TY - JOUR
T1 - Silica cubes with tunable coating thickness and porosity
T2 - From hematite filled silica boxes to hollow silica bubbles
AU - Castillo, Sonja I R
AU - Ouhajji, Samia
AU - Fokker, Sander
AU - Erné, Ben H.
AU - Schneijdenberg, Chris T W M
AU - Thies - Weesie, Dominique
AU - Philipse, Albert P.
AU - Thies - Weesie, Dominique
PY - 2014/9/1
Y1 - 2014/9/1
N2 - 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 α-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.
AB - 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 α-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.
KW - Coating porosity
KW - Coating thickness
KW - Infrared spectroscopy
KW - Silica cubes
KW - Surface-protected silica etching
UR - http://www.scopus.com/inward/record.url?scp=84899826874&partnerID=8YFLogxK
U2 - 10.1016/j.micromeso.2014.03.047
DO - 10.1016/j.micromeso.2014.03.047
M3 - Article
AN - SCOPUS:84899826874
SN - 1387-1811
VL - 195
SP - 75
EP - 86
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
ER -