Polystyrene latexes containing poly(propyleneimine) dendrimers

Polymerization of styrene in aqueous dispersions of sodium dodecyl sulfate (SDS) and the poly(propyleneimine) dendrimer DAB-dendr-(NH2)(64) with initiation by potassium persulfate at 80 degreesC produced latexes with diameters in the range of 26-64 nm and coefficients of variation of diameters of less than 10%. Stable latexes were obtained starting with 1.0 to 4.0 molar ratios of SDS to dendritic primary amine end groups, 5.5 to 11 wt % of SDS relative to styrene, and SDS concentrations below the critical micelle concentration in water at 25 degreesC. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) showed both individual particles and small clusters. TEM and AFM measurements of particle sizes agreed well. Dynamic light scattering measurements gave larger sizes and large polydispersities, presumably due to the presence of clusters.