Here we combine the best aspects of native cellulose nanofibers (NFC) cleaved from plant cell walls and functionalized few-walled carbon nanotubes (CNT) aerogels in their hybrids in a synergistic manner. In more detail, we foresee that the mechanically excellent NFC nanofibers, as available from widely abundant sustainable plant-based sources and facile processes could be templates for functionalization by small weight fractions of CNT, thus combining the bulk availability of NFC and advanced electrical properties of CNT. Incorporating both NFC and CNT within the aerogels allows combining the attractive features of both components: the wide availability, easy processing, and sustainability of the NFC majority component and the advanced electrical properties of the CNT minority component.  We have described the first such hybrid aerogels, denoted here as hybrid nanofiber/nanotube aerogels, because both components have the tendency to form aerogels separately. The aerogels have been freeze-dried from aqueous hybrid gels. The hybrid nanofiber/nanotube aerogels are ductile, with reduced brittleness, as promoted by the particular native structure of NFC, which is retained by directly cleaving it from plant cell walls without dissolution steps. The aerogel morphology can be tuned by the freeze-drying process, as slow cooling by immersion of a hydrogel sample into liquid nitrogen leads to nanofiber aggregation into sheets, whereas quick cooling in liquid propane suppresses the sheet formation and allows fibrils in thin samples. They show elastic mechanical behavior in combination with reversible electrical response under compression allowing responsive conductivity and pressure sensing. We foresee that combining nanocellulosics and carbon nanotubes allows a wide variety of responsive electroactivity, pressure sensing, and functional materials, combining the best aspects of both nanofiber components even towards larger scale applications.

Modifying native nanocellulose aerogels with carbon nanotubes for mechanoresponsive conductivity and pressure sensing

247th National Meeting (2014)

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