  Phase separation in binary mixtures in the presence of Janus particles has
been studied in terms of a Cahn-Hilliard model coupled to the Langevin
equations describing the particle dynamics. We demonstrate that the phase
separation process is arrested leading to unexpected regular stripe patterns in
the concentration field. The underlying pattern forming mechanism has been
elucidated: The twofold absorption properties on the surface of Janus particles
with respect to the two components of a binary mixture trigger in their
neighborhood spatial concentration variations. They result in an effective
interaction between the particles mediated by the binary mixture. Our findings
open a route to design composite materials with nanoscale lamellar morphologies
where the pattern wavelength can be tuned by changing the wetting properties of
the Janus particles.
