Robust Self-Healable and Three-Dimensional Printable Thermoplastic Elastomeric Waterborne Polyurethane for Artificial Muscle and Biomedical Scaffold Applications

Abstract

Waterborne polyurethanes (WPUs) with smart attributeslike self-healing and shape-memory, reprocessability, and excellentintegrated mechanical properties are the key connotations for advancedapplications. Congenitally, these properties are associated with conflictingfeatures, which makes it puzzling to optimize these paradoxical propertiesin a single material. Herein, this study introduces an easy but impactfulstrategy to answer this dilemma, which is based on the triple synergisticeffect of ‘dynamic hard domains (2-aminophenyl disulfide, 2-APDS)’,‘asymmetric IPDI-IPDA (isophorone diisocyanate-isophorone diamine)architecture’, and ‘shape memory effect (SME)’. The loosely packed IPDI-IPDA moieties and the SME promote the reversible S−S metathesisreactions, resulting in high healing efficiency as well as mechanical strength,simultaneously. Based on this tactic, a series of robust self-healable WPUs (SHWPUs) was synthesized with good healing efficiency(70.22−79.94%), shape recovery (88.4−97.4%), excellent mechanical strength (16.09−26.23 MPa), high elongation at break(1604−2071%), outstanding toughness (188.3−216.6 MJ m−3), high fracture energy (46.74−66.33 kJ m−2), biocompatibility, andbiodegradability. Outstandingly, a SHWPU film could lift a dumbbell of 25 kg, which is 53,648 times heavier than its own weightwithout any crack. Taking advantage of good shape recoverability, the elastomer was tested for “artificial muscle” contraction.Impressively, the SHWPU-1 film could vertically and successfully lift a 100 g load, which is 251.19 times heavier than its weightunder ambient conditions. Moreover, a series of 3D printable gelatin/SHWPU-2 inks were prepared, which possess the potential forbone scaffolds. Additionally, this thermoplastic SHWPU could be reprocessed at 80 °C under 60−80 kg cm−2 pressure. Thus, theSHWPU elastomer exhibited all characteristics of advanced materials with smart attributes and eco-friendly nature.