Enhanced Reactivity of the Epoxy Oligomers in Organized Monolayers at the Air-Water Interface

Abstract

The behaviors of monolayers of novolac and diglycidyl ether of bisphenol A type epoxy oligomers on the surface of water were studied. Using a surface balance technique and FT-IR spectroscopy, it was found that the time evolution of surface pressure and surface area of the monolayers is controlled by the chemcial reactions of these oligomers with water and carbon dioxide. The specific reactivity of epoxy oligomers in a one-layer organized system at the air-water interface (in bulk similar reactions may proceed only under severe conditions) is enabled by the increased concentration and the mobility of protons in a thin layer of water adjacent to the monolayer and by the basicity of the epoxy groups of the oligomers. Surface reactions of epoxy oligomers are shown to be topochemical in nature ; the kinetics of these reactions may be described by the Avrami-Erofeev equation. The magnitudes of the parameters of this equation which were determined for the monolayers of each of the oligomers lead to the conclusion that, generally, the dynamics of epoxy oligomer monolayers is controlled by chemical transformations in and rearrangement of the surface layer.