Water‐in‐oil Emulsions Stabilized by Hydrophobized Microfibrillated Cellulose

Abstract

The properties of water‐in‐toluene emulsions stabilized solely by hydrophobized microfibrillated cellulose (MFC) were investigated. By varying the degree of surface substitution (DSS), the wettability of the MFC was altered. All emulsions prepared with MFC displayed excellent stability to coalescence. The stability to gravity‐induced sedimentation increased with increasing MFC concentration, the highest stability being obtained with MFC of moderate hydrophobicity. Drop sizes increased with increasing DSS, with a corresponding decrease in stability to sedimentation. An increase in the toluene:water ratio at constant MFC concentration resulted in a decrease in the average drop size. For all emulsions, the polydispersity in drop size decreased with decreasing average drop diameter. Keywords: Pickering emulsionsmicrofibrillated cellulose (MFC)hydrophobicationwater‐in‐oil emulsionsparticle wettability We would like to thank the Nanomat Research Programme of the Norwegian Research Council for a grant to fund M.A. Södra Cell, Borregaard, Akzo Nobel and Domsjø Fabriker are also gratefully acknowledged for financial support. Bjørn Steinar Tanem at Sintef Materials and Chemistry is acknowledged for TEM analyses. The Norwegian Paper and Fibre Research Institute is thanked for providing the MFC.