Vertically aligned multi-layered structures to enhance mechanical properties of chitosan-carbon nanotube films.

Pure chitosan and carbon nanotube (CNT)/chitosan nanocomposite films were fabricated via a sublimation-drying process at −196 °C, during which polymeric repulsion generates unique pores with multi-layered structures. The films were then transformed into multi-layered and vertically aligned multi-layered (VAM) structures by compression. Due to the cross-linking between layers, the films prepared at −196 °C showed significantly better mechanical properties than the films prepared at −78 and −20 °C. Furthermore, a peculiar phenomenon was observed in that pure chitosan which exhibited better mechanical properties than the nanocomposites. To explain these results, we suggest a model in which the VAM structure supports more load than the CNT fillers. [ABSTRACT FROM AUTHOR]