Multifunctional carbon nanotube (CNT)–cellulose films were fabricated by dissolving cellulose and dispersing CNTs homogeneously in aqueous alkaline–urea solution. We found that the resulting composite films with 2–10 wt% CNTs have both normal flexible paper and conducting CNT characteristics, which show a volume resistivity that can be controlled over a wide range of 1.35–540 Ohm cm. The composite films achieved multifunctional sensing ability for monitoring stress–strain, temperature and humidity. Both the mechanical properties and thermal stabilities of the composite films with CNTs were enhanced. This work provided a novel and simple pathway to regenerate cellulose films with carbon nanotubes as multifunctional biomaterials for electronic, magnetic, semiconducting and biotechnological applications.

The current paper provides an overview to emphasize the role of functionalization of multiwalled carbon nanotubes (MWCNTs) in manipulating cure kinetics of epoxy nanocomposites, which itself determines ultimate properties of the resulting compound. In this regard, the most commonly used functionalization schemes, that is, carboxylation and amidation, are thoroughly surveyed to highlight the role of functionalized nanotubes in controlling the rate of autocatalytic and vitrification kinetics. The current literature elucidates that the mechanism of curing in epoxy/MWCNTs nanocomposites remains almost unaffected by the functionalization of carbon nanotubes. On the other hand, early stage facilitation of autocatalytic reactions in the presence of MWCNTs bearing amine groups has been addressed by several researchers. When carboxylated nanotubes were used to modify MWCNTs, the rate of such reactions diminished as a consequence of heterogeneous dispersion within the epoxy matrix. At later stages of curing, however, the prolonged vitrification was seen to be dominant. Thus, the type of functional groups covalently located on the surface of MWCNTs directly affects the degree of polymer‐nanotube interaction followed by enhancement of curing reaction. Our survey demonstrated that most widespread efforts ever made to represent multifarious surface‐treated MWCNTs have not been directed towards preparation of epoxy nanocomposites, but they could result in property synergism.

Smart multi-walled carbon nanotube (MWCNT)-coated cellulose fibers with a unique sensing ability were manufactured by a simple dip coating process. The formation of electrically-conducting MWCNT networks on cellulose mono- and multi-filament fiber surfaces was confirmed by electrical resistance measurements and visualized by scanning electron microscopy. The interaction between MWCNT networks and cellulose fiber was investigated by Raman spectroscopy. The piezoresistivity of these fibers for strain sensing was investigated. The MWCNT-coated cellulose fibers exhibited a unique linear strain-dependent electrical resistance change up to 18% strain, with good reversibility and repeatability. In addition, the sensing behavior of these fibers to volatile molecules (including vapors of methanol, ethanol, acetone, chloroform and tetrahydrofuran) was investigated. The results revealed a rapid response, high sensitivity and good reproducibility for these chemical vapors. Besides, they showed good selectivity to different vapors. It is suggested that the intrinsic physical and chemical features of cellulose fiber, well-formed MWCNT networks and favorable MWCNT-cellulose interaction caused the unique and excellent sensing ability of the MWCNT-coated cellulose fibers, which have the potential to be used as smart materials.

Aerogels composed of carbon nanotubes (CNTs) and cellulose were fabricated by the flash freezing/lyophilization process using wet-gel precursors, which were regenerated from a homogeneous dispersion of CNTs and cellulose in alkaline–urea aqueous solution. The morphology and textural properties of the resultant composite aerogels were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and nitrogen adsorption–desorption tests. All the prepared materials exhibited both a nanostructured solid network (specific surface areas between 140 and 160 m² g⁻¹) and a nanoporous network (including macropores, mesopores and micropores). The results from thermogravimetric analysis and tensile tests revealed that the composite aerogels have good thermal stability and excellent mechanical properties, respectively. The Young's modulus of the composite aerogels could be tuned to reach about 90 MPa. And composite aerogels with 3–10 wt% CNTs have a conductivity of about 2.3 × 10⁻⁴ to 2.2 × 10⁻² S cm⁻¹, with the conductivity threshold at MWCNT volume fractions being as low as 3 × 10⁻³. Furthermore, these cellulose–CNT composite aerogels showed good sensitivity to ambient pressure.