Flexible Poly(ether-block-amide)/Carbon Nanotube Composites for Electromagnetic Interference Shielding

Conductive nanofillers usually act as nucleating agents in the semicrystalline polymer matrix, and the crystals formed on the filler surface can impede electrical percolation development. In this work, flexible poly(ether-block-amide)/carbon nanotube (PEBA/CNT) nanocomposites were fabricated for electromagnetic interference (EMI) shielding applications. It was demonstrated that CNTs can nucleate the crystallization of the polyamide (PA) block of PEBA and induce the transformation of the crystals from the gamma-form to the alpha-form. Reducing the content of the PA block in PEBA from 50 to 20 wt % decreased the crystallinity of the nanocomposite and thus resulted in a higher electrical conductivity and an increment in EMI shielding performances. However, when ionically conductive polyethylene oxide was used as the polyether block, the hindrance effect of PA crystallization on electrical percolation was effectively mitigated, allowing for both high conductivity and enhanced amide dipole moment with a high PA content (e.g., 50 wt %), which is favorable for electromagnetic wave absorption. As a result, a high EMI shielding effectiveness with increased absorption can be achieved in PEBA/CNT nanocomposites.