One-shot synthesis of star gradient copolymers with controllable graft density

Long-standing conventional synthetic methods limit the scope of polymer architectural design such as connectivity, sequence and symmetry. Herein, we report a series of star gradient copolymers with variable grafting densities and backbone lengths. These star copolymers were obtained by one-shot ring-opening metathesis polymerization (ROMP) of an ω-norbornenyl polystyrene macromonomer (PS) and an endo-norbornenyl penta-fluorophenyl ester monomer (PFP), mediated by the highly active Blechert's type three-arm olefin metathesis catalyst. The kinetic studies of the copolymerization process revealed that a gradient sequence distributed along the star backbone and the tapered structure changed with the feed ratio between the PS and PFP. These copolymers were further modified with the activated ester chemistry to afford novel star-polymer-based functional materials.