Stabilization of Polymer Mesoglobules via Specific Interactions of Macromolecules with Dissolved Substance

A theoretical model describing the aggregates (mesoglobules) of different shapes formed in solution of macromolecules with functionalized monomer units capable of specific bonding with added small molecules or with ions of chaotropic salt is proposed. Models of amphiphilic polymer globules are generalized to derive and analyzed the free energy expression for highly condensed aggregates with solute molecules attached in the surface layer. In the limit of high bond energy, the morphological diagrams of the solution are calculated accounting for the possibility of formation of spherical aggregates, nanoworms, layers (vesicles), or macrophase separation. The diagrams are presented depending on the bond energy, the initial surface tension of the polymer phase (without solute), and other parameters. For the model of solute binding with groups on polymer backbones, the solubilization into necklace-like structures with small mixed micelles is predicted provided that the second virial coefficient of molecular interactions is not overly low. However, if the molecules are bound to the pendant polymer groups spatially separated from solvophobic (hydrophobic) groups, then the lamellae (presumably, vesicles), nanoworms (cylinders), and spherical mesoglobules can be formed.