Afsaneh Nabifar

Another Perspective on the Nitroxide Mediated Radical Polymerization (NMRP) of Styrene Using 2,2,6,6‐Tetramethyl‐1‐piperidinyloxy (TEMPO) and Dibenzoyl Peroxide (BPO)

Polymerization conditions for the bimolecular NMRP of styrene using TEMPO and BPO were revisited and expanded with the objective of creating a more complete and reliable source of experimental data for parameter estimation and model validation purposes. Three different experimental techniques were assessed for the NMRP of styrene. The reliability of results produced in vials with inert nitrogen atmosphere was evaluated, taking as reference the more reliable technique using sealed ampoules with inert atmosphere. Polymerization rate data obtained in vials could be considered reliable if monomer loss was taken into account, but the reliability of molecular weight data at high conversions may be questionable. Polymerizations at 120 and 130°C and with TEMPO to BPO, molar ratios of 0.9 to 1.5 were carried out. Comparison of the experimental data collected against predictions obtained with a detailed kinetic model previously reported in the literature suggest that either the present understanding of the reaction system is incomplete, or some of the kinetic rate constants reported in the literature are not accurate, or both. Guidelines on how to address and design future experimental and modeling studies are offered.

Kinetic Aspects of Styrene Polymerization with an Acyloxyamine

The present paper evaluates largely unstudied kinetic aspects of styrene polymerization with a (relatively new) acyloxyamine over several temperature levels and contrasts these features with regular styrene polymerization and styrene polymerization with TEMPO. These comparisons show that the system behaves rather like regular thermal polymerization of styrene at temperatures between 120–180°C. However, at higher temperatures (> 180°C), acyloxyamine has an initiator-like contribution, giving the rate of polymerization an extra boost while decreasing molecular weights. This is further corroborated by mathematical modeling for both conversion and molecular weight averages.