The behaviour of polymers in multi-component and multiphase systems such as solutions, blends and interfaces derived from both natural and synthetic sources and the subsequent influence of this on their physical properties is the theme of this book. Important new material on multiphase polymer systems such as block copolymers and liquid crystalline polymers is provided, and the solution and surface properties of enzymes and surface active polymers is described both theoretically and experimentally. The application of theory to the development of new cellulosic materials is particularly noteworthy. The relationship between end-use properties, such as adhesion, wetting, and colloidal stability, and molecular structure at the interface is addressed. Examples include the capillary pressure of nylon microporous membranes, a new technique for characterizing the adhesion between incompatible polymers, and the influence of the glass transition temperature at the fiber/matrix interface on interfacial shear strength.Characterization of polymer films, both electrochemically and via optical techniques is covered and the interactions of amphiphilic ions with polyacrylate polymer are described. The final two chapters introduce the topic of enzyme mobility at an interface and show how this may affect their role as biological catalysts.