Partial swelling of latex particles with monomers

Two methods are described for exptl. detg. the concns. of monomer in both the aq. phase and the latex particle phase during partial swelling of latex particles, and therefore also during interval III of an emulsion polymn. The ratio of the monomer concns. in the aq. phase, both below and at satn., can be related to the vol. fraction of polymer in the latex particles via the Vanzo equation. Comparison of theory and expts. for the Me acrylate and Me acrylate-styrene copolymer systems shows that the monomer partitioning is insensitive to temp., latex particle radius, polymer compn., polymer mol. wt., and polymer crosslinking. Thermodn. treatment of these and previously published partitioning results shows, at high vol. fractions of polymer, that the conformational entropy of mixing of monomer and polymer is the significant term detg. the degree of partial latex particle swelling by monomer. Theor. predictions of exptl. results are quite insensitive to values of the Flory-Huggins interaction parameter and to the latex particle-water interfacial tension. A simple model is developed for the estn. of monomer partitioning which requires only the satn. monomer concns. in the particle and aq. phases