Université de Fribourg

Catalytic living ring opening metathesis polymerisation: the importance of ring strain in chain transfer agents

Liu, Peng ; Yasir, Mohammad ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2019, vol. 58, no. 43, p. 15278–15282

A recently developed catalytic living ring opening metathesis polymerisation (ROMP) was investigated using a series of reversible chain transfer agents (CTA) carrying either cyclopentene or cyclohexene rings, differing only in ring strain. All cyclopentene derivatives examined showed significantly faster reaction rates than the corresponding cyclohexene derivatives. This resulted in lower...

Université de Fribourg

Enolesters as chain end-functionalizing agents for the living ring opening metathesis polymerization

Liu, Peng ; Yasir, Mohammad ; Kurzen, Helena ; Hanik, Nils ; Schäfer, Mark ; Kilbinger, Andreas F. M.

In: Journal of Polymer Science Part A: Polymer Chemistry, 2017, vol. 55, no. 18, p. 2983–2990

Functional enolethers have previously been used to introduce functional end groups at the chain end of ruthenium carbene complex initiated living ring opening metathesis polymers. Here, we investigated whether the weaker π-donating enolesters could equally be used in regio selective reactions with ruthenium carbene complexes and thus as polymer end-functionalization reagents. Enolesters such as...

Université de Fribourg

Tandem ring‐opening–ring‐closing metathesis for functional metathesis catalysts

Nagarkar, Amit A. ; Yasir, Mohammad ; Crochet, Aurelien ; Fromm, Katharina M. ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2016, vol. 55, no. 40, p. 12343–12346

Use of a tandem ring-opening–ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs’ catalysts. Hydroxy functionalized...

Université de Fribourg

One-step ring opening metathesis block-like copolymers and their compositional analysis by a novel retardation technique

Yasir, Mohammad ; Liu, Peng ; Markwart, Jens C. ; Suraeva, Oksana ; Wurm, Frederik R. ; Smart, Jansie ; Lattuada, Marco ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2020, p. -

Using a one-step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers (M1–M5) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2...

Université de Fribourg

Catalytic living ring-opening metathesis polymerization with Grubbs’ second- and third-generation catalysts

Yasir, Mohammad ; Liu, Peng ; Tennie, Iris K. ; Kilbinger, Andreas F. M.

In: Nature Chemistry, 2019, vol. 11, no. 5, p. 488–494

In a conventional living ring-opening metathesis polymerization (ROMP), an equal number of ruthenium complexes to the number of polymer chains synthesized are required. This can lead to high loadings of ruthenium complexes when aiming for shorter polymers. Here, a reversible chain-transfer agent was used to produce living ROMP polymers from norbornene derivatives using catalytic amounts of...