Cellulose is an ageless and abundant biopolymer, meeting renewable and sustainable requirements for innovation and development. Due to the inherent hydrophilicity, cellulose nanocrystals (CNCs) cannot be uniformly dispersed in most non-polar and hydrophobic polymer matrices. However, the surface primary hydroxyl groups of CNCs can be easily modified to achieve different surface properties, which can affect the dispersion in various matrix polymers, self-assembly, and the strength regulation of particle-particle and particle-matrix bonding.

The Martini coarse-grained force field is one of the most popular coarse-grained models for molecular dynamics (MD) modelling in biology, chemistry, and material science. Recently, a new force field version, Martini 3, had been reported with improved interaction balance and many new bead types.[1] Here, we present a new cellulose nanocrystal (CNC) model based on Martini 3.[2] The calculated CNC structures, lattice parameters, and mechanical properties reproduce experimental measurements well and provide an improvement over previous CNC models. Then, surface modifications with COO- groups, i.e., 2,2,6,6-tetramethylpiperidinyloxyl radical (TEMPO) oxidation, and interactions with Na+ ions were fitted based on the atomistic MD results to reproduce the interactions between surface-modified CNCs. Finally, the colloidal stability and dispersion properties were studied with varied NaCl concentrations, aspect ratios of CNCs, and number of CNCs. A good agreement with experimental results was found. Our work brings new progress toward CNC modelling to describe different surface modifications and colloidal solutions that were not available in previous coarse-grained models.[2]

References
[1] P. C. T. Souza et al., Nat. Methods, 2021, vol. 18, pp. 382–388,
[2] J. Pang, A. Y. Mehandzhiyski, and I. Zozoulenko, Cellulose, 2022, vol. 29, pp. 9493–9509,