A Novel Sulfur-Containing Carbon Nanotubes with Graphene Nanoflaps for Stretchable Sensing, Joule Heating, and Electro-Thermal Actuating

Stretchable conductors based on nanopercolation networks have garnered great attention for versatile applications. Carbon nanotubes (CNTs) are well-suited for creating high-efficiency nanopercolation networks. However, the weak interfacial shear strength (IFSS) between CNTs and elastomer hardly dissipates the deformation energy and thus deteriorates the conductive network. Herein, a novel sulfur-containing CNTs attached with abundant graphene nanoflaps using a two-step sulfidation strategy are developed. The sulfur functionality creates a strong interfacial interaction with the elastomer polymer, while the graphene nanoflaps provide an enhanced, intertwined shear interface with elastomer that is capable of efficiently dissipating the deformation energy. As a result, the optimized nanocomposite significantly improves the IFSS between nanofiller and elastomer, displaying remarkable conductive robustness (Delta R/R-0 approximate to 1.8 under 200%), superior stretchability (> 450%), and excellent mechanical durability (approximate to 30 000 cycles). Moreover, the nanocomposite demonstrates excellent Joule heating efficiency (approximate to 150 degrees C in 12 V), stretchable heating conversion (approximate to 200%), and long-term stability (> 24 h). To illustrate its capabilities, the nanocomposite is used to track human physiological signals and perform electric-thermal actuating as a set of soft tongs. It is believed that this innovative approach will provide value for the development of wearable/stretchable devices, as well as human-machine interaction, and bio-robotics in the future.