Functional polymer brushes in aqueous media from self-assembled and surface-initiated polymers.

This review focuses on the behavior of single-component, water-soluble neutral and charged brushes. Selected examples illustrate how solvation effects, hydrophobic interactions, and electrostatic interactions create complex behaviors not easily captured in mean-field treatments. In particular, we distinguish between two classes of polymer brushes: those that can be described classically within the context of generalized van der Waals potentials and those that can be described by model-dependent potentials arising from specific interactions. In classical systems, only a few global parameters are needed to predict behavior. Nonclassical systems, in contrast, necessitate several local details, which do not necessarily lead to universal scaling laws. Although these nonclassical interactions present unique opportunities for engineering functional surfaces, they also present new challenges for designing well-defined systems with precise control over distributions in the degree of polymerization and tethering density.