Spontaneous Rearrangement in Langmuir-Blodgett Layers of Tripalmitin Studied by Means of ATR Infrared Spectroscopy and Electron Microscopy

1. Under the conditions used in our investigation, tripalmitin layers of the Langmuir Blodgett (LB) type undergo a spontaneous transition, leading from a liquid crystalline (LB) state to a microcrystalline (CR) state. 2. This transition is accompanied by a shift of the methylene bending band from 1469 to 1473 cm-1 and a shift of the ester group motion from about 1169 to 1182 cm1 . In both cases the half widths of the absorption bands are reduced. 3. The two components of the methylene bending band comprise, within experimental error, all of the tripalmitin present. This is demonstrated by the constancy of the sum of the two band areas attributed to the LB and the CR state respectively. Furthermore, this observation indicates that the liquid crystalline and the crystalline state are the two main types of structural organization occuring in these layers.