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Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization
We describe a method of partial moments devised for accurate simulation of the time/conversion evolution of polymer composition and molar mass. Expressions were derived that enable rigorous evaluation of the complete molar mass and composition distribution for shorter chain lengths (e.g., degree of...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9696826/ https://www.ncbi.nlm.nih.gov/pubmed/36433139 http://dx.doi.org/10.3390/polym14225013 |
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author | Johnson, Charles H. J. Spurling, Thomas H. Moad, Graeme |
author_facet | Johnson, Charles H. J. Spurling, Thomas H. Moad, Graeme |
author_sort | Johnson, Charles H. J. |
collection | PubMed |
description | We describe a method of partial moments devised for accurate simulation of the time/conversion evolution of polymer composition and molar mass. Expressions were derived that enable rigorous evaluation of the complete molar mass and composition distribution for shorter chain lengths (e.g., degree of polymerization, X(n) = N < 200 units) while longer chains (X(n) ≥ 200 units) are not neglected, rather they are explicitly considered in terms of partial moments of the molar mass distribution, [Formula: see text] (where P is a polymeric species and n is its’ chain length). The methodology provides the exact molar mass distribution for chains X(n) < N, allows accurate calculation of the overall molar mass averages, the molar mass dispersity and standard deviations of the distributions, provides closure to what would otherwise be an infinite series of differential equations, and reduces the stiffness of the system. The method also allows for the inclusion of the chain length dependence of the rate coefficients associated with the various reaction steps (in particular, termination and propagation) and the various side reactions that may complicate initiation or initialization. The method is particularly suited for the detailed analysis of the low molar mass portion of molar mass distributions of polymers formed by radical polymerization with reversible addition-fragmentation chain transfer (RAFT) and is relevant to designing the RAFT-synthesis of sequence-defined polymers. In this paper, we successfully apply the method to compare the behavior of thermally initiated (with an added dialkyldiazene initiator) and photo-initiated (with a RAFT agent as a direct photo-iniferter) RAFT-single-unit monomer insertion (RAFT-SUMI) and oligomerization of N,N-dimethylacrylamide (DMAm). |
format | Online Article Text |
id | pubmed-9696826 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-96968262022-11-26 Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization Johnson, Charles H. J. Spurling, Thomas H. Moad, Graeme Polymers (Basel) Article We describe a method of partial moments devised for accurate simulation of the time/conversion evolution of polymer composition and molar mass. Expressions were derived that enable rigorous evaluation of the complete molar mass and composition distribution for shorter chain lengths (e.g., degree of polymerization, X(n) = N < 200 units) while longer chains (X(n) ≥ 200 units) are not neglected, rather they are explicitly considered in terms of partial moments of the molar mass distribution, [Formula: see text] (where P is a polymeric species and n is its’ chain length). The methodology provides the exact molar mass distribution for chains X(n) < N, allows accurate calculation of the overall molar mass averages, the molar mass dispersity and standard deviations of the distributions, provides closure to what would otherwise be an infinite series of differential equations, and reduces the stiffness of the system. The method also allows for the inclusion of the chain length dependence of the rate coefficients associated with the various reaction steps (in particular, termination and propagation) and the various side reactions that may complicate initiation or initialization. The method is particularly suited for the detailed analysis of the low molar mass portion of molar mass distributions of polymers formed by radical polymerization with reversible addition-fragmentation chain transfer (RAFT) and is relevant to designing the RAFT-synthesis of sequence-defined polymers. In this paper, we successfully apply the method to compare the behavior of thermally initiated (with an added dialkyldiazene initiator) and photo-initiated (with a RAFT agent as a direct photo-iniferter) RAFT-single-unit monomer insertion (RAFT-SUMI) and oligomerization of N,N-dimethylacrylamide (DMAm). MDPI 2022-11-18 /pmc/articles/PMC9696826/ /pubmed/36433139 http://dx.doi.org/10.3390/polym14225013 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Johnson, Charles H. J. Spurling, Thomas H. Moad, Graeme Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title | Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title_full | Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title_fullStr | Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title_full_unstemmed | Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title_short | Evolution of Molar Mass Distributions Using a Method of Partial Moments: Initiation of RAFT Polymerization |
title_sort | evolution of molar mass distributions using a method of partial moments: initiation of raft polymerization |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9696826/ https://www.ncbi.nlm.nih.gov/pubmed/36433139 http://dx.doi.org/10.3390/polym14225013 |
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