1.4 Linking Fabrication-Induced Nanostructure to Water Transport in Cellulose Nanofibril Films via QENS and Molecular Simulations
- Maria Sol Malizia
- PhD student,
- KTH
- Co-author(s): Aliz Lelik, Lucas Kreuzer, Marcell Wolf, Korneliya Gordeyeva, Jakob Wohlert, Daniel Söderberg
- Supervisor (PhD-students/postdocs): Daniel Söderberg
- Understanding water–cellulose interactions at the nanoscale is essential for optimizing cellulose nanofibril (CNF) films for sustainable composites, coatings, and biomedical applications. In this study, we investigate how fabrication routes influence nanostructure and, consequently, water transport properties in CNF films. Films were prepared using three distinct processing methods: casting (CF), vacuum filtration (VF), and printing/extrusion (PF), each producing different fibrillar organization and pore architectures. Quasi-elastic neutron scattering (QENS) was employed to probe both local and long-range diffusion dynamics of confined water. Clear processing-dependent differences in mobility were observed. Printed films (PF) exhibit strong local confinement, reflected by high elastic incoherent structure factor (EISF) values and low mean-square displacements (⟨u²⟩), while maintaining moderate global diffusivity and high water retention values (WRV). Vacuum-filtered films (VF) display the highest global diffusivity and lowest WRV, consistent with a more open pore network. Casted films (CF) show the highest local mobility but only moderate long-range diffusion, suggesting looser nanoscale packing combined with reduced pore connectivity. To support the experimental findings, molecular simulations were performed to independently estimate water diffusion coefficients, enabling cross-validation of the QENS-derived transport parameters. The combined results indicate that nanoscale confinement and pore connectivity jointly govern water dynamics, with behavior consistent with confinement regimes below ~3 nm. Direct structural quantification of such small pores remains experimentally challenging and is ongoing. Future work will focus on simulating QENS spectra based on experimentally informed pore size distributions to establish a quantitative link between nanostructure and dynamical response. This study demonstrates the power of combining neutron spectroscopy and simulations to elucidate processing–structure–transport relationships in cellulose-based materials.
- Time of presentation: 10.00