Versatile phosphonium-catechol dispersant for inorganic nanoparticle stability across diverse media and manufacturing processes

Inorganic nanoparticles (NPs) have significant potential for various applications; however, achieving stable dispersion in organic media and polymers remains a key challenge for their industrial use. We developed a novel dispersant, tributyl(3-((3,4-dihydroxyphenylamino)-3-oxopropyl)phosphonium chloride) (TPC), which contains a catechol group for strong NPs binding and a phosphonium chloride moiety for effective dispersion. The versatility of TPC was demonstrated by stabilizing TiO₂, Fe₂O₃, and ZnO NPs in methanol using bead milling, as confirmed by TGA, DLS, zeta potential, and TEM analyses. In addition, TPC exhibited broad compatibility across solvents with varying dielectric constants. Furthermore, several hybrid polymer films were prepared by casting and photosolidification from monomers to assess their dispersibility and TPC-polymer matrix interactions, using Cole-Cole plots. Notably, poly(D,L-lactic acid) hybrid films retained their dispersion stability after recycling, highlighting the sustainability of TPC-coated NPs for material design. This study presents the first integration of phosphonium cations with catechol groups as dispersants, offering not only a breakthrough approach for developing nanocomposite materials with superior stability and performance, but also establishing a versatile platform concept that introduces a new design principle for universal and sustainable dispersant development across diverse nanomaterials and polymer systems.