Sustainable Supramolecular Plastics Usable Under High Humidity: Cross-Linking Strategy Enabled by Hydrogen Bonding and Coordination Interactions

It remains a great challenge to prepare sustainable plastics with good mechanical properties, water resistance, and recyclability. Herein, an organic–inorganic hybrid network cross-linked by reversible and dynamic bonds is proposed. Calcium phosphate oligomers as inorganic components are polymerized into ordered nanochains under the regulation of syringaldehyde-grafted poly(vinyl alcohol) and lignin. Density functional theory simulations reveal the presence of high-density hydrogen and coordination bonds in the structure, which can be preferentially broken as sacrificial bonds to dissipate energy, resulting in the tunable and robust mechanical properties of the supramolecular plastics. Even at 70% relative humidity, the plastics exhibit good mechanical performances with a tensile strength of 59 MPa and a toughness of 103 MJ/m3, which are superior to some common bioplastics and reported moisture-resistant plastics. The water molecules break only a small portion of the sacrificial bonds, so the plastics show good water resistance and form stable and tough elastomers when immersed in water. Impressively, these robust plastics exhibit reprocessing potential without losing their original mechanical performance. Also, the plastics exhibit 99.9% UV-shielding efficiency and harsh environmental durability. With these advantageous features, this work unveils a new avenue for the development of sustainable and promising polymeric materials.