Making carbon nanotube films viscoelastic, ductile and repairable by forming a double network with branched polyethylenimine

Abstract Manipulating nanostructure assemblies is a key to promote their applications as structural and functional materials. For carbon nanotubes (CNTs), it is absent of the ability to reconstruct their entangled network. In this work, we report a strategy to realize efficient manipulation of CNT networks by forming a double network using branched polyethylenimine. The double network is highly viscoelastic and ductile for the efficient film stretching or creeping toward high CNT alignment, which can dramatically improve the mechanical strength of CNT films. Under the viscous drag from the polymer network, CNTs show enhanced movability to reconstruct new networks, making the film repairable. A key origin of such repairability lies in the branched polymeric structure. This double-networking strategy provides a new possibility to manipulate CNT assemblies toward high-performance applications.