Nanostructures and Surface Dewettability of Epoxy Thermosets Containing Hepta(3,3,3-trifluoropropyl) Polyhedral Oligomeric Silsesquioxane-Capped Poly(ethylene Oxide)

Abstract

Hepta(3,3,3-trifluoropropyl) polyhedral oligomeric silsesquioxane (POSS)-capped poly(ethylene oxide) (PEO) was synthesized via the reaction of hydrosilylation between hepta(3,3,3-trifluoropropyl)hydrosilsesquioxane and allyl-terminated PEO. The POSS-capped PEO was characterized by means of Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The organic-inorganic amphiphile was incorporated into epoxy resin to prepare the organic-inorganic nanostructured thermosetting composites. The morphology of the hybrid composites was characterized with field emission scanning electronic microscopy (FESEM) and transmission electronic microscopy (TEM). The formation of nanostructures was addressed on the basis of miscibility and phase behavior of the sub-components (viz. POSS and PEO chains) of the organic-inorganic amphiphile with epoxy after and before curing reaction. The static contact angle measurements indicate that the organic-inorganic nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The atomic force microscopy (AFM) showed that there is significant migration of the POSS moiety at the surface of the thermosets. The improvement in surface properties was ascribed to the enrichment of the POSS moiety on the surface of the nanostructured thermosets, which was evidenced by X-ray photoelectron spectroscopy (XPS).