| Abstract
| - Conjugated polyphenylenevinylene oligomer (PPV) encapsulated inside basic zeolites X and Y has been prepared starting from the p-phenylenedimethylene-1,1‘-bis(tetrahydrothiophen-1-ium) monomer introduced through ion exchange followed by heating the intermediate poly[1-(S-tetrahydrothiophenium)-p-phenylenethylene] oligomer at 220 °C under vacuum for 24 h. The photophysics of PPV encapsulated inside zeolite reveals the formation of polarons. The resulting PPV exhibits a weak electroluminescence.
- Conjugated polyphenylenevinylene oligomer (PPV) encapsulated inside basic zeolites Xand Y has been prepared starting from the p-phenylenedimethylene-1,1‘-bis(tetrahydrothiophen-1-ium) monomer introduced through ion exchange followed by heating theintermediate poly[1-(S-tetrahydrothiophenium)-p-phenylenethylene] oligomer at 220 °Cunder vacuum for 24 h. PPV loading ranged between 1.8 and 5 wt %, the sulfur content ofthe solid being lower than 0.03 wt %, corresponding to 1 S atom every 400 carbons. Theorganic oligomer has been characterized by diffuse reflectance UV−vis, IR, and MAS 13CNMR, all the data being in agreement with that reported in the literature for pure PPV anddifferent from those of the tetrahydrothiophenium containing intermediate polymerencapsulated inside zeolites. The solids exhibit the green emission characteristic of PPV.Although the length of the oligomer could not be determined by solid−liquid extraction orby treatment of the zeolite with HF, samples with lower precursor loading showed a 20-nmred-shifted emission with respect to that reported for well-prepared PPV. Thus, it is assumedthat the length of the encapsulated oligomer has to be enough to make its propertiesindistinguishable from those of the nonencapsulated PPV polymer. The zeolite-encapsulatedPPV was fairly stable to laser flash photolysis (laser power ∼ 10 mJ pulse-1). The transientspectrum has been mainly attributed to PPV polarons. A cell of a thin film of encapsulatedPPV prepared by deep coating shows a current intensity vs voltage response characteristicof a diode and a weak electroluminescence operating at a dc voltage of 2.5 V.
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