TY - JOUR
T1 - Control of structure, pore size and morphology of three-dimensionally ordered mesoporous silicas prepared using the dicationic surfactant [CH3(CH2)15N(CH3)2(CH 2)3N(CH3)3]BR2
AU - Garcia-Bennett, Alfonso E.
AU - Williamson, Sylvia
AU - Wright, Paul A.
AU - Shannon, Ian J.
PY - 2002/12/1
Y1 - 2002/12/1
N2 - The synthesis of mesoporous silicas in the presence of the dicationic gemini surfactant [CH3(CH2)15N(CH3)2(CH 2)3N(CH3)3]Br2 (C16-3-1) has been investigated at low temperatures (-4 °C) under basic and acidic conditions. Under basic conditions, the SBA-2 phase (based on a close-packed arrangement of micelles and exhibiting frequent stacking faults) is observed, with hollow sphere morphology. Under strongly acidic conditions, the phase SBA-1 (Pm3̄n) and the SBA-2 family of phases (based on the close packing of micelles) are observed, depending on the surfactant and silicate content of the original gel. Conditions under which the pure hexagonally close-packed end member of the family (P63/mmc) is formed have been identified. SBA-1 and the pure hexagonally close-packed end member are prepared with well-defined morphologies. The adsorption of nitrogen and the hydrocarbons cyclopentane and mesitylene reveal that SBA-2 prepared in basic media has a cage structure where the cages are linked through small <4 Å) micropores, whereas the silicas prepared in acidic media have larger pores after calcination. SBA-1 and a poorly ordered SBA-2, prepared using C16-3-1 under acidic conditions, are able to adsorb mesitylene (diameter ca. 8 Å), whereas the hexagonal end member of the SBA-2 series prepared under acidic conditions is able to adsorb cyclopentane (diameter ca. 5 Å) but not mesitylene.
AB - The synthesis of mesoporous silicas in the presence of the dicationic gemini surfactant [CH3(CH2)15N(CH3)2(CH 2)3N(CH3)3]Br2 (C16-3-1) has been investigated at low temperatures (-4 °C) under basic and acidic conditions. Under basic conditions, the SBA-2 phase (based on a close-packed arrangement of micelles and exhibiting frequent stacking faults) is observed, with hollow sphere morphology. Under strongly acidic conditions, the phase SBA-1 (Pm3̄n) and the SBA-2 family of phases (based on the close packing of micelles) are observed, depending on the surfactant and silicate content of the original gel. Conditions under which the pure hexagonally close-packed end member of the family (P63/mmc) is formed have been identified. SBA-1 and the pure hexagonally close-packed end member are prepared with well-defined morphologies. The adsorption of nitrogen and the hydrocarbons cyclopentane and mesitylene reveal that SBA-2 prepared in basic media has a cage structure where the cages are linked through small <4 Å) micropores, whereas the silicas prepared in acidic media have larger pores after calcination. SBA-1 and a poorly ordered SBA-2, prepared using C16-3-1 under acidic conditions, are able to adsorb mesitylene (diameter ca. 8 Å), whereas the hexagonal end member of the SBA-2 series prepared under acidic conditions is able to adsorb cyclopentane (diameter ca. 5 Å) but not mesitylene.
UR - http://www.scopus.com/inward/record.url?scp=0036925578&partnerID=8YFLogxK
U2 - 10.1039/b205470c
DO - 10.1039/b205470c
M3 - Article
AN - SCOPUS:0036925578
VL - 12
SP - 3533
EP - 3540
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
SN - 0959-9428
IS - 12
ER -