Polymerisationsauslösung mit substituierten ethanen, 8. Polymerisation von styrol

The free radical polymerization of styrene initiated by 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane (TPPA) can be described as a kind of dead end polymerization. At the beginning of the polymerization, mainly oligomers are formed by primary radical chain termination. These oligomers can be characterized by thin layer and gel permeation chromatography and by mass spectroscopy. With increasing conversion and decreasing initiator concentration the molecular weight of the polymers is increasing. Contrary to the polymerization of methyl methacrylate with the same initiator, in the case of styrene the formed oligomers are not able to initiate once more the polymerization because the end groups formed by initiator radicals and styrene units are rather stable at normal polymerization temperatures (60 – 100°C).