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Université de Fribourg

Cellulose whisker/epoxy resin nanocomposites

Tang, Liming ; Weder, Christoph

In: ACS Applied Materials and Interfaces, 2010, vol. 2, no. 4, p. 1073-1080

New nanocomposites composed of cellulose nanofibers or “whiskers” and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of ∼10 and ∼84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight...

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...

Université de Fribourg

Review: current international research into cellulose nanofibres and nanocomposites

Eichhorn, S. J. ; Dufresne, A. ; Aranguren, M. ; Marcovich, N. E. ; Capadona, J. R. ; Rowan, S. J. ; Weder, Christoph ; Thielemans, W. ; Roman, M. ; Renneckar, S. ; Gindl, W. ; Veigel, S. ; Keckes, J. ; Yano, H. ; Abe, K. ; Nogi, M. ; Nakagaito, A. N. ; Mangalam, A. ; Simonsen, J. ; Benight, A. S. ; Bismarck, A. ; Berglund, L. A. ; Peijs, T.

In: Journal of Materials Science, 2010, vol. 45, no. 1, p. 1-33

This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments...

Université de Fribourg

Functional polymer blends and nanocomposites

Weder, Christoph

In: Chimia, 2009, vol. 63, no. 11, p. 758–763

The broad class of (multi)functional polymers with unusual combinations of optical, electronic, mechanical and other properties is attracting significant interest, because it conceptually combines the advantages of polymers - low cost, ease of processing and a range of attractive mechanical characteristics - with the specific, tailorable properties of functional organic molecules. The caveat is...

Université de Fribourg

Biomimetic mechanically adaptive nanocomposites

Shanmuganathan, Kadhiravan ; Capadona, Jeffrey R. ; Rowan, Stuart J. ; Weder, Christoph

In: Progress in Polymer Science, 2010, vol. 35, no. 1-2, p. 212–222

The development of a new class of mechanically adaptive nanocomposites has been inspired by biological creatures such as sea cucumbers, which have the ability to reversibly change the stiffness of their dermis. Several recent studies have related this dynamic mechanical behaviour to the distinctive nanocomposite architecture of the collagenous tissue, in which interactions among rigid collagen...

Université de Fribourg

Bio-inspired mechanically-adaptive nanocomposites derived from cotton cellulose whiskers

Shanmuganathan, Kadhiravan ; Capadona, Jeffrey R. ; Rowan, Stuart J. ; Weder, Christoph

In: Journal of Materials Chemistry, 2010, vol. 20, p. 180-186

A new series of biomimetic, stimuli-responsive nanocomposites, which change their mechanical properties upon exposure to physiological conditions, was investigated. The materials were produced by introducing percolating networks of cellulose whiskers isolated from cotton into poly(vinyl acetate). Below the glass-transition temperature (Tg∼ 63 °C), the tensile storage moduli...

Université de Fribourg

Stimuli-responsive mechanically adaptive polymer nanocomposites

Shanmuganathan, Kadhiravan ; Capadona, Jeffrey R. ; Rowan, Stuart J. ; Weder, Christoph

In: ACS Applied Materials & Interfaces, 2009, vol. 2, no. 1, p. 165–174

A new series of biomimetic stimuli-responsive nanocomposites, which change their mechanical properties upon exposure to physiological conditions, was prepared and investigated. The materials were produced by introducing percolating networks of cellulose nanofibers or “whiskers” derived from tunicates into poly(vinyl acetate) (PVAc), poly(butyl methacrylate) (PBMA), and blends of these...

Université de Fribourg

Luminescent mechanochromic sensors based on poly(vinylidene fluoride) and excimer-forming p-phenylene vinylene dyes

Lott, Joseph ; Weder, Christoph

In: Macromolecular Chemistry and Physics, 2009, vol. 211, no. 1, p. 28-34

Cyano-substituted excimer-forming oligo(phenylene vinylene) dyes (cyano-OPVs) with terminal alkyl tails of different length were blended with two fluorinated host polymers with similar chemical composition but differing crystallinity. These blends were used to fabricate luminogenic mechanochromic thin films, which change their emission color upon deformation. The alkyl tails affect the solubility...

Université de Fribourg

Influence of temperature on low-power upconversion in rubbery polymer blends

Singh-Rachford, Tanya N. ; Lott, Joseph ; Weder, Christoph ; Castellano, Felix N.

In: Journal of the American Chemical Society, 2009, vol. 131, no. 33, p. 12007–12014

The upconverting properties of a dye cocktail composed of palladium(II) octaethylporphyrin (PdOEP, triplet sensitizer) and 9,10-diphenylanthracene (DPA, triplet acceptor/annihilator) were investigated as a function of temperature in several low glass transition temperature (Tg) polymer hosts including an ethyleneoxide-epichlorohydrin copolymer (EO-EPI) and the polyurethanes...