Nanoparticles in Lysine−Silica Sols

Davis, Tracy M.; Snyder, Mark A.; Krohn, John; Tsapatsis, Michael

doi:10.1021/cm061982v

Cited by 118 publications

(148 citation statements)

References 20 publications

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“…Silica particles obtained by the lysine synthesis method [46,47] were prepared by hydrolysis of tetraethyl orthosilicate (TEOS) (98 %, Aldrich), in an aqueous solution of l-lysine (Sigma-Aldrich) at 60 8C. In a typical synthesis, the molar composition of the reactants was 60 TEOS:1.7 lysine:9500 water.…”

Section: Methodsmentioning

confidence: 99%

“…For this experiment, we used silica spheres synthesized in-house using the aminoacid synthesis methods [46][47][48] for particles smaller than 90 nm and a seeded Stçber method [48,49] for larger particles. Because the model is not dynamic, it does not allow prediction of the process conditions for which resulting films will have the desired monolayered banded structure.…”

Section: Experiments To Test the Modelmentioning

confidence: 99%

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

et al. 2009

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Nanoparticle films coated on smooth substrates by convective assembly from dilute suspensions in dip-coating configuration are known to have discrete film morphologies. Specifically, the film morphology is characterized by alternating bands of densely packed particles and bands of bare substrate. Convective assembly is a frontal film-growth process that occurs at the three-phase contact line formed by the substrate, the suspension in which it is submersed, and the surrounding air. The bands are parallel to this contact line and can be either monolayered or multilayered. Monolayered bands result whenever the substrate is withdrawn from the suspension at a rate too high for particles to assemble into a continuous film. We report a new insight to the mechanism behind this banding phenomenon, namely, that inter-band spacing is strongly influenced by the constituent particle size. We therefore propose a geometric model relating the inter-band spacing to the particle size. By making banded films with systematically varied particle sizes (silica/zeolite, 20 to 500 nm), we are able to quantitatively validate our model. Furthermore, the model correctly predicts that multilayered banded films have higher inter-band spacings than monolayered banded films comprising the same particles.

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Section: Methodsmentioning

confidence: 99%

Section: Experiments To Test the Modelmentioning

confidence: 99%

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

et al. 2009

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“…Lys-Sil silica sols of different particle sizes were prepared by the hydrolysis of TEOS with water in the presence of the basic amino acid lysine, as reported by Davis et al 19 and Thomassen et al…”

Section: Synthesis Of Silica Nanoparticlesmentioning

confidence: 99%

Surfactant adsorption and aggregate structure at silica nanoparticles: Effects of particle size and surface modification

et al. 2012

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The influence of particle size and a surface modifier on the self-assembly of the nonionic surfactant C 12 E 5 at silica nanoparticles was studied by adsorption measurements and small-angle neutron scattering (SANS). Silica nanoparticles of diameter 13 to 43 nm were synthesized involving the basic amino acid lysine. A strong decrease of the limiting adsorption of C 12 E 5 with decreasing particle diameter was found. To unveil the role of lysine as a surface modifier for the observed size dependence of surfactant adsorption, the morphology of the surfactant aggregates assembled on pure siliceous nanoparticles (Ludox-TMA, 27 nm) and their evolution with increasing lysine concentration at a fixed surfactant-to-silica ratio was studied by SANS. In the absence of lysine, the surfactant forms surface micelles at silica particles. As the concentration of lysine is increased, a gradual transition from the surface micelles to detached wormlike micelles in the bulk solution is observed. The changes in surfactant aggregate morphology cause pronounced changes of the system properties, as is demonstrated by turbidity measurements as a function of temperature. These findings are discussed in terms of particle surface curvature and surfactant binding strength, which present new insight into the delicate balance between the two properties.

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“…Tsapatsis and co-workers reported the preparation of silica nanospheres with a size of ca. 5 nm by addition of TEOS to an un-buffered, aqueous solution of lysine 72) . They also succeeded in the fabrication of multilayer and near-monolayer-ordered coatings of silica nanospheres on a silicon substrate 73) .…”

Section: Mechanism Of Formation Of Snssmentioning

confidence: 99%

Syntheses and Applications of Well-ordered Porous Silicas by Using Anionic Surfactants and Basic Amino Acids

Yokoi

2012

J. Jpn. Petrol. Inst.

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Well-ordered mesoporous materials have attracted a great deal of attention because of their controllable structures and compositions, which make them suitable for a wide range of applications in catalysis, environmental clean-up, and development of advanced materials. In general, the mesoporous materials can be synthesized based on the self-assembly of surfactants and inorganic precursors. In addition to the use of the surfactants including cationic and nonionic surfactants, a synthesis route for preparing mesoporous silicas using anionic surfactants has been developed by using aminosilane or quaternized aminosilane as a co-structure-directing agent. Thus obtained "anionic surfactant templating mesoporous silica" (AMS) is synthetically interesting not only for their structural diversity but also for the opportunity to functionalize the pore surface. The removal of the surfactant from the so-called "as-synthesized" AMS by solvent extraction results in the mesoporous silica with aminopropyl groups intact. Thus obtained amino-functionalized AMS can be applied to solid-base catalysis, adsorption, drug delivery, etc. Besides well-known surfactant-templating route, a silica material having three-dimensionally ordered mesopores can be also obtained via a hard-sphere packing (HSP) route based on the formation of a colloidal array of uniform-sized silica spheres. A novel and simple liquid-phase method for forming uniform-sized silica nanospheres (SNSs) has been developed by using basic amino acid as a base catalyst for hydrolysis of tetraethyl orthosilicate Si(OC2H5)4. The size of SNSs can be tuned ranging from 8 to 550 nm by employing the seed regrowth method. Interestingly, the arrangement of SNSs into the cubic closed packed (ccp) structure was achieved simply by solvent evaporation. The thus-formed colloidal array of SNSs has three-dimensional interparticle voids with high uniformity in size, and can be categorized into well-ordered mesoporous silicas.

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Nanoparticles in Lysine−Silica Sols

Cited by 118 publications

References 20 publications

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

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

Surfactant adsorption and aggregate structure at silica nanoparticles: Effects of particle size and surface modification

Syntheses and Applications of Well-ordered Porous Silicas by Using Anionic Surfactants and Basic Amino Acids

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