Novel synthesis and characterization of hyperbranched polymers

We approached a novel synthesis of hyperbranched polymers via living anioni c polymerization. The first-generated star polymer (1G-S) was prepared by c opolymerization of poly(4-methylstyrene)-block-polystyrene diblock anions w ith a small amount of divinylbenzene. The peripheral 4-methylstyrene units in the arm were metalated with s-butyllithium/tetramethylethylenediamin com plex in cyclohexane. The second-generated hyperbranched polymers (2G-H) wer e prepared by equilibrium polymerization of such 1G-S polyanions with a-met hylstyrene in tetrahydrofuran at -78 degrees C, and subsequently the termin al branch ends were capped with a small amount of 4-methylstyrene. The char acterization of such hyperbranched polymers was carried out in detail. The ratio values of radius of gyration (R-G) to hydrodynamic radius (R-H) for t he 2G-H were in the range of 0.96-1.18. The 2G-H behaved like soft spheres or loose star-structures that were constructed with flexible chains in the inner parts. (C) 2000 Elsevier Science Ltd. All rights reserved.