Charles J. Brumlik

TEMPLATE SYNTHESIS OF METAL MICROTUBULE ENSEMBLES UTILIZING CHEMICAL, ELECTROCHEMICAL, AND VACUUM DEPOSITION TECHNIQUES

Abstract : Microtubules are an interesting type of microstructure that resemble miniature drinking straws. Such tubular microstructures are found in nature. In addition, we and others have been investigating strategies for making synthetic analogs. We are especially interested in the idea of making metal microtubules. Four procedures for preparing metal microtubules are described in this paper. The general approach, called template-synthesis, entails using the pores in a microporous membrane as templates for forming the tubules. Microporous anodic aluminum oxide membranes and nuclear track-etch membranes are used as the template membranes. Gold and silver microtubules are made with outer diameters as small as 200 nm. These microstructures are characterized by scanning electron microscopy.

A new interfacial polymerization method for forming metal/ conductive polymer Schottky barriers

Abstract We have recently described a new interfacial polymerization method for forming thin films of electronically conductive polymers. In this method, the pores in a microporous support membrane are filled with an oxidative polymerization reagent (e.g. Fe 3+ ) and this membrane-confined solution is exposed to a vapor phase containing a monomer which can be oxidatively polymerized to yield a conductive polymer. This procedure causes a thin, defect-free film of the conductive polymer to grow across the surface of the microporous support membrane. This interfacial polymerization method creates the possibility of coating thin conductive polymer films onto any desired material. This would be accomplished by first coating the surface of the microporous support membrane with a thin film of the desired material and then conducting interfacial polymerization at this modified membrane surface. We demonstrate this concept in this paper by conducting interfacial polymerization of polypyrrole onto aluminum to form Al/polypyrrole Schottky barriers. These Schottky barriers showed better rectification than previous metal/polypyrrole Schottky barriers described in the literature. We have also used this new interfacial polymerization procedure to form ohmic gold/polypyrrole junctions.

Interfacial polymerization of thin polymer films onto the surface of a microporous hollow-fiber membrane

Abstract Two methods for synthesizing thin films of chemically selective polymers onto the surface of microporous hollow-fiber membranes are described. The first involves interfacial redox polymerization and yields thin films of electronically conductive polymers (e.g., polypyrrole,poly (N-methylpyrrole), poly-aniline) on the outside surface of the hollow-fiber membrane. The second method entails interfacial photopolymerization of styrenic monomers on the surface of the hollow-fiber membrane. Such coated hollow-fiber membranes are potentially useful in membrane-based separation technologies such as pervaporation and industrial gas separations. We also investigated the transport properties of the coated hollow-fiber membranes described here using a simple pervaporation-type experiment.

Modification of Fluoropolymer Surfaces with Electronically Conductive Polymers

Abstract We describe methods for coating fluoropolymer surfaces with thin films of electronically conductive polymers. Modification of the fluoropolymer surface prior to coating with conductive polymer is necessary to achieve good adhesion between the fluoropolymer membrane and the conductive polymer coating. We describe four different procedures for modifying the fluoropolymer surface so as to promote strong adhesion. These procedures are based on a wet chemical treatment of the fluoropolymer or on exposure of the fluoropolymer surface to a hydrogen plasma, an ultraviolet lasr or an electron beam. Finally, we show that it is possible to ‘write’ patterns with the conductive polymer onto the fluoropolymer surface.

UV laser ablation of electronically conductive polymers

Abstract The UV laser ablation of thin polypyrrole and polyaniline films coated on an insulating substrate is described. UV laser ablation is used to pattern the conductive polymer coating; patterns with submillimeter features are easily obtained with edge resolution on the order of a few microns.