Synergistic effect of GNP and Ag-NPs in PBAT films for high thermal conductivity and enhanced EMI shielding performance

This study presents a novel, lightweight and flexible PBAT/GNP/Ag composite film engineered for simultaneous high-performance thermal management and EMI shielding. Utilizing a facile vacuum filtration and hot-pressing approach, a parallel-oriented layered PBAT/GNP skeleton was constructed. Ag nanoparticles of varying sizes and loadings were subsequently incorporated via solution adsorption, forming a unique "brick-mortar-gravel" structure where GNP serves as the continuous conductive "brick" phase, PBAT acts as the "mortar" phase and Ag particles function as discrete "gravel". The composite film incorporating 20 nm Ag nanoparticles achieved ultrahigh in-plane thermal conductivity of ca. 81 W∙m -1 ∙K -1 , which is 90% higher than that of the PBAT/GNP composite film. Meanwhile, the highest electrical conductivity of 3696 S∙m -1 was achieved for this composite film, which is 133% higher than the film without Ag nanoparticles addition. Moreover, the composite film also exhibited outstanding EMI shielding effectiveness of above 45 dB in K-band, effectively blocking more than 99.99% of incident radiation, with a remarkable surface-specific shielding effectiveness of ca. 9500 dB∙cm 2 ∙g -1 . Finally, the PBAT matrix imparts necessary flexibility to the otherwise brittle GNP-dominated film. This improved bending tolerance, combined with a low density below 1.1 g∙cm -3 , demonstrates a viable strategy in this work for constructing advanced multifunctional materials, which is crucial for applications in flexible electronics and EMI protection. ● Fabrication of parallel-oriented PBAT/GNP/Ag film was achieved. ● Coupling of GNP and Ag-NPs boosted thermal and EMI shielding performance. ● An EMI SE of 45 dB was achieved, blocking over 99.99% of electromagnetic waves.