Polymer derived SiOC microcellular foams were etched by means of a 20 vol.-%HF solution. An increase in one order of magnitude in specific surface area (SSA) values compared to the unetched samples was observed. This SSA increase was accompanied by micro- and mesopores formation. The limited increase in the specific surface area was attributed to several factors: the smaller dimension of the etchable SiO2 nanodomains and the more amorphous nanostructure of these polymer derived ceramics compared to the sol–gel derived ones. Moreover a possible role of the carbon residue deriving from polymethylmetacrylate (PMMA) microbeads used as porosity source was supposed. Higher SSA values (up to 65 m2 g−1) were reached by inducing a slight phase separation, accompanied by a growth of the nanodomains size, and by an oxidative treatment that partly removed the residual carbon. Microcellular ceramic foams with a bimodal pore size distribution were produced.

Etching of SiOC ceramic foams

BIASETTO, LISA;COLOMBO, PAOLO
2008

Abstract

Polymer derived SiOC microcellular foams were etched by means of a 20 vol.-%HF solution. An increase in one order of magnitude in specific surface area (SSA) values compared to the unetched samples was observed. This SSA increase was accompanied by micro- and mesopores formation. The limited increase in the specific surface area was attributed to several factors: the smaller dimension of the etchable SiO2 nanodomains and the more amorphous nanostructure of these polymer derived ceramics compared to the sol–gel derived ones. Moreover a possible role of the carbon residue deriving from polymethylmetacrylate (PMMA) microbeads used as porosity source was supposed. Higher SSA values (up to 65 m2 g−1) were reached by inducing a slight phase separation, accompanied by a growth of the nanodomains size, and by an oxidative treatment that partly removed the residual carbon. Microcellular ceramic foams with a bimodal pore size distribution were produced.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2265566
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