Seminar with Orlando Rojas – Lignin Colloids in Action: From Molecular Structure and Clustering to Functional Particles

Abstract:

Lignin is a major source of renewable aromatic carbon and its valorization is complicated, and enabled, by its chemical and structural diversity. Rather than representing a single, uniform macromolecule, “lignin” comprises a family of materials whose botanical origin, isolation history, and processing determine molecular association, interfacial behavior, and functionality.

This presentation examines how lignin can be retained and reconfigured within wood or isolated and assembled into colloidal constructs. Particular attention is given to the progression from molecular heterogeneity and clustering to particle formation, surface organization, and hierarchical assembly. By controlling solvent exchange, surface chemistry, particle size, and drying conditions, lignin is easily organized into spherical particles, particulate coatings, membranes, Pickering emulsion stabilizers, supraparticles, inks, and porous carbon architectures.

Selected examples illustrate how particle shape, wetting behavior, packing, optical absorption, and multiscale porosity translate into functions including hydrophobic and UV-protective surfaces, photonic response, superblack coatings and inks, carbon dioxide adsorption, and electrochemical energy storage. Reconfiguration and redistribution of lignin within native wood can likewise enable functions such as broadband light absorption and rain-driven contact electrification.

A central message is that maximum lignin purity is not always necessary. Instead, the intended function should determine the required degree of fractionation, functionalization, and colloidal control. This structure-assembly-function perspective offers a pathway for converting diverse technical lignins into higher-value materials through scalable, resource-efficient, and application-driven processes.