A closer look at an aggregation model of the Stöber process

Lee, Kangtaek; Sathyagal, Arun; McCormick, Alon V.

doi:10.1016/s0927-7757(98)00566-4

Cited by 110 publications

(90 citation statements)

References 23 publications

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“…It is predicted that RLMCA occurs on two length scales with the smaller particles now acting as monomers [4]. This mechanism is supported by Feeney et al [17], Lee et al [18] and Harris et al [13]. Once the soluble silica concentration has dropped below the critical nucleation concentration, it is hypothesised that monomer addition subsequently occurs on the surface of the aggregated particles in accordance with LaMer and Dinegar's theory of monomer addition [19], leading to smoothing of the colloid surface [8,12,16].…”

Section: Introductionmentioning

confidence: 82%

“…It is proposed that particle growth follows a nucleation and aggregation mechanism [4,17], in which initial negatively charged particles (<10 nm) are unstable due to their size, resulting in aggregation and a collective reduction in surface area. Competition between nucleation and aggregation is dependent on reactant concentrations and has a large effect on final particle properties such as size [18]. Uniformity in particle size can be achieved with this mechanism as a result of size dependent aggregation rates [8,18] determined by colloid interaction potentials.…”

Section: Introductionmentioning

confidence: 99%

“…Competition between nucleation and aggregation is dependent on reactant concentrations and has a large effect on final particle properties such as size [18]. Uniformity in particle size can be achieved with this mechanism as a result of size dependent aggregation rates [8,18] determined by colloid interaction potentials. The aggregation rate is fastest between small-large particles and slowest between large-large particles [18].…”

Section: Introductionmentioning

confidence: 99%

“…Uniformity in particle size can be achieved with this mechanism as a result of size dependent aggregation rates [8,18] determined by colloid interaction potentials. The aggregation rate is fastest between small-large particles and slowest between large-large particles [18]. Initial particles restructure through Ostwald ripening, in which aggregates dissolve and then reprecipitate, consuming smaller particles to form larger more stable ones.…”

Section: Introductionmentioning

confidence: 99%

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Controlling particle size in the Stöber process and incorporation of calcium

Greasley

Page

Sirovica

et al. 2016

Journal of Colloid and Interface Science

150

152

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The Stӧber process is commonly used for synthesising spherical silica particles. This article reports the first comprehensive study of how the process variables can be used to obtain monodispersed particles of specific size. The modal particle size could be selected within in the range 20 -500 nm. There is great therapeutic potential for bioactive glass nanoparticles, as they can be internalised within cells and perform sustained delivery of active ions. Biodegradable bioactive glass nanoparticles are also used in nanocomposites. Modification of the Stӧber process so that the particles can contain cations such as calcium, while maintaining monodispersity, is desirable. Here, while calcium incorporation is achieved, with a homogenous distribution, careful characterisation shows that much of the calcium is not incorporated. A maximum of 10 mol% CaO can be achieved and previous reports are likely to have overestimated the amount of calcium incorporated.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Controlling particle size in the Stöber process and incorporation of calcium

Greasley

Page

Sirovica

et al. 2016

Journal of Colloid and Interface Science

150

152

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“…In contrast, the upper limit at W~10 (DLVO) theory for colloidal stability. 23,34,[35][36][37] This analysis will lead to our hypotheses and objectives for the design of a straightforward, scalable synthesis of alkanethiol functionalized Ag nanoparticles.…”

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confidence: 99%

A Straightforward, One-Step Synthesis of Alkyl Thiol Capped Silver Nanoparticles

Farrell¹

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Classical nucleation theory and Derjaguin, Landau, Verwey, Overbeek (DLVO) theory for colloidal stability were applied to gain insight into the synthesis of dodecanethiol (DDT)-functionalized silver nanoparticles (NPs) by reduction of silver nitrate with sodium borohydride in ethanol. This analysis indicated the importance of quickly establishing a dense DDT ligand brush on inherently unstable primary particles to achieve colloidal stability. The DLVO calculations also indicated that the electrostatic potential was a minor contributor to repulsive interactions, signifying that it would be possible to control NP size and uniformity in solutions with high ionic strength, as long as sufficient DDT was available to form a densely packed ligand layer on the NPs. These insights were applied to design a new straightforward, one-step, one-phase synthesis for the production of alkyl thiol-functionalized silver NPs. To test the insights from DLVO theory, a battery of 16 samples were synthesized in the parameter space R=3-12, S=1-12 where R= [NaBH 4 samples with R=3 or S=1 were polydisperse, however, samples in the R=6-12 and S=3-12 range had uniform particle sizes with average diameters between 3.5-4.7 nm.Additionally, samples with R=72-108 and S=12 were synthesized to test particle stability at high ionic strength; again uniform NPs with average diameters from 3.5-3.8 nm were produced. Ultimately, the insights gained from DLVO theory successfully guided the development of a one-step, one-phase technique for the synthesis of uniform, spherical alkyl thiol-functionalized silver NPs. In future work, this technique will be extended to facilitate the grafting of polymers from phase-separated ligand domains on NP surfaces.ii AcknowledgementsThere are a number of individuals who deserve recognition and thanks for enabling the work contained in this thesis. First, I would like to thank my advisor, Dr.David Green for humoring my constant skepticism and questions throughout this project; I know so much more now than when we started. I would also like to specifically thank Cameron Shelton, whose assistance in managing the seemingly endless number of nanoparticle syntheses was invaluable. Finally, I would like to thank the members of Dr.Green's research group (current and past) for their help and input: Dan Sunday, Allison Galey, and Caroline Dunn.iii Figure 12: UV-VIS spectra of DDT functionalized silver nanoparticles in toluene. Curve color is consistent within a given R value. The primary feature of interest is the presence of a strong plasmon band at ~450 nm which serves to confirm the presence of silver nanoparticles. With larger particles, it is possible to make size determinations from UV-VIS spectra, however, we know from TEM that the nanoparticles are smaller than 15 nm in diameter, placing them in a size-independent regime with respect to UV-VIS. .......... 50 Figure 13: UV-VIS spectrum of R=72 S=12 silver nanoparticles with TEM inset. The peak at 450 nm demonstrates the presence of small silver nanoparticl...

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