Template-synthesis of polymeric and metallic nanostructures

Nanotubules and nanofibrils of polypyrrole have been chemically synthesized using the pores of nanoporous polycarbonate membrane filters as templates. It has previously been shown that such "template-synthesized" nanofibrils of polypyrrole can have enhanced conductivities relative to bulk forms of the polymer. Furthermore, the narrowest diameter fibrils show the greatest enhancements in conductivity. In this work, we explore the genesis of this enhancement in conductivity by determining the relative conjugation lengths in the polypyrrole fibrils using FTIR and UV-Visible-NIR spectroscopies. Using polarized infrared absorption and FTIR spectroscopies, we have followed the evolution of polymer chain orientation and conjugation length with polymer chain growth on the pore walls of the template membrane. On the basis of these results, we have proposed a bilayer model to explain the enhancement in conductivity and its strong dependence on fibril diameter.; An electroless deposition procedure for filling the pores in nanoporous filtration membranes with metal (gold) nanowires has been developed. Results of electrochemical experiments at ensembles of 30 nm-diameter and 10 nm-diameter gold-disk electrodes are described. The electrochemical response characteristics of these nanoelectrode ensembles are in agreement with predictions of the relevant electrochemical theories. Cyclic voltammetric detection limits for electroactive species at ensembles containing 10 nm-diameter gold disks can be as much 3 orders of magnitude lower than at a large-diameter gold-disk electrode.; Electrochemical theory predicts that nanoelectrode ensembles can be used to determine fast rate constants for heterogeneous electron transfer. In this work, we use the nanoelectrode ensembles fabricated by the template synthetic method, to determine extremely high values of rate constants for fast aqueous redox couples. A derivatized ferrocene is shown to have a rate constant of 70cm/s, a value which is beyond the measurement capabilities of conventional macroelectrodes and microelectrodes. We also describes some unusual, and heretofore unobserved, effects of supporting electrolyte concentration on the voltammetry of these nanoelectrode ensembles. Using digital simulations, we have proposed a simple theory of ion-pairing in solution to explain these effects.