Electromagnetic Interference Shielding Performance of Anisotropic Polyimide/Graphene Composite Aerogels

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• Anisotropic materials offer unique properties due to their directional structure.
• Graphene incorporation enhances material performance.
• Aerogels provide a lightweight scaffold with high surface area.

Purpose of the Study:

• To fabricate anisotropic polyimide (PI)/graphene composite aerogels.
• To investigate the influence of unidirectional freezing on pore structure and material properties.
• To evaluate the electromagnetic interference (EMI) shielding, thermal, and mechanical performance.

Main Methods:

• Synthesis of a poly(amic acid) (PAA) ammonium salt/graphene dispersion.
• Fabrication via unidirectional freezing, freeze-drying, and thermal imidization.
• Characterization of structural, conductive, thermal, and EMI shielding properties.

Main Results:

• Highly arranged tubular pores were achieved through unidirectional ice crystal growth.
• Anisotropic conductivity, EMI shielding, heat transfer, and compression performance were observed.
• Low-density (0.076 g·cm⁻³) aerogels exhibited high specific EMI SE (1373–1518 dB·cm²·g⁻¹) at 13 wt% graphene, primarily via microwave absorption.
• Excellent thermal stability with a 5% weight loss temperature >546 °C in nitrogen.

Conclusions:

• Unidirectional freezing is an effective method for creating anisotropic PI/graphene aerogels.
• The fabricated aerogels demonstrate superior lightweight EMI shielding and thermal properties.
• This approach offers an easy, environmentally friendly route to advanced PI-based composite aerogels.