SOLUBLE BIMETALLIC mu -OXOALKOXIDES - 9. epsilon -CAPROLACTONE AND beta -PROPIOLACTONE BLOCK COPOLYMERIZATION.

The fast and living ring-opening polymerization of lactones by bimetallic mu -oxoalkoxides in homogeneous organic phase has led to successful block copolymerization. The catalyst is coordinatively associated in organic media; however, interaction with lactones can induce, following their nature, different rearrangements of the catalytic aggregates, depending on the nature of these lactones. Consequently, epsilon -caprolactone and beta -propiolactone block copolymers are quantitatively obtained only in the presence of a completely dissociated catalyst.