Stretchable, Strong, Recyclable Helicide Elastomer Based on Dynamic Covalent Interactions

Abstract

Current methods for making and disposing synthetic polymers have been widely pursued and are largely unsustainable. As a part of the solution, the reversible nature of dynamic covalent bonds emerges as an extraordinarily diverse and valuable feature in the development of exotic molecules and extended structures. With these bonds, it should be possible to construct recyclable and mechanically interlocked molecular structures using relatively simple precursors with preorganized geometries. A new helicide-based elastomer network is developed here with self-healing, recycling, and degradation features using a similar concept. The best self-healing performance (100%) was noted over 10–20 min, with various H2O, HCl, and NaOH solutions that delivered mechanical properties in the 1–1.4 MPa range. For hydrolytic degradation, the parameters are defined based on the type of binding, the pH of the solutions, and the copolymer network, which endowed a degradation time of approximately 4–11 h for each prepared sample. However, due to the reversible nature of the dynamic bonds, the material showed good recyclable mechanical properties compared to the pristine samples after five consecutive cycles, which meet the requirements of recyclable materials and recyclable packaging.

Endowing Polyurethane with Degradability via a Cleavable Bis(cyclohexanone) Oxalyldihydrazone Structure for Adhesive Detachment

“…It can be found that the adsorption peak at 3299 cm –1 , assigned to the N–H bond stretching vibration, exhibits only a little change after degradation, when the C–O stretching peak observed at 1084 cm –1 is used as an internal standard. However, the intensity and the width of the adsorption peak at 1725 cm –1 , which is attributed to the CO bond stretching vibration, decline after degradation. , These results reveal that the bis­(cyclohexanone) oxalyldihydrazone structures in SPU were decomposed after degradation, while the urethane linkages in SPU were stable through the degradation conditions.…”