During the last decade there has been a huge interest in new materials from nanocellulosic either in the form of cellulose nano crystals (CNC) or cellulose nanofibrils (CNF)1. The interest is partly based on our urgent need for renewable raw materials in today’s society and partly on new efficient production methods both for CNC and CNF. However, both the CNC and the CNF are prepared at very low solids concentration and their handling and conversion to final materials poses significant challenges. We have shown that it is possible to prepare strong, low density CNF foams using solids concentration between 1 and 10 g/l. To do this we have used a pickering foam technique where surface modified CNFs are used to stabilize air bubbles which become so stable that they can be dried with a maintained structure. By using fluorescently labelled CNF and high speed photography it was shown that the fibrils do concentrate at the air/water interface and that they are able to stabilize two air bubbles forced together. On a more fundamental level our results also show that the accumulation of the CNFs at the air/water interface both increases the complex viscoelastic modulus of the interfaces and decreases the interfacial tension. It is also demonstrated that the aspect ratio of the particles is important since CNF is much more efficient in increasing the foam stability compared with CNC with a similar chemical composition and the efficient gel-forming ability of the CNF at the interface is suggested to be a major explanation to the excellent foam stability during dewatering and drying of the foam. Klemm, D., Kramer, F., Moritz, S., Lindström, T., Ankerfors, M., Gray, D. and Dorris, A. (2011) Nanocelluloses : A new Family of Nature – Based Materials. Angewandte Chemie (International Ed. in English), 200, 5438–5466.

Pickering foams from cellulose nanofibrils

249th National Meeting (2015)

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