Track-etched capillary pore membranes

Figure 5.12 shows AFM images of the surface of three track-etched capillary pore membranes with nominal pore diameters of 10, 50, and 100 nm. Differences in the pore sizes of these three membranes are clearly visible in the AFM pictures. However,... 

Fig. 5.12a-c. AFM images of three track-etched capillary pore membranes with nominal pore sizes a 10 nm, b 50 nm, and c 100 nm.Two of these pores in PCTE 10 are indicated by arrows. The bottom parts show800-nm-long line profiles across typical pore opening. Reprinted from [9]. Copyright 1992, with kind permission from Elsevier... 

Figure 1.3 Schematic diagram illustrating the preparation of capillary pore membranes by a track-etching process.

To date, none of these methods has produced submicron capillary-pore membranes at a reasonable cost in the large areas suitable for industrial applications except the "track-etch" membrane produced by Nudepore Corp. 

The most commonly used hard templates are anodic aluminum oxide (AAO) and track-etched polycarbonate membranes, both of which are porous structured and commercially available. The pore size and thickness of the membranes can be well controlled, which then determine the dimension of the products templated by them. The pores in the AAO films prepared electrochemically from aluminum metals form a regular hexagonal array, with diameters of 200 nm commercially available. Smaller pore diameters down to 5 nm have also been reported (Martin 1995). Without external influences, capillary force is the main driving force for the Ti-precursor species to enter the pores of the templates. When the pore size is very small, electrochemical techniques have been employed to enhance the mass transfer into the nanopores (Limmer et al. 2002). 

This experimental investigation focuses on the preparation of polycrystalline magnesium oxide nanorods via capillary-driven infiltration of a precursor solution into the cylindrical pores of a track-etched polycarbonate membrane followed by thennal decomposition procedure. The nanomaterial was fully characterized by SEM, EDX,... 

Nuclear track-etch membranes (capillary-pore type). 

Ion track-etched membranes are an ideal template for preparation of metallic and organic nanostructures of desired shapes, which have a great potential for industrial applications (Dauginet-De Pra et al. 2002). The hollow track space of membranes can be easily filled with atoms of practically any kind by means of the electrochemical deposition from the electrolyte solution, the chemical polymerization from solution of the desired monomer and initiator, or the capillary action of the pores that enables the solution of the dissolved material entering into the pores followed by slow evaporation of the solvent (Chakarvarti 2009). 

Track-etched polycarbonate filters and hydrophilic cellulose membrane filters (both 0.2 micron pore diameter, Whatman Filter Co.) were used to recover supernatant solutions. Total chelating agent and metal ion-chelating agent complex concentrations were determined using a Quanta 4000E capillary electrophoresis instrument (Waters Corp.) and bare fused-silica capillaries (75 microns wide, 60 cm long. Polymicro Technol.). The capillary electrolyte consisted of 25 mM phosphate buffer (pH 7.0) and 0.5 mM tetradecyl trimethylammonium bromide (TTAB) electroosmotic flow modifier (see (29)). 

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