Bio-inspired dual crosslinked network mediated by plant polyphenols for toughening natural rubber latex-based elastomeric composites

Elastomeric composites comprising natural fiber and natural rubber latex (NRL) have immense potential as substrates for making soft smart materials owing to their remarkable flexibility, barrier properties, lightweight nature, and softness. However, most natural fibers have inadequate interfacial compatibility with NRL matrix, which affects the mechanical properties and scalable production of these composites. Efforts to improve their compatibility generally involve complex processes or incorporation of numerous petroleum-derived chemical additives. In this study, inspired by special adhesive structure of marine mussels, a convenient and low energy consumption method for fabricating high-performance NRL-based soft smart materials was developed by using bayberry tannin, the plant polyphenols, to modify leather collagen fibers (LCFs). As a multifunctional modifier, the bayberry tannin on fiber surface forms hydrogen bonds with the allyl hydrogens in the molecular chain of NRL and participates in the covalent crosslinking reaction during vulcanization to achieve a dual crosslinked network that enhances the interfacial compatibility between LCFs and NRL. The phenolic hydroxyl groups of bayberry tannin also effectively scavenge free radicals and enhance the aging resistance of the composite. Compared to pure NRL, the developed composite exhibited substantial improvements in tensile strength (16.56 MPa, increased by160%), elongation at break (550%, increased by28%) and fracture toughness (34.12 MJ/m3, increased by 230%) at a fiber content of 5%. Therefore, this paper introduces a fresh perspective on fabricating high-performance NRL-based soft materials for smart applications and proposes a novel approach for the valueadded utilization of collagen solid waste.