Versatile Surfactant/Swelling-Agent Template for Synthesis of Large-Pore Ordered Mesoporous Silicas and Related Hollow Nanoparticles

Abstract

A surfactant/swelling-agent pair suitable for templating a variety of well-defined large-pore nanoporous silicas was identified. The pair includes a poly­(ethylene oxide)-poly­(propylene oxide)-poly­(ethylene oxide), PEO-PPO-PEO, block copolymer surfactant (Pluronic F127, EO106PO70EO106) with a large fraction of long hydrophilic PEO blocks and a swelling agent (toluene) that strongly solubilizes in micelles of the PEO-PPO-PEO surfactant family. Such a combination affords micellar templates for both spherical and cylindrical mesopores with potential to hinder cross-linking of micelle-templated nanostructures due to stabilization of nanoparticles by long PEO chains. Under low-temperature conditions (11–12 °C), the Pluronic F127/toluene pair affords ultralarge-pore FDU-12 (ULP-FDU-12) silica with face-centered cubic structure of spherical mesopores and related hollow nanospheres, as well as large-pore SBA-15 (LP-SBA-15) with two-dimensional hexagonal structure of cylindrical mesopores and related silica nanotubes. ULP-FDU-12 reaches the unit-cell parameter of 69 nm, which is very large. LP-SBA-15 has a unit-cell parameter up to 26 nm and pore diameter up to ∼20 nm and is exceptionally well ordered. The hollow nanospheres and nanotubes are attainable through lowering of the silica-precursor/surfactant ratio. The materials templated by spherical micelles form when the surfactant/swelling-agent solution is kept under stirring for extended periods of time before the addition of the silica precursor. The sizes of entrances to the hollow nanospheres can be continuously tuned by adjusting the hydrothermal treatment temperature. The ordered mesoporous silicas can be converted from open-pore to closed-pore materials through the thermally induced pore closing. The diversity in morphology, pore size, and pore connectivity makes the proposed surfactant/swelling-agent templating system unprecedented in the large mesopore domain.

Highly ordered Nanomaterial Functionalized Copper Schiff Base Framework: Synthesis, Characterization, and Hydrogen Peroxide Decomposition Performance

“…Extensive studies have been conducted on their synthesis, characterization, and applications [35][36][37]. In literature, different catalytic systems have been employed where hydrogen peroxide decomposition was carried out using 17.8 g·L −1 of H 2 O 2 and 2.5 g·L −1 of bimetallic magnetic carbon xerogels with cobalt and iron microparticles at 50 • C and pH = 3 for 2 h. A maximum yield of 65% H 2 O 2 decomposition was reported [38].…”

Single-micelle-templated synthesis of hollow silica nanospheres with tunable pore structures

“…35,36 However, under appropriate conditions, commercially available triblock copolymer surfactants, such as Pluronic F127 (EO 106 PO 70 EO 106 ) and F108 (EO 132 PO 50 EO 132 ) (which have been used to template OMMs 34,37 ) interact with silica species to form individual or aggregated HSNs, which are also referred to as single-micelle-templated hollow nanospheres. 2,20,38,39 While the latter can form under different conditions, 2,3,15,20 they tend to be achievable at low ratios of the silica precursor to the block-copolymer surfactant. [37][38][39][40] While the details of the single-micelle-templating process may vary, it is considered that a silica precursor (for instance, tetraethyl orthosilicate, TEOS) or its hydrolysis products interact with poly(ethylene oxide) (PEO) blocks in the micelle corona and cross-link therein forming a spherical shell.…”

Ordered arrays of hollow carbon nanospheres and nanotubules from polyacrylonitrile grafted on ordered mesoporous silicas using atom transfer radical polymerization

“…S4). The corresponding unit-cell parameter was 50 nm, as calculated from the position of (311) peak [42]. The modification with the ATRP initiator, the polymer grafting, stabilization and carbonization, as well as the silica dissolution changed somewhat the relative intensity of the peaks on the SAXS patterns, but the (111)/(200) and (311) peak positions were largely unchanged throughout the process.…”