Cover Image, Volume 51, Issue 15



The structure and crystallinity of polyelectrolytes has long been known to affect their ionic conductivity, but the effects of water of hydration on polyelectrolyte structure are not commonly studied. On page 1162, Yujun Yang and Hong Huo show that the structure of the complex formed in PEO/anhydrous MgCl2 is significantly different to that of the complexes formed in PEO/hydrated MgCl2, indicating that the “crystal water” of the metal salts strongly affects the complex structure in polymer electrolytes. The cover displays a room-temperature polarized optical microscopy image of a (PEO)9MgCl2·4H2O complex, with both inner and outer PEO spherulites. The finer outer spherulite grows radically along the dark inner spherulite and the birefringence turns bright.