Design of 2-hydroxyethyl methacrylate-functional macromonomer dispersants by semi-batch cobalt chain transfer polymerization

Acrylic resins for automotive coatings are produced in nonaqueous dispersions (NAD) of nanometer size. These must be sterically stabilized by oligomeric dispersants, which are complex reactive oligomers possessing vinyl and hydroxyl functionalities, controlling the size of the nanocolloid. Hence, we have developed a kinetic Monte Carlo (kMC) model to improve the molecular structure of 2-hydroxyethyl methacrylate-functionalized poly (butyl methacrylate) (pBMA) dispersants of ca. 6,000 g/mol produced via semi-batch cobalt chain transfer polymerization (CCTP). The kMC-predicted degree of functionalization is benchmarked against a novel analytic expression suitable for oligomers. Stepwise adjustment of the semi-batch feed program illustrates the successive improvement in molecular structure of the dispersant product, finally arriving at a functionalization degree close to the theoretical maximum for CCTP.