Anionic polymerization of acrylic monomers. 15. Living anionic copolymerization of mixtures of methyl metacrylate and tert-butyl acrylate as promoted by dibenzo-18-crown-6
[en] Although mu-coordinating ligands such as LiCl are effective in promoting the well-controlled living anionic block copolymerization of methyl methacrylate (MMA) and tert-butyl acrylate (tBuA), whichever monomer is first polymerized, it has been previously shown that a copolymerization of mixtures of these two monomers does not proceed as expected, giving poor results in terms of both conversion and molecular weight distribution: that was accounted for by the easy back-biting nucleophilic attack of a highly sensitive methyl ester group by a moderately hindered PtBuA anion. It is now reported that such a situation can be completely modified, when a cation-binding sigma-ligand, i.e., dibenzo-18-CE-6, is used in chelating a sodium counterion and surrounding it with a steric barrier, blocking a large enough space area around the ion pair. In fact, a living copolymerization process of mixtures of MMA and tBuA prevails in THF at -78-degrees-C, in the presence of that Na+/DB-18-CE-6 system. The living copolymer is found, although in a relatively small extent, to be of a statistical type rather than a blocky one or a mixture of two corresponding homopolymers. Furthermore, using the extended Kelen-Tudos method, the monomer reactivity ratios are determined to be r(MMA) = 0.02 and r(tBuA) = 8.81.
Research center :
Center for Education and Research on Macromolecules (CERM)
Disciplines :
Chemistry Materials science & engineering
Author, co-author :
Wang, Jin-Shan; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Jérôme, Robert ; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Bayard, Philippe; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Baylac, Laurent; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Patin, Maryse; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Teyssié, Philippe ; Université de Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Language :
English
Title :
Anionic polymerization of acrylic monomers. 15. Living anionic copolymerization of mixtures of methyl metacrylate and tert-butyl acrylate as promoted by dibenzo-18-crown-6
Publication date :
01 August 1994
Journal title :
Macromolecules
ISSN :
0024-9297
eISSN :
1520-5835
Publisher :
American Chemical Society, Washington, United States - District of Columbia