We report the experimental observation of a morphological instability of a confined polymerair double layer sandwiched between two plates set to different temperatures. The homogeneous temperature gradient across the double layer causes the breakup of the polymer film into columns or stripes spanning the two plates. Experimentally, the characteristic wavelength of these patterns varies with the inverse of the initial heat flux through the bilayer. To gain insight into the nature of the instability, we have developed a phenomenological model that describes the heat flow in terms of diffusion through the bilayer. In an idealized microscopic model for the heat flow through the bilayer system, thermal modes in the polymer film with wavelengths ranging from the film thickness to the Debye limit contribute to the heat flux. The low end of this frequency spectrum causes a thermal radiation pressure at the polymer-air surface that destabilizes the film, while the high-frequency modes ascertain the heat conduction through the bilayer.

A capillary surface instability caused by a high temperature gradient is used to replicate sub‐micrometer patterns (see Figure for an example). As opposed to convection effects, the film instability is driven by the diffusion of heat across the polymer film. By lateral modulation of the temperature gradient, this instability can be harnessed as a lithographic technique.

Redox chemistry of organometallic poly(ferrocenylsilane) polymers (soluble in organic or aqueous environment) is discussed. Poly(ferrocenyldimethylsilane) (PFDMS) was oxidized in CH 2 Cl 2 solution with different oxidants. Oxidation was accomplished with stepwise increasing amounts of ferric chloride (FeCl 3 ), iodine (I 2 ) and tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA Áþ SbCl À 6 ). The process was followed by UV-visible spectroscopy. Mixed-valence salts with different Fe(III)/Fe(II) ratios were obtained. The oxidation products were characterized by Mo¨ssbauer spectroscopy, which proved to be a very valuable tool to analyze mixed valence ferrocenyl compounds. Mo¨ssbauer analysis demonstrated that 100% oxidation could be achieved with TBPA AE + . Decamethylferrocene (DMFC) was found to be a suitable reducing agent for the oxidized polymer. The reduction process was monitored by UV-visible spectroscopy. The polymer was characterized by gel permeation chromatography (GPC) following the oxidation/reduction cycle and evidence of some fragmentation of the chains was observed. A water-soluble PFS polycation was successfully oxidized with FeCl 3 for pH values between 4 and 5. Ascorbic acid (vitamin C) was found to completely reduce the oxidized water-soluble polymer.

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