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Computational and Experimental Evaluation of Peroxide Oxidants for Amine-Peroxide Redox Polymerization

Musgrave, Charles B., III and Kim, Kangmin and Singstock, Nicholas R. and Salazar, Austyn M. and Stansbury, Jeffrey W. and Musgrave, Charles B. (2020) Computational and Experimental Evaluation of Peroxide Oxidants for Amine-Peroxide Redox Polymerization. Macromolecules, 53 (22). pp. 9736-9746. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20201117-072430127

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Abstract

Amine–peroxide redox polymerization (APRP) is the prevalent method for producing radical-based polymers in the many industrial and medical applications where light or heat activation is impractical. We recently developed a detailed description of the APRP initiation process through a combined computational and experimental effort to show that APRP proceeds through SN2 attack by the amine on the peroxide, followed by the rate-determining homolysis of the resulting intermediate. Using this new mechanistic understanding, a variety of peroxides were computationally predicted to initiate APRP with fast kinetics. In particular, the rate of APRP initiation can be improved by radical and anion stabilization through increased π-electron conjugation or by increasing the electrophilicity of the peroxy bond through the addition of electron-withdrawing groups. On the other hand, the addition of electron-donating groups lowered the initiation rate. These design principles enabled the computational prediction of several new peroxides that exhibited improved initiation rates over the commonly used benzoyl peroxide. For example, the addition of nitro groups (NO₂) to the para positions of benzoyl peroxide resulted in a theoretical radical generation rate of 1.9 × 10⁻⁹ s⁻¹, which is ∼150 times faster than the 1.3 × 10⁻¹¹ s⁻¹ radical generation rate observed with unsubstituted benzoyl peroxide. These accelerated kinetics enabled the development of a redox-based direct-writing process that exploited the extremely rapid reactivity of an optimized redox pair with a custom inkjet printer, capable of printing custom shapes from polymerizing resins without heat or light. Furthermore, the application of more rapid APRP kinetics could enable the acceleration of existing industrial processes, make new industrial manufacturing methods possible, and improve APRP compatibility with biomedical applications through reduced initiator concentrations that still produce rapid polymerization rates.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acs.macromol.0c02069DOIArticle
ORCID:
AuthorORCID
Musgrave, Charles B., III0000-0002-3432-0817
Kim, Kangmin0000-0002-5814-9225
Singstock, Nicholas R.0000-0003-2093-0216
Stansbury, Jeffrey W.0000-0003-1880-005X
Musgrave, Charles B.0000-0002-5732-3180
Alternate Title:Computational and Experimental Evaluation of Peroxide Oxidants for Amine–Peroxide Redox Polymerization
Additional Information:© 2020 American Chemical Society. Received: September 7, 2020; Revised: October 28, 2020; Published: November 13, 2020. This work was supported in part by the NSF grant CHE-1214131 and NIH/NIDCR R01DE023197. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
NSFCHE-1214131
NIHR01DE023197
Issue or Number:22
Record Number:CaltechAUTHORS:20201117-072430127
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201117-072430127
Official Citation:Computational and Experimental Evaluation of Peroxide Oxidants for Amine–Peroxide Redox Polymerization. Charles B. Musgrave III, Kangmin Kim, Nicholas R. Singstock, Austyn M. Salazar, Jeffrey W. Stansbury, and Charles B. Musgrave. Macromolecules 2020 53 (22), 9736-9746; DOI: 10.1021/acs.macromol.0c02069
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106687
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Nov 2020 18:11
Last Modified:24 Nov 2020 17:20

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