Synthesis and self‐assembly of helical polypeptide‐random coil amphiphilic diblock copolymer

Three amphiphilic rod‐coil diblock copolymers, poly(2‐ethyl‐2‐oxazoline‐ b ‐γ‐benzyl‐ L ‐glutamate) (PEOz‐ b ‐PBLG), incorporating the same‐length PEOz block length and various lengths of their PBLG blocks, were synthesized through a combining of living cationic and N ‐carboxyanhydride (NCA) ring‐opening polymerizations. In the bulk, these block copolymers display thermotropic liquid crystalline behavior. The self‐assembled aggregates that formed from these diblock copolymers in aqueous solution exhibited morphologies that differed from those obtained in α‐helicogenic solvents, that is, solvents in which the PBLG blocks adopt rigid α‐helix conformations. In aqueous solution, the block copolymers self‐assembled into spherical micelles and vesicular aggregates because of their amphiphilic structures. In helicogenic solvents (in this case, toluene and benzyl alcohol), the PEOz‐ b ‐PBLG copolymers exhibited rod‐coil chain properties, which result in a diverse array of aggregate morphologies (spheres, vesicles, ribbons, and tube nanostructures) and thermoreversible gelation behavior.