Electrospining: Composite materials with switchable EMI shielding and efficient infrared stealth properties

Background

Intelligent electromagnetic interference shielding materials with adjustable electromagnetic shielding performance have become an important and urgent issue of concern in the information society. Recently, Professor Liu Tianxi and Associate Professor Wang Zicheng of Jiangnan University made a switchable and low-reflectivity EMI shielding composite material by chemically plating nickel on the surface of polyurethane non-woven fabric (Ni@TPU) and then combining it with liquid metal (LM) grid. The related research content was published in the journal "Chemical Engineering Journal" (IF 13.3) with the title "Stretchable liquid metal grid/metallized polyurethane composites with switchable electromagnetic interference shielding and efficient infrared stealth performance".

The main point of this paper

1.Chemical nickel plating on the surface of polyurethane nonwoven fabric (Ni@TPU) and combining it with liquid metal (LM) grid to prepare switchable low reflectivity electromagnetic interference shielding composite materials.

2.The synergistic combination of Ni@TPU and LM grid effectively promotes the rational construction of layered impedance matching. At the same time, it promotes the destructive interference between the electromagnetic waves reflected by Ni@TPU and the LM grid. Therefore, excellent low reflectivity EMI shielding performance can be achieved.

3.More importantly, by repeatedly stretching Ni@TPU/LM, switchable EMI shielding performance can be easily achieved. In addition, the fluffy nonwoven fabric and the low infrared emissivity LM grid give it excellent infrared stealth performance.

This excellent low reflectivity electromagnetic interference shielding switching performance, combined with flexible infrared stealth performance, makes it an intelligent electromagnetic interference shielding material with great application prospects in the application scenario of camouflaged container windows.

What are the key properties of developed electromagnetic interference (EMI) shielding composites?

1. EMI shielding effect (EMI SE): The composite material has a significant EMI shielding effect at frequencies of 27–40 GHz, and the shielding effect can reach 33.0 ~ 31.0 dB at a thickness of 1.2 mm.

2. Low reflectivity: The composite material is designed to have low reflectivity, and the reflection coefficient (R) can be reduced to about 0.4, which helps to reduce secondary pollution caused by reflected electromagnetic waves.

3. Dynamic adjustability: The EMI shielding performance can be dynamically adjusted by external stimuli such as temperature, voltage, humidity, and stress. This allows the on/off switchable EMI shielding effect of the composite material to vary between 1.5 and 25.5 dB.

4. Stretchability and flexibility: The composite material is stretchable and can maintain performance under mechanical deformation, which is critical for applications such as flexible electronics and soft robotics.

5. Hierarchical impedance matching: The combination of Ni@TPU and LM grid forms a hierarchical impedance matching structure, which enhances the introduction and dissipation of incident electromagnetic waves.

Stretchable liquid metal composites have a variety of potential applications, including:

1. Smart Electromagnetic Interference (EMI) Shielding Materials: Due to their switchable and low reflectivity EMI shielding properties, these composites can be used in smart communication devices to effectively protect devices from electromagnetic interference while maintaining signal integrity.

2.Flexible Electronics: The stretchability and flexibility of the composites make them suitable for use in flexible electronic devices such as wearable technology.

3.Infrared Stealth Applications: The low infrared emissivity of the composites makes them suitable for applications that require infrared stealth, such as camouflage materials for military or security purposes.

4.Soft Robotics: The mechanical properties of the composites enable their integration into soft robotic systems, where flexibility and the ability to adapt to dynamic environments are critical.

5.Sensors and Actuators: They can be used to develop advanced sensors and actuators, which require responsive and adaptable materials to enhance their functionality in various applications.