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

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

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

Effect of aging on silica aerogel properties

Iswar, Subramaniam ; Malfait, Wim J. ; Balog, , Sandor ; Winnefeld, Frank ; Lattuada, Marco ; Koebel, Matthias M.

In: Microporous and Mesoporous Materials, 2017, vol. 241, p. 293–302

Silica aerogels’ unique physical and chemical properties make them fascinating materials for a wide variety of applications. In addition to hydrophobization by silylation, aging is very important in the synthesis of silica aerogel by ambient pressure drying. Here we systematically study the effect of aging on the physico-chemical properties of silica aerogel with emphasis on ambient dried...