Design of Acrylic Dispersants for Nonaqueous Dispersion Polymerization: The Importance of Thermodynamics

Abstract

Poly(acrylic) nanoparticles produced by nonaqueous dispersion (NAD) radical polymerization are important components in many automotive coating formulations. A series of experiments show that the properties of final dispersions (particle size distribution, viscosity, and stability) correlate to the thermodynamics of the NAD system, as characterized by solubility parameters and solubility distances among the continuous phase, the soluble polymeric dispersant, and the polymer particles. The insights gained have enabled the design of a macromonomer dispersant containing greater than 10 mol% 2-hydroxyethyl methacrylate, a necessary functional comonomer addition for end-use properties. Stable NAD products were synthesized by changing the principal component of the dispersant from butyl methacrylate to 2-ethylhexyl methacrylate.