Influence of Polymerization Temperature on Molecular Weight, Photoluminescence, and Electroluminescence for a Phenyl-Substituted Poly(p-phenylenevinylene)

Abstract

We present the synthesis and characterization of poly(2-(2′′,5′-bis(2′′-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) (BEHP-PPV) polymerized at different temperatures. The photoluminescence efficiencies in the solid state of BEHP-PPV obtained at 144 and 0 °C are 28% and 60%, respectively. 1 H NMR measurements showed a lower concentration of structural defects for BEHP-PPV obtained at lower temperatures, which can explain the increased photoluminescence efficiencies for these polymers. Polymerization temperatures below 0 °C decrease the molecular weight without changing the photoluminescence efficiency to any large extent. The electroluminescence efficiencies follow the trend in the photoluminescence efficiencies.

Efficient Oxygen‐Induced Molar‐Mass Control of Poly(p‐phenylene vinylenes) Synthesized via the Gilch Route

“…Throughout, the NMR spectra of the PPVs prepared in the presence of oxygen showed the same characteristic absorptions and the same relative signal intensities as those of reference PPVs obtained in the absence of oxygen. Also, the characteristic small additional absorptions which are assigned to intrinsic defects within the Gilch-PPVs, i.e., ethylene-, ethinylene-, and cis-configurated vinylene moieties, [23][24][25][26][27] proved to be unaffected by the oxygen. The only change in the spectra of PPVs formed in the presence of oxygen was an additional very weak absorption in the d % 10 ppm region of the proton spectra which was interpreted as resulting from oxygen-containing chain termini, most likely aldehyde moieties.…”

Soluble PPVs with few structural defects: Synthesis and characterization

“…In another attempt to avoid structural defects Johansson et al found that a low polymerization temperature (À 78, À 35 -C) avoids gelation but polymers still contains a considerable amount of bromine. Polymerization in refluxing xylene shows complete dehydrobromination; however, polymers with low molecular weights were obtained because of chain scission of the polymers backbones at high temperature [20].…”

Synthesis and characterization of poly(fluorene vinylene) copolymers containing thienylene–vinylene units

“…As a branch of PF derivatives, poly(fluorene vinylene)s, which have similar structures to poly(p‐phenylenevinylene) (PPV), exhibit special properties when the dialkylfluorene units are alternated with the vinylene units in the polyfluorene main chain. Normally, poly(fluorene vinylene) homopolymer has been prepared via a Gilch reaction, but there is no insoluble gel formed, as poly(p‐phenylenevinylene) (PPV) did, during the polymerization process 8. The vinylene units in the polymer backbone lead the absorption spectra to broaden and the photoluminescence (PL) emission spectra to redshift in comparison with PFs 9.…”