Abstract

Many colloidal, surfactant, macromolecular and biological systems such as proteins, hydrophobically modified polymers, and biopolymers form gels and glasses under different formulation conditions. Gels can be formed through numerous routes based upon the interactions and self-association present in these systems and can be tuned through modulating the formulation conditions such pH, electrolyte levels, extent of hydrophobic modification, etc. For instance, gels can be obtained through the formation of networks in self-assembling systems such as proteins, surfactant and macromolecular systems, through depletion based attraction in colloid/polymer mixtures, through strong short range attractive interactions present in many colloidal systems etc. Systems having short range attractive and long range repulsive interactions also tend to exhibit rich phase behavior including gel phases. Colloidal glasses are also formed in many cases in which the macroscopic properties such as rheology are influenced by the drastic slowing down of dynamics under high packing conditions.