pH-responsive flocculation and dispersion behavior of Janus particles in water

Ito, Masanori; Enomoto, Ryusuke; Osawa, Kazuki; Daiko, Yusuke; Yazawa, Tetsuo; Fujii, Syuji; Yokoyama, Yuichi; Miyanari, Yuki; Nakamura, Yoshinobu; Nakao, Aiko; Iwasaki, Yasuhiko; Yusa, Shin‐ichi

doi:10.1038/pj.2011.94

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…Recently, we fabricated Au-SiO 2 Janus particles with poly(sodium 6-acrylamidohexanoate) grafted to the Au side by a grafting-to method. 57 In this study, hydrophobic thiol-terminated polymers, namely, PS-SH and PPFBEM-SH (Figure 1), were grafted to the Au side of the Au-SiO 2 Janus particles via thiol−Au interactions, and the resulting hairy Janus particles were used to stabilize bubbles.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Although the hairy Janus particles were synthesized by a grafting-from method in some of these studies, , few reports described the synthesis of these Janus particles by a grafting-to method. Recently, we fabricated Au-SiO 2 Janus particles with poly(sodium 6-acrylamidohexanoate) grafted to the Au side by a grafting-to method . In this study, hydrophobic thiol-terminated polymers, namely, PS-SH and PPFBEM-SH (Figure ), were grafted to the Au side of the Au-SiO 2 Janus particles via thiol–Au interactions, and the resulting hairy Janus particles were used to stabilize bubbles.…”

Section: Resultsmentioning

confidence: 99%

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Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic–Hydrophobic Surface Characteristics

Fujii¹,

Yokoyama²,

Nakayama³

et al. 2017

Langmuir

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Micrometer-sized polymer-grafted gold-silica (Au-SiO) Janus particles were fabricated by vacuum evaporation followed by polymer grafting. The Janus particle diameter, diameter distribution, morphology, surface chemistry, and water wettability were characterized by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The optical microscopy results showed that the polystyrene (PS)-grafted Au-SiO Janus particles exhibited monolayer adsorption at the air-water interface and could stabilize bubbles, preventing their coalescence for more than 1 month. The hydrophobic PS-grafted Au and hydrophilic SiO surfaces were exposed to the air and water phases, respectively. Bare Au-SiO and poly(2-(perfluorobutyl)ethyl methacrylate) (PPFBEM)-grafted Au-SiO Janus particles could also stabilize bubbles for up to 2 weeks. By contrast, bare silica particles did not stabilize bubbles and were dispersed in water. The bubbles that formed in the PS-grafted Janus particle system were more stable than those formed in the bare Au-SiO Janus particles, PPFBEM-grafted Au-SiO Janus particles, and SiO particle systems because of the high adsorption energy of the PS-grafted particles at the air-water interface.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic–Hydrophobic Surface Characteristics

Fujii¹,

Yokoyama²,

Nakayama³

et al. 2017

Langmuir

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“…Au–SiO 2 Janus particles were fabricated according to previous study . Two-dimensional (2D) SiO 2 colloidal crystals were prepared by forming a droplet of a 1-butanol dispersion of the SiO 2 particles (10 wt %) at the end of a pipet.…”

Section: Methodsmentioning

confidence: 99%

“…Au−SiO 2 Janus particles were fabricated according to previous study. 41 Two-dimensional (2D) SiO 2 colloidal crystals were prepared by forming a droplet of a 1butanol dispersion of the SiO 2 particles (10 wt %) at the end of a pipet. The drop was carefully brought into contact with the surface of water sitting on a glass substrate (Matsunami,76 mm × 26 mm).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Micrometer-Sized Gold–Silica Janus Particles as Particulate Emulsifiers

et al. 2013

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Micrometer-sized gold-silica Janus particles act as an effective stabilizer of emulsions by adsorption at the oil-water interface. The Janus particles were adsorbed at the oil-water interface as a monolayer and stabilized near-spherical and nonspherical oil droplets that remained stable without coalescence for longer than one year. Gold and silica surfaces have hydrophobic and hydrophilic features; these surfaces were exposed to oil and water phases, respectively. In contrast, bare silica particles cannot stabilize stable emulsion, and completed demulsification occurred within 2 h. Greater stability of the emulsion for the Janus particle system compared to the silica particle system was achieved by using the adsorption energy of the Janus particles at the oil-water interface; the adsorption energy of the Janus particles is more than 3 orders of magnitude greater than that of silica particles. Suspension polymerization of Janus particle-stabilized vinyl monomer droplets in the absence of any molecular-level emulsifier in aqueous media led to nonspherical microspheres with Janus particles on their surface. Furthermore, polymer microspheres carrying Au femtoliter cups on their surfaces were successfully fabricated by removal of the silica component from the Janus-particle stabilized microspheres.

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“…Each component or “face” can be functionalized to achieve anisotropic properties via methods like sputtering and pickering emulsions. [ 1–3 ] For instance, Janus particles of amphiphilic nature can possess hydrophilic properties on one face and hydrophobic properties on the other, and can thus function as surfactants. [ 4–6 ] While sputtering and Pickering emulsions are primarily used for the synthesis of inorganic Janus particles, microfluidics is the predominant technique for the fabrication of polymer‐based Janus particles.…”

Section: Figurementioning

confidence: 99%

Synthesis of Polymeric Janus Superstructures via a Facile Synthesis Method

Lim

Low

Loo

2020

Macromol. Rapid Commun.

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Polymeric Janus particles can be exploited for a myriad of applications. Through the understanding of interfacial tensions, theragnostic agents such as drugs or nanomaterials can be successfully encapsulated into Janus particles without losing their anisotropic structure. In this work, it is reported that how Janus superstructures, as a further extension of the Janus morphology, can be obtained by blending other synthesis parameters into the solvent emulsion process, while adhering to the requirements of the Harkin's spreading coefficient (HSC) theory. Designing such unique structures for drug delivery can provide a broader range of possibilities and applications beyond conventional Janus particles.

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pH-responsive flocculation and dispersion behavior of Janus particles in water

Cited by 8 publications

References 29 publications

Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic–Hydrophobic Surface Characteristics

Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic–Hydrophobic Surface Characteristics

Micrometer-Sized Gold–Silica Janus Particles as Particulate Emulsifiers

Synthesis of Polymeric Janus Superstructures via a Facile Synthesis Method

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