Structure-property relation of films of cellulose nanofibrils containing renewable additives established by chemical mapping

We suggest an approach for high-resolution chemical mapping by Atomic Force Microscopy (AFM) to reveal submicron hierarchy of films from renewable components. The chemical mapping is demonstrated for films that are constructed of cellulose nanofibrils, hydroxypropylated hemicelluloses and sorbitol. Distribution of the components depending on the precursor dispersion composition and the source of the cellulose nanofibrils or hemicellulose additive (softwood vs. hardwood) were investigated. The difference in adhesion between the film components and the AFM tip enables qualitative mapping of the components in the film. We correlate the submicron organization of the films to their mechanical and barrier performance. Furthermore, quantitative mapping of hydroxypropylated hemicellulose additive with varying degree of substitution will be discussed and the potential to probe functional cellulose surfaces with respect to degree of functionality will be assessed.