Degradable and cationic long-subchain hyperbranched block copolymers with well-defined block subchain: Synthesis, characterization and degradation

Self-assembly of long-subchain hyperbranched block copolymer (hyperblock) could achieve a novel micelle with multiple hydrophobic cores (multi-core micelle), while the hydrophobic components are generally consecutive in the core or shell of an independent conventional assembly. However, only a few studies focus on the synthetic methods and structure–property relationship of hyperblock. In this work, a degradable and cationic hyperblock with well-defined block subchain was prepared via seesaw-type macromonomer strategy. To improve the control of block subchain structure, degradable and pre-cationic block macromonomer with one alkynyl group in the chain middle and two azide groups at both chain ends, i.e. alkynyl -(PLA- b -PBocAEA-N 3 ) 2 , was deliberately designed and synthesized via the combination of ring-opening polymerization, atom transfer radical polymerization and azidation. After “click” polymerization, degradable and pre-cationic hyperblock of lhb -(PLA- b -PBocAEA) were achieved, which is further modified with PEG and confirmed the degradation property. Finally, degradable and cationic hyperblock lhb -(PLA- b -PAEA)-g-PEG was obtained by deprotection of amino groups. All the intermediates and products were confirmed by NMR, FT-IR and GPC measurements.