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Mechanistic and kinetic studies on the polymerization of styrene initiated by dimethyl sulfonium 2‐pyridyl carbonyl methylide
Author(s) -
Bhatnagar Urvi,
Srivastava A. K.
Publication year - 1991
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990250104
Subject(s) - chemistry , polymerization , polymer chemistry , sulfonium , monomer , photochemistry , radical polymerization , styrene , radical , hydroquinone , polymer , copolymer , organic chemistry , salt (chemistry)
Dimethyl sulfonium 2‐pyridyl carbonyl methylide (Y py‐s ) initiated radical polymerization of styrene in dimethyl sulfoxide at 85±0.1°C for 6 h under a nitrogen blanket using dilatometric techniques has been studied. The initiator and monomer exponent values were calculated to be 0.5 and 1.2, respectively. The system follows ideal radical kinetics with bimolecular termination. The higher monomer exponent value is ascribed to significant solvent effects on the initiation rate. The overall activation energy and average value of k 2 p /k t are 52.0 kJ mol −1 and 1.0 × 10 −3 litre mol −1 s −1 , respectively. The polymerization was retarded in the presence of hydroquinone or benzene; dimethylformamide, however, enhanced the rate of polymerization. Kinetic data and ESR studies indicate that the overall polymerization takes place via triplet carbene formation which acts as a source of free radicals.