Synthesis of Functional Poly(ε-caprolactone)s via Living Ring-Opening Polymerization of ε-Caprolactone Using Functionalized Aluminum Alkoxides as Initiators

The new aluminum compounds 1-3 modified by unsaturated alcohol, Me3-nAl(O(CH2)(4)OCH=CH2)(n) (n = 1 (1), 2 (2), 3 (3)), are synthesized and investigated by multinuclear (H-1, C-13, Al-27) NMR spectroscopy. The compounds 1-3 initiate living ring-opening poly-merization of epsilon-caprolactone in bulk at 40-80 degrees C to afford polyesters with controlled molecular weight (M-n up to 35 000 g mol(-1)) and relatively narrow molecular weight distribution (M-w/M-n < 1.8). Among initiators studied here, aluminum trialkoxide shows the highest activity, whereas aluminum dialkoxide is a less active. In all cases, the fragment of unsaturated alcohol is transferred to the end of the polymeric chain with high degree of functionality (>85%) yielding macromonomers. These macromono-mers are copolymerized with maleic anhydride to give poly(vinyl ether-co-maleic anhydride)g- poly(epsilon-caprolactone) graft copolymers.