| Abstract
| - Micro- and submicrosized ZnO−polymer hybrid materials were synthesized by precipitating zinc oxide froman aqueous medium in the presence of poly(styrene−acrylic acid) latex nanoparticles, prepared by miniemulsionpolymerization. Up to 10 wt % of the latex becomes incorporated into the crystals. Although the long-rangeorder of the inorganic material is essentially not altered by the polymer, studies by photoluminescence (PL)spectroscopy and electron paramagnetic resonance (EPR) show that the latex particles influence the opticaland paramagnetic properties of the hybrids, which can be correlated with changes in the defect structure.Typical PL emission spectra showed a narrow UV peak and a defect-related broad band in the green−yellowspectral region. The former emission is attributed to exciton recombination, whereas the latter seems to berelated with deep-level donors. Latex acts as a quencher of the visible emission, and compared to pure ZnO,ZnO−latex hybrids show a significantly lower PL intensity in the visible range. A noticeable dynamic behaviorof the PL, clearly more remarkable in the presence of latex, was observed, and it is explained in terms ofphotodesorption of oxygen adsorbed at surface positions. EPR provided additional information about crystaldefects and species with unpaired electrons. All EPR spectra showed a single signal at g ≈ 1.96, whoseintensity and temperature dependence did not correlate with those of the PL visible band. These findingsindicate that the green−yellow emission and the EPR signal of our samples have a different physical origins.
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