Thick Silica Foam Films through Combined Catalytic Decomposition of H2O2 and Sol–Gel Processes
Materials and Design 2016
Martin Timusk, Agnes Kuus, Kathriin Utt, Triin Kangur, Andris Šutka, Martin Järvekülg, Māris Knite

A novel method for the preparation of thick silica foam films is reported that combines an alkoxide-based hydrolytic sol–gel process and in situ catalytic decomposition of hydrogen peroxide on a catalyst-coated support. A hydrogen peroxide/nitric acid aqueous solution was used to carry out acid-catalysed hydrolysis of tetramethoxysilane. Complete stability of H2O2 in the resulting silica sols over extended periods (N120 min) was demonstrated by in situ Raman spectroscopy. The H2O2-loaded sols were sprayed on MnO2-coated substrates, resulting in heterogeneous catalytic decomposition of H2O2 and effective foaming and simultaneous gel formation due to oxygen gas and water formation. Silica foam films with a well-defined closed-cell porosity were annealed at 600 °Cwithout any damage to the closed-cell porous filmmorphology. Up to 530 μmthickfilms were prepared with macropore sizes in the range of 29–47 μm, exceptionally thin macropore wall thicknesses of 16–50 nm and a bulk density as low as 64 kg/m3, comparable to that of the aerogels. The lowest measured thermal conductivity of the prepared foams was 0.018±0.001 W/(m∗K), which is also similar to silica aerogels, enabling the prepared foams to be used as efficient thermal insulation materials.

Atslēgas vārdi
Silica foam, Low-density material, Closed-cell porosity, Sol–gel, Hydrogen peroxide, Manganese dioxide

Timusk, M., Kuus, A., Utt, K., Kangur, T., Šutka, A., Järvekülg, M., Knite, M. Thick Silica Foam Films through Combined Catalytic Decomposition of H2O2 and Sol–Gel Processes. Materials and Design, 2016, Vol.111, 80.-87.lpp. ISSN 0264-1275. Pieejams: doi:10.1016/j.matdes.2016.08.092

Publikācijas valoda
English (en)
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