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Martin Steinhart

Publications and source records attributed to Martin Steinhart.

7 recordsLinked to original sources
PubMed2006

Coherent kinetic control over crystal orientation in macroscopic ensembles of polymer nanorods and nanotubes.

We show that the crystal orientation in polymer nanotubes and nanorods inside porous templates is controlled by the kinetics of nucleation and growth under 2D confinement. Two clear limiting cases are identified: In separated nanostructures, any crystal orientation allowing the growth of lamellar crystals along the pores appears statistically. If a bulklike surface film connects the nanostructures, macroscopic arrays with uniform crystal orientation are obtained, in which the dominant growth direction of the crystals is aligned with the long axes of the pores of the template.

Crystallization↗
PubMed2005

Liquid crystalline nanowires in porous alumina: geometric confinement versus influence of pore walls.

Aligned liquid crystalline nanowires within ordered porous alumina templates show a pronounced texture on a macroscopic scale. We have investigated the influence of the geometric confinement and the nature of the pore walls on the mesophase formation by means of X-ray diffraction. The apparent texture is the result of a complex interplay of the pore geometry, interfacial phenomena, and the thermal history. Pores with a diameter of a few hundred nm guide the mesophase formation more efficiently than those with a diameter below 100 nm.

Aluminum Oxide↗
PubMed2004

Nanotubes by template wetting: a modular assembly system.

The wetting of porous templates with polymer melts and solutions or polymer-containing mixtures is a simple and versatile method for the preparation of tubular structures with diameters ranging from a few tens of nanometers to micrometers. The tube walls can be made of a multitude of materials, some of which have thus far been altogether impossible to use or very limited in their ability to be incorporated into nanostuctures. Template wetting also makes it possible to modify the nanotubes in a variety of ways, for example through the controlled generation of pores or the embedding of nanoparticles into the walls. This method offers a promising approach to functionalized nanotube-template hybrid systems and free-standing nanotubes.

Journal Article↗
PubMed2003

Nanotubes à la carte: wetting of porous templates.

Nanotubes have an outstanding potential both for applications in nanotechnology and as the subject of basic research. Wetting of porous templates is a simple technique that overcomes many limitations of established preparation methods. It extends the range of processable materials, for example, by a broad range of multicomponent mixtures or by high-performance polymers such as poly(oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene) (PEEK) and polytetrafluoroethylene (PTFE). Inducing controlled phase transitions generates a large specific surface, a specific nanoporosity, or oriented crystalline domains within the nanotube walls. Template wetting provides customized nanotubes and allows us to investigate how the wall curvature affects the structure formation.

Journal Article↗