Biomimetic ultra-strong, ultra-tough, degradable cellulose-based composites for multi-stimuli responsive shape memory

Fabrication of ultra-strong, ultra-tough, sustainable, and degradable bio-based composites is urgently needed but remains challenging. Here, a biomimetic sustainable, degradable, and multi-stimuli responsive cellulose/PCL/Fe 3 O 4 composite with ultra-strong mechanical strength and ultra-high toughness was developed. To prepare the proposed composites, the soft poly(ε-caprolactone) (PCL) side chain was grafted onto the rigid cellulose backbone, then the cellulose graft copolymer (EC- g -PCL) reacted with rigid hexamethylenediamine modified Fe 3 O 4 nanoparticle (Fe 3 O 4 -NH 2 ) to construct the crosslinking network using MDI-50 as a crosslinker. Given by the construction of crosslinking network and the “hard” and “soft” interactive structure, the composites showed ultra-strong mechanical strength (25.7 MPa) and ultra-high toughness (107.0 MJ/m 3 ), and the composite specimen could lift a weight of approximately 21,200 times its mass. The composites also exhibited rapid degradation ability with high degradation efficiency. In addition, the composites showed excellent thermal responsive shape memory property with a shape recovery ratio above 96 %. Most importantly, the Fe 3 O 4 nanoparticles endowed the composites with photothermal conversion property, the composites exhibited superior NIR light-triggered shape memory capability. The EC- g -PCL/Fe 3 O 4 composites with ultra-strong mechanical strength and ultra-high toughness have promising applications in heavy-lift, object transportation, and self-tightening knots.