Versatile phenolic composites by in situ polymerization of concentrated dispersions of carbon nanotubes

Uniform dispersion of carbon nanotubes in a polymer matrix is a prerequisite for high-performance nanotube-based composites. Here, we report an in situ polymerization route to synthesize a range of phenolic composites with high loading of single-wall carbon nanotubes (SWCNTs, >40 wt%) and continuously tunable viscoelasticity. SWCNTs can be directly and uniformly dispersed in cresols through noncovalent charge-transfer interactions without the need for surfactants, and further concentrated before in situ polymerization of the solvent molecules, yielding phenolic composites in the forms of conductive pastes, highly stretchy doughs, and hardened solids with high nanotube loading and much enhanced electrical conductivity (up to 2.7 × 10⁴ S m^-1). These conducting phenolic composites provide a versatile material foundation for many areas. As a proof of concept, the conductive paste is used to construct ultrasensitive motion sensors that can operate at unprecedently low voltages (e.g. 0.1-10 mV). Moreover, the ease of processing and shaping of phenolic composite solids from the dough state is demonstrated.