Cylindrical Polymer Nanostructures by Solution Template Wetting

Abstract

Wetting of porous templates, e.g., porous aluminum oxide with pore diameters in the range from 25 up to several 100 nm, by polymer melts has been demonstrated previously to be a highly effective way toward the preparation of polymer nanotubes. The concept evaluated in this contribution is to perform wetting from polymer solutions rather than from melts with particular emphasis on the influence of the molecular weight of the polymer used for wetting. Narrow molecular weight fractions were used for this purpose. The aim is to extend the nature of nanostructures which become available by wetting and to allow functionalization of the nanostructures by additives such as drugs or biological objects which decompose at elevated temperatures. Polystyrene was used as model polymer. Results are first of all that the quality of the solvent—good, Θ, or poor—and the polymer concentration are important wetting parameters as far as the preparation of stable cylindrical structures is concerned and second that nanowires, nanotubes, or cylindrical structures with a regular arrangement of voids can be prepared reproducibly by a proper variation of the molecular weight of the polymer used.