LOW-TEMPERATURE PLASMA TREATMENT OF MAGNESIUM STEARATE LANGMUIR-BLODGETT-FILMS

Ultrathin Langmuir-Blodgett (LB) multilayers have been the focus of in terest for use as gas separation membranes because of their well-defin ed thickness and defect-free structure. A considerable drawback from a technological point of view is the low thermal, chemical and mechanic al stability of these films. One solution to this problem is the conve rsion of an organic multilayer structure, containing inorganic ions, t o an organo-ceramic ultrathin film by low-temperature plasma treatment . This article describes the interfacial behaviour and the deposition of magnesium stearate monolayers and their subsequent conversion to or gano-ceramic structures. X-ray, FTIR and AFM measurements were used to characterize the Langmuir-Blodgett (LB) multilayer Structures, chemic al compositions and surface topographics respectively: The LB-films co nsist of highly ordered Y-type multilayer structures with a stepwise s urface height profile and nearly all amphiphiles are complexed as the magnesium salt. The modification of these LB-films by both argon and o xygen plasma leads to a decrease in the content of organic material by physical ablation and chemical etching processes. Whilst an internal order is retained within the plasma-treated films, the surface roughne ss increases significantly. Two parameters of the plasma process, the radio frequency power and the exposure time, were varied in order to f ind suitable process conditions. It is shown that the non-uniform mult ilayer structure can be converted to a uniform grainy organo-ceramic s tructure by plasma treatment.