Biobased materials in the circular economy: A strategic review on the advanced functionalization and applications of biopolymers

This strategic review synthesizes recent advances in the functionalization and application of four foundational biopolymers: chitosan, cellulose, lignin, and starch. Moving beyond descriptive summaries of synthesis strategies, the analysis integrates a comparative sustainability evaluation linking material chemistry to Life Cycle Assessment (LCA) metrics and economic constraints. Across packaging and coating applications, starch- and cellulose-based systems generally exhibit lower cradle-to-gate global warming potentials than more energy-intensive chitosan films, yet their industrial adoption remains limited by moisture sensitivity and mechanical variability. Comparative trends in global warming potential, eutrophication, and end-of-life behaviour are discussed, together with limitations arising from inconsistent functional units and system boundaries across LCA studies. The review further examines how functionalization strategies that improve durability and barrier performance may simultaneously hinder biodegradation and recycling, creating trade-offs relevant to circular-economy implementation. Laboratory-scale performance gains, including antimicrobial grafting and nano structuring for energy storage, are contrasted with techno-economic barriers to scale-up, reflected in significant cost disparities between commodity polysaccharides and chemically modified biopolymers. In addition, the analysis highlights that physical disintegration under composting conditions does not necessarily indicate complete biological mineralization. Overall, the review identifies solvent-free processing, additive minimization, and standardized degradation protocols as key priorities for translating biopolymer innovations into scalable, environmentally credible material systems.