The current book describes the chemical and physical behaviour of polymers and biopolymers that form highly associating structures in equilibrium solution. It summons the established results known of polymer complexes in solution, taking into account also the recent developments in biotechnology concerning this topic, in technological applications of polymer-protein interactions, in fluorescence and scattering techniques for the study of intra- and interpolymer association and in the study of ionomers in solution. The book covers the whole range from synthesis and fundamental aspects to applications and technology of associated polymers.

In the first half of this century, great strides were made in under standing the behavior of polymers in dilute solutions or in the solid state. Concentrated solutions, on the other hand, were commonly regarded as mainly of interest to practitioners, being too complex for the rigorous application of statistical theory. Given the preoccupation with the isolated polymer molecule and the attendant focus on the state of infinite dilution, it is not surprising that aggregation, and inter-polymer associ ation in general, was the bugaboo of experimentalists. These attitudes have changed remarkably over the last few decades. The application of sealing theory to polymer solutions has stimulated investigation of the semi-dilute state, and the region between infinite dilution and swollen gel is no longer perceived as terra incognita. New techniques, such as dynamic light scattering, have proven to be of much value in such investigations. At the same time, it has become clear that consideration of strong inter- and intra-polymer forces, superimposed on the familiar description of the statistical chain, is prerequisite to the application of polymer science to numerous systems of interest. Para mount among these, of course, are biopolymers, their complexes and assemblies. The isolated random coil must be viewed as tl rarity in nature."

Throughout most of this century, progress in Polymer Science took place by way of studies of dilute polymer solutions and of the solid state. More recently, attention has been focused on the semi-dilute regime. The elucidation of transi- ent network and temporal gel states under conditions of moderate concentra- tion by numerous hydrodynamic and optical techniques is now well established and a solid theoretical underpinning for these phenomena is in place. However, in most of the systems studied, interpolymer interactions are relatively weak forces, because in solutions oftypical polymers, strong interpolymer interactions lead to bulk phase separation. However, polymers that form highly associating structures in equilibrium solution now constitute an important class of synthetic macromolecules, and it is evident that strong intermacromolecular interactions - without accompanying phase separation - are prevalent in biopolymer sys- tems as well. This behavior is generally characteristic of amphiphilic polymers, which contain both hydrophilic and hydrophobic repeat units. It is also charac- teristic of systems in which two macromolecular species are complementary, such as hydrogen-bond-donating and hydrogen-bond-accepting polymers, or polycations and polyanions. Interest in associating polymer systems currently derives from both applied and fundamental questions. Synthetic water-soluble polymers bearing hydro- phobic groups exhibit special rheological properties that make them well-suited as thickeners and viscosity-modifiers. Drag-reduction effects may arise in such polymer solutions, and may also be observed in polymer complexes based on hydrogen-bonding.