Polymerization of styrene by poly(bisphenol a 4,4′-azobis-4-cyanopentanoate)

A free radical initiator, poly(bisphenol A 4,4′-azobis-4-cyanopentanoate) (BPA), containing more than one azo group per molecule, was used to polymerize styrene in N,N-dimethylformamide (DMF) at 60°C. Polymerization rates were measured gravimetrically or dilatometrically, and the molecular weights of the isolated polystyrenes were determined viscometrically, both before and after hydrolysis. BPA has a relatively low initiator efficiency of 0.28. The activation energy and velocity constant at 60°C for decomposition of BPA per azo group in DMF were found spectroscopically to be 105.9 kJ/mole and 2.08 × 10^?5 sec^?1, respectively. The molecular weights of unhydrolysed polystyrenes increased with increasing conversion and a theory is developed to explain these results.