TY - JOUR
T1 - Hierarchical porous silica via solid-phase hydrolysis/polycondensation of cubic siloxane-based molecular units
AU - Iyoki, Kenta
AU - Sugawara-Narutaki, Ayae
AU - Shimojima, Atsushi
AU - Okubo, Tatsuya
PY - 2013/1/21
Y1 - 2013/1/21
N2 - Hierarchical micro-mesoporous silica has been synthesized by solid-phase conversion of molecular crystals of an alkoxy derivative of a cubic siloxane unit (Si8O12) as a molecular building unit. Seven methoxy groups and one adamantoxy group are introduced in a cage by the reaction of octa(hydridosilsesquioxane) (H8Si8O12) with the corresponding alcohols, which are then eliminated in a step-by-step manner. First, the methoxy groups are hydrolyzed by simply dispersing the precursor powder in an acidic aqueous solution. The formation of Si-O-Si linkages between the cages while retaining the bulky adamantoxy groups is confirmed by solid-state NMR. At this stage, broad mesopores (ca. 2 to 7 nm) are formed, as confirmed by nitrogen adsorption-desorption. The adamantoxy groups are then removed by calcination to generate relatively narrow micropores (∼1 nm in diameter). Various control experiments performed suggest that the stepwise solid-phase reaction of bifunctional building blocks is crucial to the formation of such micro-mesoporous silica, providing a new pathway to nanoporous materials with controlled architectures.
AB - Hierarchical micro-mesoporous silica has been synthesized by solid-phase conversion of molecular crystals of an alkoxy derivative of a cubic siloxane unit (Si8O12) as a molecular building unit. Seven methoxy groups and one adamantoxy group are introduced in a cage by the reaction of octa(hydridosilsesquioxane) (H8Si8O12) with the corresponding alcohols, which are then eliminated in a step-by-step manner. First, the methoxy groups are hydrolyzed by simply dispersing the precursor powder in an acidic aqueous solution. The formation of Si-O-Si linkages between the cages while retaining the bulky adamantoxy groups is confirmed by solid-state NMR. At this stage, broad mesopores (ca. 2 to 7 nm) are formed, as confirmed by nitrogen adsorption-desorption. The adamantoxy groups are then removed by calcination to generate relatively narrow micropores (∼1 nm in diameter). Various control experiments performed suggest that the stepwise solid-phase reaction of bifunctional building blocks is crucial to the formation of such micro-mesoporous silica, providing a new pathway to nanoporous materials with controlled architectures.
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U2 - 10.1039/c2ta00024e
DO - 10.1039/c2ta00024e
M3 - Article
AN - SCOPUS:84876557092
VL - 1
SP - 671
EP - 676
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
SN - 2050-7488
IS - 3
ER -