Synthesis and Characterization of Core-Shell Particles obtained in a Seeded Emulsion Copolymerization of Styrene and Methacrylic Acid

GONZALEZ, VERÓNICA D.G; GUGLIOTTA, LUIS M.; VEGA, JORGE R.; MEIRA, GREGORIO R.

Santa Fe, Argentina

Congreso; 3rd Mercosur Congress on Process Systems Engineering and 1st Mercosur Congress on Chemical Engineering; 2001

Facultad de Ingeniería Química, CERIDE, INTEC, INGAR

The seeded emulsion copolymerization of styrene and methacrylic acid was investigated with the aim of producing latex particles with carboxylic functionality, for their further use in inmunodiagnostic tests. The synthesis is carried out in two steps. In the first step, a seed of monodisperse polystyrene latex (the core) was produced through an emulsifier-free batch polymerization. In the second step, a shell of a styrene - methacrylic acid copolymer was added onto the base polystyrene particles, by application of both batch and semibatch control strategies. A mathematical model was used to predict the following reaction variables: the monomer conversion, the particle diameters, the average copolymer composition, the average molecular weights, and the mass fraction and composition of the copolymer produced in aqueous phase. The semibatch operation involved a constant addition of the comonomer mixture; and the mathematical model allowed to calculate the total required time. The following was analyzed: a) the polydispersity of the particle diameters, by transmission electron microscopy (TEM) and multiangle dynamic light scattering (DLS); b) the solid contents, by gravimetry; c) the surface charge, by conductimetry; d) the copolymer composition, by IR spectroscopy; e) the particle diameters and shell thickness, by DLS; and f) the critical coagulation concentration, by DLS and turbidimetry.