Superstructure silver micro-tube composites for ultrahigh electromagnetic wave shielding

Absorption-dominant electromagnetic shielding materials can effectively reduce secondary pollution in the shielding process, and have greater significance in practical applications. Herein, silver (Ag) micro-tubes with superstructure, which were fabricated via using poly(lactic acid) (PLA) fibers as templates, were used to achieve the composites with ultrahigh, lightweight, and absorption-dominant electromagnetic shielding performance. The Ag nanoparticles were firstly deposited on the surface of PLA fibers by chemical reduction. The Ag micro-tubes were obtained by etching the PLA fibers in the core. The Ag nanoparticles were stuck together to form the Ag micro-tubes by polymer chains. The ultrahigh electromagnetic interference (EMI) shielding effectiveness (SE) of ∼110 dB was found in the Ag micro-tubes composed with polydimethylsiloxane or PLA with 1.5 mm in thickness. Due to the micro-tube structure, the composites containing with Ag micro-tubes exhibited absorption dominant shielding mechanism and low density. The absorption coefficient (A) value could reach 0.79 in the composites with Ag micro-tubes. The ultrahigh EMI SE performance and absorption dominant shielding mechanism of the composites was ascribed to the superstructure of the Ag micro-tubes which could efficiently create surface plasmon resonance, electronic vibration, interfacial polarization, capacitance effect and conductive loss. The work provides a new idea for preparing ultrahigh electromagnetic shielding materials with high absorption and low density.