  A common approach to study nucleation rates is the estimation of free-energy
barriers. This usually requires knowledge about the shape of the forming
droplet, a task that becomes notoriously difficult in macromolecular setups
starting with a proper definition of the cluster boundary. Here, we demonstrate
a shape-free determination of the free energy for temperature-driven cluster
formation in particle as well as polymer systems. Combined with rigorous
results on equilibrium droplet formation, this allows for a well-defined
finite-size scaling analysis of the effective interfacial free energy at fixed
density. We first verify the theoretical predictions for the formation of a
liquid droplet in a supersaturated particle gas by generalized-ensemble Monte
Carlo simulations of a Lennard-Jones system. Going one step further, we then
generalize this approach to cluster formation in a dilute polymer solution. Our
results suggest an analogy with particle condensation, when the macromolecules
are interpreted as extended particles.
