Fabrication and Characterization of Asymmetric Janus and Ternary Particles

Abstract

Asymmetric Janus and ternary silica particles with an average diameter of 450 nm were fabricated by sequentially arranged particle-embedding and surface-modification processes. Thermally induced embedding of particles into polymer-fiber substrates allowed for precise control of the degree of particle submergence and the subsequent chemical modification of the hemispherical exposed particle surfaces. In addition to Janus particles with the desired surface-functionality ratios of 1:2, 1:1, and 2:1, this unique fabrication approach was also used to produce complicated and well-defined heterogeneous materials, including bifunctionalized Janus and ternary particles. The bifunctionalized Janus particles were produced with two hemispherical surfaces alternately labeled with gold and iron oxide nanoparticles, which simultaneously enabled anisotropic surface-plasmon resonance and a magnetic response. Ternary particles were also constructed, yielding submicrometer spheres with functionalized equatorial belts. The surface distributions of functional components in these spherical materials were carefully examined for uniformities in particle embedding. Statistical analyses revealed that the functional components were distributed with a uniformity of over 80% for all of the asymmetric Janus and ternary particles.

Dynamical simulation of electrostatic striped colloidal particles

“…This suggests that dipolar Janus particles form glasses and gels at similar conditions to those of attractive colloidal particles. These predictions should be experimentally accessible in the near future as both Janus 1-4 and ternary motifs 5,6 have been successfully fabricated. We find that striped particle systems with larger number of stripes, n ≥ 4, are resistant to the formation of collapsed and arrested structures.…”

“…1 One such family of particles is that of surface striped particles. It includes Janus, 2-4 ternary, 5,6 and higher-multiplicity striped 7,8 surface patterns. In this paper, the static and dynamic properties of systems of striped particles with stripes of alternating electric charge are investigated through computer simulation.…”

“…[2][3][4][5][6][7][8][9] Janus particles-doubly striped particles with each hemisphere having a different surface chemistry-have been produced by several techniques [1][2][3][4] all which take different approaches to protecting one hemisphere of the colloidal particle while the other hemisphere is chemically modified. Generalizing this approach to multi-step protection reactions allows for the fabrication of ternary particles with three stripes of differing chemistry.…”

“…Generalizing this approach to multi-step protection reactions allows for the fabrication of ternary particles with three stripes of differing chemistry. 6 In another approach, 5 a microfluidic technique is used to create both ternary and Janus particles with diameters on the order of 100 μm. Larger number of stripes can be achieved through particle lithography, which has been used for the precise local patterning of colloidal particle with features on the order of 100 nm.…”

Synthesis and Contact Angle Measurements of Janus Particles

“…[13] As proposed by Kuo et al, the Janus ratio of JPs prepared by embedding silica particles into polymer fibres, and subsequently chemically modifying their surface, can be tuned by manipulating the temperature and thus the particle immersion into the polymer fibres. [14] Another approach, suggested by Kretzschmar et al, is based on the fabrication of patchy particles with patches of controlled size and shape by use of the template-assisted glancing angle deposition method (GLAD). The patch size and shape are determined by the metal deposition angle, the rotational angle of the template, groove size and particle size.…”