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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

Telechelics based on catalytic alternating ring-opening metathesis polymerization

Pal, Subhajit ; Alizadeh, Mahshid ; Kilbinger, Andreas F. M.

In: ACS Macro Letters, 2019, vol. 8, no. 10, p. 1396–1401

We describe a protocol to synthesize alternating telechelic ROMP copolymers of 7- oxa-norbornene derivatives and cycloalkenes under catalytic conditions. These copolymers were synthesized using Grubbs’ second-generation catalyst. The sterically less hindered backbone double bonds of the resulting alternating copolymers facilitate the chain transfer (secondary metathesis) reactions. In the ...

Université de Fribourg

The influence of substituents on gelation and stacking order of oligoaramid – based supramolecular networks

Drechsler, Susanne ; Balog, Sandor ; Kilbinger, Andreas F. M. ; Casalini, Tommaso

In: Soft Matter, 2019, vol. 15, no. 36, p. 7250–7261

Self-assembly has proven to be a powerful tool for functional, smart materials such as hydrogels derived from low molecular weight compounds. However, the targeted design of functional gelators remains difficult. Here, we present a set of four Y-shaped aromatic amide tetramers with varying functionalities able to undergo different non- covalent interactions. These compounds were explored...

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

Synthesis and properties of poly(norbornene)s with lateral aramid groups

Kong, Phally ; Drechsler, Susanne ; Balog, Sandor ; Schrettl, Stephen ; Weder, Christoph ; Kilbinger, Andreas F. M.

In: Polymer Chemistry, 2019, vol. 10, no. 16, p. 2057–2063

This paper deals with the synthesis and investigation of comb-like poly(norbornene)s carrying lateral rod-like aramid groups. Two types of norbornene-based monomers were synthesized and copolymerized with a norbornene carrying an aliphatic side chain using ring opening metathesis polymerization (ROMP). The new monomers contain aramid derivatives that display different types of non-covalent...

Université de Fribourg

Towards polymers with molecular auxeticity

Alizadeh, Mahshid ; Tennie, Iris K. ; Steiner, Ullrich ; Kilbinger, Andreas F. M.

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 25–28

For many decades, it has been challenging to synthesize auxetic materials at the molecular level. Auxetic materials exhibit counterintuitive behavior; they expand perpendicularly to the direction in which they are stretched. An aromatic macrocycle containing a sequence of N-substituted and N-unsubstituted amides was designed to resemble the re-entrant structure found in macromolecular auxetic...

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...

Université de Fribourg

Synthesis of telechelic poly(p-benzamide)s

Alizadeh, Mahshid ; Kilbinger, Andreas F. M.

In: Macromolecules, 2018, vol. 51, no. 11, p. 4363–4369

Well-defined telechelic poly(benzamide)s were synthesized by chain-growth polycondensation of phenyl-4-amino benzoate and pentafluorophenyl-4-amino benzoate derivatives with a bifunctional initiator in the presence of LiTMP as base. The polymerization was carried out at −70 °C to prevent self-initiated polymerization. To confirm the control over molecular weight, different defined...

Université de Fribourg

Functional metathesis catalyst through ring closing enyne metathesis: one pot protocol for living heterotelechelic polymers

Pal, Subhajit ; Lucarini, Fiorella ; Ruggi, Albert ; Kilbinger, Andreas F. M.

In: Journal of the American Chemical Society, 2018, vol. 140, no. 9, p. 3181–3185

Enyne ring closing metathesis has been used to synthesize functional group carrying metathesis catalysts from a commercial (Ru-benzylidene) Grubbs’ catalysts. The new Grubbs-type ruthenium carbene was used to synthesize living heterotelechelic ROMP polymers without any intermediate purification. Olefin metathesis with a mono substituted alkyne followed by ring closing metathesis with an...

Université de Fribourg

Heterotelechelic polymers by ring‐opening metathesis and regioselective chain transfer

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

In: Angewandte Chemie International Edition, 2018, vol. 57, no. 4, p. 914–917

Heterotelechelic polymers were synthesized by a kinetic telechelic ring-opening metathesis polymerization method relying on the regioselective cross-metathesis of the propagating Grubbs’ first-generation catalyst with cinnamyl alcohol derivatives. This procedure allowed the synthesis of hetero-bis-end-functional polymers in a one- pot setup. The molecular weight of the polymers could be...