Chapter 7 - Hydrophobically Modified Polyelectrolytes and Polyelectrolyte Block Copolymers

Abstract

This chapter discusses hydrophobically modified polyelectrolytes and polyelectrolyte block coplolymers. Polyelectrolyte block copolymers and hydrophobically modified polyelectrolytes (HMPs) are polymers with a high content (> 10–15 mol %) of ionizable groups bonded to hydrophobic groups. Owing to the presence of both ionizable and hydrophobic groups, electrostatic and hydrophobic interactions leading to a rich variety of organized structures in HMP solutions are an inherent trait distinguishing HMPs from other polymers. It is this interplay between coulombic and hydrophobic interactions that enables HMPs to respond to factors such as temperature, ionic strength of the solvent, pH, and so forth—by aggregating, folding, or unfolding. Because of the potential use of HMPs and polyelectrolyte block copolymers for modification of the rheology of their solutions, for targeted drug delivery in medicine, and for selective removal of organic pollutants from the aqueous phase—properties of their aqueous solutions have been studied intensively. Much of the emphasis in studies of polymer dynamics and transport in heterogeneous media and in structurally organized HMP systems has been on steady-state and time-resolved fluorometric techniques with nanosecond or picosecond time resolutions.