Thermal behavior of etched tracks and embedded metallic nanotubules

Etched ion tracks in polymers, and metallic nanotubules embedded therein have been described since quite a number of years, and first applications have already been reported in literature. Some of the proposed future applications suggest the deposition of matter within the tracks or tubules, with that matter to be subsequently thermally processed to obtain its final desired properties. For this case it is important to know the thermal behavior of both the tracks and tubules. Therefore corresponding examinations have been performed, by using ion transmission spectrometry (ITS) as the tool. For polyimide as the carrier polymer, ITS reveals unchanged track geometry up to /spl sim/450 to 500/spl deg/C, and a track widening when carbonization of that polymer sets in. These topological changes could be followed up to /spl sim/700 /spl deg/C. If silver tubules had been embedded in the tracks before, the recorded track diameter remains stable up to the highest annealing temperature, i.e., the metal tubules stabilize the track topology. Corresponding experiments with etched tracks in commercial PET foils of different provenience yield contradictory results that are ascribed to different additives of these products. Already a slight temperature increase may lead to changing track radii, and embedded silver tubules are not helpful in stabilizing the pores in PET. These results suggest the applicability of microporous foils of polyimide for the production of new nanoscopic devices up to formation temperatures of at least /spl sim/450 /spl deg/C. If carbonization of the host polymer and the presence of metallic tubules can be tolerated for the proposed application, then even processing temperatures of up to /spl sim/700/spl deg/C are possible. If, for contrast, PET microporous foils are used as templates, any thermal processing should be avoided.