Surfactant-free artificial latexes from modified styrene-maleic anhydride (SMA) copolymers

We describe the preparation of surfactant-free artificial latexes on the basis of poly(styrene-alt-maleic anhydride) (SMA) copolymers. The SMA copolymers were first partially alkyl-imidized and then partially ammonolyzed in acetone. Upon adding to water and after the removal of acetone, the modified copolymers formed stable latexes, with a diameter of ∼150 nm and a PDI < 0.2. In the absence of alkyl groups the particles became completely soluble in water after a few days. The latexes from the partially alkyl-imidized polymer were found to remain stable at pH > 2. The incorporation of alkyl groups into the copolymers significantly lowered the Tg of the polymer from 150 to 75 °C, depending on the amount of alkylamines added. It was found that the molecular weight as well as the molar mass distribution of the SMA polymers did not show major effects on the properties of the artificial latexes.