Dynamic Emissivity of Self-Assembled Magnetoresponsive Janus Particle Chain Suspensions

Abstract

Suspensions of magnetoresponsive Janus colloids form chains and undergo alignment under the influence of a magnetic field. When the magnetic field is aligned with a light path, light transmission through the sample increases as compared to randomly or orthogonally oriented chains. This study investigates the emissivity response of this suspension as a function of particle concentration and magnetic field strength. A variation of the Beer–Lambert model and ray-tracing simulations capture the behavior of the experimentally measured difference in intensity between magnetically activated and nonactivated Brownian suspensions. Experiments demonstrate up to 25% contrast in transmission of visible light, which may be further optimized through materials selection. Similar experiments when these Janus particle chains are suspended in carbon tetrachloride demonstrate an emissivity variation in the near-infrared of ∼10%, again possibly optimized through further materials selection.

Yield stress-enabled microencapsulation of field responsive microparticle suspensions

“…in the following we demonstrate the utility of the method through incorporation in a visually tangible application, as an alternative to E-ink displays. 36 In previous work by Gao et al , 45 it was shown that chains of ferromagnetic Janus particles can be rotated in a magnetic field giving rise to an optical dynamic range based on variable transmission of light. Others have shown similar, irreversible control of transmission through magnetic particles.…”

Density Matching for Microencapsulation of Field Responsive Suspensions of Non-Brownian Microparticles

“…To demonstrate the utility of this synthetic method to general applications, we can utilize one of the inherent properties of Janus particle suspensions, as shown previously by Gao et al 47 Janus particle suspensions show an optical dynamic range, depending on their orientation and degree of chaining. Among the many possible applications discussed in the Introduction , one which is particularly applicable to this observation is magnetically actuated display materials.…”