No abstract

The PDMS/Ag@PLASF/CNT composites owned good retention (> 90%) of electromagnetic interference shielding performance even after subjected to a simulated aging strategy or 10,000 bending-releasing cycles.

To ensure the normal operation of electronic equipment and provide protection from electromagnetic radiation, polymer-based electromagnetic interference (EMI) shielding materials are widely developed in the electronic communication field. However, it remains a challenge to prepare EMI shielding composites with ultrahigh EMI shielding efficiency (EMI SE), low thickness, high durability, and flexibility in harsh environments, such as extremely high or low temperatures in aerospace. In this study, we used blow spinning and compression molding to construct a highly efficient EMI shielding polyimide (PI) film containing a Ag microfiber sponge (AgMS). The three-dimensional (3D) conductive network constructed by 28-vol% AgMS endows the AgMS/PI film with very high electrical conductivity of 4.5 × 10 6 S m −1 and an EMI SE of up to 90.6 dB, at only 20-μm thickness. Even after working at −196 or 250°C for 120 h, the excellent EMI shielding performance is maintained, with EMI SE retention higher than 85.1 dB. Furthermore, AgMS/PI film exhibits outstanding thermal management performance, achieving a high saturation temperature of 200.2°C at very low supplied voltage (1.1 V), revealing a quick response time (3.1 s), excellent cyclic heating stability, and outstanding reliability. These outstanding properties indicate the great potential of AgMS/PI films in the electronic communication field under harsh environments and artificial intelligence.

No abstract

Electrically conductive shape-memory polymer composites have attracted great interest for electrical actuators because of their remote controlling capability, whereas plentiful conductive fillers are always required to achieve low-voltage actuation, which would cause degraded processability and also weaken the intrinsic feature of the shape-memory polymer matrix. The realization of low-voltage actuation with preserved actuating performance of shape-memory polymers is significant for practical application but is still challenging. Herein, we develop a novel electrically reversible actuator that can be actuated at only 15 V based on a segregated carbon nanotube (CNT)/poly(ethylene-covinyl acetate) (EVA) composite with CNTs selectively distributed on the interfaces among the polyhedral EVA regions. The segregated CNT networks endow the composite with low-voltage actuating ability, and the intrinsic characteristics of EVA endow the composite with reversible actuation. Moreover, the selectively distributed state can significantly reduce the obstruction effect of CNTs on EVA molecular chain movement during the actuating and recovery process, in comparison to the conventionally distributed state. The resultant segregated CNT/EVA has a higher reversible actuation of 5% than the conventional CNT/EVA composite (2%), even with 10 wt % CNT loading. The structural changes of these two composites were evaluated by wide-angle Xray scattering to explore the mechanism of the actuation superiority for segregated structures. Based on excellent reversible actuation, the segregated CNT/EVA was proven to assemble multifunctional actuators to realize various applications (flipping signs and lifting objects), providing inspiration in electrical actuators and biomimetic application.