Primary radical termination and unimolecular termination in the heterogeneous polymerization of acrylamide initiated by a fluorinated aro-derivative initiator: A kinetic study

Acrylamide was polymerized in acetonitrile at 82 degrees C with a perfluori nated azo-derivative initiator. The polymerization proceeded heterogeneousl y. Varying amounts of initiator and monomer were used. The activation energ y was deduced from three experiments carried out at 59, 71, and 82 degrees C. The following kinetic law, deviating a great deal from the classical law , was obtained: R-pi similar to [I-2](o)(0.76)[M](o)(1.06)(0.05% < [I-2](o) /[M](o) < 1.00%) and R-pi similar to [I-2](o)(0.29)[M](o)(1.95)(1% < [I-2]( o)/[M](o) < 7%). These results can be interpreted in light of the contribut ion of primary radical termination and the emergence of occlusion. The deve lopment of a new kinetic relationship allowed us to confirm the existence o f both of these termination reactions. The calculation of the k(prt)/K-i . k(p) ratio was also achieved. (C) 2000 John Wiley & Sons, Inc.