Preparation method of optically transparent terahertz wave-absorbing gel fiber composite fabric

Abstract

The invention belongs to the field of terahertz wave-absorbing materials, and particularly provides a preparation method of an optically transparent terahertz wave-absorbing gel fiber composite fabric, and the prepared terahertz wave-absorbing gel fiber composite fabric realizes breakthrough improvement of terahertz wave-absorbing performance based on creative gradient structure design and multi-component function cooperation; according to the invention, the gel fiber is used as a skeleton and is internally filled with MXene nanosheets to construct a conductive network, an ion transmission channel is formed by using a LiCl solution, and impedance matching is optimized through gradient concentration distribution, so that electromagnetic waves are subjected to multiple reflection and polarization loss in the fiber, and a relatively high THz absorption rate can be realized; meanwhile, the unique PDMS packaging layer endows the material with hydrophobic and wear-resistant characteristics, the limitation that a traditional wave-absorbing material is prone to being affected with damp and losing efficacy is broken through, and the performance retention rate in the 90% humidity environment exceeds 95%.

Description

Technical Field

[0001] The present invention belongs to the field of terahertz absorbing materials, and particularly provides a preparation method of an optically transparent terahertz absorbing gel fiber composite fabric. Background Art

[0002] Traditional terahertz absorbing materials mainly use metals (such as ferrites, alloys, etc.) and carbon-based materials (such as graphene, carbon nanotubes, etc.). Although these materials have good electromagnetic wave absorption characteristics, they have defects such as high mechanical rigidity, optical opacity, poor environmental stability, and frequency band limitations. With the continuous growth of the demands for high-frequency communication, equipment stealth skins, and flexible electronic protection, the rigid structures of existing terahertz absorbing materials greatly limit their equipment integration on complex surfaces. Moreover, their poor environmental stability results in insufficient reliability in outdoor or high-humidity environments. Thus, the prior art lacks a technical solution that can achieve wideband terahertz (THz) absorption, optical transparency, flexibility, and stealth functions through material structure design, which has become the core obstacle restricting the development of high-frequency electromagnetic protection materials. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of an optically transparent terahertz absorbing gel fiber composite fabric. Using gel fibers as the main body, MXene nanosheets and LiCl ions are loaded inside, and the terahertz absorption performance is synergistically enhanced through ionic conduction loss and interfacial polarization. This material can be used to produce large-area fabrics. Moreover, absorbents with gradient concentrations are filled inside the fibers to form an impedance gradient structure, optimizing the multi-stage reflection path of terahertz (THz) waves. At the same time, a PDMS transparent encapsulation layer is coated on the outer layer to achieve superhydrophobicity, breaking through the limitation that traditional absorbing materials are prone to moisture-induced failure.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A preparation method of an optically transparent terahertz absorbing gel fiber composite fabric, characterized by comprising the following steps:

[0006] Step 1. Preparation of a cellulose precursor;

[0007] Step 1.1. According to the proportion that cellulose accounts for 5wt% - 10wt% of the total content of the system, add cellulose to 100 ml of deionized water and ultrasonically disperse it to form a cellulose suspension;

[0008] Step 1.2: Add acrylamide (AAm) and N,N'-methylenebisacrylamide (MBA) to the cellulose suspension according to the proportion that AAm accounts for 15 wt% - 20 wt% of the total system content and MBA accounts for 0.5 wt% - 1 wt% of the total system content. After dissolution, add 0.3 mg of Ti3C2Tx and 5 ml of LiCl solution, and stir magnetically until it becomes transparent to form a transparent solution;

[0009] Step 1.3: Add ammonium persulfate (APS) to the transparent solution according to the proportion that APS accounts for 1 wt% of the total system content. After stirring, perform degassing treatment in a vacuum environment to remove the bubbles in the solution and form a cellulose precursor;

[0010] Step 2. Preparation of fiber spinning;

[0011] Step 2.1: Add deionized water to a polytetrafluoroethylene container to form a coagulation bath, and set the temperature of the coagulation bath to 60°C - 80°C;

[0012] Step 2.2: Place the cellulose precursor in an injection propulsion device, set the inner diameter of the needle of the injection propulsion device to 0.3 mm, and inject the cellulose precursor into the coagulation bath at a propulsion rate of 5 mL / h - 20 mL / h, and keep it for 10 - 20 minutes to complete phase inversion and form fiber spinning;

[0013] Step 2.3: Stretch the fiber at a speed of 10 mm / s - 50 mm / s through a stretching roller to complete the collection of fiber spinning;

[0014] Step 2.4: Rinse the fiber spinning collected by the stretching roller with deionized water to remove the residual solvent, and then dry it in a vacuum oven to obtain fiber spinning;

[0015] Step 3. LiCl gradient loading;

[0016] Prepare the first to Nth LiCl solutions with gradually increasing concentration gradients in the concentration range of 1M - 10M, and immerse the fiber spinning into the 1st to Nth LiCl solutions in sequence for LiCl loading: Immerse the fiber spinning in the LiCl solution in a vacuum environment and let it stand for 5 min - 10 min;

[0017] Step 4. PDMS encapsulation;

[0018] Immerse the fiber spinning completed with LiCl gradient loading into PDMS and let it stand for 5 - 10 min, take it out and dry and cure it. After curing, an optically transparent terahertz absorbing gel fiber composite fabric is formed.

[0019] Furthermore, in Step 1.2, the concentration of the LiCl solution is 1M - 10M (mol / L).

[0020] Further, in step 1.3, the draw ratio of the draw roll is set to 1:1.

[0021] Further, in step 2.4, the porosity of the fiber spinning is 60% - 85%, and the fiber diameter is 50μm - 200μm.

[0022] Further, in step 2.4, the drying temperature is 35°C - 40°C, and the drying time is 10 - 12h.

[0023] Further, in step 4, the specific process of drying and curing is: hot air drying in an oven at a temperature of 50°C - 60°C for 5 - 6h.

[0024] Further, in step 4, the thickness of the PDMS encapsulation layer is 1μm - 5μm, and the contact angle ≥ 150°.

[0025] Based on the above technical solutions, the beneficial effects of the present invention are as follows:

[0026] The present invention provides a method for preparing an optically transparent terahertz absorbing gel fiber composite fabric. The prepared terahertz absorbing gel fiber composite fabric realizes a breakthrough improvement in terahertz absorbing performance based on a creative gradient structure design and multi-component function synergy. In the present invention, the terahertz absorbing gel fiber composite fabric uses gel fibers as the skeleton, fills MXene nanosheets inside to construct a conductive network, forms an ion transport channel with LiCl solution, and optimizes impedance matching through a gradient concentration distribution, enabling multiple reflections and polarization losses of electromagnetic waves inside the fibers, and achieving a relatively high THz absorption rate. At the same time, the unique PDMS encapsulation layer endows the material with hydrophobic and wear-resistant properties, breaking through the limitation that traditional absorbing materials are prone to moisture-induced failure, and the performance retention rate exceeds 95% in a 90% humidity environment. In addition, the preparation method uses degradable cellulose, and subsequent continuous wet spinning production technology can be coordinated, which has both green and low-energy consumption and the potential for large-scale production, flexibly adapting to the needs of multiple scenarios, and providing favorable support for the development of high-frequency electromagnetic protection materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process schematic diagram of the method for preparing an optically transparent THz absorbing gel fiber composite fabric in the present invention. Among them, 1 is an injection propulsion device, 2 is a water bath heating polytetrafluoroethylene container, and 3 is a draw roll.

[0028] Figure 2 It is a schematic diagram of the optically transparent THz absorbing gel fiber composite fabric in the present invention.

[0029] Figure 3This is the reflection loss (RL) result diagram of the optically transparent THz-absorbing gel fiber composite fabric prepared by the present invention in the full wavelength range of 0.5 THz to 4.5 THz. Detailed implementation manners

[0030] To make the objectives, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0031] Example 1

[0032] This example provides a preparation method of an optically transparent terahertz-absorbing gel fiber composite fabric, as Figure 1 shown, which specifically includes the following steps:

[0033] Step 1. Preparation of cellulose precursor;

[0034] Step 1.1. According to the proportion that cellulose accounts for 5 wt% to 10 wt% of the total content of the system (cellulose precursor), add cellulose to 100 ml of deionized water, and ultrasonically disperse for 30 minutes to form a uniform cellulose suspension;

[0035] Step 1.2. According to the proportion that acrylamide (AAm) accounts for 15 wt% to 20 wt% of the total content of the system (cellulose precursor) and N,N'-methylenebisacrylamide (MBA) accounts for 0.5 wt% to 1 wt% of the total content of the system (cellulose precursor), add AAm and MBA to the cellulose suspension, dissolve and then add 0.3 mg of Ti3C2Tx and 5 ml of LiCl solution, and magnetically stir until it becomes transparent to form a transparent solution; the concentration of the LiCl solution is 10 M (mol / L);

[0036] Step 1.3. According to the proportion that ammonium persulfate (APS) accounts for 1 wt% of the total content of the system (cellulose precursor), add APS as an initiator to the transparent solution, stir for 10 min and then perform degassing treatment in a vacuum environment to remove the bubbles in the solution and form a cellulose precursor;

[0037] Step 2. Preparation of fiber spinning;

[0038] Step 2.1. Add deionized water to a polytetrafluoroethylene container, and the liquid level is higher than 2 / 3 of the container to form a coagulation bath, and set the temperature of the coagulation bath to 80 °C;

[0039] Step 2.2. Place the cellulose precursor in an injection propulsion device, set the inner diameter of the needle of the injection propulsion device to 0.3 mm, and inject the cellulose precursor into the coagulation bath at a propulsion rate of 5 mL / h to 20 mL / h, and keep it for 10 minutes to complete phase inversion to form fiber spinning;

[0040] Step 2.3: Stretch the fibers at a speed of 10 mm / s to 50 mm / s through the drafting rollers, with the draw ratio set to 1:1, and complete the fiber spinning and collection.

[0041] Step 2.4: Rinse the fiber spinning collected by the drafting rollers with deionized water to remove the residual solvent, and then dry it in a vacuum oven at a temperature of 40 °C for 12 h to obtain the fiber spinning.

[0042] Step 3: LiCl gradient loading.

[0043] Prepare multiple LiCl solutions with increasing concentration gradients in the concentration range of 1 M to 10 M. Specifically, use LiCl solutions with concentrations of 1 M, 5 M, and 10 M in sequence, and immerse the fiber spinning into the 1 M, 5 M, and 10 M LiCl solutions respectively for LiCl loading. The specific process of LiCl loading is as follows: Immerse the fiber spinning into the LiCl solution in a vacuum environment and let it stand for 5 min to 10 min; through vacuum assistance, use the difference in diffusion kinetics to form a smooth LiCl concentration gradient inside the fiber.

[0044] Step 4: PDMS encapsulation.

[0045] Immerse the fiber spinning completed with LiCl gradient loading into PDMS and let it stand for 5 min. After taking it out, dry it in a drying oven at a temperature of 60 °C with hot air for 6 h. After curing, an optically transparent terahertz absorbing gel fiber composite fabric is formed.

[0046] Based on the above steps, in this embodiment, an optically transparent terahertz absorbing gel fiber composite fabric is prepared, and its structure is as Figure 2 shown. The outer PDMS layer can play a role in reducing cross-section reflection and hydrophobicity to maintain the stability of the internal gel fiber fabric. The inner layer has a gel fiber as the framework, and MXene nanosheets are filled inside to construct a conductive network. LiCl is used to form an ion transport channel, and the impedance matching is optimized through the gradient concentration distribution, so that multiple reflections and polarization losses of electromagnetic waves occur inside the fiber, thereby achieving a higher THz absorption rate. Specifically, in the optically transparent terahertz absorbing gel fiber composite fabric prepared in this embodiment, the hollow pore diameter of the fiber is controlled at 30 μm, and the thickness of the PDMS layer is 5 μm.

[0047] Next, in the full band range of 0.5 THz to 4.5 THz, the absorption performance of the optically transparent terahertz absorbing gel fiber composite fabric (PDMS@PAM-LiC) prepared in this embodiment is compared with that of the existing absorbing materials, and the reflection loss (RL) is as Figure 3As shown, it can be seen from the figure that the reflection loss (RL) of the present invention is greater than 30 dB in the full band range of 0.5 THz to 4.5 THz, and the maximum RL value is as high as 86.5 dB, indicating that the gel fiber composite fabric prepared by the present invention can be used as an efficient THz wave-absorbing fabric structure.

[0048] The above is only the specific implementation manner of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the features disclosed, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A preparation method of an optically transparent terahertz absorbing gel fiber composite fabric, characterized in that, It includes the following steps: Step 1. Preparation of cellulose precursor; Step 1.

1. Add cellulose into 100 ml of deionized water according to the proportion that cellulose accounts for 5 wt% - 10 wt% of the total system content, and ultrasonically disperse to form a cellulose suspension; Step 1.

2. Add acrylamide (AAm) and N,N'-methylenebisacrylamide (MBA) into the cellulose suspension according to the proportion that AAm accounts for 15 wt% - 20 wt% of the total system content and MBA accounts for 0.5 wt% - 1 wt% of the total system content. After dissolution, add 0.3 mg of Ti3C2Tx and 5 ml of LiCl solution, and magnetically stir until it becomes transparent to form a transparent solution; Step 1.

3. Add ammonium persulfate (APS) into the transparent solution according to the proportion that APS accounts for 1 wt% of the total system content. After stirring, perform degassing treatment in a vacuum environment to remove the bubbles in the solution and form a cellulose precursor; Step 2. Preparation of fiber spinning; Step 2.

1. Add deionized water into a polytetrafluoroethylene container to form a coagulation bath, and set the temperature of the coagulation bath to 60°C - 80°C; Step 2.

2. Place the cellulose precursor in an injection propulsion device, set the inner diameter of the needle of the injection propulsion device to 0.3 mm, and inject the cellulose precursor into the coagulation bath at a propulsion rate of 5 mL / h - 20 mL / h, and keep it for 10 - 20 minutes to complete phase inversion and form fiber spinning; Step 2.

3. Stretch the fiber at a speed of 10 mm / s - 50 mm / s through a drafting roller to complete the collection of fiber spinning; Step 2.

4. Rinse the fiber spinning collected by the drafting roller with deionized water to remove the residual solvent, and then dry it in a vacuum oven to obtain fiber spinning; Step 3. LiCl gradient loading; Prepare the first to Nth LiCl solutions with gradually increasing concentration gradients in the concentration range of 1M - 10M, and immerse the fiber spinning into the 1st to Nth LiCl solutions in sequence for LiCl loading: Immerse the fiber spinning in the LiCl solution in a vacuum environment and let it stand for 5 min - 10 min; Step 4. PDMS encapsulation; Immerse the fiber spinning completed with LiCl gradient loading into PDMS and let it stand for 5 - 10 min, take it out and dry and cure it. After curing, an optically transparent terahertz absorbing gel fiber composite fabric is formed.

2. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 1.2, the concentration of the LiCl solution is 1M - 10M (mol / L).

3. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 1.3, the draw ratio of the drafting roller is set to 1:

1.

4. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 2.4, the porosity of the fiber spinning is 60% - 85%, and the fiber diameter is 50 μm - 200 μm.

5. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 2.4, the drying temperature is 35°C - 40°C, and the drying time is 10 - 12 h.

6. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 4, the specific process of drying and curing is: hot air drying in a drying oven at a temperature of 50°C - 60°C for 5 - 6 h.

7. The preparation method of the optically transparent terahertz absorbing gel fiber composite fabric according to claim 1, characterized in that, In Step 4, the thickness of the PDMS encapsulation layer is 1 μm - 5 μm, and the contact angle ≥ 150°.

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