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H
H
R• +
C
C
R
C
C
H
H
H
H
H
H
H
H
R
C
C
+
C
C
R
C
C
C
C
H
H
H
H
H
H
H
H
Fig. 6: Free-radical polymerization: example of styrene.
This reaction eventually leads to the formation of polystyrene, a portion of which is
shown below. Polystyrene prepared by free-radical polymerization is shown on Fig. 7 (see
below).
H
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Fig. 7: Polystyrene prepared by free-radical polymerization.
Polymerization may occur by any of three mechanisms:
free radical,
cationic,
anionic.
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