Ultrastrong metallized PBO fibers for switchable microwave shielding and Joule heating

Multifunctional fibers capable of achieving switchable electromagnetic shielding effects while integrating versatile responsive capabilities are critically important for wearable electronics and electromagnetic shielding technologies. Nevertheless, existing conductive fibers typically suffer from passive shielding characteristics and insufficient mechanical performance, whereas poly( p -phenylene-2, 6-benzobisoxazole) (PBO) fibers exhibit superior mechanical properties yet lack multifunctionality. To resolve this, we developed a metallized PBO fiber platform featuring switchable microwave shielding and Joule heating through interfacial engineering of self-assembled copper-polymer networks. A polydopamine-mediated electroless plating strategy, utilizing polydopamine-anchored silver nanoparticles as catalytic sites, enables uniform Cu 2 O/Cu coatings with high electrical conductivity (up to 1.6 × 10 5  S/m), while remarkably enhancing mechanical properties within an optimal conductivity range compared to pristine PBO fibers. The aligned conductive fibers demonstrate a 55 dB dynamic EMI shielding range via angle-dependent grating effects, enabling real-time switching between shielding (45 dB) and transmission (5 dB) states through rotational adjustment. Simultaneously, the metallized coating delivers multifunctional capabilities including rapid electrothermal response (reaching 110 °C at 0.07 A), superhydrophobicity (157.4° contact angle), and self-cleaning performance. This work successfully reconciles the longstanding conflict between ultrahigh mechanical strength and active EMI/thermal regulation functionalities, establishing a new paradigm for multifunctional fiber development in aerospace and wearable systems.