Photochromic polyhydroxyalkanoate / polylactic acid fiber and preparation method and application thereof

Abstract

The application discloses a photochromic polyhydroxyaliphatic ester / polylactic acid fiber and a preparation method and application thereof. The photochromic polyhydroxyaliphatic ester / polylactic acid fiber has a skin-core structure, the core layer material comprises a high molecular polymer, a dye and SnO 2‑x wherein 0

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyhydroxyalkanoate fibers, in particular to a photochromic polyhydroxyalkanoate / polylactic acid fiber and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of society and technology, intelligent photochromic (PC) fabrics, as a kind of intelligent product with high added value, have broad application prospects in the fields of textiles, military equipment, anti-counterfeiting, etc. As a representative of the new generation of PC materials, inorganic-organic PC materials achieve the dual goals of fast color switching and extended reversible cycling by skillfully combining the advantages of inorganic materials and organic materials, providing new ideas and methods for the preparation of intelligent photochromic fabrics.

[0003] In the process of preparing intelligent photochromic fabrics, it has become a mainstream technology to integrate photochromic materials into polymer fibers. However, with the increasing global awareness of ecological environmental protection, traditional polymer raw materials are facing challenges due to their non-renewability and environmental pollution. As a biodegradable polymer material derived from renewable resources, polyhydroxyalkanoate (PHA) has excellent biocompatibility and biodegradability. PHA not only breaks away from the dependence on fossil raw materials, but also shows broad application potential in the fields of biology, medicine, plastics, packaging, etc.

[0004] Although PHA has made significant research achievements in many fields, its research and application in the textile field are still relatively lagging. This is mainly due to the brittleness problem of PHA fibers in the preparation process, as well as the difficulty in fiber forming caused by the low nucleation density and slow crystal growth of conventional PHA. In order to overcome these difficulties, researchers try to prepare PHA blend fibers through blending modification to improve their spinnability and fiber performance. However, existing PHA fiber preparation methods, such as the polyhydroxyalkanoate fiber preparation process disclosed in CN102108563A, have problems such as long crystallization time, thick fiber diameter, and high cost, which limit the wide application of PHA fibers.

[0005] In addition, there are many challenges in the melt spinning processing of PHA. Because the melting temperature of PHA is close to the thermal degradation temperature, PHA shows high sensitivity to temperature conditions, which greatly increases the difficulty of melt spinning processing and forming. In the melt spinning process, the spinnability of the raw material varies greatly, decomposition easily occurs under high temperature conditions, and the slow solidification of the yarn is prone to sticking, etc., which further increases the difficulty of PHA fiber preparation. Although the addition of plasticizers, nucleating agents and other additives can improve these problems to some extent, these additives often affect the biocompatibility and biodegradability of PHA, and increase the cost of the final product.

[0006] Therefore, how to improve the spinnability and fiber performance of PHA fibers while maintaining the biocompatibility and biodegradability of PHA has become a technical problem to be solved. SUMMARY

[0007] To solve the above technical problems, the purpose of the present application is to provide a photochromic polyhydroxyalkanoate / polylactic acid fiber and its preparation method and application.

[0008] The above purpose of the present application is realized by the following technical solutions:

[0009] The present application provides a photochromic polyhydroxyalkanoate / polylactic acid fiber, which has a skin-core structure, the core layer material includes a high molecular polymer, a dye and SnO 2-x , wherein 0 < x < 0.5, the high molecular polymer is polyvinyl alcohol (PVA) and / or cellulose; the skin layer material includes polyhydroxyalkanoate (PHA) and polylactic acid (PLA).

[0010] The present application physically combines PHA with non-toxic and harmless biodegradable material PLA, improves the mechanical properties of PHA fibers, increases the strength and elongation at break, so that the PHA / PLA fiber has excellent biocompatibility and biodegradability. The core layer of the PHA / PLA fiber adds inorganic-organic hybrid photochromic material based on the principle of photo-bleaching, so that the PHA / PLA fiber is sensitive to visible light, and by adding different oxidation-reduction dyes, the color change of blue, green, red, purple and other colors can be realized, and the color can be reversibly changed under visible light.

[0011] Further, the molecular weight of the high molecular polymer is 70000-80000.

[0012] Further, the dye is selected from one or more of methylene blue (MB), methylene green (MG) and neutral red (NR).

[0013] The present application combines the photoreduction activity of semiconductor nanoparticles as photocatalysts and the oxidation-reduction-mediated color switching dyes as color components, such as MB, MG and NR, and mixes three color systems to make full-color ink.

[0014] Further, the mass ratio of polyhydroxyalkanoate and polylactic acid is (5-20):(100-120).

[0015] The present application provides a microfluidic device, comprising:

[0016] An internal phase propelling pump for propelling an internal phase solution;

[0017] An external phase propelling pump for propelling an external phase solution;

[0018] a glass slide;

[0019] a dispensing needle, which is located at the port of the outer capillary far away from the fiber collector, for connecting the inner capillary and the outer capillary;

[0020] an inner capillary, which is partially embedded in the inner part of the outer capillary, for transporting the inner phase solution;

[0021] an outer capillary, which is fixed on the surface of the glass slide, for transporting the outer phase solution; and

[0022] a fiber collector, for collecting the fiber formed after the interaction of the inner phase solution and the outer phase solution.

[0023] In the present application, the glass slide, the dispensing needle, the inner capillary and the outer capillary constitute a microfluidic chip.

[0024] The present application provides a preparation method of a photochromic polyhydroxyalkanoate / polylactic acid fiber, which uses the above microfluidic device to prepare the photochromic polyhydroxyalkanoate / polylactic acid fiber, and comprises the following steps:

[0025] dissolving the core layer material in a solvent to obtain an inner phase solution, wherein the core layer material comprises a high polymer, a dye and SnO 2-x , wherein 0 < x < 0.5, the high polymer is polyvinyl alcohol and / or cellulose; mixing a polyhydroxyalkanoate solution and a polylactic acid solution to obtain an outer phase solution; using an inner phase propelling pump to propel the inner phase solution into the inner capillary, using an outer phase propelling pump to propel the outer phase solution into the outer capillary through the dispensing needle, and loading a coagulation bath in the fiber collector to collect the photochromic polyhydroxyalkanoate / polylactic acid fiber in the coagulation bath.

[0026] In the preparation method provided by the present application, the cellulose molecular chain contains a large number of hydroxyl groups, which can form hydrogen bonds or other chemical bonds with the active groups on the surface of the inorganic photochromic material SnO 2-x , thereby realizing firm combination between the two and improving the stability of the composite material; the mixed solution of PHA and PLA can diffuse and volatilize in the coagulation bath to form microfibers with uniform size, and by adjusting the microfluidic spinning parameters, the fibers can have certain strength and elongation at break, so as to have a wider application prospect. The preparation method provided by the present application is simple and low in cost, and can continuously manufacture single fibers by using a controllable, reliable, safe and low-cost microfluidic spinning method, and can adjust the composition and microstructure of the single fibers.

[0027] Further, the solvent is water.

[0028] Further, the concentration of the high molecular polymer in the internal phase solution is 10-17wt%, the concentration of the dye in the internal phase solution is 0.01-0.05M, and the concentration of SnO 2-x in the internal phase solution is 30-100mg / mL.

[0029] Further, the volume ratio of the polyhydroxyalkanoate solution and the polylactic acid solution is (1-3):5.

[0030] Further, the concentration of the polyhydroxyalkanoate in the polyhydroxyalkanoate solution is 5-10wt%, and the concentration of the polylactic acid in the polylactic acid solution is 15-25wt%.

[0031] Further, the propelling rate of the internal phase propelling pump is 3-5mL / h.

[0032] Further, the propelling rate of the external phase propelling pump is 3-5mL / h.

[0033] Further, the collection rotating speed of the fiber collector is 2-4r / min.

[0034] Further, the coagulation bath is polyethylene glycol and / or ethanol, and the polyethylene glycol is preferably polyethylene glycol 400 (PEG 400).

[0035] The present application also protects the application of the above-mentioned photochromic polyhydroxyalkanoate / polylactic acid fiber in the field of textiles.

[0036] The present application has the following beneficial effects:

[0037] 1. The present application blends PHA and PLA for spinning, and the prepared PHA / PLA fiber has certain strength and elongation at break, and has excellent biocompatibility, biodegradability and transparency.

[0038] 2. The present application expands the application field of PHA fiber, combines PHA / PLA with photochromic materials, takes PHA / PLA as the skin layer material, takes dye, high molecular polymer and SnO 2-x as the core layer material, and prepares the skin-core structure fiber through microfluidic method. The PHA / PLA fiber can realize reversible color change under visible light irradiation.

[0039] 3. Since the thermal processing window of PHA is narrow, wet spinning can replace melt spinning to avoid thermal degradation. The present application uses a temporary and simplified spinning device, and is easy to operate, which is superior to the wet spinning machine used in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a schematic diagram of the microfluidic device of the present application.

[0041] Figure 2 Morphology characterization of photochromic PHA / PLA fiber prepared in Example 1; wherein (a) is a surface scanning electron microscope (SEM) image, (b) is a local enlarged view of (a), (c) is a cross-sectional SEM image, and (d) is an optical microscope (OM) image.

[0042] Figure 3 Actual photos of photochromic PHA / PLA fibers prepared in Example 1 and Examples 9-13.

[0043] Figure 4 Stress-strain curve of PLA fiber, photochromic PHA / PLA fiber prepared in Example 1 and Example 4.

[0044] Figure 5 Stress-strain curve of photochromic PHA / PLA fiber prepared in Example 1 and Examples 5-8; wherein (a) is Example 1 (22% PLA), Example 5 (20% PLA) and Example 6 (24% PLA), and (b) is Example 1 (4 r / min), Example 7 (2.4 r / min) and Example 8 (3 r / min).

[0045] Figure 6 Test results of photochromic PHA / PLA fiber prepared in Example 1 under blue light irradiation; wherein (a) is an actual photo of gradual fading under different irradiation times; (b) is a K / S curve, and (c) is a CIE chromaticity diagram (irradiation times are 0, 5, 10, 15, 20, 30 s in the direction of the arrow, respectively).

[0046] Figure 7 Test results of photochromic PHA / PLA fiber prepared in Example 2 under blue light irradiation; wherein (a) is an actual photo of gradual fading under different irradiation times; (b) is a K / S curve, and (c) is a CIE chromaticity diagram (irradiation times are 0, 5, 10, 15, 20 s in the direction of the arrow, respectively).

[0047] Figure 8 Test results of photochromic PHA / PLA fiber prepared in Example 3 under blue light irradiation; wherein (a) is an actual photo of gradual fading under different irradiation times; (b) is a K / S curve, and (c) is a CIE chromaticity diagram (irradiation times are 0, 5, 10, 15 s in the direction of the arrow, respectively).

[0048] Figure 9 Actual photo of a sample made of photochromic PHA / PLA fiber prepared in Example 1 fading under blue light (400-480 nm) irradiation and re-coloring under red light (625-665 nm) irradiation.

[0049] Figure 10 The following are the test results of the internal phase solution in Example 15 under light irradiation; (a) is a physical image of the internal phase solution fading under green light (500-550nm) irradiation and recoloring under red light (625-665nm) irradiation, (b) is the ultraviolet absorption spectrum of the internal phase solution, and (c) is a graph showing the change in absorption intensity at 662nm under 10 cycles of alternating ultraviolet light (365nm) and red light irradiation.

[0050] Explanation of reference numerals in the attached drawings: 1. Inner phase propulsion pump; 2. Outer phase propulsion pump; 3. Glass slide; 4. Dispensing needle; 5. Inner phase capillary; 6. Outer phase capillary; 7. Fiber collector. Detailed Implementation

[0051] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] 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.

[0053] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0054] This invention provides a microfluidic device, such as Figure 1 As shown, it includes:

[0055] Internal phase propulsion pump 1 is used to propel the internal phase solution;

[0056] External phase propulsion pump 2 is used to propel the external phase solution;

[0057] Slide 3;

[0058] Dispensing needle 4, located at the port of the outer phase capillary away from the fiber collector, is used to connect the inner phase capillary and the outer phase capillary;

[0059] The inner phase capillary 5 is partially embedded inside the outer phase capillary and is used to transport the inner phase solution.

[0060] An external phase capillary 6, fixed to the surface of the glass slide, is used to transport the external phase solution; and a fiber collector 7 is used to collect fibers formed after the interaction of the internal phase solution and the external phase solution.

[0061] In the following examples, SnO 2-x The nano-powder was prepared as follows: 0.96 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123), 53.3 mL of N,N-dimethylacetamide (DMAC), and 10.7 mL of deionized water were mixed at room temperature, and then 0.24 g of tin powder (Sn) and 2.81 g of crystalline tin tetrachloride (SnCl4·5H2O) were added under vigorous stirring, and stirred for 1 h to obtain a mixed solution. The mixed solution was transferred into a 100 mL polytetrafluoroethylene-lined reaction kettle, and reacted at 180 °C for 4 h. The precipitate obtained by the reaction was washed with distilled water three times, dried, ground, and SnO 2-x nano-powder was obtained.

[0062] In the following examples, the molecular weight of PVA was 74885.

[0063] Example 1

[0064] A preparation method of a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, comprising the following steps:

[0065] (1) SnO 2-x nano-powder was obtained. 2-x The dispersion liquid was obtained. 40 mL of the dispersion liquid was added into a blue cap bottle, and 6.5 g of PVA was added. The mixture was stirred in a water bath at 95 °C for 4 h under magnetic stirring, and then 1.6 mL of MB solution (the concentration in the internal phase solution was 0.01 M) was added after cooling. The mixture was stirred at room temperature for 2 h under magnetic stirring, and then stood to defoam to obtain a uniform internal phase solution. 6 g of PHA was dissolved in 94 g of chloroform (CF) to obtain a PHA solution, and 22 g of PLA was dissolved in 78 g of dichloromethane (DCM) to obtain a PLA solution. The PHA solution and the PLA solution were mixed in a volume ratio of 2:5 to prepare an external phase solution.

[0066] (2) Build microfluidic device. The inner phase circular tube capillary is embedded in the outer phase square capillary, the outer phase square capillary is fixed on the surface of the glass slide, and then the joint near the inner phase circular tube capillary is sealed with a dispensing needle to form a microchannel. The inner diameter of the inner phase circular tube capillary is 0.5 mm, and the inner diameter of the outer phase square capillary is 1 mm. The inner phase solution and the outer phase solution in step (1) are respectively filled into two syringes, the syringes are connected to the push pump, the inner phase push pump and the inner phase capillary are connected by a polytetrafluoroethylene tube, and the outer phase push pump and the dispensing needle are connected by a polytetrafluoroethylene tube. The port of the outer phase capillary away from the inner phase capillary is immersed in the PEG 400 coagulation bath of the fiber collector, wherein the push rate of the inner phase push pump is 3 mL / h, the push rate of the outer phase push pump is 3 mL / h, and the collection rotation speed of the fiber collector is 4 r / min. The fibers collected in the coagulation bath are washed with deionized water for 3 times, and dried to obtain the photochromic PHA / PLA fiber.

[0067] The morphology of the photochromic PHA / PLA fiber prepared in Example 1 is shown in Figure 2 The skin layer of the photochromic PHA / PLA fiber presents a transparent state, which does not affect the color change of the core layer, and can achieve the effects of ecological environmental protection and protection of the inner phase fluid state to prolong the service life.

[0068] Example 2

[0069] A preparation method of a photochromic polyhydroxyalkanoate / poly-lactic acid (PHA / PLA) fiber, which is basically the same as Example 1, and the difference lies in that in step (1), SnO 2-x nanopowder is added to deionized water, and a SnO 2-x dispersion liquid with a concentration of 40 mg / mL is prepared by drying and quantitative preparation. 30 mL of the dispersion liquid and 10 mL of deionized water are added in a blue cap bottle, 6.5 g of PVA is added, and magnetic stirring is carried out in a water bath kettle at 95°C for 4 h. After cooling, 1.6 mL of MB solution (the concentration in the inner phase solution is 0.01 M) is added, and magnetic stirring is carried out at room temperature for 2 h. After standing and defoaming, a uniform inner phase solution is obtained.

[0070] Example 3

[0071] A preparation method of a photochromic polyhydroxyalkanoate / poly-lactic acid (PHA / PLA) fiber, which is basically the same as Example 1, and the difference lies in that in step (1), SnO 2-x nanopowder is added to deionized water, and a SnO 2-xThe dispersion liquid, 20 mL of the dispersion liquid and 20 mL of deionized water were added into a blue cap bottle, and 6.5 g of PVA was added in a water bath at 95°C and magnetically stirred for 4 h. After cooling, 1.6 mL of MB solution (the concentration in the internal phase solution was 0.01 M) was added, and magnetically stirred at room temperature for 2 h. After standing and defoaming, a uniform internal phase solution was obtained.

[0072] Example 4

[0073] A preparation method of a photochromic polyhydroxyalkanoate / polylactic acid (PHA / PLA) fiber, which is basically the same as that of Example 1, except that in step (1), 6 g of PHA is dissolved in 94 g of chloroform (CF) to obtain a PHA solution, 22 g of PLA is dissolved in 78 g of dichloromethane (DCM) to obtain a PLA solution, and the PHA solution and the PLA solution are mixed at a volume ratio of 1:5 to prepare an external phase solution.

[0074] Example 5

[0075] A preparation method of a photochromic polyhydroxyalkanoate / polylactic acid (PHA / PLA) fiber, which is basically the same as that of Example 1, except that in step (1), 6 g of PHA is dissolved in 94 g of chloroform (CF) to obtain a PHA solution, 20 g of PLA is dissolved in 80 g of dichloromethane (DCM) to obtain a PLA solution, and the PHA solution and the PLA solution are mixed at a volume ratio of 2:5 to prepare an external phase solution.

[0076] Example 6

[0077] A preparation method of a photochromic polyhydroxyalkanoate / polylactic acid (PHA / PLA) fiber, which is basically the same as that of Example 1, except that in step (1), 6 g of PHA is dissolved in 94 g of chloroform (CF) to obtain a PHA solution, 24 g of PLA is dissolved in 76 g of dichloromethane (DCM) to obtain a PLA solution, and the PHA solution and the PLA solution are mixed at a volume ratio of 2:5 to prepare an external phase solution.

[0078] Example 7

[0079] A preparation method of a photochromic polyhydroxyalkanoate / polylactic acid (PHA / PLA) fiber, which is basically the same as that of Example 1, except that in step (2), the collection speed of the fiber collector is 2.4 r / min.

[0080] Example 8

[0081] A preparation method of a photochromic polyhydroxyalkanoate / polylactic acid (PHA / PLA) fiber, which is basically the same as that of Example 1, except that in step (2), the collection speed of the fiber collector is 3 r / min.

[0082] Example 9

[0083] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which is substantially the same as that of Example 1, except that in step (2), the inner phase push pump has a push rate of 0.5 mL / h.

[0084] Example 10

[0085] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which is substantially the same as that of Example 1, except that in step (2), the inner phase push pump has a push rate of 1 mL / h.

[0086] Example 11

[0087] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which is substantially the same as that of Example 1, except that in step (2), the inner phase push pump has a push rate of 2 mL / h.

[0088] Example 12

[0089] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which is substantially the same as that of Example 1, except that in step (2), the inner phase push pump has a push rate of 4 mL / h.

[0090] Example 13

[0091] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which is substantially the same as that of Example 1, except that in step (2), the inner phase push pump has a push rate of 5 mL / h.

[0092] The actual photochromic PHA / PLA fiber prepared by Example 1 and Examples 9-13 is shown in Figure 3 .

[0093] Example 14

[0094] A method for preparing a photochromic polyhydroxyalkanoate / poly(lactic acid) (PHA / PLA) fiber, which comprises the following steps:

[0095] (1) SnO 2-x nanopowder is added to deionized water, and a SnO 2-xThe dispersion solution was added to a blue cap bottle, 6.5 g of PVA was added, and magnetic stirring was performed in a water bath at 95°C for 4 h. After cooling, 1.6 mL of the MG solution (concentration in the internal phase solution was 0.01 M) was added, and magnetic stirring was performed at room temperature for 2 h. After standing to remove bubbles, a uniform internal phase solution was obtained. 6 g of PHA was dissolved in 94 g of chloroform (CF) to obtain a PHA solution, and 22 g of PLA was dissolved in 78 g of dichloromethane (DCM) to obtain a PLA solution. The PHA solution and the PLA solution were mixed in a volume ratio of 2:5 to prepare an external phase solution.

[0096] (2) Build a microfluidic device. The internal phase circular tube capillary was embedded in the external phase square capillary, the external phase square capillary was fixed on the surface of the glass slide, and then the joint near the internal phase circular tube capillary was sealed with a dispensing needle to form a microchannel. The internal diameter of the internal phase circular tube capillary was 0.5 mm, and the internal diameter of the external phase square capillary was 1 mm. The internal phase solution and the external phase solution in step (1) were respectively filled into two syringes, the syringes were connected to the push pumps, polytetrafluoroethylene tubes were used to connect the internal phase push pump and the internal phase capillary, and polytetrafluoroethylene tubes were used to connect the external phase push pump and the dispensing needle, and the port of the external phase capillary far away from the internal phase capillary was immersed in the PEG 400 coagulation bath of the fiber collector, wherein the push rate of the internal phase push pump was 4 mL / h, the push rate of the external phase push pump was 3 mL / h, and the collection rotation speed of the fiber collector was 4 r / min. The fibers collected in the coagulation bath were washed with deionized water for 3 times, and dried to obtain the photochromic PHA / PLA fiber.

[0097] Example 15

[0098] A method for preparing a photochromic polyhydroxyalkanoate / poly-lactic acid (PHA / PLA) fiber, comprising the following steps:

[0099] (1) SnO 2-x The nano-powder was added to deionized water, and a SnO 2-x The dispersion solution was added to a blue cap bottle, 6.5 g of PVA was added, and magnetic stirring was performed in a water bath at 95°C for 4 h. After cooling, 1.6 mL of the MG solution (concentration in the internal phase solution was 0.01 M) was added, and magnetic stirring was performed at room temperature for 2 h. After standing to remove bubbles, a uniform internal phase solution was obtained. 6 g of PHA was dissolved in 94 g of chloroform (CF) to obtain a PHA solution, and 22 g of PLA was dissolved in 78 g of dichloromethane (DCM) to obtain a PLA solution. The PHA solution and the PLA solution were mixed in a volume ratio of 2:5 to prepare an external phase solution.

[0100] (2) Replace the microfluidic chip with a side shaft joint coaxial needle (25 / 18 type), load the inner phase solution and the outer phase solution in step (1) into two syringes respectively, and install the syringes on the push pump. Inject the inner phase solution from the inner phase needle and the outer phase solution from the side shaft outer phase needle. Collect the fiber using a fiber collector equipped with a PEG 400 coagulation bath, wherein the push rate of the inner phase push pump is 4 mL / h, the push rate of the outer phase push pump is 3 mL / h, and the collection rotation speed of the fiber collector is 4 r / min. Wash the fiber collected in the coagulation bath with deionized water for 3 times, and dry to obtain the photochromic PHA / PLA fiber.

[0101] Test Example

[0102] The mechanical properties of the PLA fiber, the photochromic PHA / PLA fiber prepared in Example 1 and Examples 4-8 were tested. The test method was as follows: the fiber sample was cut into 100 mm, and the two ends of the fiber were marked for clamping, ensuring that the clamping part of the fiber was in good condition without obvious damage or defects. One end of the fiber sample was fixed in the upper clamp of the mechanical tester, ensuring that the fiber was firmly clamped and that the clamping part was aligned with the axial direction of the fiber. Then, the other end of the fiber was installed in the lower clamp, so that the fiber was in a straightened state, and the test speed was set to 20 mm / min.

[0103] The test results are shown in Figure 4 and Figure 5 As can be seen from Figure 4 , the average breaking strength of the pure PLA fiber is 43.6 MPa, and the average breaking elongation is 427.6%. With the addition of PHA, the breaking strength and breaking elongation of the fiber are slightly improved. When the volume ratio of the PHA solution to the PLA solution is 1:5, the average breaking strength of the PHA / PLA fiber is 43.9 MPa, and the average breaking elongation is 463.7%. When the volume ratio of the PHA solution to the PLA solution is 2:5, the average breaking strength of the PHA / PLA fiber is 48.3 MPa, and the average breaking elongation is 481.6%. The above shows that the addition of PHA in the outer phase solution can improve the mechanical properties of the PLA fiber, but excessive addition of PHA will affect the spinnability of the fiber, and also lead to a decrease in the breaking strength and breaking elongation of the fiber.

[0104] In addition, when the collection rotation speed is less than 2.4 r / min and greater than 4 r / min, the fiber cannot be well formed. From Figure 5It can be seen that when the collection speed is 2.4 r / min, the average breaking strength of the fiber is 10.4 MPa, and the average breaking elongation is 430.1%; when the collection speed is 3 r / min, the average breaking strength of the fiber is 13.7 MPa, and the average breaking elongation is 430.4%; when the collection speed is 4 r / min, the average breaking strength of the fiber is 17.6 MPa, and the average breaking elongation is 430.6%. It can be seen that as the collection speed increases, the breaking elongation of the fiber does not change significantly, but the breaking strength of the fiber increases significantly. This is because the external force is conducive to the orientation of the polymer macromolecular chain, the arrangement of the amorphous structure in the PLA fiber tends to be regular, and the orientation improves the crystallization, which induces the orientation recrystallization of the molecular chain along the force direction. Moreover, as the collection speed increases, the multiple of the fiber stretching increases, the orientation degree of the fiber increases, and the macromolecular chain arrangement is regular, so when the fiber is subjected to external force, the breaking strength of the fiber is improved.

[0105] The change of the photochromic PHA / PLA fiber prepared in Example 1-3 under blue light (400-480 nm) irradiation was tested, and the test method was as follows: the Lab and Yxy data were measured by a spectrophotometer, the measurement wavelength range of the spectrophotometer was between 400 nm and 700 nm, and D65 light source was preferred. The photochromic PHA / PLA fiber sample was placed flat on the measurement platform, and the sample surface was ensured to be flat and closely attached to the measurement port to avoid gaps or wrinkles that would affect the accuracy of the measurement results. At the same time, the change of the surface color of the sample under different light conditions was measured in reflection mode.

[0106] The test results are shown in Figure 6 , Figure 7 and Figure 8 The test data of Lab and Yxy are shown in Table 1.

[0107] Table 1

[0108]

[0109] The actual photos of the sample made of the photochromic PHA / PLA fiber prepared in Example 1 fading under blue light (400-480 nm) irradiation and re-coloring under red light (625-665 nm) irradiation are shown in Figure 9 .

[0110] Figure 10Figure showing the results of the test of the inner phase solution in Example 15 under light; wherein (a) is the actual figure of the inner phase solution fading under green light (500-550 nm) irradiation and re-coloring under red light (625-665 nm) irradiation, (b) is the ultraviolet absorption spectrum of the inner phase solution, and (c) is the absorption intensity change at 662 nm during 10 cycles of alternating ultraviolet light (365 nm) and red light irradiation. It can be seen from (a) that the inner phase solution fades under green light irradiation and re-colors under red light irradiation, and from (b) that the two absorption peaks of MG at 612 nm and 662 nm gradually decrease and completely disappear, indicating that the corresponding inner phase solution can effectively fade and recover under ultraviolet light and red light. It can be seen from (c) that the color change system has excellent repeatability and reversibility during multiple cycles, but the absorption spectrum intensity decreases to some extent as the number of color conversion reactions increases due to the accumulation of photodegradation side reactions. Figure 10 It can be seen from (a) that the inner phase solution fades under green light irradiation and re-colors under red light irradiation, and from (b) that the two absorption peaks of MG at 612 nm and 662 nm gradually decrease and completely disappear, indicating that the corresponding inner phase solution can effectively fade and recover under ultraviolet light and red light. It can be seen from (c) that the color change system has excellent repeatability and reversibility during multiple cycles, but the absorption spectrum intensity decreases to some extent as the number of color conversion reactions increases due to the accumulation of photodegradation side reactions. Figure 10 It can be seen from (a) that the inner phase solution fades under green light irradiation and re-colors under red light irradiation, and from (b) that the two absorption peaks of MG at 612 nm and 662 nm gradually decrease and completely disappear, indicating that the corresponding inner phase solution can effectively fade and recover under ultraviolet light and red light. It can be seen from (c) that the color change system has excellent repeatability and reversibility during multiple cycles, but the absorption spectrum intensity decreases to some extent as the number of color conversion reactions increases due to the accumulation of photodegradation side reactions.

[0111] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Those skilled in the art should understand that other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A photochromic polyhydroxyalkanoate / polylactic acid fiber, characterized in that, The photochromic polyhydroxyalkanoate / polylactic acid fiber has a skin-core structure and is prepared by wet spinning. The core layer material includes a polymer, a dye, and SnO 2-x , where 0 < x < 0.

5. The polymer is polyvinyl alcohol and / or cellulose, and the dye is selected from one or more of methylene blue, methylene green, and neutral red. The skin layer material includes polyhydroxyalkanoate and polylactic acid.

2. The photochromic polyhydroxyalkanoate / polylactic acid fiber according to claim 1, characterized in that, The mass ratio of the polyhydroxy fatty acid ester to the polylactic acid is (5-20):(100-120).

3. A method for preparing photochromic polyhydroxyalkanoate / polylactic acid fiber, characterized in that, The preparation of photochromic polyhydroxy fatty acid ester / polylactic acid fiber using a microfluidic device includes the following steps: Dissolve the core layer material in a solvent to obtain an internal phase solution. The core layer material includes a polymer, a dye, and SnO 2-x , where 0 < x < 0.

5. The polymer is polyvinyl alcohol and / or cellulose, and the dye is selected from one or more of methylene blue, methylene green, and neutral red; Mix the polyhydroxyalkanoate solution and the polylactic acid solution to obtain an external phase solution; Use an internal phase pump to push the internal phase solution into an internal phase capillary, and use an external phase pump to push the external phase solution through a dispensing needle into an external phase capillary. A coagulation bath is installed in the fiber collector, and the photochromic polyhydroxyalkanoate / polylactic acid fiber is collected in the coagulation bath; The microfluidic device includes: An internal phase propulsion pump is used to propel an internal phase solution. An external phase propulsion pump is used to propel an external phase solution. glass slide; The dispensing needle is located at the port of the outer phase capillary away from the fiber collector and is used to connect the inner phase capillary and the outer phase capillary. The inner phase capillary is partially embedded inside the outer phase capillary and is used to transport the inner phase solution. An external phase capillary, fixed to the surface of the glass slide, for transporting the external phase solution; and A fiber collector is used to collect fibers formed after the interaction between the internal and external phase solutions.

4. The preparation method according to claim 3, characterized in that, The concentration of the polymer in the inner phase solution is 10-17 wt%, the concentration of the dye in the inner phase solution is 0.01-0.05 M, and the concentration of SnO in the inner phase solution is... 2-x The concentration is 30-100 mg / mL.

5. The preparation method according to claim 3, characterized in that, The volume ratio of the polyhydroxyalkanoate solution to the polylactic acid solution is (1-3):

5.

6. The preparation method according to claim 3, characterized in that, The propulsion rate of the internal phase propulsion pump is 3-5 mL / h.

7. The preparation method according to claim 3, characterized in that, The coagulation bath is polyethylene glycol and / or ethanol.

8. The application of photochromic polyhydroxyalkanoate / polylactic acid fiber prepared by the method according to any one of claims 1-2 or any one of claims 3-7 in the field of textiles.

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