Development of magnetically aligned single-walled carbon nanotubes-gelatin composite films.

Magnetically aligned and highly dispersed single-walled carbon nanotubes (SWNTs)-gelatin composite films were fabricated on a quartz substrate of newly designed disassemblable sample cells. After an SWNTs-gelatin composite sol in each sample cell was exposed to vertical DC magnetic fields to 28 T during the sol-gel transition, a side plate with a polytetrafluoroethylene film attached to the inner surface was removed from the sample cell carefully, and the composite gel left on the other side plate made of quartz was dehydrated in a nonmagnetic circumstance. We have found that the alignment of SWNTs is retained in uniform composite films obtained after the nonmagnetic drying process. Both polarized absorption measurements and polarized Raman scattering measurements were performed in order to confirm the alignment of SWNTs in the composite films consistently. The optical anisotropy of the composite films increased somewhat superlinearly as a function of the magnetic field applied during the sol-gel transition and reached to 0.13 at 28 T. The nonmagnetic drying process would make it easy to apply higher magnetic fields to the fabrication of aligned SWNTs films as it consumes resources to keep operating high field magnets such as hybrid magnets during the drying process.