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Shape memory thin films of polyurethane: Synthesis, characterization, and recovery behavior
Author(s) -
Dehaghani Maryam Zarghami,
Kaffashi Babak
Publication year - 2020
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.49547
Subject(s) - prepolymer , polyurethane , dynamic mechanical analysis , materials science , differential scanning calorimetry , fourier transform infrared spectroscopy , scanning electron microscope , glass transition , shape memory alloy , composite material , chemical engineering , polymer , physics , engineering , thermodynamics
Polyurethane thin films with inherent two phase segregated characters are exceptional candidates for the development of shape memory materials. However, controlling the phase behavior of such complex structures for decoding their recovery behavior still experiences its early stage of development. In this work, polyurethane thin films were synthesized based on two polyols, ester‐based polyols (ESP), and ether‐based polyols (ETP) together with diphenyl diisocyanate (MDI). The effects of ingredient ratio of PETP (ether‐based prepolymer)/PESP (ester‐based prepolymer) on the chemical structure and final properties of polyurethanes were studied by the Fourier‐transformed infrared spectroscopy (FTIR), the differential scanning calorimetry (DSC), the scanning electron microscopy (SEM), the dynamic mechanical thermal analysis (DMTA), a tensiometer, and the atomic force microscopy (AFM). The shape memory behaviors were explored by the thermomechanical cycles applied by a DMTA device in the controlled force mode. The PU films showed various properties compared with the bulk PU since they formed spherulitic textures with different structures. All the PU films except PU‐0 showed high shape recovery ca. 90% in the first cycle with a large glassy storage modulus in the range of 2,800–4,040MPa, and a recovery ratio enhanced by increasing the number of cycle to a maximum of 95%.