Tailoring the properties of nanocellulose-sepiolite hybrid nanopapers by varying the nanocellulose type and clay content

Abstract

The development of nanocellulose-clay materials resulted of great relevance, as it opened up the applications of nanocellulose, but it still requires new approaches that could contribute to improve the preparation procedures and the features of this type of biohybrid materials. In this context, nanocellulose-sepiolite (NC-S) biocomposite foams and films have already been successfully tested for some applications. However, the influence of the nanocellulose properties on sepiolite-cellulose interactions, and consequently on the final properties and potential applications of NC-S biohybrid materials, has not been previously studied. To address this knowledge gap, four kinds of nanocelluloses produced from elm biomass (non-chemically pretreated lignocellulose and bleached cellulose nanofibers (LCNFs and CNFs, respectively), TEMPO-oxidized cellulose nanofibers (TOCNFs) and cellulose nanocrystals (CNCs)) were characterized and used to develop NC-S nanopapers. A stronger interaction was found between sepiolite and negatively charged nanocelluloses (TOCNFs and CNCs), improving their thermal stability and mechanical properties by increasing the sepiolite content. Furthermore, the type of nanocellulose and the sepiolite content could be adjusted to tune the flammability, water permeability and mechanical and optical properties of the NC-S nanopapers.Graphical abstract