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Critical adsorption energy, solvent

Consider the complexity involved in modeling steric stabilization with a diblock copolymer. The reservoir bulk solution of copolymer is usually dilute (<1 wt % polymer) and the copolymer and solvent equilibrate between the bulk and surface regions. However, as solvent quality is decreased to the LCST phase boundary, the bulk solution will also separate into polymer-rich and polymer-lean phases. In addition, many diblock copolymers form self-assembled aggregates such as micelles and lamellae, if the concentration is above the critical micelle concentration. Thus, stabilizer can partition among up to four phases as solvent quality or polymer concentration is changed. The unique density dependence of supercritical fluids adds another dimension to the complex phase behavior possible. In the theoretical studies discussed below, surfactant adsorption energy, solubility, and concentration are chosen carefully to avoid micelle formation or bulk phase separation, in order to focus primarily on adsorption and colloid stability. [Pg.217]

There continues to be extensive interest in latexes and micellar systems. The structure of acrylic latex particles has been investigated by non-radiative energy transfer by labelling the co-monomers with fluorescent acceptor-donor systems. Phase separations could also be measured in this way. Excimer fluorescence has been used to measure the critical micelle temperature in diblock copolymers of polystyrene with ethylene-propylene and the results agree well with dynamic light scattering measurements. Fluorescence anisotropy has been used to measure adsorption isotherms of labelled polymers to silica as well as segmental relaxation processes in solutions of acrylic polymers. In the latter case unusual interactions were indicated between the polymers and chlorinated hydrocarbon solvents. Fluorescence analysis of hydrophobically modifled cellulose have shown the operation of slow dynamic processes while fluorescence... [Pg.367]

When monolayers are prepared from a liquid phase, the nature and concentration of the species dissolved in solution are critical. In particular, the presence of ions (e.g., due to the use of a buffered medium) can strtMigly influence the adsorption of molecules constituting the monolayer. The adsorptimi energy of many anions can be significant the organic molecules have to displace both solvent molecules and ions at the surface, in order to anchor the substrate the effect of this phenomenon is often underestimated in the literature. [Pg.113]


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Adsorption energy

Adsorptive energy

Critical adsorption

Critical energies

Energy critical adsorption

Solvent adsorption

Solvents energy

Solvents, adsorption energy

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