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Self-Organized Films from Cellulose I Nanofibrils Using the Layer-by-Layer Technique

Year: 2010

Journal: Biomacromolecules, 2010, 11 (4), pp 872–882, 20100827

Authors: Aulin C. *†‡, Johansson E. ‡, Wågberg L. ‡, Lindström T. §

Last authors: Tom Lindström

Organizations: BIM Kemi AB, Box 3102, SE-443 03 Stenkullen, Sweden, Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, The Royal Institute of Technology, SE-100 44 Stockholm, Sweden, and Innventia AB, Box 5604, SE-114 86 Stockholm, Sweden

Country: Sweden

The possibility of forming self-organized films using only charge-stabilized dispersions of cellulose I nanofibrils with opposite charges is presented, that is, the multilayers were composed solely of anionically and cationically modified microfibrillated cellulose (MFC) with a low degree of substitution. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using a quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The adsorption behavior of cationic/anionic MFC was compared with that of polyethyleneimine (PEI)/anionic MFC. The water contents of five bilayers of cationic/anionic MFC and PEI/anionic MFC were approximately 70 and 50%, respectively. The MFC surface coverage was studied by atomic force microscopy (AFM) measurements, which clearly showed a more dense fibrillar structure in the five bilayer PEI/anionic MFC than in the five bilayer cationic/anionic MFC. The forces between the cellulose-based multilayers were examined using the AFM colloidal probe technique. The forces on approach were characterized by a combination of electrostatic and steric repulsion. The wet adhesive forces were very long-range and were characterized by multiple adhesive events. Surfaces covered by PEI/anionic MFC multilayers required more energy to be separated than surfaces covered by cationic/anionic MFC multilayers.