A "green pathway" different from simple diffusion in soft matter: Fast molecular transport within micro/nanoscale multiphase porous systems

Soft matter has attracted extensive attention due to its special physical/chemical properties and holds great promise in many applications. However, obtaining a detailed understanding of both complex fluid and mass transport in soft matter, especially in hierarchical porous media of biological tissues, still remains a huge challenge. Herein, inspired by fast tracer transport in loose connective tissues of living systems, we observed an interesting phenomenon of fast molecular transport in situ in an artificial hierarchical multiphase porous medium (a micrometer scale hydrophobic fiber network filled with nanometer scale hydrophilic porous medium), which was simply fabricated through electrospinning technology and polymerization. The transportation speed of molecules in the micrometer fiber network is larger than simple diffusion in nanometer media, which is better described by Fick's law. We further proved that the phenomenon is based on the nanoconfined air/water/solid interface around the micrometer hydrophobic fibers. We focus on the key factors, referring to S_A, (the confined multiphase area around the microfibers) and N_G (the connectivity node degree of the skeletal portion in the nanometer hydrogel medium). Next, a quantitative parameter, V_TCM (transport chance mean-value), was introduced to describe the molecular transport capability of the fiber network within hierarchical multiphase porous systems. These fundamental advances can be applied de novo to understand the process of so-called simple diffusion in biological systems, and even to re-describe many molecular events in biologically nanoconfined spaces.