Polymer-inorganic nanocomposite films of PEO-ZnO and PEO-ZnO-LiClO4, where
PEO stands for poly(ethylene oxide), have been prepared through a film-cast
ing method. Interactions between PEO (MW = 600 000) and ZnO nanoparticles (
average size 3.5 nm, with acetate groups on the surface) decrease the photo
luminescence intensity of the PEO film to a great extent. These interaction
s, which are also manifested by the X-ray diffraction, depend on the concen
tration and the aggregation of the ZnO nanoparticles in the PEO-ZnO films.
The cooperative effect of PEO and LiClO4 changes the unidentate coordinatio
n mode of the acetate groups with zinc into three coexisting modes: unident
ate, bidentate, and bridging, suggesting that PEO segments, lithium ions, a
nd the acetate groups on ZnO nanoparticle surface form cross-linking struct
ures. Such cross-linking structures, on one hand, reduce Li+ClO4- ion pairs
to release more free ions as charge carriers in the PEO-ZnO-LiClO4 film an
d, on the other, decrease the film crystallinity to produce more amorphous
regions for charge carriers to transfer, and finally enhance the conductivi
ty of the film.