Nanofibrillated Cellulose (NFC) consists of long, flexible and interconnected cellulose nanofibers, with diameters from 10 to 100 nm and aspect ratios from 50 to 100 (Figure 1a). NFC is generally isolated from the cellulose pulp using a mechanical disintegration process in water, which generates a suspension containing entangled hydrophilic cellulose I nanofibers. The subsequent replacement of water with air using freeze-drying gives rise to a sponge, also called foam or aerogel, with an architecture displaying long and entangled cellulose I nanofibers. Nevertheless, the scope of applications of the sponges is often restricted, due to the single functionality present on the cellulosic nanofibers and the strong hydrophilic character of the porous materials.1-4 Here, we present an innovative silylation process in water to efficiently synthesize NFC sponges with tailored properties and to further broaden the application fields of the neat sponges. The highly porous (≥ 99 %) sponges are engineered by freeze-drying water suspensions of NFC in presence of alkoxysilane molecules (Figure 1b). Two examples are presented using methyltrimethoxysilane and 3-aminopropyltriethoxysilane as modifying agents, leading to functional sponges with possible applications in oil-water separation5 and CO2 capture6, 7, respectively. The sponges have been systematically characterized with Scanning Electron Microscopy (SEM), elemental analysis, solid-state Nuclear Magnetic Resonance (NMR) spectroscopy (CP-MAS 13C and 29Si) and X-Ray Photoelectron spectroscopy (XPS). References 1. Aulin et al., Soft Matter 2010, 6 (14), 3298. 2. Paakko et al., Soft Matter 2008, 4 (12), 2492. 3. Siro and Plackett, Cellulose 2010, 17 (3), 459 4. Tingaut et al., In Handbook of Green Materials: Processing Technologies, Properties and Applications 2014; Vol. 1. 5. Zhang et al., Chem. Mater. 2014, 26 (8), 2659 6. Gebald et al., Env. Sci. Technol., 2013, 47 (17), 10063 7. Gebald et al., Env. Sci. Technol. 2011, 45, (20), 9101

Synthesis of functional sponges from nanofibrillated cellulose using a silylation process in water

249th National Meeting (2015)

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