Nanostructured Thermosets from Epoxy Resin and an Organic−Inorganic Amphiphile

Abstract

Polyhedral oligomeric silsesquioxane (POSS)-capped PCL was synthesized via ring-opening polymerization of ε-caprolactone with 3-hydroxypropylheptaphenyl POSS as the initiator. The novel organic−inorganic amphiphile was incorporated into epoxy resin to prepare the organic−inorganic hybrid thermosets. The morphology of the organic−inorganic hybrids was characterized by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). It is found that the epoxy thermosets displayed a variety of nanostructures depending on the concentration of the POSS-capped PCL. The formation of nanostructures was addressed on the basis of miscibility and phase behavior of the subcomponents (viz. POSS and PCL chains) of the organic−inorganic amphiphile with epoxy after and before curing reaction. It is judged that the nanostructures in the organic−inorganic hybrid composites were formed via a mechanism of self-assembly. The static contact angle measurements show that the organic−inorganic nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The improvement in surface properties was ascribed to the enrichment of POSS moiety on the surface of the nanostructured thermosets, which was evidenced by X-ray photoelectron spectroscopy.