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Université de Fribourg

Monolithic resorcinol–formaldehyde alcogels and their corresponding nitrogen-doped activated carbons

Civioc, Romain ; Lattuada, Marco ; Koebel, Matthias M. ; Galmarini, Sandra

In: Journal of Sol-Gel Science and Technology, 2020, vol. 95, no. 3, p. 719–732

Here we report the adaptation of formaldehyde crosslinked phenolic resin-based aerogel and xerogel synthesis to ethanol-based solvent systems. Three specific formulations, namely one resorcinol–formaldehyde (RF) and two resorcinol– melamine–formaldehyde (RMF) systems were studied. As-prepared resins were characterized in terms of envelope and skeletal density. Furthermore, resin samples ...

Université de Fribourg

Handling (nano)silver as antimicrobial agent: therapeutic window, dissolution dynamics, detection methods and molecular interactions

Abram, Sarah‐Luise ; Fromm, Katharina M.

In: Chemistry – A European Journal, 2020, vol. 26, no. 48, p. 10948–10971

Silver is an antimicrobial agent well known since antiquity. With the emergence of multiresistant bacteria, it has come back into the focus of research, and ionic as well as nano‐sized silver have been studied in vitro and in vivo. The results are controversial, silver being discussed as the “silver bullet” or a “wolf in sheep's clothing”. A thorough search of literature from...

Université de Fribourg

Bimetallic salen-based compounds and their potential applications

Finelli, Alba ; Abram, Sarah-Luise ; Hérault, Nelly ; Crochet, Aurélien ; Fromm, Katharina M.

In: Crystal Growth & Design, 2020, vol. 20, no. 8, p. 4945–4958

The new bimetallic coordination compounds [LNiAg(NO3)], [LCuMn(NO3)2], [LCuCu(NO3)2], [LCuZn(NO3)2], and [{LCuBi(NO3)3}(ACN)] have been synthesized from a salen-type ligand L containing two distinct coordination sites to accommodate (different) metal ions M1 and M2. In the solid state, the formation of 1:1 compounds (LCu:M2) is always observed, but interactions between the compounds lead to ...

Université de Fribourg

In situ deprotection of polymeric binders for solution‐processible sulfide‐based all‐solid‐state batteries

Lee, Jieun ; Lee, Kyulin ; Lee, Taegeun ; Kim, Hyuntae ; Kim, Kyungsu ; Cho, Woosuk ; Coskun, Ali ; Char, Kookheon ; Choi, Jang Wook

In: Advanced Materials, 2020, p. 2001702

Sulfide‐based all‐solid‐state batteries (ASSBs) have been featured as promising alternatives to the current lithium‐ion batteries (LIBs) mainly owing to their superior safety. Nevertheless, a solution‐based scalable manufacturing scheme has not yet been established because of the incompatible polarity of the binder, solvent, and sulfide electrolyte during slurry preparation. This...

Université de Fribourg

Resonance raman optical activity shows unusual structural sensitivity for systems in resonance with multiple excited states: vitamin B12 case

Machalska, Ewa ; Zajac, Grzegorz ; Gruca, Anna ; Zobi, Fabio ; Baranska, Malgorzata ; Kaczor, Agnieszka

In: The Journal of Physical Chemistry Letters, 2020, vol. 11, no. 13, p. 5037–5043

In this work, cobalamins with different upper axial substituents and a cobalamin derivative with a ring modification were studied using chiroptical spectroscopies, in particular resonance Raman optical activity (RROA), to shed light on the influence of structural modifications on RROA spectra in these strongly chiral systems in resonance with multiple excited states at 532 nm excitation. We...

Université de Fribourg

Nanostructure generation during milk digestion in presence of a cell culture model simulating the small intestine

Hempt, Claudia ; Gontsarik, Mark ; Buerki-Thurnherr, Tina ; Hirsch, Cordula ; Salentinig, Stefan

In: Journal of Colloid and Interface Science, 2020, vol. 574, p. 430–440

Hypothesis: The development of advanced oral delivery systems for bioactive compounds requires the fundamental understanding of the digestion process within the gastrointestinal tract. Towards this goal, dynamic invitro digestion models, capable of characterising the molecular as well as colloidal aspects of food, together with their biological interactions with relevant invitro cell culture...

Université de Fribourg

Strong, machinable, and insulating chitosan–urea aerogels: toward ambient pressure drying of biopolymer aerogel monoliths

Guerrero-Alburquerque, Natalia ; Zhao, Shanyu ; Adilien, Nour ; Koebel, Matthias M. ; Lattuada, Marco ; Malfait, Wim J.

In: ACS Applied Materials & Interfaces, 2020, vol. 12, no. 19, p. 22037–22049

Biopolymer aerogels are an emerging class of materials with potential applications in drug delivery, thermal insulation, separation, and filtration. Chitosan is of particular interest as a sustainable, biocompatible, and abundant raw material. Here, we present urea-modified chitosan aerogels with a high surface area and excellent thermal and mechanical properties. The irreversible gelation of...

Université de Fribourg

One-step ring opening metathesis block-like copolymers and their compositional analysis by a novel retardation technique

Yasir, Mohammad ; Liu, Peng ; Markwart, Jens C. ; Suraeva, Oksana ; Wurm, Frederik R. ; Smart, Jansie ; Lattuada, Marco ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2020, p. -

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...

Université de Fribourg

A nano-rattle SnO2@carbon composite anode material for high-energy Li-ion batteries by melt diffusion impregnation

Maharajan, Sivarajakumar ; Kwon, Nam Hee ; Brodard, Pierre ; Fromm, Katharina M.

In: Nanomaterials, 2020, vol. 10, no. 4, p. 804

The huge volume expansion in Sn-based alloy anode materials (up to 360%) leads to a dramatic mechanical stress and breaking of particles, resulting in the loss of conductivity and thereby capacity fading. To overcome this issue, SnO2@C nano- rattle composites based on < 10 nm SnO2 nanoparticles in and on porous amorphous carbon spheres were synthesized using a silica template and tin melting...

Université de Fribourg

Metal nanoparticle–microbe interactions: synthesis and antimicrobial effects

Khan, Mujeebur R. ; Fromm, Katharina M. ; Rizvi, Tanveer F. ; Giese, Bernd ; Ahamad, Faheem ; Turner, Raymond J. ; Füeg, Michael ; Marsili, Enrico

In: Particle & Particle Systems Characterization, 2020, vol. 37, no. 5, p. 1900419

Metal nanoparticles (NPs), chalcogenides, and carbon quantum dots can be easily synthesized from whole microorganisms (fungi and bacteria) and cell‐free sterile filtered spent medium. The particle size distribution and the biosynthesis time can be somewhat controlled through the biomass/metal solution ratio. The biosynthetic mechanism can be explained through the ion‐reduction theory and...