As a mimetic nanostructure of liposomes,polymersomes,i.e.,vesicles composed of amphiphilic block copolymers,have attracted a lot of attention in the field of drug delivery and controlled release.Poly(ethylene glycol) (PEG) is a common choice as the hydrophilic block of copolymers that selfassemble into vesicles.Polysarcosine (PSar) is a non-ionic and water-soluble polypeptoid withcomparable properties to those of PEG.