DIELECTRIC-SPECTROSCOPY OF BINARY POLYSTYRENE POLY[STYRENE-B-(ETHYLENE OXIDE)] BLENDS AND TERNARY COMPOSITES OF POLYSTYRENE/POLY[STYRENE-B-(ETHYLENE OXIDE)] SWOLLEN WITH HOMOPOLY(ETHYLENE OXIDE)/

The effect of incorporating poly[styrene-b-(ethylene oxide)], PS-b-PEO into PS/PEO composites has been examined microscopically and dielectr ically. The addition of block copolymer stabilizes the dispersion of P EO in PS and can produce composites of PEO in PS in which the PEO doma in size ranges from the size of the micelle core in binary PS/PS-b-PEO composites to larger PEG-swollen micelles to micron-sized phases of P EO stabilized by small amounts of PS-b-PEO. Dielectric spectra have be en obtained as a function of frequency and temperature for binary comp osites of PS/PS-b-PEO and ternary composites of PS/PS-b-PEO/PEO, where in the total content of PEO residues is held constant at 4.7% by weigh t. The dispersion of PEO in PS enables the observation of the full die lectric spectrum of the PEO phase. The dielectric spectrum of binary c omposites of PS/PS-b-PEO shows a predominant peak for the beta' relaxa tion of PEO chain segments covalently tethered to the glassy PS contin uum. Ternary PS/PS-b-PEO/PEO composites show significant beta and beta ' relaxations. The a peak corresponds to that observed in pure PEO and in PS/PEO composites. The beta' peak corresponds to the higher temper ature WLF type molecular relaxation observed in binary PS/PS-b-PEO com posites and in PS/PEO composites. In the binary systems containing onl y PS and PS-b-PEO, the crystallinity of PEO is suppressed or disturbed . Accordingly, the gamma and alpha peaks which present themselves in p ure PEO and in PS/PEO composites are not observed.