出版社：American Association for the Advancement of Science
摘要：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 dispersion is fully immersed into the D-ANF/PVA aerogel via ultrasonication and vacuum-assisted impregnation. Ti3C2T/(ANF/PVA) EMI shielding composite films with directionally ordered structure (D-Ti3C2T/(ANF/PVA)) are then prepared by freeze-drying and hot pressing. Constructing a directionally porous structure enables the highly conductive Ti3C2T 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 Ti3C2T-Ti3C2T continuous conductive paths, which significantly improves the conductivity of the D-Ti3C2T/(ANF/PVA) EMI shielding composite film. When the amount of Ti3C2T is 80 wt%, the EMI shielding effectiveness (EMI SE) and specific SE () of D-Ti3C2T/(ANF/PVA) EMI shielding composite film achieve 70 dB and 13790 dB·cm2·g-1 (thickness and density of 120 μm and 0.423 g·cm-3), far superior to random-structured Ti3C2T/(ANF/PVA) (R-Ti3C2T/(ANF/PVA)) composite film (46 dB and 9062 dB·cm2·g-1, respectively) via blending-freeze-drying followed by hot pressing technology. Meanwhile, the D-Ti3C2T/(ANF/PVA) EMI shielding composite film possesses excellent flexibility and foldability.
