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

Abstract

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.

Keywords:

• controlled/living radical polymerization
• nitroxide mediated radical polymerization
• polystyrene
• TEMPO

5 Acknowledgements

The authors wish to acknowledge the financial support from Consejo Nacional de Ciencia y Tecnología (CONACYT) (Project CIAM U40259‐Y) (Mexico), Natural Sciences and Engineering Research Council (NSERC) (Canada), and CNPq (Brazil), through a special Inter American Materials Collaboration (IAMC or CIAM) joint project, and the additional support to E.V‐Ĺs group from Dirección General de Asuntos del Personal Académico (DGAPA), of Universidad Nacional Autónoma de México (UNAM) (Project IN100702). E.V.‐L. gratefully acknowledges DGAPA‐UNAM (PASPA Program) and the Department of Chemical Engineering of the University of Waterloo for the financial support received during his research stay at the University of Waterloo. M.R.‐L. acknowledges the graduate scholarships for PhD studies from CONACYT and Dirección General de Estudios de Posgrado (DGEP) of UNAM.

The authors gratefully acknowledge the following people: Drs. Enrique Saldívar‐Guerra (CIQA and CID‐DESC, México), and Larissa Alexandrova (IIM‐UNAM, México), for discussions as well as the use of their characterization equipment (GPCs) in the preliminary stages of the project; Drs. Pilar Carreón, Guillermina Burillo, and Emilio Bucio, from ICN‐UNAM, for use of facilities in the early stages of the project; Dr. Martha Sosa and Mr. Alejandro Solano, from FQ‐UNAM, for the use and interpretation of the ESR equipment and spectra at FQ‐UNAM; Mr. Juan Manuel Garcia Leon (IIM‐UNAM) and Mr. Salvador Ham (ICN‐UNAM), for their assistance in GPC measurements and ampoule glass blowing work, respectively; and Ellen Tuinman (Waterloo) and Juliana Belicanta Ximenes (UNICAMP, Brazil), for collecting some of the experimental data used in this paper.

Additional information

Notes on contributors

Eduardo Vivaldo‐Lima

On research leave from UNAM