Entropically driven self-assembling of softened multi-walled carbon nanotubes into a reversibly water dispersible coherent solid

A bulk multi-walled carbon nanotube pellet has been produced by self-arrangement after drying the aqueous suspension of the carbon nanotubes (CNTs) oxidized by boiling CNTs in concentrated acid. The solid can be re-dispersed in water and self-assembled again. The centimeter order bulk CNT pellet unexpectedly showed compact domains of highly aligned parts of long CNTs which size is much larger than the domain size. Viscosity measurements confirmed that the system in question is completely different from a rigid-rod nematic. We reveal the mechanism of the entropy-driven self-alignment of treated worm-like CNTs in analogy to semiflexible liquid crystalline polymer. The polymer-like behavior of treated CNTs brings the CNTs into a genus of robust polymers.