Structure and properties of new polyester elastomers composed of poly(trimethylene terephthalate) and poly(ethylene oxide)

Series of PTT-b-PEO copolymers with different composition of rigid PTT and PEO flexible segments were synthesized from dimethyl terephthalate (DMT), 1,3-propanediol (PDO), poly(ethylene glycol) (PEG, M-n = 1000 g/mol) in a two stage process involving transesterification and polycondensation in the melt. The weight fraction of flexible segments was varied between 20 and 70 wt%. The molecular structure of synthesized copolymers was confirmed by H-1 NMR and C-13 NMR spectroscopy. The superstructure of these polymers was characterized by DSC, DMTA, WAXS and SAXS measurements. It was observed that domains of three types can exist in PTT-b-PEOT copolymers: semi-crystalline PTT, amorphous PEO rich phase (amorphous PEO/PTT blended phase) and semi-crystalline PEO phase. Semi-crystal line PEO phase was observed only at temperature below 0 degrees C for sample containing the highest concentration of PEO segment. The phase structure, thermal and mechanical properties are effected by copolymer composition. The copolymers containing 30-70 wt% of PEO segment posses good thermoplastic elastomers properties with high thermal stability. Hardness and tensile strength rise with increase of PTT content in copolymers. (C) 2009 Elsevier Ltd. All rights reserved.