(555b) Crystallization and Orientation Studies in Swnt Based Nanocomposites

Single walled carbon nanotubes (SWNTs) based polymer nanocomposites are attractive because of the expected improvements in mechanical, thermal and chemical properties. Development of hierarchical structure ranging from the nano to meso to macro scale has always been a challenging issue, especially in polymer nanocomposites. In this study we report nano and mesoscale ordering in well dispersed SWNTs based polymer nanocomposites by aligning nanotubes macroscopically. For nanocomposites of SWNTs with poly(ε-caprolactone) (PCL) where the SWNTs act as nucleation sites for PCL, we have observed using small and wide angle x-ray scattering and Raman scattering that the nanocomposites adopt a shish ? kebab structure with the nanotubes forming the shish and the polymer lamellae the kebab with the long axis of the orthorhombic unit cell are parallel to the aligned nanotubes. On the other hand, for nanocomposites of SWNTs with polyethyleneoxide (PEO), where the nanotubes disrupt the crystallinity of the polymer, the lamellae normals are always perpendicular to the tube axis with no particular orientation of unit cell with respect to the draw direction. These observations are interesting as the macroscopic orientation of the nanotubes results in the micro and nano scale organization of the polymer irrespective of the nature of nanotube ? polymer interactions.