Helical ethylene-silica nanofibers with chiral pore channels inside and lamellar pores on the surfaces were prepared using cetyltrimethylammonium bromide and (S)-beta-citronellol as a co-structure-directing agent under basic conditions, the formation mechanism of which was studied by taking field-emission scanning electron microscopy images after different reaction times.
A new chiral cationic amphiphile has been synthesized. Sol-gel transcriptions were carried out to control mesoporous silica nanostructures using the organic self-assemblies of this amphiphile as templates. Left-handed coiled mesoporous silica nanoribbons were obtained in the mixture of 1-propanol and 2.5 wt% NH(3) aq. at the ratio of 2:8 and 0 °C. However, right-handed coiled mesoporous silica nanoribbons were prepared in 2.5 wt% NH(3) aq. at 25 °C. The organization of the low-molecular-weight gelators plays an important role in this handedness inversion.
The morphology, pore architecture and crystallinity of the mesoporous 1,4-phenylene-silicas were controlled using the mixtures of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS). When the SDS/CTAB molar ratio increased from 0 to 1.0, the morphology of the mesoporous 1,4-phenylene-silicas changed in a sequence of sphere, hexagonal short rod, worm-like, bent flake and flower-like structure; the pore architecture of them changed from a hexagonal arranged tubular structure to a lamellar one; and the organization of the smallest repeat units within the wall changed from a random structure to a crystalline structure. At the SDS/CTAB molar ratios of 0.3 and 0.5, 1,4-phenylene-silica nanofibers with lamellar mesopores outside and tubular pore channels inside were obtained. The lamellar mesopores should be formed by merging the rod-like micelles during the reaction process.
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