Adjusting shape-memory properties of amorphous polyether urethanes and radio-opaque composites thereof by variation of physical parameters during programming

摘要

Various composites have been prepared to improve the mechanical properties of shape-memory polymers (SMPs) or to incorporate new functionalities (e.g.magneto-sensitivity) in polymer matrices. In this paper, we systematically investigated the influence of the programming temperature T_(prog) and the applied strain ε_m as parameters of the shape-memory creation procedure (SMCP) on the shape-memory properties of an amorphous polyether urethane and radio-opaque composites thereof. Recovery under stress-free conditions was quantified by the shape recovery rate R_r and the switching temperature T_(sw), while the maximum recovery stress σ_(max) was determined at the characteristic temperature T _(σ, max) under constant strain conditions. Excellent shape-memory properties were achieved in all experiments with R_r values in between 80 and 98%. σ_(max) could be tailored from 0.4 to 3.7MPa. T_(sw) and T_(σ, max) could be systematically adjusted from 33 to 71 °C by variation of T_(prog) for each investigated sample. The investigated radio-opaque shape-memory composites will form the material basis for mechanically active scaffolds, which could serve as an intelligent substitute for the extracellular matrix to study the influence of mechanical stimulation of tissue development.