Enhancing the Stability of Aqueous Dispersions and Foams Comprising Cellulose Nanofibrils (CNF) with CaCO3 Particles

• Main Authors: Tiia-Maria Tenhunen, Tiina Pöhler, Annaleena Kokko, Hannes Orelma, Patrick Gane, Michel Schenker, Tekla Tammelin
• Format: Article
• Language: English
• Published: MDPI AG 2018-08-01
• Series: Nanomaterials
• Subjects: cellulose nanofibrils (CNF); hybrid hydrocolloid pigments; percolation network; dispersion stability; cellulose-based foam; plateau border stability in aqueous foams; inorganic-organic hybrid materials; nanocellulose-CaCO3 containing foams; stability enhancement of foams
• Online Access: http://www.mdpi.com/2079-4991/8/9/651

In this work, stability of dispersions and foams containing CaCO3-based pigments and cellulose nanofibrils (CNF) was evaluated with the aim to reveal the mechanisms contributing to the overall stability of the selected systems. The utmost interest lies in the recently developed hydrocolloid hybrid CaCO3 pigments and their potential to form bionanocomposite structures when incorporated with CNF. These pigments possess a polyelectrolyte layer deposited on the surface of the particle which is expected to enhance the compatibility between inorganic and organic components. Stability assessment of both dispersions and foams was conducted using turbidity profile scanning. In dispersions, CNF provides stability due to its ability to form a firm percolation network. If surface-modified pigments are introduced, the favourable surface interactions between the pigments and CNF positively influence the stability behaviour and even large macro-size pigments do not interfere with the stability of either dispersions or foams. In foams, the stability can be enhanced due to the synergistic actions brought by CNF and particles with suitable size, shape and wetting characteristics resulting in a condition where the stability mechanism is defined by the formation of a continuous plateau border incorporating a CNF network which is able to trap the inorganic particles uniformly.