Photooxidative stability of substituted poly(phenylene vinylene) (PPV) and poly(phenylene acetylene) (PPA)

Abstract

The addition of side groups to improve the photooxidative stability of polymers used in polymer-based light-emitting diodes (LEDs) is explored. Infrared spectroscopy and computational chemistry techniques are used to study the effects of chemical substitution of the reactive vinylene moiety in poly(phenylene vinylene) (PPV). The bond order of the vinylene group in small oligomers is calculated using semiempirical techniques to assess the improvement in stability toward oxidants such as singlet oxygen. We find that PPV dimers allow relative comparisons across a range of possible substitutions. Experimental results correlate well with these calculations. The addition of electron-withdrawing substituents, such as nitrile groups, to the vinylene moiety is found to be particularly effective in reducing the reactivity of alkoxy-substituted PPV toward singlet oxygen. The photooxidative stability of a poly(phenylene acetylene) (PPA) derivative is also studied. It appears that this family of polymers is more stable toward photooxidation than are its PPV analogs.

Interchain interactions effects on emission efficiency of poly(p-phenylene vinylene) films

“…In this plot, the ratio A 2 /A 1 at first decreases substantially (90.7%) when the salt is added and then becomes independent of salt concentration. This decline can be related to the elimination of aggregated stilbene species, and the residual intensity is attributed to the stilbene species previously present in the PPV precursor solution [24]. The results relative to the elimination step at higher temperatures are shown in Fig.…”

Solution aging and degradation of a transparent conducting polymer dispersion

“…For example, OPV devices with active layers composed of poly(phenylene vinylene) (PPV) or poly(3-hexylthiophene-2,5-diyl) (P3HT) have been shown to be susceptible to degradation by water and oxygen [9e11]. In addition, extrinsic degradation can also occur when exposing devices to UV light [12,13], elevated temperatures [14,15], high drive current [16], etc. Intrinsic degradation, on the other hand, results from factors that are built into the device, such as interfacial instability, molecular diffusion, phase separation, or reaction between components.…”

Ionizing radiation induced degradation of poly (2-methoxy-5-(2’-ethyl-hexyloxy) -1,4-phenylene vinylene) in solution

“…There is a vast literature in these subject, however not when ionizing radiation is used. [10][11][12][13]16,17 The effects of gamma radiation observed in polymers are diverse and depend on several factors, such as temperature, chemical environment, chemical structure, as well as the polymer physical state. [18][19][20] For example, the irradiation of polyethylene under inert atmosphere results in crosslinking.…”