Enhancing Aqueous Dispersibility of Uncharged Cellulose Through Biosurfactant Adsorption

Cellulose, the principal structural ingredient in plant cell walls, holds promise for a range of biobased high-tech applications. Acid (e.g., HCl) hydrolysis of cellulose microfibrils leads to cellulose nanocrystals (CNCs), which are commonly suspended in water by repulsive interactions introduced with negative charges after sulfuric acid treatment or (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation. Lack of surface charges prompts CNCs to undergo sedimentation. This work addresses the dispersibility of uncharged cellulose nano- and microparticles (CNCs and microcrystalline cellulose, MCCs) in water through the physical adsorption of a glycolipid biosurfactant, composed of a single-glucose moiety and a fatty acid tail. The methodology involves the sonication-assisted incorporation of the biosurfactant directly within HCl-hydrolyzed cellulose without any surface modification (TEMPO oxidation or sulfation). Characterization of biosurfactant-stabilized cellulose reveals an enhancement in water stability of MCCs and CNCs in time at room temperature up to at least 1 day. These results show that adsorption of glycolipid biosurfactants is an interesting approach to disperse uncharged cellulose, potentially expanding its use in various technological domains.