Charge-transfer oxygen-polystyrene complexes

Polystyrene can form a charge-transfer (CT) complex with molecular oxygen [36, 1386, 1610, 1611, 1781, 1793, 1794, 2301]. The absorption band of the CT complex extends from 350 nm toward longer wavelengths [1610]. High oxygen pressure promotes the formation of the CT complex [1794] and the rate of photo-oxidation, but does not influence the mechanism of photo-oxidative degradation [1610, 1793]. The concentration of the CT complex depends on two factors  

The solubility of oxygen in the polymer matrix, which increases with increasing pressure. 

The hydroperoxide groups can be formed directly from the CT complex when excited by UV radiation [1386]. 

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It is well known that several monomers,such as styrene, < ( methylstyrene,isoprene,vinyl acetate (jj) have shown formation of oharge-transfer complexes in the presence of oxygen. Polystyrene peroxide is formed by photoirradiation of charge-transfer complex in the initial stage of polymerisation and the further photoinduced decomposition of the polystyrene peroxide initiates the polymerisation of styrene. On the other way,the reaction between excited state of styrene and oxygen may induce the formation of an alternating copolymer with peroxide groups -0-0- in-backbone. 

Polystyrene Direct photoexcitation/photoxidation of phenyl rings. Charge-transfer complex with oxygen. -C=0 and -OOH groups from processing or from oxidation. Interactions with singlet oxygen. [32,95-101]... 

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. 

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