Swelling of latex particles

Modeling the Equilibrium Swelling of Latex Particles with Monomers... 

Morton M, Kaizerman S, Aider WJ. Swelling of latex particles. Colloid Interface Sci 1954 9 300-312. 

Fig. 14 A Schematic diagram of motion of latex particles toward the base of myelinic figures, confirming that their growth is due to swelling, not to diffusion as in (B)...

Latex IPNs offer unique synthetic opportunities. Since an IPN double network, ideally, is contained in each sub-microscopic latex particle, special effects are possible. The simplest case involves a crosshnked seed latex particle that is polymerized first. Then, monomer mix II is added. There are two subclasses. First, all of the monomer mix II can be added at once, or at least far more rapidly than the polymerization takes place. In that case, the monomer will first swell the latex particle, and then the excess monomer forms a shell around the swollen core. If the monomer mix II is added slowly, or more slowly than the initiator can polymerize the material, little monomer can swell into the particle, and a better defined core/sheU structure develops. 

The expoimaital observation [12,20-28] which led German, Maxwell and co-workers directly to simplification of the theory for partitioning, was that for equilibrium swelling of sevoal Qqres of latex particles by specific monomer mixtures, the mole fraction of each particular monomer in the latex particles and in the droplets was the same, i.e. 

Many alkali-sweUable latexes exhibit a peak in viscosity, with the viscosiQr decreasing as the pH is raised further. Veihrugge [79] has interpreted the appearance of a peak as due to very high swelling of the particles, followed by more complete solubilization at a higher pH. 

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