Investigation of the monolayer LB film properties of a silsesquioxane hybrid containing phenyl groups using SPM

Abstract

In this study, we used a silsesquioxane hybrid material between phenyl group containing carbosilane dendrimer and siloxane polymer (G1-3Ph). As expected, G1-3Ph has a networked structure. Generally, it is difficult to generate uniform monolayers as common materials. However, if the materials have a networked structure, we can easily obtain uniform monolayers because of the molecular interactions. Moreover, this networked structure should have a cavity in which ions could be placed. We have fabricated Langmuir-Blodgett (LB) films of the G1-3Ph in a thin film state. We investigated the monolayer behavior using the π-A isotherm at the air-water interface. The π-A curves indicated that the surface pressure of this LB film from the liquid to the solid state falls between 5 and 8 mN/m. The monolayer was deposited onto highly oriented pyrolytic graphite (HOPG) substrates via Y-type deposition at a surface pressure of 5.5 mN/m. We also studied the morphological properties of the silsesquioxane hybrid LB films using SPM and determined the electrical properties of the LB films using STM. The I-V and the morphological characteristics of the sample were investigated at room temperature. The experimental results correlate with the calculated I-V curves when we use the parameters indicated in the caption. This study will enable us to apply a molecular electronic device to measure morphological and electrical characteristics on the nano scale. © 2009 Elsevier B.V. All rights reserved.