Thermodynamic Aspects of Mixed-Linkage Glucan and Nanocellulose Interactions

This study addresses knowledge gaps concerning interactions between barley mixed-linkage glucans (MLGs) and TEMPO-oxidized cellulose nanocrystals (TCNC), focusing on underlying physiochemical and thermodynamic principles. Combining dynamic light scattering (DLS), quartz crystal microbalance with dissipation monitoring (QCM-D), and isothermal titration calorimetry (ITC), we systematically investigated MLG solution properties, adsorption at cellulose surfaces, and thermodynamics of interaction. DLS revealed limited aqueous solubility of MLGs, with elevated temperatures promoting aggregate formation and reducing solution stability. QCM-D experiments showed that MLG forms thick hydrogel layers at cellulose interfaces and Voigt modeling confirmed temperature-dependent viscoelastic properties of the layers. Analysis of QCM-D data with van't Hoff approach together with ITC showcased only minor enthalpic contributions and predominantly entropic interactions. Altogether, these findings clarify MLG-cellulose interconnections and interlink between solubility, interfacial behavior, and functionalities of MLG in all-polysaccharide materials architectures. Additionally, the results point towards MLG providing a hydrating layer in plant cell walls in nature.