Miscibility and intermolecular specific interactions in thermosetting blends of bisphenol S epoxy resin with poly(ethylene oxide)

Thermosetting blends composed of phloroglucinol-cured bisphenol S epoxy resin and poly(ethylene oxide) (PEO) were prepared via the in situ curing reaction of epoxy in the presence of PEO, which started from initially homogeneous mixtures of diglycidyl ether of bisphenol S, phloroglucinol, and PEO. The miscibility of the blends after and before the curing reaction was established on the basis of thermal analysis (differential scanning calorimetry). Single and composition-dependent glass-transition temperatures (T-g's) were observed for all the blend compositions after and before curing. The experimental T-g's could be explained well by the Gordon-Taylor equation. Fourier transform infrared spectroscopy indicated that there were competitive hydrogen-bonding interactions in the binary thermosetting blends upon the addition of PEO to the system, which was involved with the intramolecular and intermolecular hydrogen-bonding interactions, that is, OH... O=S, OH... OH, and OH, versus ether oxygen atoms of PEO between crosslinked epoxy and PEO. On the basis of infrared spectroscopy results, it was judged that from weak to strong the strength of the hydrogen-bonding interactions was in the following order: OH... O=S, OH... OH, and OH versus ether oxygen atoms of PEO. (C) 2005 Wiley Periodicals, Inc.