期刊
MICROPOROUS AND MESOPOROUS MATERIALS
卷 195, 期 -, 页码 75-86出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.micromeso.2014.03.047
关键词
Surface-protected silica etching; Silica cubes; Coating thickness; Coating porosity; Infrared spectroscopy
类别
资金
- Dutch Technology Foundation STW
- Ministry of Economic Affairs
We investigate the material properties of micron-sized silica coated cubic colloids, focusing on the coating thickness and porosity. The thickness of the silica coating of core-shell alpha-Fe2O3@SiO2 cubes and their corresponding hollow cubes can be tuned between 20 and 80 nm, spanning the range of silica bubbles to silica boxes. The porosity of the silica cubes can be increased controllably by surface-protected etching using hot water as mild etchant and polyvinylpyrrolidone (PVP) as protecting polymer. We introduce infrared spectroscopy as a quantitative tool to monitor the extent of etching over time and to evaluate the influence of PVP on the etching process. The molar mass of PVP does not affect the etching rate, whereas an increased amount of PVP leads to enhanced protection against etching. Silica etching is found to be a two-step process, comprising a fast initial etching followed by a slower continuation. Hollow, porous silica cubes maintain their shape after extensive thermal treatment, demonstrating their mechanical stability. (c) 2014 Elsevier Inc. All rights reserved.
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