We report a single step procedure to prepare monodisperse colloidal poly (

We studied the interfacial tension between coexisting colloid-rich and polymer-rich fluid phases in a phaseseparated colloid-polymer mixture. First, the location of the fluid-fluid binodal and the tie lines between the coexisting phases were determined using a recently proposed method that only requires the volumes of the coexisting phases as input. The spinning drop method was used to determine the very low interfacial tension between the coexisting phases. We also used the dynamics of the breakup process of the droplet of one phase suspended in the other to determine the interfacial tension.

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The depletion-induced phase separation in a mixture of colloidal particles ͑PMMA-latex͒ and nonadsorbing polymers ͓poly͑styrene͔͒ in a solvent ͑mixture of tetralin, cis-decalin, and carbon tetrachloride͒ was investigated in real space with confocal scanning laser microscopy in the initial, intermediate, and final stage. It was found that the kinetics and the morphology of the phase separation strongly depend on the polymer concentration, and thus on the strength of the depletion-induced attraction between the colloidal particles. At moderate polymer concentrations, crystallization of the PMMA particles is enhanced. At higher polymer concentrations, only aggregation is observed, resulting in amorphous sediments. The aggregation is diffusion-limited or reaction-limited, depending on the polymer concentration. Digital image processing was used to determine the dependence of the aggregation rate and the size of the clusters on the polymer concentration.

Fat-perception is thought to be related to a complex interplay between fat-associated flavor release and mouth-feel. Friction sensed between the tongue and the palate seems to play a prominent role: in previous work, we have shown that emulsions that are more sensitive toward coalescence give rise to a lowering of the orally perceived and experimentally measured friction and, probably as a consequence, to an enhanced fat-perception. In this paper, we study in detail the factors determining friction of protein-stabilized emulsions using a novel mouth-mimicking tribometer and model surfaces consisting of PDMS modified in various ways (hydrophobicity, deformability, roughness). We show that unlike in many technological applications where lubrication is essentially hydrodynamic, for physiologically relevant loads, the modified PDMS is boundary and/or mixed lubricated, which is like in-mouth lubrication. We find that an increased sensitivity of the emulsions toward coalescence results in a lower friction, confirming previous results obtained with pig's tongue. Surface-induced coalescence (or spreading of emulsion droplets) seems to be very important in this, surface hydrophobicity being the dominant trigger. Viscosity of the dispersed phase does not have such a strong influence on both the measured friction and the oral perceived friction. We do find a strong influence of the presence of bulk proteins and saliva on friction. Finally, hardly any dependence of measured friction on fat content of the emulsion was observed, indicating that only a small amount of fat is needed to alter the friction.