Anisotropic, Multifunctional GNP/BaTiO 3 /PI Composite Aerogels for Absorption-Dominant EMI Shielding and Thermal Insulation Applications

The increasing demand for lightweight, multifunctional materials with superior EMI shielding and thermal insulation properties has driven the development of advanced aerogel composites. In this work, an anisotropic polyimide composite aerogel was fabricated via an eco-friendly freeze-drying technique, using PI as the polymer matrix and GNP-BT as the hybrid filler. The unidirectional freezing process induced a unique porous morphology featuring slit-like channels and honeycomb-like structures. This anisotropic architecture imparted distinct directional properties to the aerogels, as evidenced by their enhanced electromagnetic interference (EMI) shielding effectiveness, thermal insulation, and mechanical performance. The PI/GNP/BT aerogels exhibited outstanding shielding performance, achieving an average shielding effectiveness of 44.5 dB in the X-band (8.2–12.4 GHz) along the radial direction, attributed to the synergistic effect of hybrid filler incorporation and the porous structure of the aerogel. The absorption-dominant shielding mechanism observed in our composite aerogels effectively minimizes secondary EM wave reflection, addressing a critical need for environmentally safe, high-performance EMI shielding materials. Remarkably, the aerogel achieved an excellent absorption coefficient of 0.94. Additionally, the aerogel demonstrated an excellent thermal insulation performance with a low thermal conductivity of 65 mW. m –1 .K –1 . This study offers a promising strategy for developing polyimide composite aerogels with integrated EMI shielding and thermal insulation properties.