Tuning Electromagnetic Interference Shielding Performance through Controlled Alignment of Ni Nanowires in Soft PDMS Composites

Efficientdispersion of nanostructured fillers in thermoplasticpolymers and elastomers remains an open challenge, and unless it isaddressed, the potential utilization of conducting and magnetic fillersinfluencing the electronic properties of soft nanocomposites couldnot be properly assessed. Herein, we present a unique approach toaddress this challenge by constructing a microstructural fence usingaligned magnetic networks of Ni nanowires in the direction of theapplied external magnetic field, followed by flow-induced secondaryin-planar alignment of multiwalled carbon nanotubes during the curingof the soft poly(dimethylsiloxane) (PDMS) elastomer. This mutuallyperpendicular arrangement offers unique magnetoconducting featuresto the soft elastomer matrix with moderately high conductivity, whichis the key to superior electromagnetic shielding performance. Theunique conformation of mutually perpendicular positions of both nanofillersin the bulk PDMS composites results in enhanced electromagnetic interference shielding performance (-28 dB) primarily through an absorption(80%) mechanism, driven primarily by the maximized interaction withincident electromagnetic waves inside the soft elastomer. Fundamentalinsights into the governing viscoelastic responses of these elastomercomposites were gained through oscillatory rheological studies thatinvestigate interparticle attraction within a quasi-solid network.