Characterization of novel fullerene containing polymers

Abstract

Fullerene containing poly (t-butyl methacrylate) (PtBMA-b-C 60) with average molecular weights of 8,000 and 14,000 Da (denoted by LFBMA and HFBMA respectively) and fullerene containing poly (methacrylic acid) (PMAA-b-C 60) with average molecular weights of 12,500 Da (denoted as FPMAA) were synthesized by atom transfer radical polymerization (ATRP). The aggregation behaviour of LFBMA and HFBMA in chlorobenzene-ethyl acetate mixed solvents and FPMAA in aqueous and salt solutions were studied using thermogravimetric analysis (TGA), UV-vis spectroscopy, potentiometric and conductometric titration, laser light scattering (LLS) and transmission electron microscopy (TEM). PtBMA-b-C 60 was first dissolved in chlorobenzene (which is a good solvent for both blocks), and ethyl acetate (precipitant) was added to induce its aggregation in the solvent mixtures. Ethyl acetate is a good solvent for homopolymer PtBMA and a poor solvent for C 60. It was observed that a critical precipitant composition (CPC) existed where the aggregation of the polymer chains was induced and it decreased with decreasing molecular weight (M n). Both dynamic and static light scattering studies (DLS and SLS) were used to characterize the aggregation behavior of LFBMA and HFBMA in various solvent mixtures. In LFBMA-mixed solvent systems, both unimers and aggregates coexisted. The hydrodynamic radius, R h of the aggregates decreases gradually with the addition of ethyl acetate. In the HFBMA-mixed solvent systems, only aggregates were