Strong attractive interaction between finite element models of twisted cellulose nanofibers by intermeshing of twists

Analysis of the attractive interaction between intrinsically twisted cellulose nanofibers (CNFs) is essential to control the physical properties of the higher-order structures of CNFs, such as paper and spun fiber. In this study, a finite element model reflecting the typical morphology of a twisted CNF was used to analyze the attractive interaction forces between multiple approaching CNF models. For two parallel CNF models, when one of the CNF models was rotated 90° around the long-axis direction, the twisting periods meshed, giving the maximum attraction force. Conversely, when the two CNF models were approaching diagonally, the CNF models were closest at an angle of -3.2° (i.e., in left-handed chirality) to give the most stable structure owing to the right-handed twist of the CNF models themselves. Furthermore, the two nematic layers were closest when one nematic layer was approached at an angle of -2° (i.e., in left-handed accumulation chirality), resulting in the greatest attraction. The results characterize the unique distribution of the attractive interaction forces between twisted CNF models, and they underscore the importance of chiral management in CNF aggregates, especially intermeshing of twists.