Effects of a strong-interacting amorphous polymer, poly(4-vinyl phenol) (PVPh), and an alkali metal salt, lithium Perchlorate (LiClO4), on the amorphous and crystalline domains in poly(ethylene oxide) (PEO) were probed by differential scanning calorimetry (DSC), optical microscopy (OM), and Fourier transform infrared spectroscopy (FTIR). Addition of lithium Perchlorate (LiClO4, UP to 10% of the total mass) led to enhanced T-g's, but did not disturb the miscibility state in the amorphous phase of PEO/PVPh blends, where the salt in the form of lithium cation and ClO4- anion was well dispersed in the matrix. Competitive interactions between PEO, PVPh, and Li+ and ClO4- ions were evidenced by the elevation of glass transition temperatures and shifting of IR peaks observed for LiClO4-doped PEO/Pvph blend system. However, the doping distinctly influenced the crystalline domains of LiClO4-doped PEO or LiClO4-doped PEO/PVPh blend system. LiClO4 doping in PEO exerted significant retardation on PEO crystal growth. The growth rates for LiClO4-doped PEO were order-of-magnitude slower than those for the salt-free neat PEO. Dramatic changes in spherulitic patterns were also seen, in that feather-like dendritic spherulites are resulted, indicating strong interactions. Introduction of both miscible amorphous PVPh polymer and LiClO4 salt in PEO can potentially be a new approach of designing PEO as matrix materials for electrolytes. (c) 2006 Wiley Periodicals, Inc.