Kinetic Analysis of the Living Ring-Opening Polymerisation of L-Lactide with Tin-(II) Initiators. - Université de Rennes Accéder directement au contenu
Article Dans Une Revue European Journal of Inorganic Chemistry Année : 2013

Kinetic Analysis of the Living Ring-Opening Polymerisation of L-Lactide with Tin-(II) Initiators.

Résumé

A general kinetic model to describe the initiation and monomer depletion phases of the metal-catalyzed living ring-opening polymn. (ROP) of cyclic esters is presented. The model allows the description of ROP reactions in terms of rates of initiation (ki) and propagation (kp) and is in principle applicable to all metal-mediated ROP reactions. The model was validated by curve-fitting of data obtained for the living ROP of L-lactide catalyzed by a variety of Sn(II) catalysts. The catalyst was chosen from Sn(II) diisopropoxide or from heteroleptic complexes (LOx)Sn(OR), in which (LOx) is an amino or aminoether phenolate ancillary ligand and OR is isopropoxide or O-CMe3 lactate. All tested catalysts promote the controlled, living polymn. of L-lactide. No initiation phase was discerned for any of the considered catalysts in polymns. performed at 60°, whereas at 25° initiation is an order of magnitude slower than propagation and, therefore, the inclusion of ki is required for an accurate kinetic description. Sn diisopropoxide is polymeric in the solid state, but it is dimeric in toluene soln. [Sn(O(CHMe2))2]2, is an excellent example of an aggregated catalyst precursor, and is catalytically more active than the heteroleptic (LOx)Sn(OR). As dissocn. of the inactive dimer into a catalytically active monomeric complex is required, half-order dependence on metal is to be expected and was indeed found. A method to est. the related monomer-dimer equil. const. KD under polymn. conditions is also provided. [on SciFinder(R)]

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Dates et versions

hal-01069854 , version 1 (30-09-2014)

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Lingfang Wang, Manfred Bochmann, Roderick D. Cannon, Jean-Francois Carpentier, Thierry Roisnel, et al.. Kinetic Analysis of the Living Ring-Opening Polymerisation of L-Lactide with Tin-(II) Initiators.. European Journal of Inorganic Chemistry, 2013, 2013, pp.5896--5905. ⟨10.1002/ejic.201300964⟩. ⟨hal-01069854⟩
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