Face-Centered-Cubic Large-Pore
Periodic Mesoporous
Organosilicas with Unsaturated and Aromatic Bridging Groups
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Abstract
Large-pore ethenylene-bridged (−CHCH−)
and
phenylene-bridged (−C<sub>6</sub>H<sub>4</sub>−) periodic
mesoporous organosilicas (PMOs) with face-centered-cubic structure
(<i>Fm</i>3<i>m</i> symmetry) of spherical mesopores
were synthesized at 7 °C at low acid concentration (0.1 M HCl)
using Pluronic F127 triblock copolymer surfactant in the presence
of aromatic swelling agents (1,3,5-trimethylbenzene, xylenes–isomer
mixture, and toluene). In particular, this work reports an unprecedented
block-copolymer-templated well-ordered ethenylene-bridged PMO with
cubic structure of spherical mesopores and an unprecedented block-copolymer-templated
face-centered cubic phenylene-bridged PMO, which also has an exceptionally
large unit-cell size and pore diameter. The unit-cell parameters of
30 and 25 nm and the mesopore diameters of 14 and 11 nm (nominal BJH-KJS
pore diameters of 12–13 and 9 nm) were obtained for ethenylene-bridged
and phenylene-bridged PMOs, respectively. Under the considered reaction
conditions, the unit-cell parameters and pore diameters were found
to be similar when the three different methyl-substituted benzene
swelling agents were employed, although the degree of structural ordering
appeared to improve for phenylene-bridged PMOs in the sequence of
decreased number of methyl groups on the benzene ring