Effects of Ring Opening and Chemical Modification on theProperties of Dry and Moist Cellulose Predictions with Molecular Dynamics Simulations

Artikel i vetenskaplig tidskrift, 2024

ABSTRACT: Thermoplastic properties in cellulosic materials canbe achieved by opening the glucose rings in cellulose andintroducing new functional groups. Using molecular dynamics,we simulated amorphous cellulose and eight modified versionsunder dry and moist conditions. Modifications included ringopenings and functionalization with hydroxy, aldehyde, hydroxyl-amine, and carboxyl groups. These modifications were analyzed fordensity, glass transition temperature, thermal expansivity, hydrogenbond features, changes in energy term contributions duringdeformation, diffusivity, free volume, and tensile properties. Allring-opened systems exhibited higher molecular mobility, which,consequently, improved thermoplasticity (processability) com-pared to that of the unmodified amorphous cellulose. Dialcoholcellulose and hydroxylamine-functionalized cellulose were identified as particularly interesting due to their combination of highmolecular mobility at processing temperatures (425 K) and high stiffness and strength at room temperature (300 K). Water andsmaller side groups improved processability, indicating that both steric effects and electrostatics have a key role in determining theprocessability of polymers.