Ribbon polymers in poor solvents: Layering transitions in annular and tubular condensates

We study the structures of a ribbon or ladder polymer immersed in poor solvents. The anisotropic bending rigidity coupled with the surface tension leads ribbon polymers to spontaneous formation of highly anisotropic condensates in poor solvents. Unlike ordinary flexible polymers these condensates undergo a number of distinct layering transitions as a function of chain length or solvent quality, and the size of condensates becomes a non-monotonic function of chain length. We show that the fluctuations of the condensates are in general small and these condensates are stable.