A novel class of hydrophobic cellulose materials: lightweight xerocellulose

International audienceNowadays the urge to find and create new alternatives for sustainable utilisation and use of renewable materials is greater than ever. In view of these circumstances cellulose, as renewable resource, is considered a promising material which could help to provide a possible solution for this quest we are facing momentarily. The development of novel cellulosic materials with high added value is thus of great interest. Aerocellulose, an aerogel-like highly porous and ultra-light cellulose, is a new material recently developed in our laboratory1,2. Aerocellulose density is around 0.05-0.2 g/cm3, with pore sizes varying from a few nanometres to a few microns and rather high specific surface of 200-300 m2/g. It is prepared via cellulose dissolution followed by coagulation and drying with supercritical CO2. Drying under supercritical conditions is needed to minimize pore collapse and cellulose densification. Potential Aerocellulose applications can vary from biomedical, pharmaceutical and cosmetics to thermal insulation and electrochemical (when pyrolysed)3. However, for some applications cellulose hydrophilicity may cause serious problems. Additionally, the process of drying via supercritical CO2, even if very efficient, is rather time consuming, necessitates quite huge investment and could also present difficulties in terms of large scale utilisation if, for example, some continuous production of monolithic materials is required. Within this paper we are introducing a brand new form of highly porous cellulose, so-called Xerocellulose, made from hydrophobically modified cellulose. Associated functionnalization allows drying under ambient pressure at room temperature without sample high contraction and thus avoiding drying in supercritical conditions. Furthermore, due to hydrophobisation, we were also able to reduce water vapours adsorption capacity significantly. The route of cellulose ambient-dried preparation and the influence of cellulose concentration and of degree of substitution (DS) on Xerocellulose density, morphology and water adsorption capacity will be presented and discussed