Synthesis of C₆₀-End-Bonded Polymers with Designed Molecular Weights and Narrow Molecular Weight Distributions via Atom Transfer Radical Polymerization

Abstract

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 C60 under ATRP conditions to yield C60-end-bonded PSt (PSt−C60−Br) and PMMA (PMMA−C60−Br). The polymers were characterized by gel permeation chromatography (GPC), UV−vis, FT-IR, and fluorescence spectra. GPC profiles obtained by UV and RI dual detectors indicated that C60 had been covalently bonded to the polymers, and most of the C60-end-bonded polymers were monosubstituents. Furthermore, 2-aminoacetonitrile (AAN) was used as an IR label to react with PSt−C60−B; the products thus obtained show a characteristic absorption of CN group at 2369 cm-1. This result reinforces the conclusion that C60 has been covalently bonded into the polymer. The fluorescence of PMMA−C60−Br and PSt−C60−Br can be quenched by triethylamine or fumaronitrile, indicating that C60 still keeps its strong electron-accepting and strong electron-donating property after it was modified by macromolecules. A possible mechanism of the formation of C60-end-bonded PSt was deduced tentatively.