A strong and tough polymer–carbon nanotube film for flexible and efficient electromagnetic interference shielding

Abstract

Carbon nanotube (CNT) films exhibit potential use in broad areas including energy-storage, thermal management, and electromagnetic interference (EMI) shielding; however, their inefficient, expensive, and energy-consuming fabrication processes reported so far and mechanical brittleness are a major deficiency. Herein, a strong and tough carbon nanotube (CNT) film with the inclusion of natural rubber (NR) was fabricated for flexible and efficient EMI shielding by a facile, efficient, and energy-saving method. Compared to the pure CNT film, the incorporation of 50 wt% NR leads to a tremendous mechanical improvement of the CNT-NR films, e.g., a 3.1 and 486 times increase in tensile strength and toughness. The origin of the reinforcing and toughening effect of the CNT films by the addition of a rubber material mainly arises from enhanced stress transfer and the uniformly dispersed stress. The CNT-NR film displays excellent EMI shielding performance albeit at tiny thickness owing to the extremely high aspect ratio and electrical conductivity of CNTs. The critical thickness required to satisfy commercial EMI shielding applications (shielding effectiveness (SE) of 20 dB) is only 50 μm, and a very high EMI SE of 44.7 dB is achieved as the film thickness reaches 250 μm. Meanwhile, the CNT-NR film exhibits highly reliable EMI SE even after bending 5000 times at a radius of 2.0 mm. These intriguing properties of CNT-NR films, together with their advantages of environmentally friendly and facile large-scale fabrication, open up the possibility of designing highly thin and flexible films for promising electromagnetic protection, especially in aerospace, aviation, and next-generation flexible electronics.