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

Abstract

Anionic polymerization of propylene oxide was carried out in the presence of two groups of potassium salts activated 18-crown-6 (18C6), e.g. alkoxide salts (CH3OK, i-PrOK, t-BuOK, CH3OCH2CH(CH3)OK, KCH2O) and other salts (CbK, Ph3CK, Ph2PK, Ph3HBK, KK, KH, and [(CH3)3Si]2NK) in THF at room temperature. Application of various initiating systems results in polyethers which are different in level and kind of unsaturation represented by allyloxy, cis- and trans-propenyloxy, as well as vinyloxy starting groups. In the presence of selected initiator, i.e. t-BuO−K+ unsaturation increases markedly by addition of 18C6 or C222. During the initiation step oxirane ring-opening and direct deprotonation of the monomer occur simultaneously involving in some cases also the ligand. All initiators opens oxirane ring in the β-position except i-PrOK, which opens it in the β- and α-position. The mechanisms of the reactions were discussed.