Synthesis of imidized nanoparticles containing soy oil under various reaction conditions

The imidization of poly(styrene-co-maleic anhydride) nanoparticles in presence of soy oil was studied, resulting in the formation of nanoparticles with 20-80 nm diameter with a porous structure allowing to incorporate 50 wt.% soy oil. The reaction efficiency strongly depends on the amount of ammonium hydroxide as imidizing agent, which ratio was varied between 1.01 and 1.60 relatively to the maleic anhydride moieties. Finally, stable aqueous dispersions are obtained with a higher solid content and somewhat higher Zetapotential compared to purely imidized nanoparticles. There are concurring reactions between imidization and coupling of the unsaturated double bonds in soy oil to the ammonolysed maleic anhydride. Therefore, a large amount of non-embedded oil was only observed when the imidization is favoured under high concentrations of ammonium hydroxide. Using spectroscopy and thermal analysis, it is concluded that a complex organized nanostructure is formed between the poly(styrene-co-maleimide) and soy oil, which results in a suppression of T-g evaluated by (temperature-modulated) differential scanning calorimetry. (C) 2015 Elsevier Ltd. All rights reserved.