Synthesis and self-assembly of amphiphilic heterografted molecular brushes prepared by telomerization

Heterografted amphiphilic molecular brushes are highly grafted macromolecules with both hydrophilic and hydrophobic side chains attached to the backbone. These macromolecules display a unique combination of properties and can self-assemble in solution to form stable structures at very low concentration. Herein, we report a straightforward and robust methodology to access such macromolecules from precursors carrying xanthate side groups. Iterative aminolysis of a fraction of the xanthates and telomerization from the resulting thiols allow preparing heterografted molecular brushes with adjustable backbone dimensions, compositions, and grafting densities, which is exemplified with polymethacrylate hydrophobic grafts and poly(methacrylic acid), poly(acrylic acid) and poly(N-isopropylacrylamide) hydrophilic grafts. Yet, the molecular brushes display relatively high dispersities, which makes this approach not suited to synthesize well-defined heterografted molecular brushes. Nonetheless, the heterografted molecular brushes self-assemble in aqueous solution to form stable core-shell micelles, as observed by dynamic light scattering, with radii of gyration ranging from 30 to more than 100 nm, and critical micellar concentrations as low as 0.3 mg/mL.