Synthesis, structure, and dynamics of polyacrylonitrile-polystyrene and fullerene-polystyrene graft copolymers

Graft copolymers characterized by different grafting frequencies and side chains of different length were synthesized by reacting poly(styrene lithium) or poly(styrene lithium alkoxide) with polyacrylonitrile. Poly(styrene lithium alkoxide) showed a much higher efficiency in the grafting, As demonstrated by Rayleigh's light scattering and sedimentation-diffusion analysis, the mean distance between the grafting points may be controlled from 15 to 70 repeating units in the main chain (M(PAN) = 1.30 x 10(5), M(PS) = 2.40 x 10(3)). By reacting poly(styrene lithium) or disodium tetramer of alpha-methyl styrene with fullerene, two different products were obtained: a starlike structure with a fullerene core and polystyrene or oligo(alpha-methyl styrene) chains as rays, and, in the case of disodium tetramer of alpha-methyl styrene, a more complex structure, in which starlike graft copolymers were linked by oligo(alpha-methyl styrene) chains (pearl necklace structure), The mobility and dimensions of the structures of those two types were quantitatively described, In particular, it was demonstrated that the necklace structure is more than four times as large as the starlike structure. The structures of the obtained copolymers were verified by the data of high-resolution NMR and conformational calculations available in the literature for similar structures.