The deposition of positively charged latex particles with radii between 20 and 100 nm on a negatively charged mica surface is investigated with atomic force microscopy at low ionic strengths. The polystyrene latex spheres with amidine headgroups are characterized as to their size distribution, electrophoretic mobility, and aggregation behavior. Surface coverage measurements take into account the polydispersity of the particles on the surface. Deposition kinetics from a quiescent solution are, for low coverage, in good agreement with diffusion-limited adsorption. At long times, the surface coverage tends toward a maximum surface coverage θmax independent of the particle concentration but depending on ionic strength. This work extends the available data for θmax for small particle size and very low ionic strengths. The values for θmax decrease with decreasing ionic strength; this trend is described with a simple model based on random sequential adsorption and the effect of overlapping double layers. Particle size polydispersity can modify the results for θmax substantially; its influence is investigated in detail.

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Recent results on structural properties and possible bio-sensing applications of planar liquid crystal films are reviewed.

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We investigate isothermal diffusion and growth of micron-scale liquid domains within membranes of free-floating giant unilamellar vesicles with diameters between 80 and 250 μm. Domains appear after a rapid temperature quench, when the membrane is cooled through a miscibility phase transition such that coexisting liquid phases form. In membranes quenched far from a miscibility critical point, circular domains nucleate and then progress within seconds to late stage coarsening in which domains grow via two mechanisms 1), collision and coalescence of liquid domains, and 2), Ostwald ripening. Both mechanisms are expected to yield the same growth exponent, α = 1/3, where domain radius grows as time(α). We measure α = 0.28 ± 0.05, in excellent agreement. In membranes close to a miscibility critical point, the two liquid phases in the membrane are bicontinuous. A quench near the critical composition results in rapid changes in morphology of elongated domains. In this case, we measure α = 0.50 ± 0.16, consistent with theory and simulation.

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