Structural features of hemicellulose-coated lignin nanoparticles at hydrophobic interfaces

Lignin nanoparticles (LNPs) are emerging as a versatile way of functionalizing lignin, including as tailorable Pickering emulsifiers. Yet, they are prone to aggregation in acidic conditions, which limits their application in food-based emulsions. Coating the LNPs with hemicelluloses, either enzymatically by laccase or by unassisted adsorption, have so far improved their stability in acidic conditions. However, the implications of such modification towards their behaviour at the oil-water interface is not yet fully characterized, especially regarding their structural integrity as they are adsorbed at the interface. Therefore, we aim to use neutron reflectometry (NR), with its capability to probe structural features of thin adsorbed layers at buried interfaces, to characterize the structural integrity of the LNPs at the air-water and oil-water interfaces. Specifically, we aim to determine whether the spherical structure of the LNPs remain intact or deform as they are adsorbed, comparing different types of lignin and hemicellulose modification methods to deduce their effect on the formation of the interfacial layer. A thorough understanding of their interfacial behaviour will rationalize tailoring the surface properties of the LNPs for various emulsion products, such as in food or cosmetics. Consequently, this will allow lignocellulosic biomass to be used in a more sustainable, high-value, and circular manner.