Bionic self-adaptive nano-network enhanced dynamic plastic as well as preparation method and application thereof

Abstract

The invention belongs to the field of modified plastics, and particularly relates to a bionic self-adaptive nano-network enhanced dynamic plastic as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing a precursor; and constructing a dynamic network and forming a 4D structure. According to the invention, bionics, nanotechnology and dynamic chemistry are combined, and the defects of traditional modified plastics in the aspects of function integration, environmental responsiveness and recoverability are overcome.

Description

Technical Field

[0001] The present invention belongs to the field of modified plastics, and particularly relates to a bionic adaptive nano-network enhanced dynamic plastic, its preparation method and application. Background Art

[0002] As the cornerstone material of modern industry, the performance optimization of polymer modified plastics has always been a research hotspot in the field of materials science. Traditional modification technologies improve specific properties by adding reinforcing fillers (such as glass fiber, calcium carbonate, etc.) or functional additives (such as flame retardants, antioxidants, etc.) to the matrix resin, but face the following key technical bottlenecks:

[0003] Contradiction between functional integration and mechanical properties: Existing technologies (CN112175238A, US20210071025A1) show that although adding rigid fillers can improve strength, it will lead to a decrease in toughness (when the typical elastic modulus increases by 200%, the impact strength decreases by more than 60%). The introduction of flexible chain segments can improve toughness, but significantly sacrifices the rigidity of the material (such as the strength loss of the PCL toughened PLA system reaches 40%). This strength-toughness inversion effect severely restricts the requirements for the comprehensive performance of materials in the high-end equipment manufacturing field.

[0004] Insufficient environmental response intelligence: Current intelligent plastics (CN113683821A) mostly rely on a single stimulus response mechanism. For example, thermosensitive shape memory materials (JP2022084023A) cannot achieve conductivity regulation, and photo-responsive materials (WO2021174586A1) lack self-healing ability. Moreover, existing dynamic crosslinking systems (such as those based on the Diels-Alder reaction) have problems such as slow response speed (>30 minutes) and low repair efficiency (<75%), making it difficult to meet the requirements for real-time self-adaptability in emerging fields such as soft robots.

[0005] Dilemma of sustainable development: Traditional reinforced plastics (CN110759999A) use irreversible covalent crosslinking and difficult-to-separate hybrid fillers, resulting in high-temperature pyrolysis during recycling (energy consumption >5kW·h / kg) and serious performance loss (strength retention rate <50% after secondary processing). Although bio-based plastics (such as PLA) partially relieve environmental pressure, their uncontrollable degradation characteristics (JPH09151336A) limit their application in long-term products.

[0006] In recent years, researchers have attempted to improve the properties of materials through bionic structure design. For example, CN114106363A imitates the nacre structure to enhance toughness, but two-dimensional sheet fillers are prone to causing stress concentration, resulting in a decrease in fatigue life (the strength decays by 35% after 10^5 cyclic loadings). The dynamic network system reinforced with nanocellulose (ACS Appl. Mater. Interfaces 2022, 14, 8765 - 8774) achieves partial recyclability, but due to uneven filler dispersion, the mechanical properties fluctuate (strength deviation > 20%).

[0007] The root causes of the above technical defects are as follows: The existing modification systems lack a multi-scale synergistic reinforcement mechanism, fail to effectively balance the contradiction between the stability and dynamic reversibility of the covalent network, and there is a significant gap between the precision of microstructural regulation and the feasibility of macro processing. Therefore, developing a new generation of modified plastics with high strength, environmental self-adaptability, and complete recyclability has become a key challenge to break through the bottleneck of industrial upgrading. Summary of the Invention

[0008] To solve the above problems, the present invention provides a method for preparing a bionic self-adaptive nano-network reinforced dynamic plastic, comprising the following steps:

[0009] (1) Preparation of precursors: Growing a 5-nm boron nitride protective layer on the surface of MXene by atomic layer deposition (ALD); Bonding cellulose nanocrystals on the surface of carbon nanotubes by plasma-assisted grafting method; Synthesizing a polyurethane prepolymer containing disulfide bonds;

[0010] (2) Construction of the dynamic network: Melting and plasticizing the matrix resin; Synchronously injecting a dynamic cross-linking agent; Gradually adding four-dimensional nano-fillers in three segments; Initiating topological self-assembly by in-line ultraviolet irradiation;

[0011] (3) 4D structure forming: Constructing a macroscopic honeycomb structure by fused deposition 3D printing; Triggering rearrangement of nano-fillers by secondary annealing; Constructing a lotus leaf-like micro-nano structure by surface plasma treatment.

[0012] Further, in step (1), the Mn of the synthesized polyurethane prepolymer containing disulfide bonds is 8000.

[0013] Further, in step (2), the matrix resin is a PLA / PCL blend.

[0014] Further, in step (2), the dynamic cross-linking agent is an epoxy derivative of DA bond.

[0015] Further, in step (3), the conditions for secondary annealing are a temperature of 80 °C and a time of 2 h.

[0016] The present invention also provides a bionic self-adaptive nano-network enhanced dynamic plastic, which is prepared by any one of the above preparation methods.

[0017] The present invention also provides an application of the above bionic self-adaptive nano-network enhanced dynamic plastic in smart wearable devices.

[0018] The present invention has the following beneficial effects:

[0019] Compared with existing materials, the raw material cost of the material provided by the present invention is reduced by 40% compared with traditional reinforced plastics, it is compatible with existing twin-screw production lines (modification cost < 15%), and the carbon footprint is reduced by 62%. Detailed Description of the Invention

[0020] Now, various exemplary embodiments of the present invention will be described in detail. In the examples, unless otherwise specified, conventional methods are used, and unless otherwise specified, the reagents used are conventional commercially available reagents or reagents prepared by conventional methods. This detailed description should not be construed as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention.

[0021] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0023] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0024] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0025] Example 1: Preparation of Bionic Adaptive Nanonetwork Enhanced Dynamic Plastics

[0026] 1. Preparation of Precursors

[0027] (1) Preparation of MXene@boron nitride composite sheets:

[0028] Take 2 g of Ti3C2Tx MXene (Shenzhen Xicai Technology, thickness 1 - 5 nm) and place it in the ALD reaction chamber;

[0029] Using trimethylaluminum (TMA) and ammonia borane (NH3BH3) as precursors, perform 50 cycles of deposition at 200 °C;

[0030] Obtain MXene nanosheets with a 5 ± 0.3 nm boron nitride layer coated on the surface (XPS verifies that the B / N atomic ratio ≈ 1:1).

[0031] (2) CNT - cellulose nanocrystal hybrid:

[0032] Place multi - walled carbon nanotubes (Beijing Boyu Gaoke, diameter 20 nm, length 15 μm) in the plasma reactor;

[0033] Introduce an argon / oxygen mixed gas (volume ratio 9:1) and treat it at a power of 200 W for 10 minutes;

[0034] Immediately immerse it in an aqueous solution of 1 wt% cellulose nanocrystals (Zhejiang Green Science and Technology, diameter 10 nm, length 500 nm) and ultrasonically disperse for 2 hours;

[0035] After vacuum filtration and drying, obtain a hybrid material with a surface grafting rate ≥ 85% (calculated by TGA weight loss).

[0036] (3) Synthesis of dynamic cross - linked prepolymer:

[0037] Under nitrogen protection, mix polytetrahydrofuran diol (Mn = 2000) and isophorone diisocyanate (IPDI) in a molar ratio of 1:2;

[0038] Add 0.5 wt% chain extender of dithiodipropionic acid and react at 75 °C for 4 hours until the NCO content meets the standard;

[0039] After terminating the reaction, obtain a disulfide - bond - modified polyurethane prepolymer (viscosity 3500 cP @ 25 °C)

[0040] 2. Construction of Dynamic Network

[0041] (1) Melt blending process:

[0042] Use a co - rotating twin - screw extruder (KraussMaffei ZSK 26, L / D = 40);

[0043] Temperature zone setting: Zone Ⅰ 160°C / Zone Ⅱ 170°C / Zone Ⅲ 175°C / Zone Ⅳ 170°C;

[0044] Feed PLA (Zhejiang Hisun, 4032D) and PCL (Daicel Chemical Industries, Ltd., Japan, Capa 6800) into the main feed inlet at a ratio of 70:30.

[0045] Inject sequentially in Zone Ⅲ:

[0046] 0D filler: Quantum dot modified graphene oxide (0.5 wt%, particle size 15 ± 3 nm);

[0047] 1D filler: CNT-cellulose hybrid (1.5 wt%);

[0048] 2D filler: MXene@BN composite sheet (2 wt%);

[0049] Dynamic crosslinking agent (epoxy resin derivative containing Diels-Alder bond, Jiangsu Yakang New Materials Co., Ltd., E06-2) is injected laterally at 3 wt%.

[0050] (2) On-line structure regulation:

[0051] Set up an ultraviolet irradiation device (LED wavelength 365 nm, power density 50 ± 5 mW / cm 2 ) at the die head;

[0052] The screw is equipped with pulsating shear elements to generate an alternating shear field with a frequency of 5 Hz (peak shear rate 500 s -1 );

[0053] The dielectric constant is monitored in real time through an on-line dielectric sensor (Krohne, Germany, ProMax), and the ultraviolet intensity is feedback-regulated.

[0054] 3.4D Structure Forming

[0055] (1) Fused deposition modeling:

[0056] Use an industrial-grade 3D printer (Huashu Hi-Tech, HS403P);

[0057] Printing parameters: nozzle temperature 180°C, platform temperature 60°C, layer thickness 0.2 mm, filling rate 80%;

[0058] Print tensile specimens according to ASTM D638 standard, and the honeycomb structure unit size is 2 mm × 2 mm.

[0059] (2) Post-treatment process:

[0060] Place the formed parts in an oven at 80°C for annealing for 2 hours (heating rate 2°C / min).

[0061] The surface was treated with an atmospheric plasma processor (Zhongke Weina, PLASMA-300):

[0062] Power: 300 W, argon flow rate: 20 L / min, treatment time: 90 s;

[0063] A micro-nano composite structure was obtained (SEM showed that the height of the papilla structure was 5 - 8 μm and the spacing was 20 - 30 μm);

[0064] 4. Performance testing

[0065] (1) Mechanical properties:

[0066] The tensile strength was measured to be 98.7 MPa and the elastic modulus was 8.3 GPa by a universal testing machine (MTS, CMT4304);

[0067] The cantilever beam impact strength reached 85 kJ / m 2 (GB / T 1843 - 2008).

[0068] (2) Self-healing efficiency:

[0069] Scratch repair experiment (60℃ / 30 min): The surface cracks were completely healed and the tensile strength recovery rate was 92.4%.

[0070] (3) Environmental responsiveness:

[0071] Under ultraviolet light irradiation (365 nm, 100 mW / cm 2 ), the conductivity increased from 10 -8 S / m to 10 -3 S / m.

[0072] Shape memory recovery rate: 98.7% (GB / T 37192 - 2018).

[0073] The embodiments described above are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a bionic adaptive nano-network enhanced dynamic plastic, characterized in that: The following steps are involved: (1) Precursor preparation: growing a 5 nm boron nitride protective layer on the surface of MXene by atomic layer deposition (ALD); bonding cellulose nanocrystals on the surface of carbon nanotubes by plasma-assisted grafting; synthesizing a polyurethane prepolymer containing disulfide bonds; (2) Dynamic network construction: melt plasticization of matrix resin; simultaneous injection of dynamic crosslinking agent; addition of four-dimensional nanofillers in three gradient stages; online ultraviolet irradiation to induce topological structure self-assembly; (3) 4D structure forming: using fused deposition 3D printing to construct a macroscopic honeycomb structure; secondary annealing to trigger the rearrangement of nanofillers; surface plasma treatment to construct lotus leaf-like micro-nanostructures.

2. The method according to claim 1, characterized in that The Mn of the polyurethane prepolymer containing disulfide bonds synthesized in step (1) is 8000.

3. The method according to claim 1, characterized in that The collective resin in step (2) is a PLA / PCL blend.

4. The method according to claim 1, characterized in that: The dynamic cross-linking agent in step (2) is an epoxy derivative of a DA bond.

5. The method according to claim 1, characterized in that The secondary annealing conditions in step (3) are a temperature of 80° C. and a time of 2 h.

6. A bionic adaptive nano-network enhanced dynamic plastic, characterized in that: Prepared by any one of the preparation methods of claims 1-5.

7. Application of the bionic adaptive nano-network enhanced dynamic plastic as claimed in claim 6 in smart wearable devices.