Dissolving cellulose is crucial for sustainable materials development. Aqueous alkaline solutions offer economic and potential environmental advantages, but a deep understanding of their dissolution mechanism is needed for designing efficient, green technologies. Previous work often focused on hydrogen bond disruption, neglecting specific ionic roles. This study elucidates the critical functions of anionic hydroxide deprotonation, cation hydrophobic effects, and water structure during cellulose dissolution by comparing aqueous sodium hydroxide (NaOH) and benzyltrimethyl ammonium hydroxide (BzMe3NOH) systems.
We employed Molecular Dynamics (MD) to simulate solvation effects (radial distribution functions, solvation numbers, energy decomposition) and ab initio MD (AIMD) on cellotriose to examine the deprotonation phenomenon during dissolution at the atomic level.

MD simulations showed distinct cation mechanisms. Hydrophobic BzMe3N+ cations directly interact with the cellulose backbone, effectively preventing chain aggregation. Conversely, Na+ cations coordinate with cellulose oxygens (O3, O5, O6) and surrounding water molecules. This coordination leads to enthalpy reduction and stabilizes cellulose’s hydrophobic surface through specific water structuring. AIMD revealed that hydroxide ions deprotonate cellulose at the C2 hydroxyl site, creating negatively charged, mutually repulsive chains that hinder aggregation and promote dissolution.
By combining MD and AIMD, this work provides a comparative microscopic understanding of cellulose dissolution in NaOH and BzMe3NOH, highlighting hydroxide-induced deprotonation and unique cation influences. These insights advance fundamental knowledge of alkaline dissolution and offer a theoretical basis for designing improved, eco-friendly cellulose solvents.