Efficient Emulsifier-Free Emulsion Copolymerization of Functional Nanoparticles Using Biobased Itaconic Acid

This study investigates the emulsifier-free emulsion polymerization of functional copolymer nanoparticles via a free radical mechanism using potassium persulfate (KPS) as the initiator at 70 °C under. The copolymerization involved styrene (S) with either methacrylic acid (MAA), a conventional petrochemical-derived monomer, or itaconic acid (IA), a renewable monomer derived from biomass fermentation. IA exhibited superior water solubility and functionality due to its two carboxylic acid groups per molecule, enhancing polymerization rate and particle stability. The optimal synthesis's P-(S-IA) nanoparticles were achieved using 8 mol % IA with pH adjustment at 30 min after initiation, enabling high solid content preparation while maintaining colloidal stability. It demonstrated significantly improved performance over P-(S-MAA) and polystyrene (PS), including complete monomer conversion (∼100%) within 5 h, reduced average particle size (∼200 nm), and minimal coagulation (∼10 wt %) at 30 wt % solid content. In contrast, PS systems exhibited coagulation levels of up to 20% at only 10 wt % solid content, whereas P-(S-MAA) presented coagulation levels of up to 38% under similar conditions. These findings highlight the potential of IA-based functional nanoparticles for ion separation and environmental remediation as precursors for hybrid materials in photocatalysis.