Bilayer nanocomposite molecular coatings from elastomeric/rigid polymers: fabrication, morphology, and micromechanical properties

Abstract

We fabricated bilayered nanocomposite coatings composed of a hard polymer layer placed on top of an elastomeric layer. The primary layer of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) was attached to the surface by grafting to a chemically reactive silicon surface functionalized with epoxy-terminated SAM. The SEBS layer served as the compliant interlayer in the bilayered polymer coating. The topmost hard layer was a high performance polymer made of epoxy resin (EP) and an amino functionalized poly(paraphenylene) (PPP). We built the bilayered structure by spincoating the EP/PPP mixture on top of the grafted SEBS layer. The solidification of the topmost layer was initiated at low temperatures (40 - 50 °C) to avoid dewetting. The curing of the film was finished at 110 °C (15 hours) and the EP/PPP layer was strongly attached to the SEBS layer. It was found that the EP/PPP layer did not penetrate inside the elastic primary layer during the solidification. The elastic response of the hard polymer layer was affected significantly by the underlying elastomeric layer. The SEBS layer served as a compliant interlayer capable of dissipating the interfacial stresses originating from dissimilarities in the physical properties between the polymer coating and the inorganic substrate.