title: Effect of hydrophilic comonomer and surfactant type on the colloidal stability and size distribution of carboxyl- and amino-functionalized polystyrene particles prepared by miniemulsion polymerization.
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.
authors.affiliation: Department of Organic Chemistry III--Macromolecular Chemistry and Organic Materials, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Musyanovych
authors.forename: Renate
authors.initials: R
authors.lastname: Rossmanith
authors.forename: Christian
authors.initials: C
authors.lastname: Tontsch
authors.forename: Katharina
authors.initials: K
authors.lastname: Landfester
mesh_terms: D003102:Colloids; D008863:Microspheres; D010316:Particle Size; D011137:Polystyrenes / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D003102:Colloids; D011137:Polystyrenes