Results from Irradiation in Polyethylene Films

2 Results from irradiations in polyethylene films. Given these analyses, the data from irradiations of (/ )-3b in polyethylene films will now be discussed (Table 13.7). As mentioned above, the ability of the radical pairs from (/ )-3b to diffuse translationally within a cage is related qualitatively to the 2-BN/4-BN ratios whereas the ability of the 1-phenylethyl radical to tumble along the translational course that brings it to combine at either the 2- or 4-position of its 1 -naphthoxy partner is related to or %ee4B. Although a 1-phenylethyl radical center is attracted 

TABLE 13.7 Distribution Ratios and Extrapolated Enantiomeric Excesses (ees) of 2-BN and 4-BN Photoproducts (cc2b and cc4b, Respectively) from Irradiations of 99.5% Enantiomerically Pure (R)-3b in n-hexane, n-heptadecane, and Unstretched (u) and Stretched (s) Completely Amorphous (PEO) and LDPE Films at 296 K 

DYNAMICS OF RADICAL PAIR PROCESSES IN BULK POLYMERS 

FIGURE 13.4 Plots of ln(ee(K) 3b/ee3b.totai) versus —ln(l — conversion fraction) for irradiations of (i )-3b in unstretched ( ) and stretched ( ) PEO films, and in unstretched (A) and stretched ( ) LDPE films at 296K. Points at each plot from bottom to top are vertically offset by 0.05 increments. Reproduced from Ref 77 by permission of the Royal Society of Chemistry on behalf of the European Society for Photobiology and the European Photochemistry Association. 

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