Bousige Colin, Levitz Pierre, Coasne Benoit
Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5615, Laboratoire des Multimatériaux et Interfaces, F-69622, Villeurbanne, France.
Sorbonne Université, CNRS UMR 8234, PHENIX Lab, 75252, Paris, France.
Nat Commun. 2021 Feb 15;12(1):1043. doi: 10.1038/s41467-021-21252-x.
Owing to their complex morphology and surface, disordered nanoporous media possess a rich diffusion landscape leading to specific transport phenomena. The unique diffusion mechanisms in such solids stem from restricted pore relocation and ill-defined surface boundaries. While diffusion fundamentals in simple geometries are well-established, fluids in complex materials challenge existing frameworks. Here, we invoke the intermittent surface/pore diffusion formalism to map molecular dynamics onto random walk in disordered media. Our hierarchical strategy allows bridging microscopic/mesoscopic dynamics with parameters obtained from simple laws. The residence and relocation times - t, t - are shown to derive from pore size d and temperature-rescaled surface interaction ε/kT. t obeys a transition state theory with a barrier ~ε/kT and a prefactor ~10 s corrected for pore diameter d. t scales with d which is rationalized through a cutoff in the relocation first passage distribution. This approach provides a formalism to predict any fluid diffusion in complex media using parameters available to simple experiments.
由于其复杂的形态和表面，无序纳米多孔介质具有丰富的扩散态势，导致特定的传输现象。此类固体中独特的扩散机制源于受限的孔隙重排和不明确的表面边界。虽然简单几何结构中的扩散基本原理已得到充分确立，但复杂材料中的流体对现有框架提出了挑战。在这里，我们引入间歇表面/孔隙扩散形式，将分子动力学映射到无序介质中的随机游走。我们的分层策略允许通过从简单定律获得的参数来弥合微观/介观动力学。停留时间和重排时间——t、t——显示源自孔径d和温度重标度的表面相互作用ε/kT。t服从具有ε/kT势垒和针对孔径d校正的10 s前置因子的过渡态理论。t与d成比例，这通过重排首次通过分布中的截止来合理化。这种方法提供了一种形式，可使用简单实验可得的参数来预测复杂介质中任何流体的扩散。
