Self-assembly of cross-linked carbon nanotube films for improvement on mechanical properties and conductivity

•A cross-linked carbon nanotube film (CL-CNF) was developed for the first time without cross-linked agent.•Easy and reproducible esterification and acylation reactions were used.•The CL-CNF shows better mechanical properties and conductivity than uncross-linked CNF. A facile strategy for cross-linked carbon nanotube film (CL-CNF) was carried out via self-assembly of carbon nanotubes (CNTs), which was achieved based on esterification and acylation reactions of functional CNTs respectively. Comparing with uncross-linked carbon nanotube film, this strategy could benefit for enhancing mechanical properties of CNF through altering the inter-tube interaction from weaker Van der Waals force to stronger chemical bonding, but not lost its conductivity. The tensile strength and Young’s modulus of CL-CNF were remarkably enhanced, which were higher 263% and 190% than uncross-linked CNF. Meanwhile, conductivity of CNF after cross-linking increased to 210%. In this paper, the forming ester and acylation bonding in CNT network led to differences of their morphology that were observed on nanoscale. This method promoted CL-CNF as a promising material to be applied in water treatment and self-heating materials.