Mechanochemical Transformations of Polysaccharides to Value Added Products: A Review with Green Chemistry Evaluation

Abstract

Biopolymers, particularly polysaccharides, are a renewable feedstock with the potential to reduce reliance on petrochemicals and enable decarbonization and circularity efforts. Their sustainable chemical modification is essential to expand their use in the industry, yet this goal has proven hard to achieve because of their poor processability attributed to low solubility in most solvents. Mechanochemistry is a fast-emerging technique enabling the effective chemical transformation of materials in the solid state. It is effective for the chemical modification of biopolymers and composites with lower reagent, solvent and energy use compared to solution phase methods. Herein, we review recent progress in the development of mechanochemical methodologies for polysaccharide transformations, including depolymerization, nano-extraction, and chemical functionalization. We compare in detail the different techniques and their outcomes in terms of the functional properties of the final products, as well as the green metrics of each method, based on reported parameters. Conclusions are then drawn to direct future research directions to expand the range of new functional biomaterials mechanochemistry can produce in a more sustainable manner.