Achieving excellent thermally conductive and electromagnetic shielding performance by nondestructive functionalization and oriented arrangement of carbon nanotubes in composite films

Effective heat dissipation capacity and electromagnetic interference (EMI) shielding performance are urgently required for modern electronic equipment. Herein, pristine carbon nanotubes (CNTs) were first nondestructively functionalized by eco-friendly dopamine chemistry, which maintained the integrity of inherent graphitic lattice structure of CNTs. In the meanwhile, introduction of polydopamine (PDA) improved interfacial interaction between PDA-coated CNTs (CNT@PDA) and the ethylene-vinyl acetate copolymer (EVA) matrix. Favorable pathways for rapid thermal conduction and electron transmission were paved by oriented arrangement of CNT@PDA. As a result, dual-functional CNT@PDA/EVA composite films were fabricated, which exhibited remarkable inplane thermal conductivity (TC) and prominent EMI shielding effectiveness (EMI SE). The TC and EMI SE of the 70 wt% CNT@PDA/EVA composite film climbed up to 17.9 W/mK and 32.4 dB, respectively. Furthermore, the CNT@PDA/EVA composite films revealed outstanding flexibility and mechanical fatigue durability. After repeated bending test, the retention ratio of the in-plane TC and EMI SE was 98% and 97%, respectively. The inplane TC and EMI SE presented excellent retention ratio of 94% and 95% after repeated tensile test, respectively. Our work provides a valuable reference to design and fabricate dual-functional or multifunctional composites applied in modern electrical systems and electronic devices.