Lightweight, Highly Efficient, and Recyclable Absorption-Dominated Electromagnetic Interference Shielding Foams Based on Molecularly Designed Polyamide Elastomer/Carbon Nanotube Nanocomposites

In this study, a polyamide elastomer system with excellent foamability was synthesized. Single-walled carbon nanotube (SWCNT) fillers were combined to fabricate a series of nanocomposites. Following supercritical carbon dioxide (sc-CO₂) foaming, a high-quality nanocomposite foam system was successfully manufactured. With the incorporation of only 2.5 wt % SWCNT, the foamed product exhibited excellent absorption-dominated electromagnetic interference (EMI) shielding performance with a specific shielding effectiveness (SSE) value of 209.8 dB cm³ g^–1, which was resulted from the synergistic effect induced by the three-dimensional conductive network of SWCNT and multiple reflections inside the micropores. Deformation tests were conducted, in which the nanocomposite foam was bent or twisted 1000 times; the foam stably retained its EMI shielding capacity at more than 95% of the original performance. The nanocomposite foam was both recyclable and refoamable, indicating its higher sustainability than traditional foaming products with chemical residues or cross-linking. This study provides insights into the development of high-efficiency EMI shielding foams for lightweight electronic applications.