Reversible Bidirectional Shape Memory Effect in Polyurethanes through Molecular Flipping

Abstract

Reversible bidirectional shape memory is developed in thermoplastic polyurethane by designing different components to enable molecular switching from actuator domain to self-assembled rigid hard domain and vice versa under a temperature cycle. Polycaprolactone based special polyurethanes have been synthesized which exhibit appropriate self-assembly behavior suitable for the shape memory effect. Reversible bidirectional shape memory has been reported through induced strain and giving shape at particular temperature, and the results are compared with conventional polyurethanes which do not show any shape memory effect. The correlation between chemical structures, self-assembly, structural evolution, and shape memory effect has been made. Self-gripping is demonstrated revealing the novel mechanism of molecular flipping and temperature-induced structural change along with molecular aggregation. © 2016 American Chemical Society.