INFLATED VESICLES - A NEW PHASE OF FLUID MEMBRANES

The conformation and scaling properties of self-avoiding fluid vesicles subject to an internal-pressure increment DELTA-p greater-than-or-equal-to 0 are studied using Monte Carlo methods and scaling arguments. We find that there is a first-order phase transition from a low-pressure, branched polymer phase to a high-pressure, inflated phase. Evidence is presented that the crossover exponent in the branched polymer phase is zero. The behavior in the inflated phase is analyzed using a generalization of de Gennes' <<blob>> picture, and it is shown that the mean-square radius of gyration within the blobs scales with a new, independent exponent-nu = 0.787 +/- 0.020, where [R(g)2] approximately N(b)nu, and N(b) is the number of monomers in a blob.