Nanocellular poly(ether-block-amide)/MWCNT nanocomposite films fabricated by stretching-assisted microcellular foaming for high-performance EMI shielding applications

Abstract

High-performance EMI shielding materials are urgently needed for protecting from electromagnetic pollution. Traditional metal-based EMI shielding materials suffer from high density, poor corrosion resistance, and secondary radiation pollution. Here we report a facile strategy to prepare flexible and lightweight porous PEBA/MWCNT nanocomposite films with significantly enhanced EMI shielding performance. A novel biaxial stretching-assisted microcellular foaming technology is developed to refine cellular morphology. With the novel foaming technology, sub-microcellular and nanocellular PEBA/MWCNT nanocomposite films were prepared, which show nearly two orders of magnitude higher electrical conductivities than microcellular and solid PEBA/MWCNT nanocomposite films. EMI shielding tests with a rectangular waveguide structure show that porous PEBA/MWCNT nanocomposite films show remarkably enhanced EMI shielding performance compared with the unfoamed pristine sample, and their EMI shielding performance increases gradually with reducing cell sizes. While the solid PEBA/MWCNT nanocomposite film has a total shielding effectiveness of 26 dB, the nanocellular one has a total shielding effectiveness of 41 dB. More importantly, both sub-microcellular and nanocellular PEBA/MWCNT nanocomposite films show exceptional absorption-dominated EMI shielding behavior. Furthermore, the proposed strategy is shown to be universally effective for various polymer nanocomposites. Our processed porous PEBA/MWCNT nanocomposite films show a promising alternative to conventional EMI shielding materials.