Molecular dynamics study on cellulose nanofiber (CNF) alignment under the influence of external electric fields

Abstract

Cellulose nanofibers (CNFs) have attracted attention in a diverse area of applications due to their amazing mechanical properties and lightweight. Recent advances in enhancing the mechanical performance of nanocellulose filaments and films have reported efforts to align the individual cellulose nanofibers using different methods. Among them, the most recent being the use of electrical fields experimentally. It is important to investigate at the molecular level if the application of low electric fields on CNF can induce alignment and what effects these electric fields have on the molecular structure of the CNF. This study reports a molecular dynamics (MD) study of CNF model in a varying electric field (EF) strengths and direction. The MD simulations were conducted in GROningen Machine for Chemical Simulations (GROMACS) and the All-Atom Optimized Potential for Liquid Simulations (OPLS-AA) force field was used. Induced electric field alignment was investigated in terms of how quickly the alignment begins, how long it takes for complete alignment, and the ability to maintain any achieved alignment at different electric fields. To understand the electric field-induced structural changes, the hydrogen bonding network, hydrogen bond length, radius of gyration, and deviation from the original model are critically analyzed. The results show that CNF can be successfully aligned in low electric fields without compromising its molecular structure.