Directed self-assembly of colloidal crystals by dielectrophoretic ordering observed with small angle neutron scattering (SANS)Electronic supplementary information (ESI) available: Crystallographic information. See DOI: 10.1039/c0sm00400f

We report the first in situ measurements of directed self-assembly (DSA) of colloidal crystal structures by dielectrophoresis (DEP) observed with Small Angle Neutron Scattering (SANS). Development of a new sample environment allows for real time observation of electric field driven crystallization of sub-micron particles. SANS measurements for charge-stabilized colloidal dispersions of two different particle sizes as a function of electric field strength and frequency identify the order-disorder transition. The results validate a proposed master scaling curve for particle ordering developed for micron particles and thereby extends the scaling range to include sub-micron particles. This new experimental method enables the possibility of studying electric field induced alignment and ordering of colloidal nanoparticles. We report the first directed self-assembly measurements of sub-micron colloidal crystals by dielectrophoresis observed with Small Angle Neutron Scattering (DEP-SANS).