Model for the hydration of nonpolar compounds and polymers - art. no. 051805

We introduce an exactly solvable statistical-mechanical model of the hydrat ion of nonpolar compounds, based on grouping water molecules in clusters wh ere hydrogen bonds and isotropic interactions occurs interactions between c lusters are neglected. Analytical results show that an effective strengthen ing of hydrogen bonds in the presence of the solute, together with a geomet ric reorganization of water Molecules, are enough to yield hydrophobic beha vior. We extend our model to describe a nonpolar homopolymer in aqueous sol ution, obtaining a clear evidence of both "cold" and "warm" swelling transi tions. This suggests that our model could be relevant to describe some feat ures of protein folding.