Synthesis and self-assembly of amphiphilic tadpole-shaped block copolymer with disulfides at the junction points between cyclic PEG and linear PS

Shell-sheddable polymeric assemblies are a type of self-assembled structures formed by amphiphilic block copolymers with cleavable linkages at the junction points. The shell-sheddable self-assemblies have been used as nanocarriers for drugs and inorganic nanoparticles. In this research, synthesis and self-assembly of amphiphilic tadpole-shaped block copolymer with disulfide bonds at the junction points were investigated. Dialkyne-terminated polystyrene (Da-PS) was synthesized by reversible addition-fragmentation chain transfer polymerization and thiol-disulfide exchange reaction. The tadpole shaped block copolymer was synthesized by bimolecular coupling between azido-terminated PEG and Da-PS. Size exclusion chromatograph, FTIR, H-1 NMR and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass analysis results all indicated successful synthesis of the polymer. The tadpole-shaped block copolymer self-assembles into vesicles in aqueous solution. The disulfide bonds at the junction points can be cleaved by a reducing agent, resulting in aggregation of the assemblies. (C) 2017 Elsevier Ltd. All rights reserved.