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Anionic polymerisation of propylene oxide. Investigation of double‐bond and head‐to‐head content by NMR spectroscopy
Author(s) -
Yu GaEr,
Masters Andrew J.,
Heatley Frank,
Booth Colin,
Blease Trevor G.
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950506
Subject(s) - chemistry , propylene oxide , polymer chemistry , polymerization , nuclear magnetic resonance spectroscopy , chain transfer , polymer , photochemistry , organic chemistry , ethylene oxide , radical polymerization , copolymer
Propylene oxide was anionically polymerised in bulk at 80°C under a range of initial conditions, from zero hydroxyl content to a mole ratio of hydroxyl to potassium catalyst of 10. The double bond content of the polymers was measured by 1 H NMR spectroscopy over a wide range of conversions, and values of the transfer constant were determined. The results were fitted to a reaction mechanism involving suppression of the transfer reaction by hydrogen bonding of hydroxyl groups to active ion pairs. The head‐to‐head content of the polymers was measured by 13 C NMR spectroscopy. The overall proportion (approximately 4%) of ‘head‐to‐head’ reactions relative to head‐to‐tail addition was not greatly affected by suppression of the transfer reaction, since an increase in the number of head‐to‐head additions compensated the decrease in proton abstraction from methyl groups via the transfer reaction.