On the Termination Mechanism in the Radical Polymerization of Acrylates.
In a recent publication, Nakamura and co-workers studied the termination mechanism in the radical polymerization of acrylates. Contrary to conventional thinking, their conclusion is that termination is overwhelmingly by disproportionation. This finding impacts on a large body of the previous work in the polymerization of acrylic monomers which this work seeks to address. Analysis of the molecular weight distribution of acrylic polymers obtained under different polymerization conditions shows that termination by combination is the more probable mechanism for mutual termination of secondary radicals. It is proposed that in the experiments conducted by Nakamura and co-workers, backbiting plays a key role and their experimental data are reinterpreted, showing that they are more revealing with respect to the mode of termination of the midchain radical produced by backbiting, than to bimolecular termination of secondary radicals.
POLYMAT and Kimika Aplikatua Saila, University of the Basque Country UPV/EHU, Korta Zentroa, Tolosa Etorbidea 72, 20018, Donostia/San Sebastián, Spain.
Nicholas
N
Ballard
POLYMAT and Kimika Aplikatua Saila, University of the Basque Country UPV/EHU, Korta Zentroa, Tolosa Etorbidea 72, 20018, Donostia/San Sebastián, Spain.
Shaghayegh
S
Hamzehlou
POLYMAT and Kimika Aplikatua Saila, University of the Basque Country UPV/EHU, Korta Zentroa, Tolosa Etorbidea 72, 20018, Donostia/San Sebastián, Spain.
Fernando
F
Ruipérez
POLYMAT and Kimika Aplikatua Saila, University of the Basque Country UPV/EHU, Korta Zentroa, Tolosa Etorbidea 72, 20018, Donostia/San Sebastián, Spain.
José M
JM
Asua
D000179:Acrylates / Q000138:chemical synthesis*; D005609:Free Radicals / Q000737:chemistry; D007700:Kinetics; D008970:Molecular Weight; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000138:chemical synthesis*; D013816:Thermodynamics
D000179:Acrylates; D005609:Free Radicals; D019904:Polymethyl Methacrylate
acrylates; emulsion polymerization; gelation; radical polymerization; termination reactions