A new family of biohybrid materials has been developed by the assembly of two types of naturally occurring materials with fibrous morphology, the fibrous clay mineral sepiolite and cellulose nanofibers (CNF) obtained from eucalyptus pulp. The appropriate integration of both types of nanofibers has been attained by homogenization processes using high-shear mechanical treatments followed by ultrasonic irradiation in aqueous media, thus achieving very stable gels. These gels can be easily conformed by casting or vacuum filtration as thin films, which can be considered as hybrid nanopapers. From FTIR spectroscopy it can be deduced hydrogen bonding interactions between hydroxyl groups in CNF and Si-OH located at the surface of sepiolite. As a result of the interaction of both types of fibers, the resulting final materials became present as uniform films with a considerable degree of transparency, exhibiting properties such as modification of the hydrophilic character, improvement of thermal behavior and enhancement of mechanical properties of the cellulose matrix. An interesting characteristic of the hybrid nanopapers is the capacity to be functionalized enlarging its potential applications. In this way, the incorporation of diverse nanoparticulated materials during the gel preparation step, as for instance MWCNTs, provides conductive nanocomposite films, which can act as active phase in sensor devices. The incorporation of magnetite nanoparticles provided magnetic properties to the biohybrid material and the addition of zinc oxide nanoparticles allowed obtaining hybrids that present photocatalytic activity useful for the degradation of organic pollutants. It has been clearly shown that the role of sepiolite present in the biohybrid is essential to promote the immobilization of the diverse nanoparticules. These results open the way to new nanocomposite materials that could be modified by incorporation of nanoparticles of diverse nature or by adding other functional species through post-synthesis grafting reactions with the hydroxyls belonging to both types of fibrous components.

Functional bionanocomposites based on the assembly of sepiolite and cellulose nanofibers

255th National Meeting (2018)

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