Interactions between microgel particles

The behaviour of microgel dispersions falls between near-hard-sphere colloids and ultra-soft colloidal systems (e. g., polymer coils in solution and star polymers), and depending on the conditions they can exhibit physical properties of both types of particle. Microgels are the ultimate in 'designer' particles as the effective interaction between them can be modified reversibly from being essentially repulsive (the solvent-swollen state) to weakly attractive (the collapsed state) through readily achievable in situ chemical means. A brief summary of the directions in which microgel research is moving is given, with particular focus on current understanding and representations of the effective interactions between these particles.