A convenient method for the synthesis of cyclic polymers by ATRP

Cyclic polystyrene and poly(methyl methacrylate) with narrow molecular weight distribution were synthesized conveniently by intra-molecular cyclization of α-carboxyl-ω-chloride hetero-telechelic polystyrene and poly(methyl methacrylate) using potassium carbonate as the catalyst in highly dilute solution, respectively. The linear precursors were prepared successfully by atom transfer radical polymerization (ATRP) using 4-(chloromethyl)benzoic acid as an initiator. The chemical structures and molecular weights of the synthesized polymers were systematically characterized by nuclear magnetic resonance spectrum ( 1  H-NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The results revealed that high purity cyclic polymers were synthesized via a combination of intra-molecular cyclization and ATRP, and isolated easily by column chromatography on silica gel using a mixture of petroleum ether /ethyl acetate as an eluant.