Membranes with Oriented Polyelectrolyte Nanodomains

Polymer−polymer nanocomposite membranes with polyelectrolyte nanodomains oriented normal to the plane of the membrane were prepared using track-etched membranes as a host matrix. The oriented nanodomains of polyelectrolyte were synthesized in tubular and fibril forms by a plasma-induced surface graft polymerization, where nanodomains with aspect ratios as high as 240 were obtained. The morphology of nanodomains was confirmed by scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The specific conductivity of the polyelectrolyte nanodomains increased with decreasing domain size with the highest value 6 times higher than that of the isotropic bulk polyelectrolyte gel membrane. Mechanical strength of the nanocomposite was similar to the matrix in both the dry and the hydrated state, unlike the bulk polyelectrolyte gel membrane. The membranes synthesized in this study with oriented polyelectrolyte nanodomains demonstrate the ability to enhance transport in the desired direction for applications such as fuel cells.