Multilayer polymer structure comprising at least one couple of adjacent layers (L1-L2), characterized in that: layer (L1) comprises at least one polymer composition (C1) comprising at least one semi-crystalline polyphthalamide and at least one impact modifier (I1), and layer (L2) comprises at least one polymer composition (C2) comprising at least one functionalized polyolefin (FPO2), said functionalized polyolefin comprising functional groups chosen from carboxylic groups, their esters, their anhydrides and their salts. Process for manufacturing said multilayer structure, which comprises co-extruding polymer compositions (C1) and (C2) so as to obtain couple of adjacent layers (L1-L2). Shaped article comprising the invented multilayer structure and process for manufacturing the shaped article.