Video enhanced differential interference contrast microscopy: Characterizing colloidal materials

Video enhanced differential interference contrast microscopy (VEDICM) permits an immediate, rapid characterization of association colloid aggregates and other colloidal aggregates by direct visualization on a television screen. Particles with sizes down to 500 A, their dynamics, fusion and slow flocculation can be directly pictured, recorded and analyzed in real time, freezeframe, slow motion or time lapse. It is precisely in the distance regime, 500–10,000 A, joining micellar chemistry to the field of biological structures, that classical techniques do have most difficulty. In this domain surfactant aggregates-vesicles, liposomes, microemulsions, microtubules-can exhibit an astonishing dynamic structural diversity and distribution of structures. These are highly sensitive to pH, salt, temperature, and surfactant concentration in ways which are partially understood at a theoretical level, but not formerly easily accessible.In this paper, the VEDICM technique is described and its ability to follow the spontaneous growth and fusion of vesicles upon changes in chemical environment is presented.Session lecture, Ninth International Conference on Non-Aqueous Solutions, Pittsburgh, PA, August 1984.