| Abstract
| - The thermal stability of Langmuir−Blodgett multilayers ofcadmium arachidate and perdeuteratedcadmium arachidate layers deposited on hydrophobic silicon isinvestigated by neutron and X-rayreflectometry. Using this pair of techniques allows one to depthresolve changes induced by annealingand also to discriminate between the behavior of the Cd head latticeand that of the aliphatic tails. Allsamples initially have ill-defined interfaces between the tails ofadjoining protonated and deuteratedlayers, and some interchange of chains among layers occurs during thedeposition process itself. The formof the multilayer structure is thermally stable at 70 and 84 °C, eventhough aliphatic tails are lost graduallydue to ablation, leading to noticeable losses when annealing for 1 weekat 84 °C. These losses occur almostexclusively from the layers closest to air, suggesting that the rate ofablation is considerably higher thanthat of interdiffusion. There appears to be little interlayerinterdiffusion of chains when annealing forseveral hours at 84 °C. We conjecture that the type ofinteraction anchoring the two layers adjoining aninterface may influence the stability of that interface to molecularexchange across it.
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