Rustam Ibadov: Functional and circular fibers from pine bark residues

Forest-derived biomass is well placed to provide sustainable materials by upgrading higher-value side streams from pulp, paper, and sawmill operations. Among these streams, pine bark is available at large scale yet remains underexploited, typically burned for heat and power instead of being converted into advanced products. Pine bark is rich in lignin and extractives, alongside cellulose, hemicelluloses, and pectins, yielding a wide range of potential functionalities. Despite years of work on bark valorisation, viewing it mainly with traditional methods as just another lignocellulosic feedstock, has obscured its distinct anatomical, chemical, and functional traits. Wet-chemical analyses have shown that whereas wood is dominated by carbohydrates, bark is defined by a lignin and extractives-rich network interlinked with carbohydrate polymers. The elevated lignin and extractives content is often blamed for fiber recalcitrance, but the nature of this behavior remains poorly resolved. Much characterization has been performed on bulk, ground material, however once bark is milled and extracted, crucial spatial context is lost. Understanding the cellular-scale distribution of components and their topochemical interlocking may be key to unlocking the full potential of this multifunctional resource.