Lattice self-avoiding surfaces with spherical topology, rooted on a plane, are studied with Monte Carlo and scaling methods. As the adsorption energy increases, two transitions occur. The first is in the universality class of the special adsorption point for branched polymers. The adsorbed vesicle’s interior changes from branched polymer to two-dimensional compact at a second multicritical point, beyond which the perimeter on the plane keeps a self-avoiding ring dimension. This point, in a class recently discovered for interacting ring polymers, does not exist for strictly two-dimensional vesicles.

• Received 6 July 1992

DOI:https://doi.org/10.1103/PhysRevE.48.R4203