Shear alignment of fullerenes in nanotubular supramolecular complexes

Supramolecular complexes of C₆₀ and C₇₀ encapsulated within the cavity created by the helical super-structure of syndiotactic poly(methyl methacrylate) (s-PMMA) were aligned by elevated-temperature electrospinning. Using ¹³C solid-state NMR, encapsulation of C₆₀ within the nanotubular cavity was confirmed by downfield chemical shifts and significantly shorter spin-spin relaxation times compared to C₆₀ physically mixed with s-PMMA. Thermal analysis revealed a melting endotherm at 180 °C for the C₆₀/ s-PMMA electrospun fibers that is consistent with formation of the nanotubular supramolecular complex. Based on the syndiotactic content of the s-PMMA and the gravimetrically determined fullerene content in the electrospun fibers, 82% of the nanocavity is filled with C₆₀, dropping to 55% filling with C₇₀. The fibers were macroscopically aligned by electrospinning onto a split collector plate for analysis of molecular alignment. Wide-angle X-ray scattering azimuthal scans revealed high degrees of molecularlevel alignment, with an order parameter of 0.70 for the C₆₀/s-PMMA nanopods.