Enhanced electrical and electromagnetic interference shielding performance of immiscible poly(vinylidene chloride)/poly(lactic acid)/multi-walled carbon nanotube composites via constructing filler-wrapped porous structure

Herein, immiscible poly(vinylidene fluoride)/poly(lactic acid) (PVDF/PLA) blends filled with multi-walled carbon nanotubes (MWCNT) were fabricated by a facile solution flocculation method. A co-continuous structure was formed at the blend ratio of 50v/50v. By extracting PLA, MWCNTs were found wrapped on the surface of porous PVDF. The electrical percolation threshold of porous composites is 0.25 wt.%, which is much lower than compact composites (2 wt.%). By comparing the electromagnetic interference shielding effectiveness (EMI SE) between compact and porous composites, the EMI SE of compact composites containing 15 wt.% MWCNT is ca. 30 dB, whereas 60 dB for the porous composites at the same filler loading. The enhanced shielding performance is derived from the porous structure and densely packed MWCNT on the PVDF surface that facilitates the multiple reflections of electromagnetic waves. This work provides a new thought in fabricating high performance EMI material by effectively tuning filler distribution in polymer blends.