| Abstract: | Linear and symmetric star block copolymers of styrene and isoprene containing [C60] fullerene were synthesized by anionic polymerization and appropriate linking postpolymerization chemistry. In all block copolymers, the C60 was connected to the terminal polyisoprene (PI) block. The composition of the copolymers was kept constant (～30% wt PI), whereas the molecular weight of the diblock chains was varied. The polymers were characterized with a number of techniques, including size exclusion chromatography, membrane osmometry, and 1H NMR spectroscopy. The combined characterization results showed that the synthetic procedures followed led to well‐defined materials. However, degradation of the fractionated star‐shaped copolymers was observed after storage for 2 months at 4 °C, whereas the nonfractionated material was stable. To further elucidate the reasons for this degradation, we prepared and studied a four‐arm star copolymer with the polystyrene part connected to C60 and a six‐arm star homopolymer of styrene. These polymers as well as linear copolymers end‐capped, through ? N<, with C60 were stable. Possible reasons are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2494–2507, 2001 |
