Intersections of pore channels in track-etched polymer templates and membranes

Track-etched membranes (TMs) have been known as micro- and nanoporous materials with a well-determined structure. The production method, which includes irradiation with accelerated heavy ions and subsequent chemical etching, ensures the formation of uniform straight cylindrical channels in the membranes. Numerous applications of TMs take advantage of these specific properties. The pores in commercial TMs are often regarded as individual non-interconnected channels. However, due to the angle distribution of ions impinging the polymer film, the channels are non-parallel and may intersect. The intersections between the channels show up in precision experiments and play an important role in the fabrication of nanomaterials where track-etched membranes serve as templates. Polymer-metal composites and free-standing 3D metal nanostructures are representative examples of such materials. Of practical importance is thus the estimation of the number of channel intersections depending on the membrane structure parameters. This paper describes a simple approach for determining the mean numbers of channel intersections in track-etched membranes produced using ion beams from accelerators. The conditions for the formation of a percolation network are discussed.