Scientists from the CSIC’s Institute de Ciencia de Materials de Barcelona (ICMAB) have developed a new concept for functional nanomaterials. It is a multilaminated material, a ‘millefeuille’ made of bacterial cellulose layers strongly attached. Each layer can have incorporated a different type of functional nanoparticle. This laminated material can be very thin: for example, the thickness of a four layer milfeuille is only the half of a conventional sheet paper.

A drawing of this multilaminated material (ICMAB-CSIC).There is a growing demand from industry for flexible nanocomposites, which can react to some external factor, such as light or a magnetic field, and where nanoparticles can be added and controlled their properties and distribution.

Anna Roig and her team, at the Institute de Ciencia de Materials de Barcelona (ICMAB) of the CSIC, ave developed a new concept for these nanocomposites. They have created a multilaminated material, a ‘millefeuille’ made of bacterial cellulose layers which are strongly attached. Each layer can have a different type of functional nanoparticle.

The cellulose is obtained in vitro by Komagataeibacter xylinus (K. xylinus), one of the most efficient microrganisms for this task. The bacteria are in an aqueous culture enriched with glucose, where they produce the cellulose fibrils interwoven to form a flat film.

Once the diferrent layers of ultra-pure nanocellulose are produced, nanoparticles can be anchored to them. Each type of nanoparticle provides the nanocellulose with a specific function. In the experimental work, whose results have been published in the Nanoscale Horizons journal, the team added nanoparticles of two metals (gold and silver) and two semiconductors (titanium oxide and iron oxide).

The millefeuille concept expands the possibilities for integrating several nanotechnologies in a single material;  materials can be freely designed,  virtually ‘à la carte’

As there is an adhesión process during drying, after drying two films become a multifunctional single layer thicker, but also flexible and  adaptable to different geometries.  

Among renewable biopolymers, cellulose deserves special consideration since it is the most abundant one. Flexible and nanoporous cellulose facilitates the interaction of nanoparticles with the surroundings, their handling and recycling.

The millefeuille concept based on nanocellulose expands the possibilities for integrating several nanotechnologies in a single material. The laminated material can be freely designed, adding layers or nanoparticles virtually ‘à la carte’. This new material could find applications in sensors, or nanostructured devices.

For this research, the Department of Fiber and Polymer Technology del Royal Institute of Technology has participated in the characterization of the multilaminated  mechanical properties and the group of Simulation and Theory of the ICMAB-CSIC has modelled cellulose nanofibers interaction.

Nanocellulose films with multiple functional nanoparticles in confined spatial distribution Soledad Roig-Sanchez, Erik Jungstedt, Irene Anton-Sales, David C. Malaspina, Jordi Faraudo, Lars Berglund, Anna Laromaine and Anna Roig. https://pubs.rsc.org/en/content/articlelanding/2019/nh/c8nh00310f#!divAbstract