Author(s): Musyanovych A, Rossmanith R, Tontsch C, Landfester K
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Abstract Carboxyl and amino-functionalized polystyrene latex particles were synthesized by the miniemulsion copolymerization of styrene and acrylic acid or 2-aminoethyl methacrylate hydrochloride (AEMH). The reaction was started by using an oil-soluble initiator, such as 2,2'-azobis(2-methylbutyronitrile) (V-59). The effect of the functional monomer content and type of surfactant (non-ionic versus ionic) on the particle size and particle size distribution was investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). A bimodal particle size distribution was observed for functionalized latex particles prepared in the presence of the non-ionic surfactant (i.e., Lutensol AT-50) when 1 wt \% of acrylic acid or 3 wt \% of AEMH as a comonomer was employed. The copolymer particle nucleation was studied by using a highly hydrophobic fluorescent dye. From the obtained results, the formation of bimodal particle size distribution may be attributed to a budding-like effect, which takes place during the earlier stage of polymerization and is caused by the additional stabilizing energy originated from the ionic groups of a functional polymer. The reaction mechanism of particle formation in the presence of non-ionic and ionic surfactants has been proposed. The amount of the surface functional groups was determined from polyelectrolyte titration data.
This article was published in Langmuir
and referenced in Journal of Nanomedicine & Nanotechnology