In situ generated, tetrahydrosalen stabilized yttrium borohydride complex: Efficient initiator for the ring-opening polymerization of ɛ-caprolactone

In this paper, we report the preparation of a new tertrahydrosalen-stabilized yttrium complex which was employed as an initiator-precursor for the polymerization of ɛ-caprolactone (ɛ-CL) in the presence of NaBH4 to give interesting hydroxytelechelic poly(ɛ-caprolactone) (PCL). The effect of [monomer]/[initiator] ([CL]/[I]), temperature and time on the polymerization was investigated. It was found that under the condition: [CL]/[I] = 1200, 55 °C, toluene: 0.5 mL, ɛ-CL: 0.5 mL, PCL with Mw = 32,600 and PDI = 1.47 was obtained.