Amine-peroxide redox polymerization (APRP) has been highly prevalent in industrial and medical applications since the 1950s, yet the initiation mechanism of this radical polymerization process is poorly understood so that innovations in the field are largely empirically driven and incremental. Through a combination of computational prediction and experimental analysis, we elucidate the mechanism of this important redox reaction between amines and benzoyl peroxide for the ambient production of initiating radicals. Our calculations show that APRP proceeds through SN2 attack by the amine on the peroxide but that homolysis of the resulting intermediate is the rate-determining step. We demonstrate a correlation between the computationally predicted initiating rate and the experimentally measured polymerization rate with an R2 = 0.80. The new mechanistic understanding was then applied to computationally predict amine reductant initiators with faster initiating kinetics. This led to our discovery of N-(4-methoxyphenyl)pyrrolidine (MPP) as amine reductant, which we confirmed significantly outperforms current state-of-the-art tertiary aromatic amines by ~20-fold, making it the most efficient amine-peroxide redox initiator to date. The application of amines with superior kinetics such as MPP in APRP could greatly accelerate existing industrial processes, facilitate new industrial manufacturing methods, and improve biocompatibility in biomedical applications conducted with reduced initiator concentrations yet higher overall efficiency.
Kim, Kangmin, et al. "Rational Design of Efficient Amine Reductant Initiators for Amine–Peroxide Redox Polymerization." Journal of the American Chemical Society, vol. 141, no. 15, Mar. 2019. https://doi.org/10.1021/jacs.8b13679
Kim, Kangmin, Singstock, Nicholas R., Childress, Kimberly K., Sinha, Jasmine, Salazar, Austyn M., Whitfield, Savannah N., Holder, Aaron M., Stansbury, Jeffrey W., & Musgrave, Charles B. (2019). Rational Design of Efficient Amine Reductant Initiators for Amine–Peroxide Redox Polymerization. Journal of the American Chemical Society, 141(15). https://doi.org/10.1021/jacs.8b13679
Kim, Kangmin, Singstock, Nicholas R., Childress, Kimberly K., et al., "Rational Design of Efficient Amine Reductant Initiators for Amine–Peroxide Redox Polymerization," Journal of the American Chemical Society 141, no. 15 (2019), https://doi.org/10.1021/jacs.8b13679
@article{osti_1508958,
author = {Kim, Kangmin and Singstock, Nicholas R. and Childress, Kimberly K. and Sinha, Jasmine and Salazar, Austyn M. and Whitfield, Savannah N. and Holder, Aaron M. and Stansbury, Jeffrey W. and Musgrave, Charles B.},
title = {Rational Design of Efficient Amine Reductant Initiators for Amine–Peroxide Redox Polymerization},
annote = {Amine-peroxide redox polymerization (APRP) has been highly prevalent in industrial and medical applications since the 1950s, yet the initiation mechanism of this radical polymerization process is poorly understood so that innovations in the field are largely empirically driven and incremental. Through a combination of computational prediction and experimental analysis, we elucidate the mechanism of this important redox reaction between amines and benzoyl peroxide for the ambient production of initiating radicals. Our calculations show that APRP proceeds through SN2 attack by the amine on the peroxide but that homolysis of the resulting intermediate is the rate-determining step. We demonstrate a correlation between the computationally predicted initiating rate and the experimentally measured polymerization rate with an R2 = 0.80. The new mechanistic understanding was then applied to computationally predict amine reductant initiators with faster initiating kinetics. This led to our discovery of N-(4-methoxyphenyl)pyrrolidine (MPP) as amine reductant, which we confirmed significantly outperforms current state-of-the-art tertiary aromatic amines by ~20-fold, making it the most efficient amine-peroxide redox initiator to date. The application of amines with superior kinetics such as MPP in APRP could greatly accelerate existing industrial processes, facilitate new industrial manufacturing methods, and improve biocompatibility in biomedical applications conducted with reduced initiator concentrations yet higher overall efficiency.},
doi = {10.1021/jacs.8b13679},
url = {https://www.osti.gov/biblio/1508958},
journal = {Journal of the American Chemical Society},
issn = {ISSN 0002-7863},
number = {15},
volume = {141},
place = {United States},
publisher = {American Chemical Society (ACS)},
year = {2019},
month = {03}}