Synthesis of anisotropic silica colloids

Yu, Qiyu; Wang, Kun; Zhang, Jing; Li, Mingyang; Liu, Yuanyuan; Cheng, Chao

doi:10.1039/c7ra02835k

Cited by 12 publications

(11 citation statements)

References 35 publications

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“…Similar effects are also visible in images and are speculated about in several papers as well. 44,48−50 Using this precursor in the synthesis of silica rods resulted in particles that had a small hollow sphere attached to the tip of the rod where the growth started; see Figure 3a. On the contrary, TEOS from a newly opened bottle resulted in silica rods that did not have this modification.…”

Section: Resultsmentioning

confidence: 99%

“…We show that by playing with this amount of hydrolyzed silica precursors, and thus the ratio of hydrolysis versus the condensation reactions, silica condensation and deposition can also be made to occur directly from the oil phase onto the water phase, creating hollow silica sections, conditions that were described in other papers as well. 48−51 We will explain why these differences reported are due to differences in the amount of (pre)hydrolyzed silica precursors present. We also influenced the hydrolysis and condensation rates by using mixtures of tetramethoxysilane (TMOS) with TEOS to grow the rods.…”

Section: Introductionmentioning

confidence: 95%

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Shaping Silica Rods by Tuning Hydrolysis and Condensation of Silica Precursors

et al. 2018

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We present the synthesis of colloidal silica particles with new shapes by manipulating the growth conditions of rods that are growing from polyvinylpyrrolidone-loaded water-rich droplets containing ammonia and ethanol. The silica rods grow by ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS). The lengthwise growth of these silica rods gives us the opportunity to change the conditions at any time during the reaction. In this work, we vary the availability of hydrolyzed monomers as a function of time and study how the change in balance between the hydrolysis and condensation reactions affects a typical synthesis (as described in more detail by our group earlier1). First, we show that in a “standard” synthesis, there are two silica growth processes occurring; one in the oil phase and one in the droplet. The growth process in the water droplet causes the lengthwise growth of the rods. The growth process in the oil phase produces a thin silica layer around the rods, but also causes the nucleation of 70 nm silica spheres. During a typical rod growth, silica formation mainly takes place in the droplet. The addition of partially hydrolyzed TEOS or tetramethoxysilane (TMOS) to the growth mixture results in a change in balance between the hydrolysis and condensation reaction. As a result, the growth also starts to take place on the surface of the water droplet and thus from the oil phase, not only from inside the droplet onto a silica rod sticking out of the droplet. Carefully tuning the growth from the droplet and the growth from the oil phase allowed us to create nanospheres, hollow silica rods, hollow sphere rod systems (colloidal matchsticks), and bent silica rods.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Shaping Silica Rods by Tuning Hydrolysis and Condensation of Silica Precursors

et al. 2018

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“…where f(x,z,y) accounts for the equilibrium conservative forces and f for the longitudinal force responsible for the transport along the channel. In eqn (8) and (9) we assume that the aspect ratio between the long axis, 2L, and the minor axis, 2l, of the rod is such that L c l and hence we can disregard the geometric corrections to eqn (8) and ( 9) due to the finiteness of l.…”

Section: Modelmentioning

confidence: 99%

“…8 Similarly, in environmental sciences, pollutants and plant nutrients spread across the porous matrix of rocks and soil. In this perspective, substantial effort has been dedicated to the synthesis 9,10 and characterization 11 of anisotropic nanocolloids and stiff filaments. 12,13 Finally, in recent years the development of experimental techniques such as DNA 14,15 and protein 16 sequencing, resistive-pulse sensing techniques [17][18][19][20] and chromatography [21][22][23] have been developed by exploiting transport across pores.…”

Section: Introductionmentioning

confidence: 99%

Transport of neutral and charged nanorods across varying-section channels

Malgaretti

Harting

2021

Soft Matter

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“…20 In addition to the length of silica rods on cubes, we could also control their diameter because the diameter of the growing rod depends on the interfacial area between the water droplet and the end of the tip. 21,22 Once one droplet was formed on each face of the cubic seeds at medium water concentration, as described above, the solution was annealed at 60 °C for 5 min to reduce the droplet size in pentanol, and silica precursors were introduced at room temperature for growing silica rods. We expected to obtain relatively thinner rods with a uniform diameter.…”

Section: And Supplementary Movie Clip 1)mentioning

confidence: 99%

Monodisperse Magnetic Silica Hexapods

Kim

Hwang

et al. 2018

J. Am. Chem. Soc.

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A simple yet versatile solution-based process to produce colloidal silica hexapods is developed in which various shapes of silica rods are grown on the faces of cubes in a controlled manner. In the presence of hematite cubic particles, water droplets nucleate on the surface of hematite by phase separation in pentanol. By adjusting the water concentration, six droplets can form on each face of the hematite cube. A silica precursor is then administered into the system, which gradually diffuses into the water droplets through the oil phase. Within the droplets, hydrolysis and condensation of the precursors take place, leading to formation of silica rods. As a result, silica hexapods on a magnetic hematite cubic seed are produced. Furthermore, when the emulsions are aged at 60 °C prior to the silica growth, the water content in the solution decreases gradually due to evaporation and spiky sharp hexapods are produced. On the other hand, when organosilane precursor is added, pancake-like hexapods are formed due to the reduction of interfacial tension. These colloidal hexapods can further be utilized as new building blocks for self-assembly to construct functional materials or as a model system to understand collective behaviors.

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Synthesis of anisotropic silica colloids

Abstract: Morphological evolution of tadpole-like hollow silica particles, and corresponding TEM images of typical intermediate and final products.

Cited by 12 publications

References 35 publications

Shaping Silica Rods by Tuning Hydrolysis and Condensation of Silica Precursors

Shaping Silica Rods by Tuning Hydrolysis and Condensation of Silica Precursors

Transport of neutral and charged nanorods across varying-section channels

Monodisperse Magnetic Silica Hexapods

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