Synthesis and characterization of poly(copolyethers-block-polyamides) II. Characterization and properties of the multiblock copolymers

Multiblock copolymers were synthesized from an alpha,w-dicarboxy-oligododec anamide (PA12dC; (M) over bar(n) = 2095) and various alpha,w-dihydroxypolye thers ((M) over bar(n) = 1000-2000), especially, as copolyethers containing both polyoxyethylene and polyoxypropylene blocks. The polycondensation rea ction 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 o f the different oligoethers used with respect to PA12dC. The thermal proper ties, the structure and morphology of these poly(polyethers-block-polyamide s) were characterized by DSC, TGA, DMA and solid-state C-13 NMR. DSC and DM A results show that the multiblock copolymers based on copolyethers exhibit a very high degree of phase separation and these soft blocks do not crysta llize, whatever their length and composition. NMR results reveal that the c rystalline polyamide phase adopts a structure (gamma-form) similar to that of the oligoamide precursor. (C) 2000 Elsevier Science Ltd. All rights rese rved.