Native cellulose nanofibrils provide an attractive biocompatible material for preparing structured materials with wide applicability. Cellulose nanofibrils (CNFs) prepared using TEMPO oxidation carry surface carboxylate groups that can be utilized to interconnect the nanofibrils and form networked structures. In a previous study, we have shown the formation and functionlization of robust CNF hydrogels by the addition of monovalent transition metal ions. In the current study we will describe ionic bridging of nanofibril surface carboxylate groups with divalent and trivalent metal ions and the gelation of CNF aqueous dispersion. The driving force of gelation was proposed to be a screening effect of the repulsive potentials on the fibril surfaces by strong metal-carboxylate bonding, and the resultant interfibril interactionsmay be tuned by appropriate choice of cation. The storage moduli of the gels are strongly related to valency of the metal cations and their binding strength with carboxylate groups on the nanofibrils. Binding energies of cations with carboxylate groups were calculated from molecular models developed for nanofibril surfaces to validate the correlation and provide further insight into the crosslinked structures. The applications of the interconnected networks in composites and other fields will be briefly discussed.

Tuning interfibril interactions in cellulose nanofibril networks by cations

247th National Meeting (2014)

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