Silica Nanoparticle Crystals and Ordered Coatings Using Lys-Sil and a Novel Coating Device

Abstract

Silica nanoparticles with a narrow particle size distribution and controlled diameters of 10-20 nm are synthesized via hydrolysis and hydrothermal aging of tetraethylorthosilicate in an aqueous L-lysine solution. Cryo-transmission electron microscopy (cryo-TEM) reveals that the silica nanoparticles assemble to form close-packed nanoparticle crystals over short length scales on carbon-coated grids. Evaporative drying of the same sols results in nanoparticle stability and remarkable long-range facile ordering of the silica nanoparticles over scales greater than 10 microm. Whereas small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) discount the possibility of a core (silica)-shell (lysine) structure, the possibility remains for lysine occlusion within the silica nanoparticles and concomitant hydrogen bonding effects driving self-assembly. Facile ordering of the silica nanoparticles into multilayer and monolayer coatings over square-centimeter areas by evaporation-induced self-assembly is demonstrated using a novel dip-coating device.

Geometric Model Describing the Banded Morphology of Particle Films Formed by Convective Assembly

“…[34] Briefly, the substrate is submersed vertically into suspension and withdrawn at a steady rate (usually in the range 5 to 50 mm s À1 ), while the meniscus region experiences enhanced evaporation due to a gentle laminar nitrogen flow (1.5 to 5 cm 3 s À1 cm…”

“…Increasingly, high-technology applications are requiring controlled microstructures, such as colloidal crystals (such as for photonics) and hierarchical structures (as may be useful in separations). To these ends, we have been studying the method of convective assembly, [1,[3][4][5][13][14][15][16][17][18][19][20][21][22][23][24] rooted in the more general phenomenon of evaporation-induced self-assembly, [25][26][27][28][29][30][31][32] as a coating method for obtaining structured thin films, variously applying the technique to zeolite nanocrystals [33] and silica nanospheres [34] . It is by now well agreed that convective assembly of particles, in addition to yielding continuous films, [1,14,17,35] can also yield films with discrete morphologies [4,19,22,28,30,36] without patterning the substrate (others have patterned the substrate chemically or topologically to control film morphology [37,43] ).…”

Genotoxicity of Metal Nanoparticles: Focus on In Vivo Studies

“…NPs are coated with various coverings (i.e. polymers, amino acids) in order to obtain improved solubility in fl uids, higher biocompatibility, and lower toxicity (14,15). As these coatings modify the particle surface, they may also alter the particle's (geno-)toxicity or infl ammatory effects depending on the coating material (14,16).…”

Three-dimensionally ordered macro-/mesoporous carbon loading sulfur as high-performance cathodes for lithium/sulfur batteries

“…The electrochemical impedance spectroscopy (EIS) was measured over a frequency range from 0.01 to 100 kHz. Firstly, the silica opal was fabricated by the previously published method [24,25].…”