Multifunctional conductive graphite/cellulosic microfiber-natural rubber composite sponge with ultrasensitive collision-warning and fire-waring

Design and development of the conductive polymer composite sponges with multifunctionality are urgently needed to expand and meet their application in multiple fields. Herein, we proposed an ingenious strategy to fabricate the graphite (GP)/cellulosicmicrofiber (CMF)-natural rubber (NR) composite sponges though freezing at low temperature (to build the skeleton structure of sponge) and vulcanizing at high temperature (to form the pores and fix the skeleton structure of sponge). Meanwhile, the incorporation of CMF can help GP to disperse uniformly in NRL and form an entire conductive network. As results shown, GP/CMF-NR composite sponge exhibits the excellent compressive property and electrical conductivity due to the good elasticity of NR and the support strength of CMF. Significantly, GP/CMF-NR composite sponge has been successfully used as a piezoresistive sensor to detect human motions (such as fingers/wrists/elbows/knees movement), and GP/CMF-NR composite sponge also can be used as a collision warning sensor to warn the collision in a moment and protect the things from damage at some extent. More importantly, when being attacked by fires, GP/CMF-NR sponge also can be used as a fire-warning sensor with the sensitive fire-warning response time, which triggered a fire-warning lamp within 1.2 s. This investigation provides a convenient and environmentally friendly strategy for fabricating conductive natur rubber sponges and has promising applications in the field of piezoresistive sensors and fire-warning sensors.