Recyclable Carbon Nanotube/Thiol-Ended Hyperbranched Polymer Nanocomposite: Implication for Flexible Wearable Devices

Carbon nanotube (CNT) films, as two-dimensional assemblies of CNT, have attracted much interest and are widely used in many fields due to their unique structures and excellent performance. However, the preparation of high-strength and multiply recyclable CNT films remains a challenge in the sustainable development of traditional disposable CNT materials with permanent cross-links. Here, we prepare end-thiol hyperbranched polymers (BTHP- n, n = 6, 12, 24) to modify CNT film via thiol–ene click reaction. BTHP not only increases simultaneously the tensile strength, electrical conductivity, modulus, toughness by 1690, 257, 1867, and 2316%, respectively, but also remarkably improves the wettability and recyclability of CNT film. The enhancement mechanism is the combined effect of cross-linking structure between CNTs, rigid benzene and hexahydro- s -triazine rings, hyperbranched topological structure, and hydrogen bond interactions between polymer molecules. The detailed analysis of the degradation of the polymer in the modified CNT film (BTCNT) is attributed to the cleavage of the C–N and amide bonds. The close-loop recycled CNT film (100%) and monomer (72.15%) are reused to realize the cycles of BTCNT, which has good cycle performance with above 90 and 87% maintenance rate in tensile strength and electrical conductivity, respectively. This paper is hopeful to bring an applicable approach to solve the difficulty of recycling CNT films in traditional materials with permanent cross-links, while promoting the widespread application and sustainable development of CNT films in the field of flexible wearable devices.