Synthesis and characterization of poly(hexamethylene 2,6-naphthalate)-block-poly(tetrahydrofuran) copolymers with shape memory effect

Abstract

Shape memory polymers (SMPs) are able to return to their previous shape after deformation under certain conditions. Several block copolymers can exhibit shape memory behavior. The blocks in copolymers are usually immiscible, which leads to phase separation into rigid and flexible segments. For that reason, these materials combine the mechanical properties of elastomers with the processing properties of thermoplastic. Thus, a poly(hexamethylene 2,6-naphthalate) (PHN) and a series of poly(hexamethylene 2,6-naphthalate)-block-poly(tetrahydrofuran) (PHN-b-N-pTHF) copolymers were synthesized via melt polycondensation. The content of the N-pTHF flexible segment varied from 15 to 50 wt.%. The materials were characterized with the use of Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), X-ray diffraction (XRD) analysis, the tensile tests (static and cyclic), and the cyclic thermo-mechanical analysis. The PHN-b-N-pTHF 50/50 was proved to be a promising thermoplastic shape memory polymer (SMP).