All-Polymer Composite\nFilm with Outstanding Mechanical,\nThermal Conductive, and EMI Shielding Performances

Robust polymer-based composites with high thermal conductivity\n(TC) and electromagnetic interference shielding effectiveness (EMI\nSE) hold great promise for applications in rapidly developing electronics.\nTraditional composites containing inorganic fillers often suffer from\nincreases in processing difficulty, density, and significant deterioration\nin mechanical properties. Herein, we report for the first time a flexible\nmultilayered all-polymer composite of poly(<i>p</i>-phenyl-2,6-phenylene\nbisoxazole) (PBO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)\n(PEDOT:PSS), featuring excellent mechanical strength of 203.9 MPa,\nin-plane TC of 21.9 W/mK, EMI shielding effectiveness (SE) of 44.2\ndB, high-temperature stability, and flame retardancy. The excellent\nTC, mechanical strength, and flame retardancy of PBO, the remarkable\nEMI shielding performance of PEDOT:PSS, and the π–π\nstacking interactions between adjacent layers contribute to the comprehensive\nproperties, which outperform most of the traditional composites of\npolymers and inorganic fillers reported so far. This full-polymer\ndesign may pioneer a new strategy for the preparation of robust and\nlightweight multifunctional composites.