Nanocellulose based ultra-elastic and durable foams for smart packaging applications

Foams with advanced sensing properties and excellent mechanical properties are promising candidates for smart packaging materials. However, the fabrication of ultra-elastic and durable foams is still challenging. Herein, we report a universal strategy to obtain ultra-elastic and durable foams by crosslinking cellulose nanofiber and MXene via strong covalent bonds and assembling the composites into anisotropic cellular structures. The ob-tained composite foam shows an excellent compressive strain of up to 90 % with height retention of 97.1 % and retains around 90.3 % of its original height even after 100,000 compressive cycles at 80 % strain. Their cush-ioning properties were systematically investigated, which are superior to that of wildly-used petroleum-based expanded polyethylene and expanded polystyrene. By employing the foam in a piezoelectric sensor, a smart cushioning packaging and pressure monitoring system is constructed to protect inner precision cargo and detect endured pressure during transportation for the first time.