Show simple item record

dc.contributor.authorNaumann, Stefan
dc.contributor.authorMundsinger, Kai
dc.contributor.authorCavallo, Luigi
dc.contributor.authorFalivene, Laura
dc.date.accessioned2017-08-30T11:40:26Z
dc.date.available2017-08-30T11:40:26Z
dc.date.issued2017
dc.identifier.citationNaumann S, Mundsinger K, Cavallo L, Falivene L (2017) N-Heterocyclic Olefins as Initiators for the Polymerization of (Meth)Acrylic Monomers: A Combined Experimental and Theoretical Approach. Polym Chem. Available: http://dx.doi.org/10.1039/c7py01226h.
dc.identifier.issn1759-9954
dc.identifier.issn1759-9962
dc.identifier.doi10.1039/c7py01226h
dc.identifier.urihttp://hdl.handle.net/10754/625426
dc.description.abstractThe zwitterionic organopolymerization of four different acrylic monomers (N,N-dimethylacrylamide, methyl acrylate, methyl methacrylate and tert-butyl methacrylate) based on neutral initiators, so-called N-heterocyclic olefins (NHOs), is presented. Scope and underlying (deactivation-)mechanisms where studied in a combined experimental and computational effort. From a range of differently structured NHOs it emerged that imidazole-, in contrast to imidazoline- and benzimidazole-derivatives, readily polymerize the selected monomers. While the additive-free reactions proceed with a relatively low degree of control to yield largely atactic material, for the acrylamide the addition of LiCl as µ-type ligand has been shown to result in a rapid and quantitative monomer consumption. The thus generated poly(N,N-dimethyl acrylamide) was found to be highly isotactic (>90% isotactic dyads) with high molecular weight (Mn = 250 000 – 650 000 g/mol, ÐM = 1.3- 1.6). Complementing DFT calculations considered the zwitterionic chain growth with respect to competing side reactions, namely spirocycles and enamine formation. It was found that NHOs with unsaturated backbone better support the zwitterionic chain growth, with the spirocycles acting as dormant species that slow down but do not quench the polymerization process. Contrasting this, enamine formation irreversibly terminates the polymerization and is found to be energetically favored. This pathway can be blocked by introduction of substituents on the exocyclic carbon of the NHO, resulting in structures like 2-isopropylidene-1,3,4,5-tetramethylimidazoline (4) which consequently deliver the most controlled polymerizations. Finally, a good correlation of the initiation energy barrier with the buried volume (%VBur) and the Parr electrophilicity index is described, allowing for a quick and reliable screening of potential monomers based on these two readily accessible parameters.
dc.description.sponsorshipSN gratefully acknowledges support by the Dr. Leni Schöninger Foundation.
dc.publisherRoyal Society of Chemistry (RSC)
dc.relation.urlhttp://pubs.rsc.org/en/Content/ArticleLanding/2017/PY/C7PY01226H#!divAbstract
dc.rightsArchived with thanks to Polym. Chem.
dc.titleN-Heterocyclic Olefins as Initiators for the Polymerization of (Meth)Acrylic Monomers: A Combined Experimental and Theoretical Approach
dc.typeArticle
dc.contributor.departmentChemical Science Program
dc.contributor.departmentKAUST Catalysis Center (KCC)
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.identifier.journalPolym. Chem.
dc.eprint.versionPost-print
dc.contributor.institutionDepartment of Polymer Chemistry, University of Stuttgart, 70569 Stuttgart, Germany
kaust.personCavallo, Luigi
kaust.personFalivene, Laura
refterms.dateFOA2018-08-25T00:00:00Z


Files in this item

Thumbnail
Name:
c7py01226h.pdf
Size:
1.427Mb
Format:
PDF
Description:
Accepted Manuscript
Thumbnail
Name:
c7py01226h1.pdf
Size:
1.712Mb
Format:
PDF
Description:
Supplemental files

This item appears in the following Collection(s)

Show simple item record