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.