Polyester Macromonomer Syntheses and Radical Copolymerization Kinetics with Styrene

Short-chain polyester methacrylate macromonomers with alkyl, tertiary amine, carboxyl, and hydroxyl end-group functionalities are synthesized by ring-opening polymerization and subsequent modification. Monomer conversion and composition drift during batch radical copolymerizations of (macro)­monomer with styrene are tracked using the in situ NMR technique in both polar and nonpolar deuterated solvents at 80 °C. For experiments with initial methacrylate molar fraction f_xMA = 0.2, the effects of end-group functionality, solvent, and hydrogen bonding on relative reactivity are pronounced for monomeric analogues of the macromonomers. However, the polyester spacers significantly dilute these effects in macromonomer copolymerization, as polyester type, length, and end-group functionality did not influence copolymerization kinetics. Instead, the chemical identity up to several units from the methacryloyl group is the most important indicator of macromonomer relative reactivity.