Kraft lignin is a major industrial by-product of the pulp and paper industry, currently used primarily as low-value fuel. There are economic and environmental incentives to utilize kraft lignin for materials applications, however, its compositional variability and chemical complexity remains a major barrier to commercial use. Colloidal lignin particles (CLPs) have emerged as a promising strategy for reducing the heterogeneity of technical lignins by generating spherical particles with narrow size distribution. These particles can be formed from almost any lignin source without the requirement for chemical modification or reagents, high temperatures or pressures. Further, these and bio-based functional colloidal particles have a diverse range of potential value-added applications.
A fundamental understanding of the particle formation is critical to ensure fine control over particle morphology and colloidal properties. However, the impact of lignin structure on the particle formation and their properties is still not well understood. In this study, 7 industrial kraft lignins are used to produce CLPs under a wide range of synthesis conditions. Fundamental insights are gained into the particle formation process through multivariate data analysis which examined the relative impact of lignin structure and synthesis conditions, and their interactions. Key variables that dictate the functional properties of CLPs are identified.