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 obtained 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 cushioning 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.