Adjustable amine–epoxy composition in a stratified thin film with a spin‐coating process: A useful tool for establishing relationships between the local glass‐transition temperature at the interface and the network structure

An easy method for preparing supported homogeneous epoxy–amine thin films on a silica surface consisting of two distinct layers was developed via spin coating from epoxy–amine solutions. Because of these two layers had the controlled properties of the upper layer, we showed that it was possible to precisely control the epoxy–amine stoichiometry in the sublayer through the initial epoxy–amine ratio, the spin‐cast process, and the overall film thickness. First, in the thin films, the primary amine–epoxy conversion was constant, whatever the thickness and initial epoxy–amine stoichiometry for a given curing schedule. As the primary amine conversion can be independently tuned in thin films, it thus provided a rather unique and easy method for better understanding the relationship between the network structure curing at the interface and the resulting properties, such as the glass‐transition temperature (T_g) and elastic modulus. Here, we also showed that we could access the local T_g; this implied a potential application of these experimental data in predictive composite material properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42078.