Cited by 68biodegradable polymer synthesis and propertiesCarbon dioxide utilization in catalysisAdvanced Polymer Synthesis and Characterization

Rate Accelerated Organocatalytic Ring-Opening Polymerization of l-Lactide via the Application of a Bis(thiourea) H-bond Donating Cocatalyst

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Spink, Samuel S., Kazakov, Oleg I., Kiesewetter, Elizabeth T., Kiesewetter, Matthew K.·2015·Macromolecules

Abstract

A cocatalyst system consisting of an alkylamine base and a bis(thiourea) featuring a linear alkane tether is shown to dramatically increase the rate of ring-opening polymerization (ROP) of L-lactide versus previously disclosed monothiourea H-bond donors. Rate acceleration occurs regardless of the identity of the alkylamine cocatalyst, and the ROP remains controlled yielding poly(lactide) with narrow molecular weight distributions, predictable molecular weights and high selectivity for monomer. This H-bond mediated ROP of L-lactide constitutes a rare, clear example of rate acceleration with bis(thiourea) H-bond donors versus monothioureas, and the bis(thiourea) is shown to remain highly active for ROP at fractional percent catalyst loadings. Activation at a single monomer ester by both thiourea moieties is implicated as the source of rate acceleration.

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Crossref · 10.1021/acs.macromol.5b01320

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  • The most active one, a trisurea/MTBD, is approximately 100 times faster than mono-TU/MTBD for the ROP of CL, with equally good control on molecular weights and molecular weight distributions (Ð < 1.05).

    “The most active one, a trisurea/MTBD, is approximately 100 times faster than mono-TU/MTBD for the ROP of CL, with equally good control on molecular weights and molecular weight distributions (Ð < 1.05).”

    From Catalysis as an Enabling Science for Sustainable Polymers (2018) · cites this paper as [337]

  • The rate acceleration is proposed to arise from an "activated (thio)urea" mechanism in which each additional (thio)urea moiety enhances the acidity via intramolecular H-bond activation, supported by DFT calculations.

    “The rate acceleration is proposed to arise from an “activated (thio)urea” mechanism in which each additional (thio)urea moiety enhances the acidity via intramolecular H-bond activation (Scheme 13), supported by DFT calculations.”

    From Catalysis as an Enabling Science for Sustainable Polymers (2018) · cites this paper as [337]

  • Kiesewetter reported a series of bis- and tris-(thio)urea based H-bond donors, which exhibited dramatic rate acceleration compared to the mono-TU/amine systems, yet retaining the high selectivity for propagation over transesterification.

    “Kiesewetter reported a series of bis-and tris-(thio)urea based H-bond donors (Scheme 13), which exhibited dramatic rate acceleration compared to the mono-TU/amine systems, yet retaining the high selectivity for propagation over transesterification. 337,338”

    From Catalysis as an Enabling Science for Sustainable Polymers (2018) · cites this paper as [337]

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Authors
Spink, S. S., Kazakov, O. I., Kiesewetter, E. T., & Kiesewetter, M. K.
Affiliations
University of Rhode Island (US)
Corresponding author
Kiesewetter, Matthew K.
Venue
Macromolecules
Published
2015-08-20
Volume
48
Issue
17
Pages
6127-6131
ISSN
  • 0024-9297 (ISSN-L)
  • 1520-5835
OpenAlex
W2256649509
Cited by
68
References
31
Citations by year
2026: 2 · 2025: 2 · 2024: 9 · 2023: 3 · 2022: 4 · 2021: 3 · 2020: 9 · 2019: 14 · 2018: 7 · 2017: 5 · 2016: 8 · 2015: 2
FWCI
2.65
Type
journal article
Language
en
Open access
Locations
  • Macromolecules (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • Journal of Media Literacy Education (submittedVersion, cc-by)
Funders
  • American Chemical Society Petroleum Research Fund
  • National Institute of General Medical Sciences (8 P20 GM103430-12)
Topics
  • Physical Sciences › Materials Science › Biomaterials › biodegradable polymer synthesis and properties
  • Physical Sciences › Chemical Engineering › Process Chemistry and Technology › Carbon dioxide utilization in catalysis
  • Physical Sciences › Chemistry › Organic Chemistry › Advanced Polymer Synthesis and Characterization
Keywords
ring-opening polymerization, L-lactide, polylactic acid, organocatalysis, reaction rate enhancement, monomer selectivity, molecular weight distribution, catalyst loading

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