Improved Colloidal Stability of Bacterial Cellulose Nanocrystal Suspensions for the Elaboration of Spin-Coated Cellulose-Based Model Surfaces

Well-dispersed suspensions are a prerequisite when preparing smooth model surfaces based on neutral bacterial cellulose nanocrystals (BCNs). However, neutral nanocrystal suspensions present pronounced particle aggregation. Carboxymethyl cellulose (CMC) or xyloglucan (XG) was therefore added to aggregated BCN suspensions. Turbidity measurements, polysaccharide content, and transmission electron microscopy (TEM) analysis revealed that aggregation of BCNs in CMC/BCN and XG/BCN suspensions is dependent on the concentration of CMC and XG in the suspensions. CMC enhances BCN dispersion above the concentration ratio of 0.05. In the case of XG, a better colloidal stability is observed above the concentration ratio of 0.5. Atomic force microscopy (AFM) investigations demonstrated that cellulose-based model surfaces, spin-coated from CMC/BCN or XG/BCN solutions, exhibited more uniform topography and less roughness than the reference BCN model surface.