Molecular heterogeneity of polystyrene-modified fullerene core stars

Structure-property relationships of polymeric materials require careful characterization of macromolecular properties. In this work we use 2-dimensional chromatography, coupling temperature gradient interaction and size exclusion chromatography, as well as density functional theory calculations to clarify that when poly(styryl)lithium anions are reacted with stringently purified C₆₀, stars with greater than six arms can be attained, in contrast to prior reports. We attribute this apparent contradiction to the limited ability of size exclusion chromatography to separate polymers having branched architectures. These results clarify the chemistry of anionically modified fullerenes and also show that more sophisticated separation techniques are necessary when characterizing architecturally complex polymers.