Display omitted •New PLLA-based copolymers with ABA architecture have been successfully synthesizied.•Copolymerization of PLLA leads to better mechanical and barrier properties.•The B aliphatic central block facilittes compostability process. Novel poly(lactic acid)-based chain extended triblock copolymers have been successfully synthesized in melt. The new polymers are characterized by a triblock ABA architecture, where A, is poly(lactic acid) and B is an ad hoc synthesized random biobased aliphatic copolyester poly(propylene/neopentyl glycol succinate). PLLA homopolymer has been also prepared for the sake of comparison. The samples under study were deeply characterized from the molecular, thermal and structural point of view. Mechanical and barrier properties and compostability were also investigated, in order to assess the potentiality of these materials in food packaging applications. The results obtained show that copolymerization leads to better mechanical response and barrier properties with respect to poly(lactic) acid homopolymer. Moreover, the presence of the central B block in the main polymer chain facilitates the process of compostability.