  Inclusions dissolved in an anisotropic quasi-2D membrane acquire new types of
interactions that can drive assembly of complex structures and patterns. We
study colloidal membranes composed of a binary mixture of long and short rods,
such that the length ratio of the long to short rods is approximately two. At
very low volume fractions, short rods dissolve in the membrane of long rods by
strongly anchoring to the membrane polymer interface. At higher fractions, the
dissolved short rods phase separate from the background membrane, creating a
composite structure comprised of bilayer droplets enriched in short rods that
coexist with the background monolayer membrane. These results demonstrate that
colloidal membranes serve as a versatile platform for assembly of soft
materials, while simultaneously providing new insight into universal
membrane-mediated interactions.
