Flexible Ti <sub>3</sub> C <sub>2</sub> T <sub> <i>x</i> </sub> /(Aramid Nanofiber/PVA) Composite Films for Superior Electromagnetic Interference Shielding
Yali Zhang, Zhonglei Ma, Kunpeng Ruan, Junwei Gu
Abstract
Multifunctional electromagnetic interference (EMI) shielding materials would solve electromagnetic radiation and pollution problems from electronic devices. Herein, the directional freeze-drying technology is utilized to prepare the aramid nanofiber/polyvinyl alcohol aerogel with a directionally porous structure (D-ANF/PVA), and the Ti 3 C 2 T x dispersion is fully immersed into the D-ANF/PVA aerogel via ultrasonication and vacuum-assisted impregnation. Ti 3 C 2 T x /(ANF/PVA) EMI shielding composite films with directionally ordered structure (D-Ti 3 C 2 T x /(ANF/PVA)) are then prepared by freeze-drying and hot pressing. Constructing a directionally porous structure enables the highly conductive Ti 3 C 2 T x nanosheets to be wrapped on the directionally porous D-ANF/PVA framework in order arrangement and overlapped with each other. And the hot pressing process effectively reduces the layer spacing between the stacked wavy D-ANF/PVA, to form a large number of Ti 3 C 2 T x -Ti 3 C 2 T x continuous conductive paths, which significantly improves the conductivity of the D-Ti 3 C 2 T x /(ANF/PVA) EMI shielding composite film. When the amount of Ti 3 C 2 T x is 80 wt%, the EMI shielding effectiveness (EMI SE) and specific SE (SSE/ t ) of D-Ti 3 C 2 T x /(ANF/PVA) EMI shielding composite film achieve 70 dB and 13790 dB·cm 2 ·g -1 (thickness and density of 120 μ m and 0.423 g·cm -3 ), far superior to random-structured Ti 3 C 2 T x /(ANF/PVA) (R-Ti 3 C 2 T x /(ANF/PVA)) composite film (46 dB and 9062 dB·cm 2 ·g -1 , respectively) via blending-freeze-drying followed by hot pressing technology. Meanwhile, the D-Ti 3 C 2 T x /(ANF/PVA) EMI shielding composite film possesses excellent flexibility and foldability.