Polystyrene, fluorescence radicals

The absorption band around 520 nm is very similar to that of polystyrene excimer (2,3,5). The decay follows first order kinetics with a lifetime of 20 ns. The decay rate agrees with that of the excimer fluorescence and excimer absorption. The longer life absorptions, attributed to the triplet states and free radicals (2,5), were observed at wave lengths <400 nm, although the anionic species of polystyrene with the absorption maximum at 410 nm as seen in solid films (cf. Figure 5) was not observed. Figure 9 shows the absorption spectrum observed in the pulse radiolysis of CMS solution in cyclohexane. 

This value agrees with the lifetime of the excimer of polystyrene. The intensity of the excimer fluorescence decreased with increasing chloromethylation ratio. Electrons produced in cyclohexane, one of the precursors of the excimer, were scavenged by chloromethylated part of polystyrene. Absorption spectra of the excited states and the polymer radicals were measured by laser photolysis of the cyclohexane solutions. The results are summarized in Fig. 10 [67]. 

A transformation method can introduce some functional groups at the junction as in B-63, which bear a fluorescent dye between the polyisoprene and polystyrene segments.375 The preparation is based on quenching the living anionic polymerization of isoprene with l-(9-phenanthryl)-l-phenylethylene followed by addition of excess a,a -dibromo-/>xylene, which affords a C—Br terminal effective for the copper-catalyzed radical polymerization of styrene. 

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