Polymer association in poor solvents: from monomolecular micelles to clusters of chains and phase separation

We report some recent results obtained in our laboratory on the poor-solven t behavior of macromolecules. We first discuss the globular collapse of sho rt chains that, unlike long ones, may form compact ordered states. We then address the collapse of random AB copolymers, which may provide significant clues to understanding biophysical issues such as the protein folding prob lem or the DNA arrangement in a living cell. Afterwards, we turn to the man y-chain problem of homopolymer aggregation into polymolecular micelles or c lusters of chains and eventually phase separation. The unifying feature of our approach consists in the self-consistent free-energy minimization with inclusion of intra- and inter-molecular interactions, whenever they are req uired, that enables us to describe the chain conformation in detail.