Synthesis of C60-end-bonded polymers with designed molecular weights and narrow molecular weight distributions via atom transfer radical polymerization

Bromo-terminated polystyrene (PSt-Br) and poly(methyl methacrylate) (PMMA-Br) with designed molecular weights and narrow molecular weight distributions were prepared by atom transfer radical polymerization (ATRP). These bromo-terminated polymers were allowed to react with C-60 under ATRP conditions to yield C-60-end-bonded Pst (PSt-C-60-Br) and PMMA (PMMA-C-60-Br). The polymers were characterized by gel permeation chromatography (GPC), W-vis, FT-IR, and fluorescence spectra. GPC profiles obtained by UV and RI dual detectors indicated that C-60 had been covalently bonded to the polymers, and most of the C-60-end-bonded polymers were monosubstituents. Furthermore, 2-amino-acetonitrile (AAN) was used as an IR label to react with PSt-C-60-B; the products thus obtained show a characteristic absorption of CN group at 2369 cm(-1). This result reinforces the conclusion that C-60 has been covalently bonded into the polymer. The fluorescence of PMMA-C-60-Br and PSt-C-60-Br can be quenched by triethylamine or fumaronitrile, indicating that C-60 still keeps its strong electron-accepting and strong electron-donating property after it was modified by macromolecules. A possible mechanism of the formation of C-60-end-bonded PSt was deduced tentatively.