Formation Mechanism of Multilayer Polyamic Acid Alkylamine Salt Langmuir–Blodgett Films

Abstract

In this paper we present atomic force microscopy (AFM) and friction force microscopy (FFM) analyses on the surface structure of mono- and multilayer films prepared from two types of polyamic acid with long alkylamine chains, which were utilized as the precursors of polyimide Langmuir–Blodgett (LB) films. The characteristic domain structures on the monolayer films, namely, the plateau type and the hollow type, were examined while changing the film preparation conditions and the chemical structures of the precursors. The surface structures of the multilayer LB films were also analyzed by AFM, FFM and FT-IR techniques. It was found that the domain structures that appeared on the monolayer film were transformed to a smooth domain-free structure by multilayer deposition of the LB film. The formation and smoothing mechanism of the domain structures was discussed taking into account the fluidity of the polymer groups controlled by the frictional force at the film interface.