Nano-sized latex particles obtained by emulsion polymerization using an amphiphilic block copolymer as surfactant

Abstract

A series of emulsion systems based on styrene and a mixture of styrene/butyl acrylate (BA) in the presence of the polystyrene-co-maleic anhydride cumene terminated (SMA) copolymer as surfactant were developed. The extent to which varying the monomer and surfactant concentration, as well as the copolymer molecular weight ( M w) could affect the polymer particle size during the polymerization was examined. The particle size was determinated by dynamic light scattering (DLS) and atomic force microscopy (AFM). The system showed that the particle diameter is increased with increased content of monomer. It was also observed that as surfactant concentration is decreased the particle size is increased. On the other hand, by increasing the copolymer molecular weight the particle diameter is also increased. The experimental results demonstrated that it is possible to obtain nano-sized particles with the SMA block copolymer as surfactant. Surface tension measurements were made in order to understand the SMA copolymers behavior in aqueous solution. SMA copolymers of 1600, 1700 and 1900 M w were studied under two different alkaline conditions in order to understand its behavior at different ionic strength.