INTERACTIONS, DYNAMICS, AND ELASTICITY IN CHARGE-STABILIZED COLLOIDALCRYSTALS

We describe real-space imaging measurements of the interactions and el astic properties of charge-stabilized colloidal crystals. Interactions between charge-stabilized latex spheres self-assembled into colloidal crystals are extracted from single-particle dynamics using new techni ques in digital video microscopy. The spheres' cooperative behavior ma kes possible simultaneous measurements of their crystals' bulk moduli. Together, these measurements offer new insights into the microscopic origins of charge-stabilized colloidal crystals' bulk elastic properti es. In particular, they demonstrate that the crystals' elastic propert ies cannot be ascribed to the linear superposition of pairwise interac tions. This result highlights the potential pitfalls of using the conv entional Derjaguin, Verwey, Landau, and Overbeek (DLVO) theory to desc ribe the bulk properties of charge-stabilized colloidal suspensions. ( C) 1998 American Institute of Physics. [S0021-9606(98)52043-0].