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Qayouh H.,Laboratoire Of Chimie Bio Organique Et Macromoleculaire | Qayouh H.,CNRS Macromolecular Chemistry and Physics Laboratory | Lahcini M.,Laboratoire Of Chimie Bio Organique Et Macromoleculaire | Six J.-L.,CNRS Macromolecular Chemistry and Physics Laboratory | Kricheldorf H.R.,Institute For Technische Und Makromoleculare Chemie
Journal of Applied Polymer Science | Year: 2012

Hexamethylcyclotrisiloxane (D 3) was polymerized in bulk at 100°C, and the conversion was monitored by 1H-NMR spectroscopy. Various metal triflates, which were inactive as neat salts, were combined with chlorosilanes, chlorostannanes, phenyl phosphonyl chloride, and carboxylic acid chlorides, which were also inactive when added alone. Most 1: 1 combinations proved to produce active catalysts for the ring-opening polymerization of D 3. When the anions of sodium salts were varied alkylsulfonates and the sulfates were more reactive than the triflate. The samarium triflate/diphenyldichlorosilane combination was found to be the most reactive catalyst on the basis of the triflate ions. Regardless of the catalyst combination, the main reaction products in the early stages of all polymerizations were octamethylcyclotetrasiloxane (D 4) and decamethylcyclopentasiloxane (D 5). The polymerization mechanism is discussed. The reactive catalyst combinations also polymerized D 4 at 100°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 Copyright © 2012 Wiley Periodicals, Inc. Source


Lahcini M.,Cadi Ayyad University | Qayouh H.,Cadi Ayyad University | Qayouh H.,Institute For Technische Und Makromoleculare Chemie | Yashiro T.,Institute For Technische Und Makromoleculare Chemie | And 3 more authors.
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry | Year: 2010

The usefulness of bismuth, calcium, magnesium and zinc salts for the preparation of poly(butylene succinate), PBSu, was studied. Two different approaches were compared. Firstly, 1,4-butanediol (or in a few experiments ethanediol) dimethyl succinate were condensed at temperatures up to 240°C in the presence of Bi2O3. Regardless of the feed ratio, only low molar mass polyesters having two diol endgroups were obtained. Secondly, 1,4-butanediol and succinic anhydride were polycondensed in refluxing decalin with azeotropic removal of water. BiCL3, BiBr3, BiI 3, and Bi-triflate were used as catalyst and the monomer/catalyst ratio was varied. The highest molar masses were achieved with BiCl3. Analogous polycondensations catalysed with ZnCl2, Zn-triflate, MgCl2, Mg-triflate and CaCl2 were unsuccessful. Yet the BiCl3, decalin method was also successfully applied to the combination of succinic anhydride and 1,5-pentanediol. Copyright © Taylor & Francis Group, LLC. Source


Lahcini M.,Cadi Ayyad University | Qayouh H.,Cadi Ayyad University | Qayouh H.,Institute For Technische Und Makromoleculare Chemie | Yashiro T.,Institute For Technische Und Makromoleculare Chemie | And 3 more authors.
Macromolecular Chemistry and Physics | Year: 2011

εCL was polymerized using the triflates of lanthanum, samarium, magnesium, aluminum, scandium, and bismuth as catalysts. Bismuth triflate proved to be extraordinarily reactive, and catalyzed polymerizations of εCL even at 20°C. Adding DTBMP reduced the polymerization rate only slightly. Furthermore, no evidence of a cationic mechanism was found by end-group analyses. Polymerization at 20°C either in bulk or in solution only yielded polyesters of low or medium molecular weights ($ Mn up to 30000 Da). Yet addition of alcohols allowed for a proper control of molecular weight and end-groups. Additionally, low catalyst concentrations and low temperature resulted in narrow molecular weight distributions and polylactones almost free of cyclic compounds. Polymerizations of ε-caprolactone in bulk at temperatures of 20-120°C showed an extraordinarily high catalytic activity of Bi(OTf)3. Depending on the reaction conditions, low and high polydispersities can be obtained. The molecular weight may be controlled by cocatalysts (initiators). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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