Novel synthesis and characterization of hyperbranched polymers

We approached a novel synthesis of hyperbranched polymers via living anionic polymerization. The first-generated star polymer (1G-S) was prepared by copolymerization of poly(4-methylstyrene)-block-polystyrene diblock anions with a small amount of divinylbenzene. The peripheral 4-methylstyrene units in the arm were metalated with s-butyllithium/tetramethylethylenediamine complex in cyclohexane. The second-generated hyperbranched polymers (2G-H) were prepared by equilibrium polymerization of such 1G-S polyanions with α-methylstyrene in tetrahydrofuran at -78 °C, and subsequently the terminal branch ends were capped with a small amount of 4-methylstyrene. The characterization of such hyperbranched polymers was carried out in detail. The ratio values of radius of gyration (R_G) to hydrodynamic radius (R_H) for the 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.