Multiwalled carbon nanotube/polyacrylonitrile composite fibers prepared by in situ polymerization

Multi-walled carbon nanotubes (CNTs) were mixed with polyacrylonitrile (PAN) by in situ polymerization or by mechanically mixing. The mixtures were then wet-spun into fibers, respectively. The effects of mixing method on the interfacial bonding between the components in the fibers and the properties of the fiber were investigated by Raman spectroscopy, TEM, SEM, and tensile strength testing. By in situ polymerization mixing, a thin layer of PAN molecules is observed to cover the surface of the CNT, which increases the diameter of CNT evidently. Results of Raman spectroscopy indicate that the layer of PAN molecules are strongly attached onto the surface of CNT through grafting polymerization, leading to strong chemical bonding between CNTs and PAN matrix in the obtained fibers. In contrast, no obvious chemical interactions are observed between them in the fibers prepared by mechanically mixing. In both cases, the CNTs have significantly strengthened the PAN fibers. However, the fibers prepared from in situ polymerization mixing are much stronger because of the interfacial bonding effect between the PAN molecules and CNTs.