A one pot synthetic method was developed for prepn. of amphiphilic block copolymers using episulfide anionic polymn. for generating sym. or asym. tri- or multi-block copolymers via living mechanism. The method is based on in situ generated thiolates, which ensures reproducibility of initiator concn. The mild character of the reactive species allows for incorporation of sensitive bioactive groups into the polymer structure. The polymers obtained are poly(ethylene glycol-propylene sulfide) diblocks (PEG-b-PPS) and sym. PEG-b-PPS-b-PEG triblocks. The method shows tolerance for impurities in reagents and in the one pot environment, which allows its use by operators with limited skills in org. synthesis. The PEG-b-PPS-b-PEG copolymers show lyotropic properties. [on SciFinder (R)]