Soluble bimetallic μ‐oxoalkoxides. VII. Characteristics and mechanism of ring‐opening polymerization of lactones

Abstract

The ring‐opening polymerization of unsubstituted lactones by Al2Zn and Al2Co(II) μ‐oxoalkoxides in homogeneous organic phase is described. Under these conditions, the chain propagation is very fast and proceeds without transfer or termination reactions. The composition and structure of the main products resulting from the first polymerization steps have been determined, and fit with a monomer insertion mechanism into the aluminum‐alkoxide bonds of the catalyst.

Synthesis of low molecular weight-hydroxy polycaprolactone macromonomers by coordinated anionic polymerization in protic conditions

“…Each of these parameters depends on the other ones, and it is difficult to control each of m-oxo bimetallic alkoxides display high activities for the polymerization of lactones. 17 Convenient them separately.…”

Ring-opening polymerization of ?-caprolactone initiated by rare earth complex catalysts

“…(Al, Zn) m-oxo alkoxides {(RO) 2 Al{O{ Zn{O{Al(OR) 2 }, [9][10][11][12][13] , with a coordination-insertion mechanism. With a PHB{O{AlEt 2 macPoly( 1-caprolactone) ( 21,22 In the present article, we focused on the study of Anhydrous yttrium chloride was prepared by…”

Novel Macromolecular Architectures Based on Aliphatic Polyesters: Relevance of the “Coordination-Insertion” Ring-Opening Polymerization

“…3.3) yielded star-shaped copolymers with unimodal and narrow MWD (PDI= 1.1-1.3) (Scheme 36, shown for a 6-arm star). Whatever the hydroxyl functionality of the starting dendritic initiator the initiation efficiency evaluated by 13 C NMR analysis was very high (>90%). Furthermore, the resulting hydroxy endfunctionality of the star-shaped copolymers was explored to prepare novel radial block copolymers.…”

“…Accordingly, copolymerization of εCL with δVL [35], TOSUO [36], and γBL [37] initiated with Al(OfPr) 3 in toluene at 25 0 C leads to highly statistical copolymers as confirmed by triad analysis by 13 C NMR spectroscopy. At the same time, the control over the molecular parameters and the narrow molecular weight distributions already observed in the respective homopolymerizations are maintained.…”

“…The most frequently encountered Lewis acid catalyst is undoubtedly the stannous 2-ethylhexanoate, currently referred to as stannous octoate (Sn(OCt) 2 ). On the other hand, when metal alkoxides containing free p-, d-, or forbitals of a favo poxide [13][14][15], tetraphenylporphinato aluminum alkoxides [16], and diethyl aluminum methoxide [17], respectively. Confirming the observed living character of the polymerization promoted by aluminum alkoxides, the extent of side reactions, mainly the "back-biting" ones, has been studied by Penczek et al, who have quantitatively described the degree of livingness by the so-called selectivity parameter (β).…”