Nanostructured Mesoporous Silica Wires with Intrawire Lamellae via Evaporation‐Induced Self‐Assembly in Space‐Confined Channels

Abstract

Evaporation-induced self-assembly (EISA) of silica sol-gel ethanol-water solution mixtures with block-copolymer were studied inside uniform micro/nano-channels. Nanostructured mesoporous silica wires, with various intrawire self-assembly structures including lamellae, were prepared via EISA process but in space-confined channels with the diameter ranging from 50 nm to 200 nm. Membranes made of anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC) were utilized as the arrays of space-confined channels (i.e., 50, 100, and 200 nm EPC and 200 nm AAO) for infiltration and drying of mixture solutions; these substrate membranes were submerged in mixture solutions consisting of a silica precursor, a structure-directing agent, ethanol, and water. After the substrate channels were filled with the solution under vacuum impregnation, the membrane was removed from the solution and dried in air. The silica precursor used was tetraethyl othosilicate (TEOS), and the structure-directing agent employed was triblock copolymer Pluronic-123 (P123). It was found that the formation of the mesoporous nanostructures in silica wires within uniform channels were significantly affected by the synthesis conditions including (1) preassemble TEOS aging time, (2) the evaporation rate during the vacuum impregnation, and (3) the air-dry temperature. The obtained intrawire structures, including 2D hexagonal rods and lamellae, were studied by scanning transmission electron microscopy (STEM). A steric hindrance effect seems to explain well the observed polymer-silica mesophase formation tailored by TEOS aging time. The evaporation effect, air-drying effect, and AAO versus EPC substrate effect on the mesoporous structure of the formed silica wires were also presented and discussed.

Designing and Fabricating Ordered Mesoporous Metal Oxides for CO2 Catalytic Conversion: A Review and Prospect

“…Zhang et al [60] found that it is necessary to add acetylacetone during the hydrolysis process because acetylacetone as a complexing agent can inhibit the hydrolysis rate of the titanium source, thus preventing the rapid formation of precipitates and favoring the formation of ordered mesoporous structures. Hu et al [61] used EISA method to improved sol-gel and obtained titanium dioxide samples. They found that the constant volatilization of solvents and inorganic acids also enhances the polycondensation between inorganic particles.…”

Synthesis, Morphology, and Luminescence Properties of Poly(urethane-acrylate) Nanowires Bonding with the Eu(III) Complex

“…Porous AAO membranes are usually used as a template to prepare 1D polymer nanostructures because of the simple preparation method, low-cost, and high uniformity of the nanostructures. 15 − 17 Many methods can been used for preparing polymer nanowires and nanocables through the AAO template, such as electrodeposition, 18 , 19 self-assembled, 20 chemical vapor deposition, 21 photolithographic approaches, 22 layer-by-layer deposition, 23 , 24 and physical wetting. 25 …”

“…Porous AAO membranes are usually used as a template to prepare 1D polymer nanostructures because of the simple preparation method, low-cost, and high uniformity of the nanostructures. 15−17 Many methods can been used for preparing polymer nanowires and nanocables through the AAO template, such as electrodeposition, 18,19 self-assembled, 20 chemical vapor deposition, 21 photolithographic approaches, 22 layer-by-layer deposition, 23,24 and physical wetting. 25 The rare earth (RE) complexes have been attractive materials because of their distinct and desired luminescence performances, for instance, low excitation energy, good monochromaticity, and long fluorescence lifetimes.…”

Fabrication and characterization of mesoporous silica nanochannels inside the channels of anodic alumina membrane

“…Recently, synthesis of mesoporous silica inside the columnar channels of an anodic alumina membrane (AAM) has been extensively studied, and 1D or 2D hexagonally ordered or stacked (circular) mesostructure has been fabricated inside the columnar AAM channels by using cationic, nonionic and block copolymer surfactants as template and structuralguided synthesis (Martin, 1994;Nishizawa et al, 1995;Wu et al, 2004a,b;Platschek et al, 2006;Hu et al, 2014). However, the extensive synthesis conditions might lead to very difficult control over the 3D channel geometry in the final replica along the entire AAM channels.…”

“…Yet, recent progresses could be utilized to modify the synthesis protocols for more morphological control and better future applicability. Thus; fabrication of intrawire nanoporous structure with its lamellar disks perpendicular to the mesoporous silica wire axis (Hu et al, 2014), synthesis of silica nanotubes with orientation controlled mesopores (Zhang et al, 2012) and synthesis of polymers, metal oxides, and alloys magnetic nanoparticles coordinated with mesoporous silica membranes (Cauda et al, 2012 andAlamri et al, 2014) could be achieved.…”