Effect of multi-scale diffusion on the permeability behavior of intercalated nanocomposites

• We measured the aspect ratio of lamellar stacks by XRD analysis.
• We estimated the aspect ratio of lamellar stacks by experimental permeability data.
• Neglecting intra-stack diffusion leads to an over-estimation of the aspect ratio.
• Accounting for intra-stack diffusion allows to obtain a more realistic estimate.

This paper is aimed to study the morphology of intercalated nanocomposites, by coupling experimental permeability data with different analytical models. X-Ray diffraction provided the reference morphological features of the nanocomposite, including gallery thickness and aspect ratio of the lamellar stacks. Afterward, the water permeability of two intercalated nanocomposites was used for the calculation of the nanofiller aspect ratio, following different approaches. The obtained results indicate that an assumption of impermeable stacks involves a significant over-estimation of the nanofiller aspect ratio. Further, when the morphological features determined in the assumption of impermeable particles are used for estimation of the nanocomposite diffusivity by the use of the Fricke model, results do not show a satisfactory agreement with experimental data. On the other hand, fitting experimental permeability data with an analytical model accounting for intra-stack diffusion provided an estimation of the nanofiller aspect ratio in excellent agreement with that obtained by XRD. Further, applying the Fricke equation with the morphological features determined by the permeable stack model, an excellent agreement to the experimental data was obtained. The results indicate the relevance of intra-stack diffusion in intercalated nanocomposite, and the need to account for it when modeling mass transfer in nanocomposites.

Modeling diffusion in intercalated nanocomposite must be able to account for dual scale diffusion. Multi-scale diffusion model provides an estimation of the aspect ratio of lamellar stacks which is in excellent agreement with XRD analysis. In contrast, neglecting multi-scale diffusion leads to an over-estimation of the aspect ratio of lamellar stacks.Figure optionsDownload high-quality image (133 K)Download as PowerPoint slide