Ultrafast Formation of Free-Standing 2D Carbon Nanotube Thin Films through Capillary Force Driving Compression on an Air/Water Interface

The Langmuir–Blodgett (LB) technique has been demonstrated as the most popular way to achieve freestanding two-dimensional (2D) carbon nanotubes (CNTs) thin films on the surface of liquid, yet still suffers some limitations, such as the need of expensive instruments with complicated surface pressure detection and time-consuming processes, and thus is inaccessible to a large number of researchers. Here, we present a cheap, reliable, and ultrafast strategy to fabricate free-standing 2D CNTs networks on an air/water interface by a highly simplified LB method free of instruments, yet only with porous materials assisted capillary force driving compression. The formation of free-standing 2D CNTs networks with controlled thickness, transmittance, and conductivity could be further transferred to other various substrates. Growing polymer from one side of the flexible CNTs network allows us to achieve 2D hybrid Janus materials of polymer grafted CNTs thin films. This endows the conductive 2D CNTs hybrid networks with responsive chemical functionality, which is highly important for scalable developments as next generation flexible electronics in chemical sensing.