ABSTRACT
Although ketens (R1R2C=C=O) are regarded as the monomers which polymerize into various reactive polymers and their precursors, the polymerization of ketens, in general difficult to control. S. Uchino et al. reported living anionic polymerization of etbylphenylketen (1) with the use of n-BuLi and related initiating systems (Scheme 1) (186, E53; 1129, E886). The best results involved the formation of the nearly monodisperse polymer (Mw!Mn < "'1.2) in tetrahydrofuran solvent at ooc with nBuLi as an initiator. Under these reaction conditions, the polymer molecular weight increased further upon the addition of a fresh feed of monomer to the completely polymerized reaction mixture, indicating the living nature of the polymerization. The "living polyesters" (2) prepared are unique in that they have narrowlydistributed molecular weights and a reactive carbon-carbon double bond in each repeat unit.
