Track-etched polycarbonate

Within the scope of thermoelectric nanostructures, Sima et al. [161] prepared nanorod (fibril) and microtube (tubule) arrays of PbSei. , Tej by potentiostatic electrodeposition from nitric acid solutions of Pb(N03)2, H2Se03, and Te02, using a 30 fim thick polycarbonate track-etch membrane, with pores 100-2,000 nm in diameter, as template (Cu supported). After electrodeposition the polymer membrane was dissolved in CH2CI2. Solid rods were obtained in membranes with small pores, and hollow tubes in those with large pores. The formation of microtubes rather than nanorods in the larger pores was attributed to the higher deposition current. 

The electroless plating procedure described above was used to plate the Au nanotubules into the pores of commercially available polycarbonate track-etch filters [Osmonics, 6 pm thick, pore dia. = 50 nm (28 nm-dia. Au tubules) or 30 nm (all other Au tubules), 6 X 10 pores cm ]. The... 

Polybenzimidazole (PBI) Polybenzlmldlazolone (PBIL) Polycarbonate (track-etched) Polyester (track-etched)... 

Kim, K.J. et al., Chemical and elechical characterization of virgin and protein-fouled polycarbonate track-etched membranes by FTIR and sheaming-potential measurements,/. Membr. Sci., 134, 199, 1997. 

FIGURE 18.2 PolypyiTole nanotubules synthesized in polycarbonate track-etched membrane. (Reprinted from Radial. Mean., 44, Chakarvarti, S.K., Track-etch membranes enabled nano-/microtechnology A review, 1085-1092, Copyright 2009, with permission from Elsevier.)... 

Figure 1. SEM images of original PETE membrane (100 nm pore size) (al) surface view, (a2) cross-section view PETE composite membranes with (bl-b2) 100 nm crosslinked PAMPS domains, (b2) 100 nm crosslinked PAA domains and polycarbonate track-etched (PCTE) membrane composites with (cl) 50 nm crosslinked PAMPS domains, (c2) 100 nm crosslinked PAMPS domains, (c2) 2000 nm crosslinked PAMPS domains.

Xie, R., Chu, L.-Y., Chen, W.-M., Xiao, W., Wang, H.-D. and Qu, J.-B. 2005. Characterization of microstructure of poly(N-isopropylamide)-grafted polycarbonate track-etched membranes prepared by plasma-graft pore-filling polymerization.. 7. Memh. Sci. 258 157-166. 

FIGURE 22.5 (a) Photos of a polycarbonate track-etch membrane prior (0 h) and after electroless gold plat-... 

Investigations have been conducted with polycarbonate track-etched templates, aluminum oxide membranes and nonporous mica [344-352], and in all cases the nanomaterial preparation consists primarily of a controlled electrodeposition of copper from a precursor solution (usually CUSO4) inside the nanochannels of the template. In a second step, the template is removed, thus releasing the elongated nanostructures. By following this approach, Gao and coworkers [353] prepared dense and continuous copper nanowires which were 30 xm long and had a uniform... 

Track-etched membranes are made by exposing thin films (mica, polycarbonate, etc) to fission fragments from a radiation source. The high energy particles chemically alter material in their path. The material is then dissolved by suitable reagents, leaving nearly cylindrical holes (19). 

FIG. 20-66 Track-etched 0.4-)lm polycarbonate membrane. Courtesy Milli-pore Corporation.)... 

The deposition of a conductive polymer (polypyrrole) into either a track-etched polycarbonate or alumina membrane was either achieved by electrochemical reduc-... 

Membranes with very regular pores of sizes down to around 10 nm can be prepared by track-etching [10], and, in principle, those membranes can be used for the fractionation of macromolecules in solution. A relatively thin (<35 pm) polymer film (typically from polyethylene terephthalate)/PET/or aromatic polycarbonate/PC/) is first bombarded with fission particles from a high-energy source. These particles... 

Fig. 3. (a) SEM image of the particle track-etched polycarbonate membrane, with a pore diameter of 1 (im (Martin, 1994). (b) SEM image of 2-/xm pores in a single-crystal mica film prepared by particle track-etching (Sun et al., 2000a). 

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). 

FIG. T2-70 Track-etched 0.4 gm polycarbonate membrane. (Courtesy Milli-... 

The scope of applications of MF has been broadened in recent years by the introduction of inert membranes, particularly polypropylene, polycarbonate, and Teflon . In general, these materials cannot be made by the methods developed for the cellulosics because of their insolubility. Both Teflon and pol)propylene MF membranes have been made by a controlled stretching procedure in which microtears are introduced Microporous polycarbonate membranes have been prepared by a unique radiation-track-etch method A thin polycarbonate film is exposed to ionizing radiation which leaves labile sites that can later be chemically etched to produce straight-throi channels. The pore size can be controlled by the etching conditions. The pores in these membranes, contrary to those in cellulosic membranes, are quite uniform in diameter. 

There are various kinds of plastic material suitable for use as track-etch detector, of which LR 115 (cellulose nitrate), MAKROFOL (polycarbonate) and CR-39 (allyl-diglycol poly carbonate) are the most popular. These materials are described by Fantini and Richard (1981) and Cartwright et al. (1978). 

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