Bio-based polyurethanes with shape memory behavior at body temperature: effect of different chain extenders

Abstract

In this work, a series of bio-based shape memory polyurethanes were synthesized from polylactide copolymer diols, isophorone diisocyanate (IPDI) and chain extenders, in which the chain extenders are used to adjust their transition temperatures and shape memory properties. These bio-based polyurethanes (bio-PUs) show a T_g in the range of 28.7–34 °C, which is very closed to the body temperature and can be adjusted by the carbon chain length of the chain extenders. Moreover, they have low Young's modulus (34.7 MPa) and high elongation (434.0%). Through a series of shape memory tests, the bio-PUs exhibit good shape memory behavior at the body temperature with a shape recovery rate greater than 90%. Especially, the bio-PU from 1,4-cyclohexanedimethanol (CHDM) with a non-planar ring structure displays the highest shape recovery rate, which may be because CHDM in the hard segments acts as a “molecular spring”. Therefore, these shape memory bio-PUs are expected to have many practical applications in medical devices.