title: Dielectric effects on the ion distribution near a Janus colloid.
abstract: Spherical Janus colloids, particles with different surface properties on their two hemispheres, are generally heterogeneous in permittivity. This dielectric heterogeneity may affect their behavior in electrolytes and external electric fields, but is typically not taken into account in computational studies. We apply the iterative dielectric solver developed by Barros and Luijten [Phys. Rev. Lett., 2014, 113, 017801] in combination with preconditioning techniques that can accurately and efficiently compute the polarization of dielectrically anisotropic particles. Employing this approach, we systematically study the ion distribution around neutral and charged Janus particles with various permittivities, immersed in symmetric and asymmetric electrolytes. We demonstrate that neutral Janus colloids may carry a nonzero dipole moment in asymmetric salts. For charged Janus colloids, dielectric effects can substantially influence the electric double layer. These findings also have implications for other dielectrically anisotropic entities, such as proteins.
authors.affiliation: Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Huanxin
authors.initials: H
authors.lastname: Wu
authors.affiliation: Graduate Program in Applied Physics, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Han
authors.affiliation: Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA and Department of Materials Science and Engineering Northwestern University, Evanston, Illinois 60208, USA. luijten@northwestern.edu and Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Erik
authors.identifier: http://orcid.org/0000-0003-2364-1866
authors.initials: E
authors.lastname: Luijten