Osmotic Effects in Track‐Etched Nanopores

Abstract

Asymmetrically etched ion-track membranes attract great interest for both fundamental and technical reasons because of a large variety of applications. So far, conductometric measurements during track etching provide only limited information about the complicated asymmetric etching process. In this paper, monitoring of osmotic phenomena is used to elucidate the initial phase of nanopore formation. It is shown that strong alkaline solutions generate a considerable osmotic flow of water through newborn conical pores. The interplay between diffusion and convection in the pore channel results in a substantially nonlinear alkali concentration gradient and a rapid change in the pore geometry after breakthrough. Similar phenomena are observed in experiments with cylindrical track-etched pores of 15-30 nm in radius. A theoretical description of the diffusion-convection processes in the pores is provided.

Efficient Gating of Ion Transport in Three‐Dimensional Metal–Organic Framework Sub‐Nanochannels with Confined Light‐Responsive Azobenzene Molecules

“…A single bullet-shaped nanochannel was fabricated in polyethylene terephthalate (PET, 12μm thickness) membrane by surfactant controlling and ion track-etching technology [29] . Due to the difficulty of locating the nanochannel in the single-channel membrane, a multi-channel membrane with channel density of 10 8 cm -2 was fabricated with the same method for further characterization of the nanochannel morphology.…”

Perfect blackbody sheets from nano-precision microtextured elastomers for light and thermal radiation management

“…2a). Each swift heavy ion degrades the polymer chain locally within a few nanometres along its trajectory, 39,44,45 leading to preferential nano-track etching. Importantly, a high-grade CR-39 polymer is homogeneously amorphous, 46 offering highly isotropic bulk erosion, even under long-time etching.…”

“…41 Consequently, we obtained the flawless micro-etch pits of nanometrically smooth walls and sharp edges, which can be hardly achieved with other polymer sheets. 39,45 Ion exposure density and etching time determine the pit opening diameters, while the appropriate choice of ion species (neon ions or heavier) and accelerated energy (4200 MeV) yields the desired pit aspect ratio (45). 47 In the current situation of the ion beam irradiation chamber we used, a substrate of 100 mm  100 mm size can be processed (a custom sample scanner would enable larger area fabrication).…”

Recent Progress in the Membrane Distillation and Impact of Track-Etched Membranes

“…The size and density of pores can be adjusted in a wide range: from a few nanometers to 15 μm for size and from 10 6 to 10 9 pores/cm 2 for density. The porosity of the membrane is mainly determined by the duration of irradiation and the pore size, and pore geometry is mainly determined by the etching time, temperature, concentration, additives and etching bath configuration [ 166 , 167 , 168 , 169 , 170 ]. It should be noted that the mechanical properties of PET film may change during TeM fabrication.…”