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Université de Fribourg

Light-responsive azo-containing organogels

Ayer, Mathieu A. ; Schrettl , Stephen ; Balog, Sandor ; Simon, Yoan C. ; Weder, Christoph

In: Soft Matter, 2017, vol. 13, no. 22, p. 4017-4023

While azo compounds are widely employed as radical initiators, they have rarely been used as stimuli-responsive motifs in macromolecular constructs. In this study, an azo-based cross-linker was prepared and reacted with poly(vinyl alcohol) to afford a series of stimuli-responsive organogels. Irradiation of these materials with UV light causes de-cross-linking and triggers a solid-to-liquid phase...

Université de Fribourg

Azo-Containing Polymers with Degradation On-Demand Feature

Ayer, Mathieu A. ; Simon, Yoan C. ; Weder, Christoph

In: Macromolecules, 2016, vol. 49, p. 2917–2927

Molecules comprising aliphatic azo moieties are widely used as radical polymerization initiators, but only a few studies have explored their usefulness as stimuli-responsive motifs in macromolecular constructs. The controlled degradation of azo-containing polymers has indeed remained largely unexplored. Here we present the syntheses of linear azo-containing polyamides and polyurethanes and...

Université de Fribourg

Mechanochemistry with Metallosupramolecular Polymers

Balkenende, Diederik W. R. ; Coulibaly, Souleymane ; Balog, Sandor ; Simon, Yoan C. ; Fiore, Gina L. ; Weder, Christoph

In: Journal of the American Chemical Society, 2014, vol. 136, no. 29, p. 10493-10498

The transduction of mechanical force into useful chemical reactions is an emerging design approach to impart soft materials with new functions. Here, we report that mechanochemical transductions can be achieved in metallo-supramolecular polymers. We show that both reversible and irreversible reactions are possible and useful to create me-chanically responsive materials that display new...

Université de Fribourg

Mechanochemistry in polymers with supramolecular mechanophores

Haehnel, Alexander P. ; Sagara, Yoshimitsu ; Simon, Yoan C. ; Weder, Christoph

In: Topics in current chemistry, 2015, vol. 369, p. 345-375

Mechanochemistry is a burgeoning field of materials science. Inspired by nature, many scientists have looked at different ways to introduce weak bonds into polymeric materials to impart them with function and in particular mechano-responsiveness. In the following sections, the incorporation of some of the weakest bonds, i.e. non- covalent bonds, into polymeric solids is being surveyed. This...

Université de Fribourg

Visualization of polymer deformation using microcapsules filled with charge-transfer complex precursors

Lavrenova, Anna ; Farkas, Jacob ; Weder, Christoph ; Simon, Yoan C.

In: ACS Appl. Mater. Interfaces, 2015, vol. 7, no. 39, p. 21828–21834

The visualization of polymer deformation using microcapsules filled with charge- transfer complex precursors is reported. Poly(urea-formaldehyde) microcapsules filled with toluene and either hexamethylbenzene as donor or chloranil as acceptor were prepared by in situ polymerization of an oil-in-water emulsion. The resulting microcapsules were incorporated in a poly(dimethylsiloxane) matrix by...

Université de Fribourg

Healable Supramolecular Polymer Solids

Montero de Espinosa, Lucas ; Fiore, Gina L. ; Weder, Christoph ; Foster, E. Johan ; Simon, Yoan C.

In: Progress in Polymer Science, 2015, vol. 49-50, p. 60-78

The reversible nature of non-covalent interactions between constituting building blocks permits one to temporarily disassemble supramolecular polymers through the application of an appropriate external stimulus “on command”. This framework has recently emerged as a general design strategy for the development of healable polymer systems. The approach exploits that the temporary disassembly...

Université de Fribourg

Synthesis of poly(sulfonate ester)s by ADMET polymerization

Parkhurst, Rebecca R. ; Balog, Sandor ; Weder, Christoph ; Simon, Yoan C.

In: RSC Advances, 2014, vol. 4, p. 53967-53974

Many hydrocarbon polymers containing heteroatom defects in the main chain have been investigated as degradable polyethylene-like materials, including aliphatic polyesters. Here, acyclic diene metathesis (ADMET) polymerization was used for the synthesis of aliphatic poly(sulfonate ester)s. The requisite sulfonate ester containing α,ω-diene monomers with varying numbers of methylene groups...