Membrane pores conical

FIGURE 43.7 Examples of porous structures produced in thin polymeric films using various methods of irradiation and chemical treatment. (Reprinted from Apel, P., Radial. Meas., 34, 559, 2001. With permission from Elsevier.) (A) Cross section of a polycarbonate membrane with cylindrical nonparallel pore channels (B) polypropylene membrane with slightly conical parallel pores (C) polyethylene terephthalate membrane with cigar-like pores and (D) polyethylene terephthalate membrane with bow-tie pores. 

The most simple pore morphologies (Figs. 2.1A and B) are those of more or less straight cylindrical or conical-shaped pores. This type of pore is formed in so-called track etch and in "anopore" membranes. The latter is obtained by anodic oxidation of A1 metal foils and results in porous (amorphous) alumina (mesoporous) membranes. A detailed discussion is given by Burggraaf and Keizer in Ref. [1]. These types of membrane are useful for fundamental trans-... 

Fig. 2.1. Schematic picture of pore shapes. A and B are single wall, symmetric and asymmetric membranes respectively with straight cylindrical (a) or conical (b) pore shape (c) represents a ceramic asymmetric multilayered membrane with intercormected pores.

Figure 2.2 Schematic representation of the main types of membrane pores (a) isolated (b) dead-end (c) straight cylindrical (d) constricted (e) conical.

The recessed nanopore electrode shown in Figure 2.2b comprises a Pt or Au microdisk electrode embedded at the bottom of a conical-shaped pore synthesized in a glass membrane. These electrodes are fabricated with pore orifice radii as small as a few nanometers. EDL gating refers to the ability to control the flux of redox-active molecules from the bulk solution to the electrode surface, through the orifice (Figure 2.25), by either chemical (e.g., pH) or external stimuli (e.g., photons) that... 

Fig. 2.3. Schematic picture of pore types in a porous membrane, a Isolated pore b,f dead end pore c,d tortuous and/or rough pores (d) with constrictions (c) e conical pore.

OF CYLINDRICAL-/CONICAL-/DIAMOND-SHAPED PORES AND MEMBRANES... 

Single conically shaped nanopores were etched into 0.07 cm samples of a 12 pm thick polycarbonate membrane. For most of the studies reported here, the large-diameter opening of the pore was 5 pm (Figure 20.24a), and the small-diameter opening was 60 nm (Figure 20.24b). 

Mukaibo, H., Home, L.R, Park, D., Martin, C.R. Conholling the length of conical pores etched in ion-hacked poly(ethylene terephthalate) membranes. Small 5, 2474—2479, 2009. 

Membrane that can be integrated into a microfluidic system Uniform conical pores of 100 nm or smaller are created in Si by interferometric lithography Enhanced transport of pyridine as compared to commercial Alters Ileri et al. 2009... 

The stability of membrane is determined not only by macroscopic parameters, such as surface and linear tension, but also by the molecular geometry of lipids conic molecules of the broad head-narrow tail type are prone to forming inverted pores, and membranes made up of them have a short life-time. 

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