Carbon black dispersing agents based on fully hydrophilic poly(N‐vinylamide): Surface adsorption via selective interactions

Abstract

AbstractInterface‐stabilizing polymers are frequently used in commercial applications to provide long‐lasting dispersions of colloids in liquid media. Dispersing high concentrations of pigments in aqueous solution can be particularly challenging. Here, we present a novel, fully hydrophilic dispersing agent system for carbon black (CB) pigments based on partially hydrolyzed poly(N‐vinylamides). These highly water‐soluble polymers adsorb onto CB through specific interactions between the polymer and surface‐bound moieties, rather than the hydrophobic effect. They participate in hydrogen bonding, ion–dipole interactions and can be partially positively charged to engage in ion pair formation, providing strong surface affinity. Dispersants are synthesized using free radical copolymerization of N‐vinylform‐ and ‐acetamide, acidic hydrolysis, and subsequent PEGylation. Molecular water solubility of the synthesized polymers is confirmed by using fluorescence spectroscopy. Highly concentrated CB dispersions are prepared in acidic, neutral, and basic media, which we identify to strongly affect the interactions between polymer and CB. The stability of CB dispersions is analyzed using ultracentrifugation and thermogravimetric analysis. The presented polymers are able to provide significantly more stable dispersions than a commercial reference product, showcasing the suitability of poly(N‐vinylamines) as potent CB dispersing agents.