Polymer nanocomposites reinforced with C60 fullerene: effect of hydroxylation

Novel nanocomposite films of polycarbonate (PC) with fullerene derivatives, such as pristine fullerene C-60 and polyhydroxylated-fullerenes, C-60(OH)(12) and C-60(OH)(36), were prepared. The optical, thermal, and mechanical properties of the composites were measured. Nanocomposite films of poly (vinyl alcohol) (PVA) with C-60(OH)(36) were prepared as a reference to show how improved dispersion of the nanofiller affects the overall transparency of the composites. Ultraviolet-visible spectroscopy showed that the addition of hydroxylated fullerenes did not affect visible light transmittance of the films significantly in the range of 400-800 nm. Differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) measurements showed the increased thermal stability of PC/C-60(OH)(12) film as compared to pristine PC film. This phenomenon was explained by the rigid polymer interphase regions formed around C-60(OH)(12) due to the plausible hydrogen bonding and hydrophobic interaction. On the other hand, the lower thermal stability of PC-C-60(OH)(36) was assumed to be caused by large agglomeration of the C-60(OH)(36) particles and the partial hydrolysis of the polycarbonate matrix. Tensile testing of the composites showed reduction in elongation at break and yield tensile strength. These results may be caused by the particle agglomerations which act as the initiation points for cracks.