Size-Dependent Mechanical Behaviors of Cellulose Nanocrystals Induced by Interfacial Zone: Implications for Advanced Electronic Devices Design

XR Zheng and HM Yang and WJ Xia and Y Zhang, ACS APPLIED NANO MATERIALS, 8, 3974-3984 (2025).

DOI: 10.1021/acsanm.4c06805

Cellulose nanopaper, a kind of thin film mainly constructed from nanocellulose, has gained much attention due to its lightweight and excellent mechanical properties compared to the plastic substrates, showing great potential in the design of electronic devices. Understanding the surface confinement effect of the cellulose nanocrystal (CNC) is essential for tuning the mechanical properties of cellulose nanopaper. Here, an all-atom molecular dynamics simulation is used to systematically investigate the surface confinement effect and size effect at the nanoscale on the dynamics and mechanical properties of CNC. The introduction of free surfaces leads to a reduction in the density and an increase in the molecular mobility in the zones near free surfaces. The interfacial zone thickness estimated from the Debye-Waller factor gradient exhibits a different variation trend with increasing CNC chain length from that estimated from the density gradient, indicating a decoupling relationship between structure and dynamics variations in the interfacial zone. Moreover, the elastic moduli of CNC exhibit power scaling laws with the density and Debye-Waller factor, while a linear scaling law is observed between elastic moduli and the normalized interfacial zone thickness. The local molecular stiffness distribution further reveals that the enhanced modulus of CNC with increasing chain length is attributed to a reduction in the contribution of the interfacial zone on the mechanical properties. Our study provides fundamental insights into the influence of the interfacial zone on the dynamical and mechanical properties of CNC at a molecular level, shedding light on the design of high-performance electronic devices.

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