Facile Strategy to Construct Metal–Organic Coordination Thermoplastic Starch with High Hydrophobicity, Glass-Transition Temperature, and Improved Shape Recovery

In this work, a new type of metal–organic coordination polymer (MOP) was developed with thermoplastic starch (TPS) by reactive extrusion with zinc acetate (ZA). The resulting material, denoted as TPS-ZA, showed interfacial and mechanical improvements compared with crude TPS, including low wettability, good shape memory, high heat resistance, and high strength. The high hydrophobicity of TPS-ZA is surprising considering that ZA added in the TPS is highly soluble in water. Morphology characterizations revealed that the improvements were related to the micro/nanohierarchical architectures induced by coordination-driven self-assembly. Marked improvement in glass-transition temperature (from 48 to 89 °C) and transition from hydrophilicity to hydrophobicity (water contact angle from 56 to 118°) are noted for TPS-ZA with a ZA content of only 3−5 wt %. Meanwhile, the novel cluster aggregates serving as netpoints endow TPS-ZA with significant improvement in shape memory, with nearly 180° recovery angle and 99% shape fixity. We hence showcase reactive extrusion here as a facile strategy to prepare MOP with properties more suitable for daily applications. The prepared TPS-ZA may serve as a multifunctional disposable plastic to replace petroleum-based plastic material and remedy the pollution of "microplastics".