Multilayers of cellulose derivatives and chitosan on nanofibrillated cellulose

• Polysaccharide multilayers were formed on nanofibrillated cellulose.
• Conditions for the multilayer forming of different systems on NFC were optimized.
• Steric forces were dominant in case of surface interaction of these systems.
• Chitosan was able to decrease the steric repulsion of the cellulosic surfaces.
• Adhesion was increased when the cellulosic surfaces were coated with chitosan.

The aim of this work was to study the effect of solution conditions and polysaccharide structure on their Layer-by-Layer (LbL) deposition on nanofibrillated cellulose (NFC). Multilayer build-up of cellulose derivatives and chitosan on NFC model surfaces was studied using Quartz Crystal Microbalance with Dissipation (QCM-D) and Colloidal Probe Microscopy (CPM). The type of cationic polysaccharide was found to significantly affect the multilayer build-up and surface interactions. Cationic cellulose derivative quaternized hydroxyethyl cellulose ethoxylate (HECE) formed highly water-swollen layers with carboxymethyl cellulose (CMC), and the build-up was markedly influenced by both the ionic strength and pH. The ionic strength did not significantly influence the multilayer build-up of chitosan–CMC system, and adsorbed chitosan layers decreased the viscoelasticity of the system. Based on the results, it was also confirmed that electrostatic interaction is not the only driving force in case of the build-up of polysaccharide multilayers on nanofibrillated cellulose.