CONTROL OF DENSITY IN SELF-ASSEMBLED ORGANOSILANE MONOLAYERS BY LANGMUIR-BLODGETT DEPOSITION

We report studies of the organization in octadecyltrichlorosilane mono layers that have been prepared by the Langmuir-Blodgett technique. The monolayers, which are covalently bound to an acid-treated mica surfac e, have been examined by scanning force microscopy in both topographic and frictional-force modes. Both the sizes and number of silane domai ns on the surface can be altered by choice of the density of the film before transfer from the water surface. When the transfer is carried o ut in the liquid expanded-liquid condensed two-phase region, the size distribution of islands on the mica surface is bimodal. Parts of the f ilm that originate from the liquid expanded phase consist of small isl ands whose size can be controlled by the rate of transfer.