Soft Nanocomposites--From Interface Control to Interphase Formation.

We report measurements of structure, mechanical properties, glass transition temperature, and contact angle of a novel nanocomposite material consisting of swellable silsesquioxane nanoparticles with grafted poly(ethyl methacrylate) (PEMA) brushes and PEMA matrices with varying molecular weight. We measured the interparticle distance at the surface of the composites using scanning probe microscopy (SPM) and in the bulk of ∼0.5 μm thick films by grazing incidence small angle X-ray scattering (GISAXS).

Nanoscale thermomechanics of wear-resilient polymeric bilayer systems.

We explore the effect of an ultrathin elastic coating to optimize the mechanical stability of an underlying polymer film for nanoscale applications. The coating consists of a several nanometer thin plasma-polymerized norbornene layer. Scanning probes are used to characterize the system in terms of shear-force-induced wear and thermally assisted indentation.

Electric-field-induced condensation: an extension of the Kelvin equation.

The Kelvin equation relates the vapor pressure of a volatile liquid to the curvature of the liquid surface. It describes phenomena such as capillary condensation, capillary adhesion, nucleation, and the adsorption of vapors into porous media. Here we propose an extension of the Kelvin equation, which takes into account changes of the vapor pressure due to electric fields.

Nanomechanical properties of advanced plasma polymerized coatings for mechanical data storage.

In this paper we report on the unprecedented deformation behavior of stratified ultrathin polymer films. The mechanical behavior of layered nanoscale films composed of 8-12 nm thin plasma polymerized hexamethyldisiloxane (ppHMDSO) films on a 70 nm thick film of polystyrene was unveiled by atomic force microscopy nanoindentation. In particular, we observed transitions from the deformation of a thin plate under point load to an elastic contact of a paraboloid of revolution, followed by an elastic-plastic contact for polystyrene and finally an elastic contact for silicon.

Interface roughness of plasma deposited polymer layers.

The interface roughness of adjacent films which were made by plasma polymerization of hexamethyldisiloxane were investigated. Multilayered structures were made by using different plasma conditions in alteration resulting in different mechanical properties within each layer. Scanning force microscopy on the face side of fractured pieces of the multilayer structures revealed a significant phase contrast between the layers.

Determination of cross-link density in ion-irradiated polystyrene surfaces from rippling.

The irradiation of polymer surfaces with ion beams leads to pronounced chemical and physical modifications when the ions are scattered at the atoms in the polymer chain. In this way, different products of decomposition occur. Here we show that by changing the ion fluence and the mass of the ion the local mechanical properties as Young's modulus of a polystyrene surface layer can be tailored.