Investigations of the structure and conformations of star-shaped polymers with fullerene branching centers functionalized by carbonyl groups

Star-shaped polystyrenes (PS)$_6$C$_{60}$ in deuterated toluene, in which the surface of the fullerene C$_{60}$ center is modified by the attachment of one to three polar C=O groups, have been studied using small-angle neutron scattering. It has been found that a decrease in the concentration of solutions (from 1.0 $\to$ 0.1 g/dL) leads to a change in the local conformation of the arms on scales $R\sim 1/q\le 1$ nm from coiled to straightened fragments. The effect is enhanced in the presence of one or two C=O groups on the surface of the fullerenes. The results have been discussed in terms of the influence of fullerenes on the structure of the solvent.