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Effect of ring‐size in cationic polymerization of cyclosiloxanes. D 6 ‐polymerization initiated by trifluoromethanesulfonic acid
Author(s) -
Gobin C.,
Masure M.,
Sauvet G.,
Sigwalt P.
Publication year - 1986
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19860060122
Subject(s) - cationic polymerization , polymerization , ring opening polymerization , chemistry , polymer chemistry , reaction rate constant , ring (chemistry) , triflic acid , catalysis , kinetics , organic chemistry , polymer , physics , quantum mechanics
Cationic polymerization of dodecamethylcyclohexasiloxane (D 6 ) initiated with triflic acid at 20°C in CH 2 Cl 2 shows a stationary concentration of active centres. This has permitted the measurement of k px [P n * ] for the various D x cyclics, and of the ratios of propagation rate constants k p5 /k p4 ∼ 2,2 ± 0,4 and k p6 /k p4 ∼ 5,8 ± 1,2. On the other hand, the back‐biting rate constants were not significantly different for various cyclics formation (k 4 ∼ k 5 ∼ k 6 ). These values have been compared with those obtained from D 4 and D 5 polymerizations.