Self-Assembly of Pluronic F127—Silica Spherical Core–Shell Nanoparticles in Cubic Close-Packed Structures

Abstract

A new ordered mesoporous silica material (COK-19) with cubic symmetry is synthesized by silicate polycondensation in a citric acid/citrate buffered micellar solution of Pluronic F127 triblock copolymer near neutral pH. SAXS, nitrogen adsorption, TEM, and electron tomography reveal the final material has a cubic close packed symmetry (Fm3̅m) with isolated spherical mesopores interconnected through micropores. Heating of the synthesis medium from room temperature to 70 °C results in a mesopore size increase from 7.0 to 11.2 nm. Stepwise addition of the silicate source allows isolation of a sequence of intermediates that upon characterization with small-angle X-ray scattering uncovers the formation process via formation and aggregation of individual silica-covered Pluronic micelles.

Water soluble polymer–surfactant complexes-stabilized Pd(0) nanocatalysts: Characterization and structure–activity relationships in biphasic hydrogenation of alkenes and α,β-unsaturated ketones

“…According to their spatial organisation [31] and the bond length of the carbon chains in the HEA16Cl molecules (0.154 nm for C-C bonds and 0.149 nm for C-N + bonds), it could be stated that the HEA molecules are strained and have normal orientation at the particle's surface, as illustrated in Figure 4. Finally, the organic shell in the systems based on M6PEI possesses a size around 4 to 5 nm, which is in good agreement with previous works on determination of shell thickness [48][49][50] considering the organic doublelayer formed by the surfactants and the polymer molecules [31].…”

Material properties determining the insecticidal activity of highly divided porous materials on the pharaoh ant (Monomorium pharaonis)

“…For the COK‐12‐I and COK‐19‐I materials this theory would appear to hold, as they were the second and third least effective materials. By contrast, in their ordered mesoporous counterparts (COK‐12‐II and COK‐19‐II, ‐III and ‐IV), the pores are ordered and wider (classified as mesopores) . These mespores, therefore, would be expected to enhance the adsorption of the epicuticular wax molecules.…”

“…By contrast, in their ordered mesoporous counterparts (COK-12-II and COK-19-II, -III and -IV), the pores are ordered and wider (classified as mesopores). 42 These mespores, therefore, would be expected to enhance the adsorption of the epicuticular wax molecules. In line with this theory, the most mesoporous material, COK-19-IV, was in joint fourth place when considering insecticidal effectivity.…”

“…Two types of titanium dioxide nanopowders were added to increase the variety of the materials tested and their properties, even though these particular materials are known to be hazardous (see Section 2.3), and would be undesirable to be used in final applications. The OMS materials, COK-19 and COK-12, were synthesized in-house according to Kerkhofs et al 42 and Jammaer et al, 43 respectively. COK-12 synthesis performed at 0 ∘ C (COK-12-I) instead of the original 20 ∘ C (COK-12-II) generated an amorphous microporous material in which the pores were no longer ordered.…”

Aluminosilicate nanofibers with ordered pores derived from block copolymer electrospun nanofibers

“…Its individual blocks are composed of 101 repeating units of PEO and 56 repeating units of (PPO). Because of its high hydrophobic/hydrophilic ratio (>1.5) (the methyl group from PPO being more hydrophobic than PEO), it is used as a surfactant and soft template to produce mesoporous materials via self‐assembly …”