Université de Fribourg

Functional polymers through mechanochemistry

Schrettl, Stephen ; Balkenendea, Diederik W. R. ; Calvino, Céline ; Karman, Marc ; Lavrenova, Anna ; Neumann, Laura N. ; Sagaraa, Yoshimitsu ; Verde-Sestoa, Ester ; Giannantonio, Michela di ; Simon, Yoan C. ; Fromm, Katharina M. ; Lattuada, Marco ; Weder, Christoph

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 7–11

While coupling mechanical and chemical processes is widespread in living organisms, the idea to harness the mechanically induced dissociation of weak covalent and non- covalent bonds to create artificial materials that respond to mechanical stimulation has only recently gained attention. Here we summarize our activities that mainly revolve around the exploitation of non-covalent interactions...

Université de Fribourg

Effect of clustering on the heat generated by superparamagnetic iron oxide nanoparticles

Lattuada, Marco

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 39–42

Magnetic nanoparticles have been the subject of enormous investigations for their potential use as cancer treatment via hyperthermia. This is due to their ability to generate heat when exposed to an external magnetic field oscillating at sufficiently high frequency. There are many different parameters that need to be considered when designing the optimal nanoparticle formulation for...

Université de Fribourg

Effect of aging on thermal conductivity of fiber-reinforced aerogel composites: An X-ray tomography study

Iswara, Subramaniam ; Griffa, Michele ; Kaufmann, Rolf ; Beltran, Mario ; Huber, Lukas ; Brunner, Samuel ; Lattuada, Marco ; M.Koebel, Matthias ; Malfait, Wim J.

In: Microporous and Mesoporous Materials, 2019, vol. 278, p. 289–296

Silica aerogels display an ultra-low thermal conductivity (λ) and are used as thermal superinsulators. Here, we study the influence of aging and drying processes on the microstructure and thermal conductivity of fiber-reinforced silica aerogel composites. Glass wool-silica gel composites were aged for variable times, hydrophobized, and dried either at ambient pressure or from supercritical...

Université de Fribourg

Nanoparticle administration method in cell culture alters particle-cell interaction

Moore, Thomas L. ; Urban, Dominic A. ; Rodriguez-Lorenzo, Laura ; Milosevic, Ana ; Crippa, Federica ; Spuch-Calvar, Miguel ; Balog, Sandor ; Rothen-Rutishauser, Barbara ; Lattuada, Marco ; Petri-Fink, Alke

In: Scientific Reports, 2019, vol. 9, no. 1, p. 900

As a highly interdisciplinary field, working with nanoparticles in a biomedical context requires a robust understanding of soft matter physics, colloidal behaviors, nano- characterization methods, biology, and bio-nano interactions. When reporting results, it can be easy to overlook simple, seemingly trivial experimental details. In this context, we set out to understand how in vitro...

Université de Fribourg

Protein amyloid fibrils as template for the synthesis of silica nanofibers, and their use to prepare superhydrophobic, lotus-like surfaces

Rima, Simonetta ; Lattuada, Marco

In: Small, 2018, vol. 14, no. 46, p. 1802854

In this work, amyloid fibrils are used as a template for the preparation of long silica fibers, with a variety of aspect ratios and surface roughness. Starting with β‐ lactoglobulin fibrils with typical diameters of about 20 nm and a length of several micrometers, two different strategies are followed to grow silica: either in water at acidic pH values, or in ethanol–water mixtures under...

Université de Fribourg

Modeling analysis of ultrasonic attenuation and angular scattering measurements of suspended particles

Fleckenstein, Peter ; Storti, Giuseppe ; Deschwanden, Fabian ; Gruber, Peter ; Lattuada, Marco

In: The Journal of the Acoustical Society of America, 2018, vol. 143, no. 2, p. 1049–1063

A combination of two models previously developed by Faran, and Atkinson and Kytömaa (Faran-AK model) was used to calculate the ultrasonic attenuation and the backscattering signal of a suspension of particles. The model of Atkinson and Kytömaa yielded the viscoelastic contributions while the model of Faran yielded the scattering contribution. A comparison with the more fundamental model by...

Université de Fribourg

Triggered metal ion release and oxidation: ferrocene as a mechanophore in polymers

Giannantonio, Michela Di ; Ayer, Mathieu A. ; Verde-Sesto, Ester ; Lattuada, Marco ; Weder, Christoph ; Fromm, Katharina M.

In: Angewandte Chemie International Edition, 2018, vol. 57, no. 35, p. 11445–11450

The introduction of mechanophores into polymers makes it possible to transduce mechanical forces into chemical reactions that can be used to impart functions such as self‐healing, catalytic activity, and mechanochromic response. Here, an example of mechanically induced metal ion release from a polymer is reported. Ferrocene (Fc) was incorporated as an iron ion releasing mechanophore into...

Université de Fribourg

Reinforced and superinsulating silica aerogel through in situ cross-linking with silane terminated prepolymers

Iswar, Subramaniam ; Snellings, Geert M. B. F. ; Zhao, Shanyu ; Erni, Rolf ; Bahk, Yeon Kyoung ; Wangd, Jing ; Lattuada, Marco ; Koebel, Matthias M. ; Malfait, Wim J.

In: Acta Materialia, 2018, vol. 147, p. 322–328

Silica aerogels have only half the thermal conductivity of conventional insulation, but their application potential is limited by the poor mechanical properties. The fragility arises from the thin necks between the silica nanoparticle building blocks. Here, we produce strong silica aerogels through co-gelation of the polyethoxydisiloxane precursor with a variety of silane terminated...

Université de Fribourg

Bioinspired stimuli-responsive color-changing systems

Isapour, Golnaz ; Lattuada, Marco

In: Advanced Materials, 2018, vol. 30, no. 19, p. 1707069

Stimuli-responsive colors are a unique characteristic of certain animals, evolved as either a method to hide from enemies and prey or to communicate their presence to rivals or mates. From a material science perspective, the solutions developed by Mother Nature to achieve these effects are a source of inspiration to scientists for decades. Here, an updated overview of the literature on...

Université de Fribourg

Tracking of fluorescently labeled polymer particles reveals surface effects during shear-controlled aggregation

Caimi, Stefano ; Cingolani, Alberto ; Jaquet, Baptiste ; Siggel, Marc ; Lattuada, Marco ; Morbidelli, Massimo

In: Langmuir, 2017, vol. 33, no. 49, p. 14038–14044

Surface chemistry is believed to be the key parameter affecting the aggregation and breakage of colloidal suspensions when subjected to shear. To date, only a few works dealt with the understanding of the role of the physical and chemical properties of the particles’ surface upon aggregation under shear. Previous studies suggested that surface modifications strongly affect polymer...