Reference : Metal-free strategies for the synthesis of functional and well-defined polyphosphoesters
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Materials science & engineering
http://hdl.handle.net/2268/121700
Metal-free strategies for the synthesis of functional and well-defined polyphosphoesters
English
Clement, Benoît [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Grignard, Bruno [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Koole, Leo [Maastricht University (The Netherlands), Lead Partner of the BioMiMedics Interreg EMR IV-A consortium > > > >]
Jérôme, Christine mailto [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Lecomte, Philippe mailto [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
12-Jun-2012
Macromolecules
American Chemical Society
45
11
4476-4486
Yes (verified by ORBi)
International
0024-9297
Washington
DC
[en] ring-opening polymerization ; cyclic phosphate
[en] We report here metal-free strategies using organocatalysis based on supramolecular recognition for the ring-opening polymerization (ROP) of several cyclic phosphate monomers (CPMs) by a variety of organocatalysts such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]undec-5-ene (TBD), and a bicomponent thiourea−tertiary amine catalyst. Each of these catalysts is efficient to produce linear polyphosphoesters (PPEs) from CPMs but with different sensitivity toward transesterification side reactions. The strong basicity of DBU is sufficient to activate an alcohol initiating the polymerization in the absence of any other cocatalyst. Nevertheless, side chain transfer reactions leading to branched and/or cyclic polymeric structures are observed, especially for high monomer conversion. Unlike DBU, TBD is a dual catalyst activating both the alcohol and the monomer. This dual activation allows shorter polymerization time, but SEC analyses of polyphosphates reveal bimodal molecular weight distribution due to chains coupling. Finally, a mixture of DBU and thiourea (TU) appears by far the most efficient catalyst to carry out fast and controlled polymerization while minimizing transesterification reactions, even at near-complete conversion. Compared with polymerizations carried out with Sn(Oct)2 as a metal catalyst, the control of polymerization is much better so that it is possible to prepare polyphosphoesters (PPEs) with molecular weight close to 70 000 g mol−1 and polydispersity index below 1.10. Simultaneous activation by TU of both CPMs and the alcohol group of the initiator by DBU proves to be an effective and robust ROP catalytic system to synthesize polymers with predictable molecular weight and narrow polydispersity. The chain extension experiments through the use of hydroxy end- capped PPEs as macroinitiators confirm the controlled/living nature of the DBU/TU-catalyzed ROP of CPMs and pave the way to the synthesis of block copolymers based on polyphosphates.
Center for Education and Research on Macromolecules (CERM)
The Interreg Euregio Meuse Rhine IV-A consortium BioMiMedics ; The European Union (through Interreg IV-A) ; The government of Wallonia (Belgium) ; The “Provincie Nederlands Limburg” (The Netherlands) ; Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy ; Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS ; The “Région Wallonne” and the "FEDER" in the frame of the SINOPLISS project
Researchers
http://hdl.handle.net/2268/121700
10.1021/ma3004339
http://pubs.acs.org/doi/pdf/10.1021/ma3004339

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