POLYETHERS CONTAINING STABLE IONIC END-GROUPS

Polyethers of low and medium molecular weight containing at both ends stable ionic groups (phosphonium ions) were obtained by living cationi c polymerization of tetrahydrofuran initiated by difunctional initiato r: trifluoromethanesulfonic anhydride, followed by termination with tr iphenylphosphine. It was shown, that products contain significant quan tities of low molecular weight diphosphonium salt; a plausible explana tion is presented. Alternative approach to the synthesis of diionicall y terminated polyethers was based on the conversion of hydroxyl end-gr oups of polyether diols, which can be obtained by cationic Activated M onomer (AM) polymerization of e.g. oxiranes, into phosphonium ion end- groups. Using this approach, poly(ethylene oxide)'s with M(n) ranging from 300 to 3400, terminated at both ends with stable ionic groups, we re prepared and characterized. Measurements of NMR relaxation times an d viscosity measurements provide the evidence for the aggregation of i onic end-groups. The potential applications of inter- and intramolecul ar aggregation are discussed. It is shown, that intramolecular aggrega tion of ionic terminal groups in low molecular weight poly(ethylene ox ide) leads to cyclic structures resembling crown ethers and showing co mparable efficiency for complexing cations.