Degradable thermally repairable CNTs / PBAT composite fiber and its preparation method and application

Abstract

The present invention relates to a degradable, thermally repairable CNTs / PBAT composite fiber, its preparation method, and application. The preparation method comprises the following steps: (1) premixing poly(butylene adipate / terephthalate) (PBAT), triallyl isocyanurate (TAIC), and benzophenone (BP), followed by melt extrusion and ultraviolet radiation crosslinking to obtain a crosslinked PBAT fiber; dispersing carbon nanotubes (CNTs) and sodium dodecyl sulfate (SDS) in a mixture of ethyl acetate and anhydrous ethanol and ultrasonically treating the mixture to obtain a CNTs dispersion; and (2) immersing the crosslinked PBAT fiber in the CNTs dispersion, removing the fiber from the mixture and hanging it to dry, thereby obtaining a thermally repairable CNTs / PBAT composite fiber. The CNTs / PBAT composite fiber of the present invention has the advantages of being degradable, thermally repairable, sensitive, lightweight, small in size, and having a simple manufacturing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional composite materials, and specifically relates to a degradable thermally repairable CNTs / PBAT composite fiber and a preparation method and application thereof. Background Art

[0002] In the context of the rapid development of modern information technology, wearable sensors are ubiquitous in our daily lives. Like human sensory organs, they not only provide a more convenient lifestyle but also facilitate exploration of the world. The substrate materials for strain sensors can be divided into rigid substrates (metals, semiconductors) and flexible substrates (polymers). Common rigid substrates for strain sensors include metal wires, metal films, and silicon wafers. Rigid materials have poor flexibility and a small strain range, making them difficult to meet the requirements of the new generation of wearable devices. Flexible polymer fiber materials offer significant advantages as flexible substrates for wearable strain sensors. They possess unique permeability, biocompatibility, light weight, and flexibility, allowing them to conform tightly to any curved surface. They can be woven into clothing, attached to the skin, placed on clothing, or incorporated into jewelry. They provide a noninvasive, real-time, and comfortable way to continuously monitor personal physical, chemical, and biological signals. They have shown great potential for application in various fields, including health monitoring, disease diagnosis, rehabilitation medicine, and human-computer interaction.

[0003] Traditional polymers such as polyethylene terephthalate, polycarbonate, and silicone rubber are common substrate materials for strain sensors. However, their non-degradability and short service life limit their application in wearable devices. Polybutylene adipate / terephthalate (PBAT) is a biodegradable material that is more aligned with sustainable development strategies than traditional non-degradable polymers. Furthermore, PBAT is a semi-crystalline copolymer with crystallization-induced elongation and melt-induced expansion, resulting in its rapid and efficient thermal repair properties, significantly extending the service life of flexible strain sensors.

[0004] The degradable flexible strain sensor prepared by the present invention through a simple and easy-to-operate method is more in line with the sustainable development strategy. Its high bonding strength with CNTs gives it excellent sensing performance, good durability and resistance to harsh environments, increasing its application scenarios and expanding its scope of use in the wearable field. Summary of the Invention

[0005] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide a degradable thermally repairable CNTs / PBAT composite fiber and its preparation method and application that meet one or more of the above-mentioned needs.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A method for preparing a degradable thermally repairable CNTs / PBAT composite fiber comprises the following steps:

[0008] (1) premixing polybutylene adipate / terephthalate (PBAT), triallyl isocyanurate (TAIC), and benzophenone (BP), followed by melt extrusion and UV radiation crosslinking to obtain crosslinked PBAT fibers;

[0009] Carbon nanotubes (CNTs) and sodium dodecyl sulfate (SDS) were dispersed in a mixture of ethyl acetate and anhydrous ethanol and subjected to ultrasonic treatment to prepare a CNTs dispersion.

[0010] (2) The cross-linked PBAT fiber was immersed in a CNTs dispersion, taken out and hung to dry, thereby obtaining a thermally repaired CNTs / PBAT composite fiber.

[0011] As a preferred embodiment, in step (1), the mass ratio of PBAT, TAIC and BP is 100:(1-1.5):(1-1.5).

[0012] As a preferred embodiment, in step (1), the time of ultraviolet radiation cross-linking is 0.5 to 2 hours.

[0013] As a preferred embodiment, in step (1), the ratio of CNTs, SDS, ethyl acetate and anhydrous ethanol is (150-204 mg): (100-136 mg): (100 mL): (0-50 mL).

[0014] As a preferred embodiment, in step (1), the ultrasonic treatment time is 15 to 20 minutes.

[0015] As a preferred embodiment, in step (2), the immersion temperature is 69-72°C.

[0016] As a preferred embodiment, in step (2), the immersion time is 1 to 20 minutes.

[0017] As a preferred solution, in step (2), the hanging and drying time is 24 to 36 hours.

[0018] The present invention also provides a degradable thermally repairable CNTs / PBAT composite fiber prepared by the preparation method described in any of the above schemes.

[0019] The present invention also provides the application of the thermally repaired CNTs / PBAT composite fiber as described in the above scheme for strain sensing.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The CNTs / PBAT composite fiber of the present invention not only offers advantages such as biodegradability, thermally repairable sensing, light weight, small size, and simple manufacturing process, but also exhibits melt-induced shrinkage under constant and stress-free conditions. This fuels the self-healing behavior of the flexible strain sensor, enabling efficient and rapid repair of the CNTs conductive network damaged by hysteresis. Therefore, this biodegradable, thermally repairable flexible strain sensor composite fiber is an ideal candidate for the next generation of wearable devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 are SEM images of the cross-section and surface of the PBAT fiber and the CNTs / PBAT composite fiber of Example 1 of the present invention;

[0023] Figure 2 3. This is a comparison chart of the resistance of the cross-linked PBAT fibers of Examples 1-4 of the present invention at different ratios of ethyl acetate to anhydrous ethanol;

[0024] Figure 3 This is a comparison chart of the sensing performance of the cross-linked PBAT fibers of Examples 1-4 of the present invention at different ratios of ethyl acetate to anhydrous ethanol;

[0025] Figure 4 This is a comparison chart of the sensing performance of CNTs / PBAT fibers obtained by immersing the cross-linked PBAT fibers of Example 1 of the present invention in a suspension of CNTs and ethyl acetate for 10 minutes;

[0026] Figure 5 1 is a comparison chart of the sensing performance of the CNTs / PBAT fibers of Examples 1, 5, and 6 of the present invention;

[0027] Figure 6 This is a curve chart of 2000 cycles of the CNTs / PBAT composite fiber of Example 1 of the present invention before and after thermal repair. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described below through specific embodiments.

[0029] Example 1:

[0030] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0031] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0032] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 10 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNTs suspension solution;

[0033] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 10 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0034] like Figure 1 As shown, the CNTs of the CNTs / PBAT composite fiber prepared in this embodiment are evenly distributed on the surface of the PBAT fiber, constructing a perfect conductive network.

[0035] like Figure 2 As shown in the graph, the resistance of the cross-linked PBAT fibers of this example at different ethyl acetate:anhydrous ethanol ratios increases with increasing ethanol concentration until it reaches a near-constant state. Lower resistance indicates a greater degree of swelling and the greatest damage to the fiber matrix. When the ethyl acetate:anhydrous ethanol ratio is 10:3, the resistance stabilizes and exhibits the highest resistance stability.

[0036] like Figure 3 The figure shows the sensing performance of the cross-linked PBAT fiber prepared in Example 1 of the present invention under different conditions of ethyl acetate and anhydrous ethanol. Figure 2 Compared with the properties of ethyl acetate and anhydrous ethanol, too much ethyl acetate will destroy the structure of the fiber, and too much anhydrous ethanol will evaporate quickly at high temperature, which will affect the stability of the resistance of CNTs / PBAT composite fibers ( Figure 3 d) When ethyl acetate:anhydrous ethanol=10:3, the resistance is the most stable and the highest measurement factor is obtained at strains of 2.5%, 7.5%, and 12.5%.

[0037] like Figure 4As shown, the cross-linked PBAT fiber prepared in Example 1 of the present invention was immersed in a suspension of CNTs and ethyl acetate for 10 minutes to obtain a CNTs / PBAT composite fiber. Ten sensing tests were performed at a strain of 12.5%. In 5 cycles, the sensing performance was basically the same as that in Example 1. However, since the pure ethyl acetate solution will destroy the internal structure of the PBAT fiber, it can be seen that after 5 cycles, the fiber matrix was damaged and the sensing performance was destroyed.

[0038] like Figure 5 As shown in the figure, the thermal sensing performance of the CNTs / PBAT composite fiber of this embodiment at different immersion times is shown. It can be observed that when the immersion time is 3 minutes, its measurement factor is the lowest. This is mainly because the immersion time is too short, resulting in a high resistance and insensitivity under small strains. When the immersion time is 5 minutes, the measurement factor at 2.5% and 7.5% is the largest and very stable. When the immersion time is 10 minutes, due to the extended immersion time, more CNTs are deposited on the surface of the PBAT fiber, and the CNTs are entangled together, making it insensitive under small strains, but having a higher measurement factor at a strain of 12.5%.

[0039] like Figure 6 Figure 2 shows the cycling curves of the CNTs / PBAT composite fiber of this embodiment before and after thermal repair. It can be observed that the sensing performance remains essentially unchanged before and after thermal repair. Furthermore, the repaired CNTs / PBAT composite fiber maintains very stable sensing performance after 2000 cycles, demonstrating the excellent thermal repair capabilities of the CNTs / PBAT composite fiber, extending the service life of CNTs / PBAT fiber strain sensors in practical applications.

[0040] Example 2:

[0041] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0042] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0043] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 20 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0044] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 10 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0045] The CNTs / PBAT composite fiber of this embodiment was characterized by the same method as in Example 1. The results showed that the sensing performance of the composite fiber was similar to that of the composite fiber obtained in Example 1, and the sensing performance was more stable.

[0046] Example 3:

[0047] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0048] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0049] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 30 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0050] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 10 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0051] The CNTs / PBAT composite fiber of this embodiment was characterized by the same method as in Example 1, and its sensing performance under small strain was even better.

[0052] Example 4:

[0053] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0054] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0055] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 40 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0056] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 10 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0057] The CNTs / PBAT composite fiber of this embodiment was characterized by the same method as that of Example 1. The results showed that the resistance of the composite fiber was greater than that obtained in Example 1, and the stability of the resistance was also slightly lower than that in Example 1.

[0058] Example 5:

[0059] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0060] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0061] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 30 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0062] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 3 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0063] The CNTs / EVA composite fiber of this example was characterized using the same methods as in Example 1. The results showed that the sensing performance of the composite fiber was less stable and had a smaller measurement factor than that of the composite fiber obtained in Example 1. This was due to the short immersion time, which resulted in uneven distribution of CNTs on the surface of the CNTs / PBAT composite fiber and higher resistance.

[0064] Example 6:

[0065] The preparation method of the CNTs / PBAT composite fiber of this embodiment specifically includes the following steps:

[0066] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0067] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in a mixed solution of 100 mL of ethyl acetate and 30 mL of anhydrous ethanol and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0068] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 5 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0069] The CNTs / PBAT composite fiber of this example was characterized using the same methods as in Example 1. The results showed that the composite fiber exhibited more stable sensing performance compared to Example 1. Compared to the immersion time in Example 1, the immersion time in this example was more appropriate. The immersion time of 10 minutes in Example 1 was too long, resulting in entanglement of the CNTs on the surface of the CNTs / PBAT composite fiber, making its sensing performance less stable than that of this example.

[0070] Comparative Example 1:

[0071] The preparation method of the CNTs / PBAT composite fiber of this comparative example specifically comprises the following steps:

[0072] (1) PBAT, TAIC, and BP were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g, and the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device. The mixture was then irradiated with a UV lamp for 60 min to obtain cross-linked PBAT fibers.

[0073] (2) 150 mg of CNTs and 100 mg of SDS were dispersed in 100 mL of ethyl acetate and sonicated for 20 min using a probe sonicator to obtain a uniformly dispersed CNT suspension solution;

[0074] (3) The cross-linked PBAT fiber was placed in a CNTs suspension solution at a temperature of 71°C for swelling and impregnation. The immersion time was 10 minutes and the hanging drying time was 24 hours to obtain CNTs / PBAT composite fibers.

[0075] The CNTs / PBAT composite fiber of this example was characterized using the same methods as in Example 1. The results showed that the sensing performance of the composite fiber was similar to that of the composite fiber obtained in Example 1. However, the cyclic durability of this example was extremely poor. After five cycles of stretching and relaxing, the fiber matrix was damaged, as evidenced by an increase in resistance. This low cyclic durability significantly limits the application of PBAT composite fibers in flexible strain sensors.

[0076] Comparative Example 2:

[0077] The preparation method of the CNTs / PBAT composite fiber of this comparative example specifically comprises the following steps:

[0078] (1) PBAT, TAIC, BP ​​and CNTs were mixed uniformly at a ratio of 100 g: 1 g: 1.5 g: 150 mg, the mixture was melt-extruded using a twin-screw extruder and then spun using a collecting device, and then irradiated with a UV lamp for 60 min to obtain a cross-linked CNTs / PBAT composite fiber.

[0079] The CNTs / PBAT composite fiber of this example was characterized by the same method as that of Example 1. The results showed that the unit resistance of the composite fiber of this comparative example was basically non-conductive compared with the composite fiber obtained in Example 1.

[0080] In the above embodiment and its alternatives, the mass ratio of PBAT, TAIC, and BP can also be 100:1:1, 100:1.5:1, 100:1.2:1.2, etc.

[0081] In the above embodiment and its alternatives, the time for UV radiation cross-linking can also be 0.5 h, 1.5 h, 2 h, etc.

[0082] In the above embodiment and its alternatives, the ratio of CNTs, SDS, ethyl acetate, and anhydrous ethanol can also be any ratio of (150-204 mg): (100-136 mg): (100 mL): (0-50 mL), which can be determined according to actual application requirements.

[0083] In the above embodiment and its alternatives, the ultrasonic treatment time can also be 15 minutes, 16 minutes, 18 minutes, etc.

[0084] In the above embodiment and its alternatives, the immersion temperature can also be 69° C., 70° C., 72° C., etc., and the immersion time can also be 1 min, 12 min, 15 min, 18 min, 20 min, etc.

[0085] In the above embodiment and its alternatives, the hanging drying time can also be 30 hours, 32 hours, 36 hours, etc.

[0086] Given the numerous embodiments of the present invention, the raw materials and amounts involved can be selected within a limited range according to actual needs. The experimental data for each embodiment is voluminous and it is not suitable to list and explain them one by one here. However, the content required for verification and the final conclusions obtained in each embodiment are similar. Therefore, the verification content of each embodiment will not be described one by one here.

[0087] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, based on the ideas provided by the present invention, there may be changes in the specific implementation methods, and these changes should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing a degradable thermally repairable CNTs / PBAT composite fiber, characterized in that: The following steps are involved: (1) Polybutylene adipate / terephthalate (PBAT), triallyl isocyanurate (TAIC) and benzophenone (BP) are pre-mixed, melt-extruded and cross-linked by ultraviolet radiation to obtain cross-linked PBAT fibers; Carbon nanotubes (CNTs) and sodium dodecyl sulfate (SDS) were dispersed in a mixture of ethyl acetate and anhydrous ethanol and subjected to ultrasonic treatment to prepare a CNTs dispersion. In step (1), the ratio of CNTs, SDS, ethyl acetate, and anhydrous ethanol is (150-204 mg): (100-136 mg): (100 mL): (10-50 mL); (2) The cross-linked PBAT fiber was immersed in the CNTs dispersion, taken out and hung to dry to obtain the thermally repaired CNTs / PBAT composite fiber.

2. The preparation method according to claim 1, characterized in that In the step (1), the mass ratio of PBAT, TAIC and BP is 100: (1-1.5): (1-1.5).

3. The preparation method according to claim 1, characterized in that In the step (1), the time of ultraviolet radiation cross-linking is 0.5 to 2 h.

4. The preparation method according to claim 1, characterized in that In the step (1), the ultrasonic treatment time is 15 to 20 minutes.

5. The preparation method according to claim 1, characterized in that In the step (2), the immersion temperature is 69-72°C.

6. The preparation method according to claim 5, characterized in that In the step (2), the immersion time is 1 to 20 minutes.

7. The preparation method according to claim 6, characterized in that In the step (2), the hanging and drying time is 24 to 36 hours.

8. The degradable thermally repairable CNTs / PBAT composite fiber prepared by the preparation method according to any one of claims 1 to 7.

9. The use of the thermally repairable CNTs / PBAT composite fiber according to claim 8, characterized in that: Used for strain sensing.

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