Impact of hydrogen bonding on inclusion layer of urea to cellulose: Study of molecular dynamics simulation

Abstract

Molecular dynamics simulation was applied for investigating the inclusion layer of urea to a single cellulose chain in urea-water solvent mixture. The formation of urea layer surrounding the cellulose chain, which mediated by different patterns of hydrogen bonding, was confirmed by radial distributing function and angular number distribution. Furthermore, the temperature properties of hydrogen bonding revealed that urea molecules are more favorable to interacting with cellulose than water molecules at a certain temperature range. Cellulose-urea interaction energy and hydrogen bond number were also calculated as a function of temperature and the result of calculation further proved the hypothesis that there exists a dominative hydrogen bonding pattern between cellulose and urea, in which oxygen atoms of urea as proton-acceptors and hydroxyl hydrogen atoms of cellulose as proton-donors. The cellulose-urea interaction is dependent of temperature, in which hydrogen bonding between cellulose and urea decreased gradually with temperature increasing at temperature above 265 K and it reached a plateau phase with temperature above 283 K.