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Janus particles

Hossein Rezvantalab, Daniel J Beltran-Villegas, Ronald G Larson
Brownian dynamics simulations of single-patch Janus particles under sedimentation equilibrium reveal that the phases found at fixed temperature and volume fraction are extremely sensitive to small changes in lateral box dimension. We trace this sensitivity to an uncontrolled parameter, namely, the pressure component parallel to the hexagonally ordered layers formed through sedimentation. We employ a flexible-cell constant-pressure scheme to achieve explicit control over this usually overlooked parameter, enabling the estimation of phase behavior under given pressure anisotropy...
August 14, 2017: Journal of Chemical Physics
Qing Bo Meng, Peng Yang, Tianyang Feng, Xuyang Ji, Qian Zhang, Daliang Liu, Shuyao Wu, Fuxin Liang, Zhaoliang Zheng, Xi-Ming Song
A type of ionic liquid functionalized high-aspect-ratio Janus SiO2 nanosheets (IL-Janus nanosheets), which possesses a side terminated by imidazolin salt groups and the opposite side terminated by phenyl groups, was prepared and its emulsification performance was investigated. The surface wettability of ionic liquid functionalized side could be tailored via simple anion exchanging, giving the amphiphilic or totally hydrophobic Janus nanosheets. The influence of several parameters including surface wettability, particle concentration, oil composition, oil-water ratio as well as initial location of the nanosheets on the stability, morphology and type of the Pickering emulsions (O/W or W/O) stabilized by the amphiphilic IL-Janus nanosheets was evaluated...
July 27, 2017: Journal of Colloid and Interface Science
Ekanem E Ekanem, Zilin Zhang, Goran T Vladisavljević
Patchy and patchy Janus particles composed of poly(dl-lactic acid) (PLA) and polycaprolactone (PCL) regions were produced with a controlled size, patchiness, composition, and shape anisotropy by microfluidic emulsification and solvent evaporation. Isotropic particles composed of PCL patches embedded in the PLA matrix were produced from relatively small drops with a diameter of 14-25 μm because of the fast solvent extraction as a result of high interfacial area of the particles. Anisotropic patchy Janus particles were formed from large drops, 100-250 μm in diameter...
August 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Zhen Wang, Yapei Wang
Pickering emulsions with the use of particles as emulsifiers have been extensively used in scientific research and industrial production due to their edge in biocompatibility and stability compared with traditional emulsions. The control over Pickering emulsion stability and type plays a significant role in these applications. Among the present methods to build controllable Pickering emulsions, tuning the amphiphilicity of particles is comparatively effective and has attracted enormous attention. In this review, we highlight some recent advances in tuning the amphiphilicity of particles for controlling the stability and type of Pickering emulsions...
November 8, 2016: Materials
Dong Woo Kang, Woong Ko, Bomsock Lee, Bum Jun Park
We investigated the geometric and chemical factors of nonspherical Janus particles (i.e., Janus ellipsoids) with regard to the pinning and unpinning behaviors of the Janus boundary at the oil-water interface using attachment energy numerical calculations. The geometric factors were characterized by aspect ratio (AR) and location of the Janus boundary (α) separating the polar and apolar regions of the particle. The chemical factor indicated the supplementary wettability (β) of the two sides of the particle with identical deviations of apolarity and polarity from neutral wetting...
August 6, 2016: Materials
Ryan Kastilani, Ryan Wong, Lilo D Pozzo
Bottom-up approaches to the synthesis of nanostructures are of particular interest because they offer several advantages over the traditional top-down approaches. In this work, we present a new method to self-assemble nanoparticles into controlled heteroaggregates. The technique relies on carefully balancing attractive electrostatic forces with repulsive steric hindrance that is provided by surface-grafted polyethylene glycol (PEG). Two different-sized gold nanoparticles (GNP) were used as a model system; 13 nm GNPs were functionalized with PEG-thiol and dodecanoic thiol, while 7 nm GNPs were functionalized with PEG-thiol and (11- Mercaptoundecyl)trimethylammonium bromide...
August 3, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Xue-Hui Ge, Yu-Hao Geng, Jian Chen, Jianhong Xu
Self-assembly is the process to form ordered compound structures. The theories and experiments of nano-sized Janus particles have proved that the assembled cluster structures are related to the unit number. The micro-meter sized amphiphilic Janus particles could also act as surfactants to stabilize droplets and aggregate to the clusters. When the scale order increases to the millimeter size, the connection between particles are usually shape match mechanism. Similar to the millimeter sized particles, sub-millimeter sized particles are larger and heavier that their gravity could not be ignored while the Brownian motion could be neglected...
August 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Davit Jishkariani, Yaoting Wu, Da Wang, Yang Liu, Alfons van Blaaderen, Christopher B Murray
Janus nanoparticles (NPs) often referred to as nanosized analogs of molecular surfactants are amphiphilic structures with potential applications in materials science, biomedicine, and catalysis, and their synthesis and self-assembly into complex architectures remain challenging. Here, we demonstrate the preparation of Janus heterodimers via asymmetric functionalization of Fe3O4-Pt and Fe3O4-Au heterodimeric NPs. The hydrophobic and hydrophilic dendritic ligands that carry phosphonic acid and disulfide surface binding groups selectively coat the iron oxide and platinum (or gold) parts of the heterodimer, respectively...
August 11, 2017: ACS Nano
Victoria López, Maria Rocío Villegas, Verónica Rodríguez, Gonzalo Villaverde, Daniel Lozano, Alejandro Baeza, María Vallet-Regí
The development of targeted nanocarriers able to be selectively internalized within tumor cells, and therefore to deliver anti-tumor drugs specifically to diseased cells, constitutes one of the most important goals in nano-oncology. Herein, the development of Janus mesoporous silica particles asymmetrically decorated with two targeting moieties, one of them selective for folate membrane cell receptors (folic acid) and the other one able to bind to mitochondria membrane (triphenylphosphine, TPP), is described in order to achieve sequential cell to organelle vectorization...
August 16, 2017: ACS Applied Materials & Interfaces
Xiaoguang Wang, Ye Zhou, Young-Ki Kim, Daniel S Miller, Rui Zhang, Jose A Martinez-Gonzalez, Emre Bukusoglu, Bo Zhang, Thaddeus M Brown, Juan J de Pablo, Nicholas L Abbott
We report on the internal configurations of droplets of nematic liquid crystals (LCs; 10-50 μm-in-diameter; comprised of 4-cyano-4'-pentylbiphenyl and 4-(3-acryloyloxypropyloxy)benzoic acid 2-methyl-1,4-phenylene ester) sedimented from aqueous solutions of sodium dodecyl sulfate (SDS) onto interfaces formed with pure glycerol. We observed a family of internal LC droplet configurations and topological defects consistent with a remarkably abrupt transition from homeotropic (perpendicular) to tangential anchoring on the surface of the LC droplets in the interfacial environment...
July 28, 2017: Soft Matter
Robert Wolk, Ehrin J Armstrong, Peter R Hansen, Bruce Thiers, Shuping Lan, Anna M Tallman, Mandeep Kaur, Svitlana Tatulych
BACKGROUND: Psoriasis is a systemic inflammatory disease associated with increased cardiovascular (CV) risk and altered lipid metabolism. Tofacitinib is an oral Janus kinase inhibitor. OBJECTIVE: The aim of the study was to investigate the effects of tofacitinib on traditional and nontraditional lipid parameters and CV risk markers in patients with psoriasis from a phase III study, OPT Pivotal 1. METHODS: Patients with psoriasis were randomized to tofacitinib 5 or 10 mg twice daily (BID) or placebo BID...
June 24, 2017: Journal of Clinical Lipidology
Sven Sagebiel, Lucas Stricker, Sabrina Engel, Bart Jan Ravoo
This communication reports a novel method to prepare Janus particles with light-responsive arylazopyrazole (AAP) polymer caps, which can be reversibly cross-linked to chain-like colloidal oligomers in the presence of cyclodextrin (CD) functionalized superparamagnetic nanoparticles. The resulting colloidal molecules are light-responsive and can be controlled by an external magnetic field.
August 17, 2017: Chemical Communications: Chem Comm
Xianglei Liu, Yimin Xuan
Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i...
July 24, 2017: Nanoscale
Lei Tang, Jun Yang, Qinqin Yin, Linghui Yang, Deying Gong, Feng Qin, Junyang Liu, Qin Fan, Jiahong Li, Wenling Zhao, Weiyi Zhang, Jiyu Wang, Tao Zhu, Wensheng Zhang, Jin Liu
A series of atypical asymmetric gemini surfactants with an amphiphilic carbonate group (-O-CO-O-) have been prepared. Some of these compounds could self-assemble in water into gourd-shaped Janus particles (JPs). Initial results suggested that the formation of JPs was highly likely to be related to their atypical gemini surfactant structure. To our knowledge, this is the first report on JPs that are self-assembled from a single kind of small organic molecule. We believe that our results will be utilized in many fields...
July 19, 2017: Chemical Communications: Chem Comm
Binbin Luo, John W Smith, Zixuan Wu, Juyeong Kim, Zihao Ou, Qian Chen
Highly anisometric nanoparticles have distinctive mechanical, electrical, and thermal properties and are therefore appealing candidates for use as self-assembly building blocks. Here we demonstrate that ultra-anisometric nanoplates, which have a nanoscale thickness but a micrometer-scale edge length, offer many materials design capabilities. In particular, we show that these nanoplates "copolymerize" in a predictable way with patchy spheres into one- and two-dimensional structures with tunable architectural properties...
July 17, 2017: ACS Nano
Ali Kharazmi, Nikolai V Priezjev
The diffusion of a Janus rod-shaped nanoparticle in a dense Lennard-Jones fluid is studied using molecular dynamics (MD) simulations. The Janus particle is modeled as a rigid cylinder whose atoms at each end have different interaction energies with fluid molecules, thus comprising wetting and nonwetting surfaces. We found that both rotational and translational diffusion coefficients are larger for Janus particles with lower average wettability, and these values are bound between the two limiting cases of uniformly wetting and nonwetting particles...
July 27, 2017: Journal of Physical Chemistry. B
Wen Yang, Vyacheslav R Misko, Jacques Tempere, Minghui Kong, Francois M Peeters
Similar to the spontaneous formation of colonies of bacteria, flocks of birds, or schools of fish, "living crystals" can be formed by artificial self-propelled particles such as Janus colloids. Unlike usual solids, these "crystals" are far from thermodynamic equilibrium. They fluctuate in time forming a crystalline structure, breaking apart and re-forming again. We propose a method to stabilize living crystals by applying a weak confinement potential that does not suppress the ability of the particles to perform self-propelled motion, but it stabilizes the structure and shape of the dynamical clusters...
June 2017: Physical Review. E
Al C de Leon, Bradley J Rodier, Qinmo Luo, Christina M Hemmingsen, Peiran Wei, Kevin Abbasi, Rigoberto Advincula, Emily B Pentzer
Janus particles have recently garnered significant attention for their distinct properties compared to particles that are homogeneously functionalized. Moreover, high aspect ratio Janus particles that are rod-like or planar (i.e., nanosheets) are especially intriguing considering their interfacial properties as well as their ability to assemble into higher order and hybrid structures. To date, major challenges facing the exploration and utilization of 2D Janus particles are scalability of synthesis, characterization of tailored chemical functionalization, and ability to introduce a diverse set of functionalities...
July 25, 2017: ACS Nano
Ognjen Ilic, Ido Kaminer, Bo Zhen, Owen D Miller, Hrvoje Buljan, Marin Soljačić
Shaping the topology of light, by way of spin or orbital angular momentum engineering, is a powerful tool to manipulate matter on the nanoscale. Conventionally, such methods focus on shaping the incident beam of light and not the full interaction between the light and the object to be manipulated. We theoretically show that tailoring the topology of the phase space of the light particle interaction is a fundamentally more versatile approach, enabling dynamics that may not be achievable by shaping of the light alone...
June 2017: Science Advances
Jun-Bing Fan, Yongyang Song, Hong Liu, Zhongyuan Lu, Feilong Zhang, Hongliang Liu, Jingxin Meng, Lin Gu, Shutao Wang, Lei Jiang
Emulsion polymerization is the most widely used synthetic technique for fabricating polymeric particles. The interfacial tension generated with this technique limits the ability to tune the topology and chemistry of the resultant particles. We demonstrate a general emulsion interfacial polymerization approach that involves introduction of additional anchoring molecules surrounding the microdroplets to synthesize a large variety of Janus particles with controllable topological and chemical anisotropy. This strategy is based on interfacial polymerization mediated by an anchoring effect at the interface of microdroplets...
June 2017: Science Advances
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