Multiblock copolymers were synthesized from an alpha,w-dicarboxy-oligododecanamide (PA12dC; (M) over bar(n) = 2095) and various alpha,w-dihydroxypolyethers ((M) over bar(n) = 1000-2000), especially, as copolyethers containing both polyoxyethylene and polyoxypropylene blocks. The polycondensation reaction was carried out in bulk at high temperature in the presence of Zr(OBu)(4) as catalyst. A kinetic study permitted one to compare the reactivity of the different oligoethers used with respect to PA12dC. The thermal properties, the structure and morphology of these poly(polyethers-block-polyamides) were characterized by DSC, TGA, DMA and solid-state C-13 NMR. DSC and DMA results show that the multiblock copolymers based on copolyethers exhibit a very high degree of phase separation and these soft blocks do not crystallize, whatever their length and composition. NMR results reveal that the crystalline polyamide phase adopts a structure (gamma-form) similar to that of the oligoamide precursor. (C) 2000 Elsevier Science Ltd. All rights reserved.