Bioinspired Rubber Composites with Mechanical Robustness, Recyclability, and Shape Memory Properties

Vitrimers display great potential for application in various industries thanks to their high strength, reprocessability, and multi-functions. However, it is still quite a challenge to fabricate rubber vitrimers as the facile designs in reversible crosslinking networks are always critical. Herein, inspired by mussel byssus, heterogeneous coordination networks are constructed in nitrile butadiene rubber (NBR) to develop novel vitrimeric structures composed of metal-phenolic network (MPN) granules with dense zinc ions (Zn2+)-tea polyphenol (TP) bonds and a soft matrix containing few Zn2+-cyano group (CN) coordination bonds. The resulting NBR composites show tunable reinforcement simply by altering the amount of Zn2+ ions. The reversibility of complexations endows the composites with good plasticity, recyclability, and stable shape memory properties. Plasticity at high temperatures changes vitrimeric networks, producing larger and spindle-like MPN granules owing to their secondary self-assembly. Despite these variations, the vitrimeric composites still maintain engineering plasticity-based shape memory properties at a relatively large strain. Therefore, it is believed that the biomimetic strategies can well fabricate rubber composites with high strength, reprocessable, and shape-memory performance.