Oxygen with poly charge-transfer complexes

Lu et al. have reported that the fluorescence intensities of Eu3+ and Tb3+ are markedly enhanced when they are bound on to a poly(acrylamide-acrylic acid copolymer). Dhake et al. have observed interesting differential effects of pressure on the fluorescence of a polymer and the corresponding monomer. Sterically hindered piperidines have for long been of interest as efficient photostabilisers of polymers. Gugumus has now reported that these stabilisers form charge-transfer complexes with molecular oxygen, thereby preventing the formation of such complexes with the polymer. 

Abdou, M.S.A., Orfino, F.P., Son, Y. and Holdcroft, S., Interaction of oxygen with conjugated polymers Charge transfer complex formation with poly(3-aIkylthio-phenes), J. Am. Chem. Soc., 119, 4518 524, 1997. 

Charge-transfer complexes of oxygen with poly(olefins) have been proposed as initiators of photodegradation (138), and it is of particular interest to note that recently oxygen-induced exci-mer fluorescence emission has been observed in poly(styrene) doped with aromatic compounds (139). 

Fig. 19.3 Reversible formation of a charge transfer complex between poly(3-alkylthiophenes), P3AT, and oxygen. R represents an alkyl group (Reprinted with permission from Jprgense et al. 2008, Copyright 2008 Elsevier)...

Abdou MSA, Orfino FP, Son S, Holdcroft S (1997) Interaction of oxygen with conjugated polymers charge transfer complex formation with poly(3-alkylthiophenes). J Am Chem Soc 119 4518-4524 Aldiss M (1989) Inherently conducting polymers processing, fabrication, applications, hmitations. Noyes Data Corporation, Park Ridge... 

Molecular oxygen can form charge transfer (CT) complexes with a number of organic low molecular liquids [2139] and solid polymers, such as polyethylene [851,2152], polypropylene, [60, 2150] poly(4-methyl-l-pentene) [2284] and polystyrene [36,1386,1610,1611,1615,1781,1793,1794,2301]. In polystyrene, at higher oxygen pressures ( 20-150 bar), CT complexes show an absorption band with 275 nm. 

In carbon tetrachloride poly(a-methylstyrene) were degraded, even without oxygen, by the irradiation of ionizing radiation [58], The decay of the charge transfer radical complex, observed in this solvent, may be due to the reaction of a chlorine atom with p-site H of poly(a-methylstyrene) the reaction leads to the formation of P-position radicals of poly(a-methylstyrene). The produced polymer radicals were unstable and dissociated into neutral and radical species. 

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