Effect of solvent pre-treatment on the structures and dissolution of microcrystalline cellulose in lithium chloride/dimethylacetamide

Abstract This study systematically investigated the structural changes of cotton-based microcrystalline cellulose (MCC) during solvent treatment in water and dimethylacetamide (DMAc), as well as how solvent exchange affects the dissolution rates of MCC in LiCl/DMAc solution. When MCC is soaked in DMAc or water for 3 days or longer, the surface cellulose layers become exfoliated from the MCC particles and these exfoliated portions are solvable in LiCl/DMAc. DMAc treatment significantly improves the nano-porosity of MCC. Thus, the chloride anions are able to diffuse into cellulose and lead to the final dissolution of cellulose chains via charge repulsion effects. On the other hand, water treatment exhibits strong pore closing effect, especially for nano-pores with a diameter < 30 nm, which prohibits the diffusion of chloride anions and the final dissolution of cellulose chains. Graphical abstract