Abstract
Efficient heat dissipation and electromagnetic interference (EMI) shielding are essential demands on packaging intensively integrated circuits in advanced electronics. Multicompetent polymer composites with thermal conduction and EMI shielding capacity have attracted tremendous interest in the material science community. We herein report the preparation of lightweight, thermal conductive polymer composites with superior EMI shielding effectiveness (SE) by building a 3D interconnected conductive network under steric confinement. The build of the 3D network relies on the coordinated stacking of flaky and spherical fillers, where the asymmetric graphite flakes (FG) are confined in the interstitial regions of the close-packing structures of hollow glass microspheres (HGμS). The lightweight HGμS can reduce the mass density of polymer composites, and their rigid close-packing structures impose mechanical compressions on FG under external forces, producing a conductive network with enhanced interconnectedness. The model system comprised of thermoplastic polyurethane (TPU), FG and HGμS has attained in-plane and through-plane thermal conductivity of 20.54 W m−1 K−1 and 6.55 W m−1 K−1 with 30 vol% FG (while remaining a low mass density of 1.21 g cm−3 that is identical to neat TPU). Meanwhile, a high EMI SE of 69 dB has been achieved at a thickness of 1 mm.