  Motivated by observations of heterogeneous domain structure on the surface of
cells, we consider a minimal model to describe the dynamics of phase separation
on the surface of a spherical particle. Finite-size effects on the curved
particle surface lead to the formation of long-lived, metastable states for
which the density is distributed in patches over the particle surface. We study
the time evolution and stability of these states as a function of both the
particle size and the thermodynamic parameters. Finally, by connecting our
findings with studies of patchy particles, we consider the implications for
self-assembly in many-particle systems.
