Solvent-Free One-Shot Synthesis of Thermoplastic Polyurethane Based on Bio-Poly(1,3-propylene succinate) Glycol with Temperature-Sensitive Shape Memory Behavior.

Abstract

In this work, a new family of fully biobased thermoplastic polyurethanes (TPUs) with thermo-induced shape memory is developed. First, a series of TPUs were successfully synthesized by the one-shot solvent-free bulk polymerization of bio-poly(1,3-propylene succinate) glycol (PPS) with various molecular weights (Mn = 1000, 2000, 3000, and 4000), 1,4-butanediol (BDO), and 4,4′-methylene diphenyl diisocyanate (MDI). These polyurethanes (PUs) are denoted as PPS-x-TPUs (x = 1000, 2000, 3000, and 4000), where x represents the Mn of PPS in the polymers. To determine the effect of the molecular weight of the soft segment of PU, all PPS–TPUs were formed with the same hard segment content (32.5 wt %). The soft segment with high molecular weight in PPS-4000-TPU caused a high degree of soft segment entanglement and formed many secondary bonds. PPS-4000-TPU exhibited better mechanical (tensile strength: 64.13 MPa and hardness: 90A) and thermomechanical properties (maximum loading: 2.95 MPa and maximum strain: 144%) than PPS-1000-TPU. At an appropriate shape memory programming temperature, all synthesized PPS-x-TPUs exhibited excellent shape memory behaviors with a fixed shape rate of >99% and a shape recovery rate of >86% in the first round and 95% in the following rounds. Therefore, these bio-TPUs with shape memory have potential for use in smart fabrics.