Mechanically robust, UV screener core–double-shell nanostructures provide enhanced shielding for EM radiations over wide angle of incidence

Abstract

Herein, we have designed and synthesized first of its kind core-double shell nano heterostructured materials in which primitive ferrite (Fe3O4) acts as a diffused shell around an amorphous conducting core (carbon nanosphere, CNS), separated by a dielectric spacer (SiO2). This material when composited with polyvinylidene difluoride (PVDF) showed an excellent electromagnetic interference (EMI) shielding effectiveness of -42 dB (>99.99% attenuation) having a 600 μm thick film and interestingly, shielding effectiveness remained unaltered even after repeated heat cycles at various service temperatures. Moreover, far-field testing revealed that over the 10-18 GHz range the antenna radiated ca. 85% of electromagnetic power even if it was shielded with the composite film containing the heterostructure, which indicated low-performance degradation of the antenna due to the presence of the shield. Intriguingly, these composites also showed excellent UV blocking (>99.996% blocking) performance. These core-double shell heterostructure nanocomposites showed enhanced Young's modulus (344%) and proof strength (173.6%) as compared to neat PVDF. Besides, these films are fairly durable as the shielding performance was not affected after being subjected to heating (up to high service temperature of 90 degrees), bending (10 000 cycles), and stretching cycles (200 cycles).