Filler-Dominated Polymer Nanocomposites: Molecular Transport in Extended Nanocavities

A deeper understanding of the molecular transport mechanisms in filler-dominated nanocomposites is a necessary step toward the development of innovative molecular separation membranes. Nanocomposite membranes were prepared with gas-impermeable Cellulose Nanocrystals (CNCs) at similar to 80 wt % content and polyethylene glycol (PEG). Molecular transport takes place according to a configurational diffusion mechanism through extended nanocavities having a cross-sectional size of similar to 0.52 nm between packed CNCs. The CO2 solubility-selectivity is favored by physical interaction with the ethylene oxide groups of dispersed PEGs. The PEG chain length affects the CO2 membrane permeability and selectivity, the first one maximized by low-molecular weight PEGs, the latter for polymeric PEGs.