Synthesis and characterization of imidized poly(styrene-maleic anhydride) nanoparticles in stable aqueous dispersion

Organic nanoparticles are synthesized by partial imidization of high‐molecular weight styrene(maleic‐anhydride) with 26 to 34 mol% maleic anhydride, in aqueous environment and presence of ammonium hydroxide. The nanoparticle dispersions have a maximum solid content of 35 wt% and good stability that critically depends on the ratio of imidized and ammonolyzed maleic anhydride moieties. The deprotonated residual maleic anhydride moieties provide dispersion stability at pH > 4, while protonation at pH