Polymerization of .epsilon.-Caprolactone Initiated by Aluminum Isopropoxide Trimer and/or Tetramer

Duda, Andrzej; Penczek, Stanisław

doi:10.1021/ma00122a001

Cited by 157 publications

(147 citation statements)

References 11 publications

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“…13,26 The fact that there is no bond between Al and O4 in LAlOCH(CH 3 )COOCH 3 is out of our expectation, because polyester ligands are usually able to form the intramolecular coordinate linkage with Al atom in active centers by oxygen atom from the acyl group of the first repeating unit adjacent to Al atom. 17,[27][28][29] The nonexistence of intramolecular coordination between the central Al atom and the carbonyl oxygen of lactyl group may result from the steric effects of bulky tert-butyl groups of the Salen ligand.…”

Section: Resultsmentioning

confidence: 99%

Five‐coordinated active species in the stereoselective polymerization of rac‐lactide using N,N′‐(2,2‐dimethyl‐1,3‐propylene) bis(3,5‐di‐tert‐butyl‐salicylideneimine) aluminum complexes

Tang

Pang

Sun

et al. 2006

J. Polym. Sci. A Polym. Chem.

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Section: Resultsmentioning

confidence: 99%

Five‐coordinated active species in the stereoselective polymerization of rac‐lactide using N,N′‐(2,2‐dimethyl‐1,3‐propylene) bis(3,5‐di‐tert‐butyl‐salicylideneimine) aluminum complexes

Tang

Pang

Sun

et al. 2006

J. Polym. Sci. A Polym. Chem.

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“…The semilogarithmic plots shown herein are linear, indicating a first-order dependence of reaction rate with respect to monomer concentration and pass through the origin indicating the absence of an induction period, 81,82 which is in contrast to some previous polymerization reactions using aluminum alkoxides where induction periods were observed. 75,83 This might also imply that the reaction is proceeding via an activated monomer mechanism but it might also be an artifact of the temperatures at which reactions were studied. Greater linearity can be seen in the plots for reactions conducted at higher temperatures, where a shorter induction period would also be expected.…”

Section: End Group Analysis By 1 H Nmr Spectroscopy and Maldi-tof Masmentioning

confidence: 99%

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

et al. 2012

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Abstract:A series of aluminum methyl and chloride complexes bearing 2(N-piperazinyl-N′-methyl)-2-methylene-4-R′-6-R-phenolate or 2(N-morpholinyl)-2-methylene-4-R′-6-R-phenolate ([ONE R1,R2 ]-) {[ R 1 = t Bu, R 2 = Me, E = NMe (L1); R 1 = R 2 = t Bu, E = NMe (L2); R 1 = R 2 = t Bu, 1 E = O (L3)} ligands were synthesized and characterized through elemental analysis, 1 H, 13 The catalytic activity of complexes 1-3 toward ring-opening polymerization (ROP) of ε-caprolactone was assessed. These complexes are more active than analogous Zn complexes for this reaction but less active than the Zn analogs for ROP of rac-lactide. Characteristics of the polymer as well as polymerization kinetics and mechanism were studied. Polymer end-group analyses were achieved using 1 H NMR spectroscopy and MALDI-TOF MS. Eyring analyses were performed and the activation energies for the reactions were determined, which were significantly lower for 1 and 2 compared with 3. This could be for several reasons: (1) the methylamine (NMe) group of 1 and 2, which is a stronger base than the ether (O) group of 3, might activate the incoming monomer via non-covalent interactions, and/or (2) the ether group is able to temporarily coordinate to the metal center and blocks the vacant coordination site towards incoming monomer, whilst the amine cannot do this. Preliminary studies using 4 and 5 towards copolymerization of cyclohexene oxide with carbon dioxide have been performed. 4 was inactive and 5 afforded polyethercarbonate (66.7% epoxide conversion, polymer contains 54.0% carbonate linkages).

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“…For example, Al(OfPr) 3 in toluene leads to a coordinative aggregation equilibrium between tetramers (A4) and trimers (A3). Depending on the monomer and reaction conditions both species (A3+A4) can act as initiators for the polymerization (case LA in toluene at 70 0 C) or only the more reactive A3 can be involved (case εCL) [54]. On the other hand, the aggregation of some aluminum alkoxides was also observed during the propagation step.…”

Section: Kinetic Aspects Of the "Coordination-insertion" Ropmentioning

confidence: 99%

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

Mecerreyes¹,

Jérôme²,

Dubois³

Advances in Polymer Science

276

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Recent developments in the macromolecular engineering of aliphatic polyesters have been overviewed. First, aluminum alkoxides mediated living ring opening polymerization (ROP) of cyclic (di)esters, i.e., lactones, lactides, glycolide, is introduced. An insight into this so-called "coordination-insertion" mechanism and the ability of this living polymerization process to prepare well-defined homopolymers, telechelic polymers, random and block copolymers is then discussed. In the second part, the combination of the living ROP of (di)lac-tones with other well-controlled polymerization mechanisms such as anionic, cationic, free radical, and metathesis polyadditions of unsaturated comonomers, as well as polyconden-sations, is reported with special emphasis on the design of new and well-tailored macromolecular architectures. As a result of the above synthetic breakthrough, a variety of novel materials have been developed with versatile applications in very different fields such as biomedical and microelectronics.

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Polymerization of .epsilon.-Caprolactone Initiated by Aluminum Isopropoxide Trimer and/or Tetramer

Cited by 157 publications

References 11 publications

Five‐coordinated active species in the stereoselective polymerization of rac‐lactide using N,N′‐(2,2‐dimethyl‐1,3‐propylene) bis(3,5‐di‐tert‐butyl‐salicylideneimine) aluminum complexes

Five‐coordinated active species in the stereoselective polymerization of rac‐lactide using N,N′‐(2,2‐dimethyl‐1,3‐propylene) bis(3,5‐di‐tert‐butyl‐salicylideneimine) aluminum complexes

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

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

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