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Université de Fribourg

Mechanoresponsive Luminescent Molecular Assemblies: An Emerging Class of Materials

Sagara, Yoshimitsu ; Yamane, Shogo ; Mitani, Masato ; Weder, Christoph ; Kato, Takashi

In: Advanced Materials, 2015, vol. 28, no. 6, p. 1073-1095

The possibility to change the molecular assembled structures of organic and organometallic materials through mechanical stimulation is emerging as a general and powerful concept for the design of functional materials. In particular, the photophysical properties such as photoluminescence color, quantum yield, and emission lifetime of organic and organometallic fluorophores can significantly depend...

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 review...

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 tem¬po¬ra¬rily disassemble supramolecular polymers through the application of an appro¬pri¬ate 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...

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 were...

Université de Fribourg

The role of mass and length in the sonochemistry of polymers

Schaefer, Mark ; Icli, Burcak ; Weder, Christoph ; Lattuada, Marco ; Kilbinger, Andreas F. M. ; Simon, Yoan C.

In: Macromolecules, 2016, vol. 49, no. 5, p. 1630–1636

The ultrasound-induced cleavage of macromolecules has become a routine experiment in the emerging field of polymer mechanochemistry. To date, it has not been conclusively proven whether the molecular weight of a polymer or its contour length is the determining factor for chain scission upon ultrasonication. Here we report comparative experiments that confirm unequivocally that the contour length...

Université de Fribourg

A Thermo‐ and mechanoresponsive cyano‐substituted oligo(p‐phenylene vinylene) derivative with five emissive states

Sagara, Yoshimitsu ; Lavrenova, Anna ; Crochet, Aurélien ; Simon, Yoan C. ; Fromm, Katharina M. ; Weder, Christoph

In: Chemistry - A European Journal, 2016, vol. 22, no. 13, p. 4374–4378

Multiresponsive materials that display predefined photoluminescence color changes upon exposure to different stimuli are attractive candidates for advanced sensing schemes. Herein, we report a cyano-substituted oligo(p-phenylene vinylene) (cyano-OPV) derivative that forms five different solvent-free solid-state molecular assemblies, luminescence properties of which change upon thermal and...

Université de Fribourg

Fate of cellulose nanocrystal aerosols deposited on the lung cell surface in vitro

Endes, Carola ; Mueller, Silvana ; Kinnear, Calum ; Vanhecke, Dimitri ; Foster, E. Johan ; Petri-Fink, Alke ; Weder, Christoph ; Clift, Martin J. D. ; Rothen-Rutishauser, Barbara

In: Biomacromolecules, 2015, vol. 16, no. 4, p. 1267–1275

When considering the inhalation of high-aspect ratio nanoparticles (HARN), the characterization of their specific interaction with lung cells is of fundamental importance to help categorize their potential hazard. The aim of the present study was to assess the interaction of cellulose nanocrystals (CNCs) with a multicellular in vitro model of the epithelial airway barrier following realistic...

Université de Fribourg

Stress-transfer in anisotropic and environmentally adaptive cellulose whisker nanocomposites

Rusli, Rafeadah ; Shanmuganathan, Kadhiravan ; Rowan, Stuart J. ; Weder, Christoph ; Eichhorn, Stephen J.

In: Biomacromolecules, 2010, vol. 11, no. 3, p. 762–768

Quantitative insights into the stress-transfer mechanisms that determine the mechanical properties of tunicate cellulose whisker/poly(vinyl acetate) nanocomposites were gained by Raman spectroscopy. The extent of stress-transfer is influenced by local orientation (or anisotropy) of the whiskers, which in turn is governed by the processing conditions used to fabricate the nanocomposites....

Université de Fribourg

Natural biopolymers: novel templates for the synthesis of nanostructures

Padalkar, Sonal ; Capadona, Jephrey R. ; Rowan, Suart J. ; Weder, Christoph ; Won, Yu-Ho ; Stanciu, Lia A. ; Moon, Robert J.

In: Langmuir, 2010, vol. 26, no. 11, p. 8497–8502

Biological systems such as proteins, viruses, and DNA have been most often reported to be used as templates for the synthesis of functional nanomaterials, but the properties of widely available biopolymers, such as cellulose, have been much less exploited for this purpose. Here, we report for the first time that cellulose nanocrystals (CNC) have the capacity to assist in the synthesis of metallic...