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.

Surface Patterning with Colloidal Monolayers

“…Carboxylic acid groups, present at the each particle's surface, are increasingly deprotonated at higher pH, thus increasing the hydrophilicity of the particles, leading to a decrease of the interfacial fraction of the colloids. Consequently, the number of charges per nm 2 , as determined from titration against an oppositely charged polyelectrolyte, [224] increases with increasing pH for all different colloidal particles used in this study (Table 5.…”

“…For the measurement, 10 mL of the latex sample with a solid content of 1 g·l -1 were used. The amounts of groups were calculated from the amount of consumed polyelectrolyte as demonstrated by Musyanovich et al [224] 6.5. [72] After equilibration for 5 min, the surface layer was compressed with a speed of 20 mm per min.…”

Optical properties of hydrogels filled with dispersed nanoparticles

“…Hydrophobic dispersed phase polystyrene nanoparticles of different sizes were obtained via miniemulsion polymerization as described in [18].…”

From polymeric particles to multifunctional nanocapsules for biomedical applications using the miniemulsion process

“…1). 17,18 A copolymerization with functional monomer(s) allows the functionalization of the nanoparticles' surface with different groups in a controlled manner (see also below).…”

“…5). 17 Recently, studies of the nanoparticle cellular uptake show that several parameters, including polymer and surfactant type (nonionic versus ionic), surface charge (cationic versus anionic), surface groups' density, and the effect of the cell type (see also below). Experiments were performed using nonbiodegradable carboxyl-or amino-functionalized polystyrene and biocompatible and biodegradable poly(L-lactide) (PLLA), poly(e-caprolactone) (PCL), and poly(D,L-lactide-coglycolide) 50:50 (PLGA) latex particles.…”