Enhancing interfacial adhesion between copper layer and poly(p-phenylene benzobisoxazole) fibers via a polyethyleneimine-assisted polydopamine co-deposition process: Towards conductivity, joule heating and microwave shielding enhancement

For metallized fibers, achieving strong interfacial adhesion between the metal coating and fiber surface remains a major challenge, particularly for practical applications that demand both conductivity and high flexibility, such as flexible circuits and wearable conductive textiles. This study introduces a universal strategy that utilizes polyethyleneimine (PEI) to assist in the co-deposition of polydopamine (PDA), resulting in a dramatic enhancement of copper adhesion on poly(p-phenylene benzobisoxazole) (PBO) fibers by promoting metal ion adsorption through the plentiful amine groups. The developed protocol achieves copper adhesion that exceeds the peel-test limit of 3 M 8919 tape (10.8 N/cm on steel substrates) while maintaining high conductivity (2×10 4 S/m). The resulting metallized PBO fabric demonstrates outstanding multifunctionality, including 56 dB electromagnetic interference (EMI) shielding effectiveness in the X-band (blocking over 99.999% of incident waves) and stable Joule heating performance. Moreover, the metallized PBO fabric showcases remarkable durability, retaining stable performance after 1000 bending cycles or 10 minutes of ultrasonic treatment. This study offers new insights into the practical application of PDA-mediated metallization on inert PBO surfaces.