Anionic polymerisation of propylene oxide. Investigation of double‐bond and head‐to‐head content by NMR spectroscopy

Abstract

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 '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 I3C 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.

The influence of initiator and macrocyclic ligand on unsaturation and molar mass of poly(propylene oxide)s prepared with various anionic system

“…Conversely, the polyethers for flexible PU foams, having a low concentration of terminal OH groups, have high unsaturation. Similar influence of hydroxyl groups on the transfer reaction was reported in several works [8,[15][16][17][18][19]. The explanation of this phenomenon is based on the strong affinity of the alkoxide for hydroxyl groups.…”

Aqueous Gels of Diblock Oxyethylene‐Oxypropylene Copolymers

“…[7] Purification was needed to remove the small proportion of homopoly(oxypropylene) produced by the transfer reaction in the oxyanionic polymerisation of propylene oxide under the conditions employed. [16] Gel permeation chromatography calibrated with poly(oxyethylene) standards was used to confirm narrow chain length distributions: i.e. ratios of weight-average to number-average chain length of 1.04 without correction for instrumental broadening, estimated to reduce to approximately 1.02 after correction.…”

Effects of block architecture and composition on the association properties of poly(oxyalkylene) copolymers in aqueous solution

“…Interest in the anionic polymerisation of alkylene oxides originated in Manchester in the 1950s with Gee and coworkers, when it concerned the mechanism of the anionic polymerisation of propylene oxide 21,22) , and this interest has continued to recent times 23,24) . Work on block copolymers of ethylene oxide and propylene oxide initially was focused on the effect of block architecture [EP, EPE, PEP and P(EP) x ] and block length on bulk-state properties [25][26][27] .…”