All-in-One layer-structured multi-functional conductive polypyrrole coated polyimide aerogel

Abstract

Lacking remarkable electromagnetic interference (EMI) shielding materials has been one of the bottlenecks in developing modern electronic devices. Elicited by multifunctional applications in harsh environment, a compromise between high EMI shielding performance and good thermal insulation should be further achieved. However, promoting EMI shielding performance leads to unavoidable thermal insulation increase and mechanical property diminishing. Thus, besides the modification for inherent properties, structure design further unlocks the potential for enhancing applications, offering greater flexibility in optimizing physical properties. Confronting the challenges, the in-situ oxidation polymerized polypyrrole (PPy) coated channel-structured polyimide (PI) composite aerogel material (PIPY) was fabricated through directional freeze-drying. The in-situ oxidation polymerization ensures the formation of a thin and uniform film with both physical and chemical crosslinking, surpassing conventional methods. The ordered structure exhibits commendable electrical conductivity and remarkable anisotropic thermal insulation properties, with the electrical conductivity reaching up to 101.7 S/cm and the heat conductivity at 46 mW m⁻¹ K⁻¹ with 34.1 wt% PPy. The EMI shielding effectiveness of PIPY in the X band (8.2–12.5 GHz) and Ku band (11.9–18.0 GHz) reaches an impressive value of 81.6 dB. The thin PPy film ensures piezoresistive sensing, particularly in perceiving subtle pressure, such as "writing record", "signal transmission" and "motion monitoring", among others.