Soluble PPVs with few structural defects: Synthesis and characterization

A series of 2,5-dialkoxy poly(1,4-phenylenevinylene) derivatives with different alkoxy side-chain lengths were synthesized via a modified Gilch polymerization. Prolonged reaction and additional base treatment at elevated temperature lead to PPVs with very low chlorine content and few structural defects. The polymers were synthesized in satisfactory yields (45–65%) and had number-average molecular weights of 10,000–14,000. Structural characterization was accomplished by FT-IR, 1H-NMR, 13C-NMR spectroscopy and by elemental analysis. All polymers are amorphous, stable up to 300 °C and soluble in both chloroform and tetrahydrofuran. The UV-Vis absorption and emission in the solid state are in the range 496–507 nm and 578–629 nm, respectively. Band gaps calculated from the UV-Vis spectra edge are in the range 2.06–2.11 eV. Light-emitting diodes (LEDs) based on these polymers were fabricated and characterized by current–voltage measurements.