In: Materials Chemistry Frontiers, 2020, vol. 4, no. 9, p. 2791–2796
The second-generation Hoveyda–Grubbs (HG2) catalyst, which has a small initiation to propagation rate ratio (ki/kp) in ring-opening metathesis polymerization (ROMP), was successfully used in a recently developed catalytic living ROMP. This proved that slow-initiating catalysts can enable ROMP in a living fashion to produce polymers with narrow dispersity and controlled molecular weight. The...
|
In: Angewandte Chemie International Edition, 2020, vol. 59, no. 32, p. 13597-13601
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...
|
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 ...
|
In: Synlett, 2019, vol. 30, no. 18, p. 2051–2057
Over the last two decades many synthetic methods have been reported to selectively introduce a number of different functional groups at the chain end of a living ring- opening metathesis polymer. In this personal account, I would like to focus on a few such methods developed in my research group over the last several years and how these led to the discovery of catalytic living ring-opening...
|
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...
|
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...
|
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...
|
In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 86–89
Besides conducting excellent fundamental research in domains of strategic importance, the National Centers of Competence in Research (NCCRs) also aim to become centers of reference for education, equal opportunities, and knowledge and technology transfer. These activities are supported by a communication strategy focused on specific target groups. This article describes some of the main...
|
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...
|
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...
|