Employing (half‐)titanocene complexes as initiators for the synthesis of end‐functionalized polylactides by coordination polymerization

ABSTRACT Seven (half‐)titanocene alkoxide complexes, [Cp2TiCl(OEt)], [Cp2TiCl(O‐2‐Bu)], [Cp2TiCl(OCH2CF2CF2H)], [CpTiCl2(OEt)], [CpTiCl2(O‐(S)‐2‐Bu)], [CpTiCl2(OCH2CF3)], and [Cp2TiCl(OCH2CF3)], were synthesized and employed in lactide coordination polymerization. These organotitanium (IV) compounds proved to be very efficient initiators for the ring‐opening polymerization of enantiomeric l‐lactide and racemic mixture of rac‐lactide, leading to end‐functionalized polymers. Kinetic studies illustrated that these compounds produce well‐defined polymers in a controlled manner. This was further demonstrated by synthesizing poly(l‐lactide‐b‐hexyl isocyanate) diblock copolymer. The effect of the alkoxy end groups on the thermal behavior of the polymers was also studied by thermogravimetric analysis and differential scanning calorimetry. The polymers were characterized using size exclusion chromatography and proton nuclear magnetic resonance spectroscopy. The optical properties of the diblock copolymer were also investigated. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2192–2202 In this work, (half‐)titanocene complexes were synthesized, characterized, and initiated the polymerization of l‐ and rac‐lactide. This is the first report of ROP of lactides with alkoxy titanocene complexes, which are more active than their half‐titanocene analogs. The alkoxy substituents were incorporated at the end of the polymeric chain. The thermal properties of the polymers have been investigated.