title: Hindered nanoparticle diffusion and void accessibility in a three-dimensional porous medium.
abstract: The inherent pore-scale heterogeneity of many natural and synthetic porous materials can make it difficult to model and predict porous transport because the underlying microscopic processes are often poorly understood. Here we present the results of single-particle tracking experiments in which we followed the pore-scale diffusion of individual nanoparticles, deep within a three-dimensional porous material of moderate porosity. We observed significant hydrodynamic damping of particle motion at subpore length scales, resulting in heterogeneous and spatially dependent mobility. The accessibility of the void space was strongly dependent on particle size, and related to the heterogeneous hydrodynamics. Our results suggest that pore-scale diffusion is more heterogeneous and volume accessibility more limited than previously expected. The method demonstrated here will enable studies of a broad new class of materials including porous polymers of technological interest.
authors: Department of Chemical and Biological Engineering, ‡Department of Mechanical Engineering, and §Materials Science and Engineering Program, University of Colorado Boulder , Boulder, Colorado 80309, United States.
authors: Michael J
authors: MJ
authors: Skaug
authors: Liang
authors: L
authors: Wang
authors: Yifu
authors: Y
authors: Ding
authors: Daniel K
authors: DK
authors: Schwartz
mesh_terms: D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry; D057446:Hydrodynamics; D009038:Motion; D053758:Nanoparticles / Q000737:chemistry*; D016062:Porosity
chemical_list: D005456:Fluorescent Dyes
keywords: diffusion; fluorescence; nanoparticle; porous media; single-particle tracking; transport