram illustrating the hollow fiber forming principle of the present invention.

[0033] Figure 3These are scanning electron microscope images of samples M0, M1, M2, and M3 of this invention;

[0034] Among them: (a) electron microscope images of sample M0 at 500x, 1000x, and 3000x magnification; (b) electron microscope images of sample M1 at 500x, 1000x, and 3000x magnification; (c) electron microscope images of sample M2 at 500x, 1000x, and 3000x magnification; (d) electron microscope images of sample M3 at 500x, 1000x, and 3000x magnification.

[0035] Figure 4 The TGA and DTA images are of samples M0 and M3 of this invention;

[0036] Among them: (a) TGA and DTA plots of M0; (b) TGA and DTA plots of M3;

[0037] Figure 5 The figure shows the tensile property test results of samples M0, M1, M2, and M3 of this invention;

[0038] Figure 6 This is an error analysis diagram of the tensile properties of samples M0, M1, M2, and M3 of this invention;

[0039] Among them: (A) is the stress error analysis diagram of hollow fiber in samples M0, M1, M2, and M3; (B) is the strain error analysis diagram of tensile elongation at break of hollow fiber in samples M0, M1, M2, and M3; (C) is the elastic modulus E error analysis diagram of hollow fiber in samples M0, M1, M2, and M3. The bars marked abcd indicate the order of values ​​from largest to smallest.

[0040] Figure 7 The diagram shows the bursting strength test results of samples M0, M1, M2, and M3 of this invention.

[0041] Figure 8 The graph shows the error analysis results of porosity and water flux for samples M0, M1, M2, and M3 in this invention.

[0042] Figure 9 The image shows the fluorescence test results of cell activity in samples M0, M1, M2, and M3 of this invention.

[0043] Among them: (a) fluorescence image of M0 cell activity; (b) fluorescence image of M1 cell activity; (c) fluorescence image of M2 cell activity; (d) fluorescence image of M3 cell activity.

[0044] Figure 10 The graph shows the average cell viability test results for samples M0, M1, M2, and M3 of this invention.

[0045] Figure 11 This is a super depth-of-field photograph of M1 hollow fiber. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments.

[0047] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0048] PET powder, particle size 300 mesh, molecular weight 40000;

[0049] PCL, powder, medical grade, particle size 150 mesh, molecular weight 50,000.

[0050] Example 1

[0051] The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons includes the following steps:

[0052] (1) Preparation of spinning solution:

[0053] Weigh 5.4 g of PET and add it to 20 mL of hexafluoroisopropanol. Stir with a magnetic stirrer at 22 °C and 80 rpm for 15 min to initially dissolve the PET, obtaining a PET solution. Add 0.6 g of PCL to the prepared initially dissolved PET solution, and then stir at 160 rpm for 16 h to obtain a PET / PCL spinning solution.

[0054] Preparation of spinning core solution: Chemically pure sodium alginate was added to deionized water and stirred at 180 rpm and 22℃ for 10 h to obtain a sodium alginate aqueous solution of 5.5 g / 100 mL as the spinning core solution.

[0055] The spinning solution and spinning core solution were allowed to stand at 22°C for 12 hours to degas.

[0056] (2) The spinning solution and spinning core solution are placed into a 20mL syringe, and the coaxial needle is connected in the structural order and placed into the spinning equipment. The diameter of the core hole of the coaxial needle is 6mm and the gap layer spacing is 0.5mm. The coagulation tank is placed directly below the coaxial needle. The bottom of the coagulation tank is first laid with 20mL of sodium alginate solution (concentration 5.5%, w / v) in an "S" shape as a fiber coagulation and stretching buffer layer. Let it stand to allow the bottom buffer layer to spread completely, and then add the coagulation bath. A 1cm air gap is set between the end of the needle and the coagulation bath. The width of the coagulation tank is 5cm and the depth is 5cm. The coagulation bath is a mixture of ethanol / water with a volume ratio of 70% and an ethanol concentration of 95%.

[0057] (3) Start the spinning equipment, control the spinning solution to enter the coagulation bath of the coagulation tank through the air gap at a speed of 4 mL / min and the spinning core solution to 4.5 mL / min, and then draw to obtain the nascent fiber. After standing in a water bath for 8 hours, the solvent is completely removed. Then, clean water is injected into the cavity 5 times through a syringe to remove the core solution, and PET / PCL composite hollow fiber M1 is obtained.

[0058] Example 2

[0059] Same as Example 1, except that the amount of PCL added is 1.0g, which yields PET / PCL composite hollow fiber M2.

[0060] Example 3

[0061] Same as Example 1, except that the amount of PCL added is 1.4g, which yields PET / PCL composite hollow fiber M3.

[0062] Comparative Example 1

[0063] Same as Example 1, except that the amount of PCL added is 0g, which yields PET hollow fiber M0.

[0064] Scanning electron microscope images of samples M0, M1, M2, and M3 are shown below. Figure 3 As shown, electron micrographs at different magnifications clearly show the pore structure of samples from M0 without PCL to M3 with 1.4g PCL. With the addition of PCL, PCL molecules interpenetrate between PET coils in the shell liquid, and there are "bridges" of PCL state between the coils. PCL itself has the characteristic of slow solidification speed in the coagulation bath. The PCL molecular chains exist in a more extended state in the solution inside the hollow fiber, which helps to improve its phase structure and transform it from a finger-like pore structure to a sponge-like pore structure.

[0065] TGA and DTA plots of samples M0 and M3 are shown below. Figure 4 As shown in the comparison of thermogravimetric properties with and without PCL, it can be seen that the addition of PCL does not significantly reduce the thermal stability of the composite fiber, and it has good retention.

[0066] Tensile properties were tested on samples M0, M1, M2, and M3 (YY / T 0500-2021), with each sample tested five times. The tensile property test results are shown in the figure below. Figure 5 As shown. Figure 6The following are error analysis diagrams for the tensile properties of samples M0, M1, M2, and M3: (A) is the error analysis diagram for the tensile stress of hollow fibers in samples M0, M1, M2, and M3; (B) is the error analysis diagram for the tensile elongation at break of hollow fibers in samples M0, M1, M2, and M3; and (C) is the error analysis diagram for the elastic modulus E of hollow fibers in samples M0, M1, M2, and M3. The bars marked abcd indicate the order of the values ​​from largest to smallest.

[0067] The experiment showed good reproducibility. The tensile properties of the fiber were mainly reflected in its tensile stress and elongation at break. The tensile properties of hollow fibers from M0 to M3 were greatly improved. The change in the fiber elastic modulus could well reflect that the toughness of the hollow fiber was greatly improved after the addition of PCL.

[0068] The bursting strength test was conducted on samples M0, M1, M2, and M3 (YY / T 0500-2021). The bursting strength test results are shown in the figure below. Figure 7 As shown, the bursting strength of hollow fibers can, to a certain extent, quantify the radial mechanical properties of hollow fibers. Hollow fibers without PCL are relatively brittle, while hollow fibers with 1.4g of PCL show better toughness and better overall bursting performance.

[0069] Error analysis of porosity and water flux for samples M0, M1, M2 and M3. Porosity: HY / T 110-2008, Water flux: HY / T 061-2017.

[0070] Porosity: Three pieces of fixed size (1) were cut from the prepared composite hollow fiber. Samples (1 cm) were vacuum dried for 8 hours; the mass of the composite hollow fiber in each sample was measured as the dry weight W. d After weighing each sample by dry weight, it was immersed in butanediol solution until saturated. After saturation, the wet weight W of the fiber was weighed again. w ; Calculate the porosity ε according to formula (1):

[0071]

[0072] In the formula, ε is the porosity of the hollow fiber, and ρ p The density of hollow fibers (based on the added PCL content, is 1.29-1.33 g / cm³). 3 ), ρ 丁 The density of butanediol is 1.015-1.018 g / cm³. 3 W w W represents the wet weight of the fiber. d This refers to the dry weight of the fiber.

[0073] Water flux: The prepared fibers are cut into 18cm lengths according to different concentrations, and three fibers are grouped together and fixed between two three-way tubes with epoxy resin to form a specific test membrane assembly. Then, the assembly is connected to the flux tester with a tube. Water is used as the flux liquid, and the water flow rate from the hollow fiber is measured at a pressure of 0.1MPa. The water flux data is calculated according to the effective area and time of the hollow fiber in the sample using formula (2) (unit: L·m). - ²·h -1 ·MPa -1 ).

[0074] formula:

[0075] In the formula, L is the hollow fiber water flux, V_water is the water output per unit time, S is the effective fiber area in the membrane module, h is the time, and P is the transmembrane pressure.

[0076] The results of the error analysis of porosity and water flux are as follows: Figure 8 As shown, the porosity of hollow fibers in samples M0, M1, M2, and M3 fluctuates within a certain range, and the water flux also shows changes in the pore structure of hollow fibers, from finger-like pores to sponge-like pores. The total pore volume is not significantly affected, but the pore structure changes. The flux performance also increases to a certain extent due to the different pore structures of hollow fibers, exhibiting good flux performance.

[0077] Cell viability was tested on samples M0, M1, M2, and M3 according to ISO 10993-5 standards. HUVEC human umbilical vein endothelial cells were used for cell growth examination. HUVEC human umbilical vein endothelial cell viability was tested using CCK-8 assay. The absorbance (OD) value at 450 nm was measured using an ELISA reader. The OD value of untreated HUVEC human umbilical vein endothelial cells was used as the control group (100%). Cell viability was calculated according to the following formula (3).

[0078] formula:

[0079]

[0080] In the formula, C v For cell activity, A s The OD value represents the sample, including cells, culture medium, CCK-8, and extracts. A c This is the OD value of the control group, including cells, culture medium, and CCK-8. A b The values ​​represent the OD values ​​for the control group, including those from the culture medium and CCK-8. All cell activity values ​​are the average of three replicates, and the results are as follows: Figure 10As shown. Cells were stained using the DAPI method and observed using an inverted fluorescence microscope at 10x magnification. The observation results are as follows. Figure 9 As shown in the figure: (a) fluorescence image of M0 cell activity; (b) fluorescence image of M1 cell activity; (c) fluorescence image of M2 cell activity; (d) fluorescence image of M3 cell activity.

[0081] Cell compatibility was characterized by cell viability tests of samples M0, M1, M2, and M3. Both PET and PCL materials have good biocompatibility. After the composite fiber is formed, the relevant material properties of the composite hollow fiber are retained. Cell compatibility tests show that the composite hollow fiber has good performance in terms of cell biocompatibility and has high application value potential in biomedical fields such as artificial blood vessel skeletons.

[0082] Example 4

[0083] Same as Example 1, except that sodium alginate solution is not used to lay the bottom of the coagulation tank.

[0084] Example 5

[0085] Same as Example 1, except that the sodium alginate solution at the bottom of the coagulation tank is not evenly distributed.

[0086] If sodium alginate is not laid at the bottom or is laid unevenly, it will cause dragging and pulling, leading to the breakage of the nascent fibers and resulting in defects in fiber formation.

[0087] The super depth-of-field photograph of M1 hollow fiber obtained in Example 1 is shown below. Figure 11 As shown, the fiber wall thickness and surface are relatively uniform, indicating that the technical solution described in this invention has good stability and reproducibility.

[0088] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0089] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A PET / PCL composite hollow fiber for use in small-diameter artificial blood vessel skeletons, characterized in that, The hollow fiber has a diameter of 3~6mm and a wall thickness of 0.5~2mm, and the fiber has a uniform sponge pore structure. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons includes the following steps: (1) Dissolve PET and PCL in a solvent to prepare a spinning solution, then prepare a spinning core solution and let it stand to remove bubbles; (2) The spinning solution and spinning core solution are placed into the syringe, the coaxial needle is connected in the structural order, and the syringe is placed into the spinning equipment. The coagulation tank is placed directly below the coaxial needle. The coagulation tank is filled with a coagulation bath, and an air gap is set between the end of the needle and the coagulation bath. (3) Start the spinning equipment so that the spinning solution and the spinning core solution enter the coagulation bath of the coagulation tank through the air gap, and then the nascent fiber is drawn. After standing in a water bath, the solvent is completely removed. Water is introduced into the cavity through a syringe to remove the spinning core solution, and PET / PCL composite hollow fiber is obtained. Step (1) The mass ratio of PET to PCL is (4.05~6.75):(0.45~1.75); The spinning core solution in step (1) is an aqueous solution of sodium alginate; The coagulation bath in step (2) is a mixture of water and ethanol; The bottom of the coagulation tank is first laid with sodium alginate solution as a fiber coagulation and stretching buffer layer. After standing, the bottom buffer layer is allowed to spread completely before the coagulation bath is added.

2. A method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 1, characterized in that, Includes the following steps: (1) Dissolve PET and PCL in a solvent to prepare a spinning solution, then prepare a spinning core solution and let it stand to remove bubbles; (2) The spinning solution and spinning core solution are placed into the syringe, the coaxial needle is connected in the structural order, and the syringe is placed into the spinning equipment. The coagulation tank is placed directly below the coaxial needle. The coagulation tank is filled with a coagulation bath, and an air gap is set between the end of the needle and the coagulation bath. (3) Start the spinning equipment so that the spinning solution and the spinning core solution enter the coagulation bath of the coagulation tank through the air gap, and then the nascent fiber is drawn. After standing in a water bath, the solvent is completely removed. Water is introduced into the cavity through a syringe to remove the spinning core solution, and PET / PCL composite hollow fiber is obtained. Step (1) The mass ratio of PET to PCL is (4.05~6.75):(0.45~1.75); The spinning core solution in step (1) is an aqueous solution of sodium alginate; The coagulation bath in step (2) is a mixture of water and ethanol; The bottom of the coagulation tank is first laid with sodium alginate solution as a fiber coagulation and stretching buffer layer. After standing, the bottom buffer layer is allowed to spread completely before the coagulation bath is added.

3. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The molecular weight of PET in step (1) is 30,000 to 40,000, and the molecular weight of PCL is 40,000 to 60,000.

4. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The mass-to-volume ratio of PET to solvent is (4.05~6.75) g: 20 mL.

5. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The specific method for preparing the spinning solution in step (1) is as follows: PET is added to a solvent, stirred and dissolved to obtain a PET solution, and then PCL is added and stirred and dissolved to obtain the spinning solution.

6. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The amount of sodium alginate added to the spinning core solution in step (1) is 4~6g / 100mL.

7. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The air gap in step (2) is 0.5~1.5cm.

8. The method for preparing PET / PCL composite hollow fibers for small-diameter artificial blood vessel skeletons according to claim 2, characterized in that, The flow rate ratio of the spinning solution to the spinning core solution in step (3) is 4~5.5 mL / min: 4~5 mL / min.

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