Abstract
A series of poly(hexamethylene 2,5-furanodicarboxylate)-block-poly(tetrahydrofuran) (PHF-b-F-pTHF) copolymers were synthesized using a two-stage procedure, employing transesterification and polycondensation. The content of pTHF flexible segments varied from 25 to 75 wt.%. 1H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses were applied to confirm the molecular structure of the materials. Differential scanning calorimetry (DSC), dynamic mechanical measurements (DMTA), and X-ray diffraction (XRD) allowed characterizing the supramolecular structure of the synthesized copolymers. SEM analysis was applied to show the differences in the block copolymers’ morphologies concerning their chemical structure. The influence of the number of flexible segments in the copolymers on the phase transition temperatures, thermal properties, as well as the thermo-oxidative and thermal stability was analyzed. TGA analysis, along with tensile tests (static and cyclic), confirmed the utilitarian performance of the synthesized bio-based materials. It was found that an increase in the amount of pTHF caused the increase of both number-average and weight-average molecular weights and intrinsic viscosities, and at the same time causing the shift of the values of phase transition temperatures toward lower ones. Besides, PHF-b-F-pTHF containing 75 wt.% of F-pTHF units was proved to be a promising thermoplastic shape memory polymer (SMP) with a switching temperature of 20 °C.
Highlights
Thermoplastic elastomers are widely used as soft materials in both industry and medicine
The most prominent representative of this type of materials is Hytrel® (Dupont, Wilmington, DE, USA), a whole group of copolymers where the rigid segment is based on poly(butylene terephthalate) (PBT) and the rubbery segment is polytetrahydrofuran, called poly(tetramethylene oxide) (PTMO)
The PHF and copolymers structure was investigated by means of Fourier transformed infrared spectroscopy (FTIR) spectroscopy
Summary
Thermoplastic elastomers are widely used as soft materials in both industry and medicine. One can find multi-blocks segmented poly(ether-ester)s (PEE)s as engineering thermoplastic elastomers due to their attractive combination of strength, cold-temperature flexibility, high entropy elasticity, melt stability, high crystallization rates, and many more [1,2]. Such great attention from many scientific groups results from the combination of rubber-like properties in the solid-state and melt processability [3]. The most prominent representative of this type of materials is Hytrel® (Dupont, Wilmington, DE, USA), a whole group of copolymers where the rigid segment is based on poly(butylene terephthalate) (PBT) and the rubbery segment is polytetrahydrofuran (pTHF), called poly(tetramethylene oxide) (PTMO). PolyTHF is primarily used as a component of thermoplastic polyurethanes, poly(ether-esters), and poly(ether-amides) [6]
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