Journal ArticleDOI
Guanidine and Amidine Organocatalysts for Ring-Opening Polymerization of Cyclic Esters
Bas G. G. Lohmeijer,Russell C. Pratt,Frank A. Leibfarth,John W. Logan,David A. Long,Andrew P. Dove,Fredrik Nederberg,Jeongsoo Choi,Charles G. Wade,Robert M. Waymouth,James L. Hedrick +10 more
TLDR
In this article, the ring-opening polymerization (ROP) of cyclic esters such as lactide (LA), δ-valerolactone (VL), and e-caprolactone(CL) was achieved.Abstract:
1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), N-methyl-TBD (MTBD), and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) are effective organocatalysts for the ring-opening polymerization (ROP) of cyclic esters such as lactide (LA), δ-valerolactone (VL), and e-caprolactone (CL). TBD is shown to polymerize LA, VL, and CL in a fast and controlled manner, whereas MTBD and DBU polymerized LA and addition of a thiourea cocatalyst led to the ROP of VL and CL being achieved. Each of the catalysts produced polymers displaying high end group fidelity, good correlation between theoretical and observed molecular weight, and linear relationships between conversion and molecular weight. The enhanced activity of TBD relative to MTBD and DBU is attributed to its bifunctionality, enabling the simultaneous activation of both the cyclic ester monomer and the alcohol group of the initiator/propagating species. Temperature-dependent NMR studies generated individual association constants for MTBD with benzyl alcohol and thiourea with VL. ...read more
Citations
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Journal ArticleDOI
Isothiourea‐based lewis pairs for homopolymerization and copolymerization of 2,2‐dimethyltrimethylene carbonate with ε‐caprolactone and ω‐pentadecalactone
TL;DR: In this paper, the homopolymerization of 2,2-dimethyltrimethylene carbonate (DTC) and its copolymerizations with e−caprolactone (CL) were carried out in detail using the isothiourea-based Lewis pairs comprised 2,3,6,7,tetrahydro−5H−thiazolo(3,2)-pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator.
Journal ArticleDOI
Construction of triblock copolyesters <i>via</i> one-step switchable terpolymerization of epoxides, phthalic anhydride and ε-caprolactone using dual urea/organic base catalysts
Yonghang Xu,Radenbach Katrin +1 more
TL;DR: A cost effective and efficient system of ureas/organic bases toward the controlled self-switchable copolymerization of epoxide/PA/CL to obtain well-defined triblock polyesters is described in this paper .
Journal ArticleDOI
Ring-opening polymerization of lactone in the presence of benzyl alcohol catalyzed by aliphatic tertiary amine: ring-opening polymerization of lactone in the presence of benzyl alcohol catalyzed by aliphatic tertiary amine
Journal ArticleDOI
Ring-Opening Copolymerization of Four-Dimensional Printable Polyesters Using Supramolecular Thiourea/Organocatalysis
TL;DR: In this article , organobases with and without supramolecular thiourea co-catalysts are demonstrated for ring-opening copolymerization of polyesters made of cis-4-cyclohexene-1,2-dicarboxylic anhydride and allyl glycidol ether, with ROCOP performed in bulk, open-air conditions.
Journal ArticleDOI
Organocatalytic controlled anionic ring-opening polymerization of carbazole-containing thiiranes
Aliaksei A. Vaitusionak,Irina V. Vasilenko,Egle Jatautiene,Jurate Simokaitiene,Ausra Tomkeviciene,Jolita Ostrauskaite,Juozas V. Grazulevicius,Sergei V. Kostjuk,Sergei V. Kostjuk +8 more
TL;DR: The anionic ring-opening polymerization of carbazole-containing monomers, with hexanethiol or pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) as initiators and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst at 20°C in tetrahydrofuran or N,N-dimethylformamide as solvents has been studied as discussed by the authors.
References
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Journal ArticleDOI
Controlled ring-opening polymerization of lactide and glycolide.
TL;DR: This work focuses on the characterization of the phytochemical components of Lactide ROP and their role in the regulation of cell reprograming.
Journal ArticleDOI
Polymerization of Lactide with Zinc and Magnesium β-Diiminate Complexes: Stereocontrol and Mechanism
Bradley M. Chamberlain,Ming Cheng,David Roger Moore,Tina M. Ovitt,Emil B. Lobkovsky,Geoffrey W. Coates +5 more
TL;DR: The substituents on the beta-diiminate ligand exert a significant influence upon the course of the polymerizations, affecting both the degree of stereoselectivity and the rate of polymerization.
Journal ArticleDOI
A review of biodegradable polymers: uses, current developments in the synthesis and characterization of biodegradable polyesters, blends of biodegradable polymers and recent advances in biodegradation studies
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Journal ArticleDOI
Extension of the self-consistent spectrophotometric basicity scale in acetonitrile to a full span of 28 pKa units: unification of different basicity scales.
Ivari Kaljurand,Agnes Kütt,Lilli Sooväli,Toomas Rodima,Vahur Mäemets,and Ivo Leito,Ilmar A. Koppel +6 more
TL;DR: The earlier compiled self-consistent spectrophotometric basicity scale in acetonitrile (AN) was expanded to range from 3.8 to 32.0 pK(a) units, that is 28 orders of magnitude, and 54 new relative basicity measurements were carried out and 37 new compounds were introduced to the scale.
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Stereochemistry of Lactide Polymerization with Chiral Catalysts: New Opportunities for Stereocontrol Using Polymer Exchange Mechanisms
Tina M. Ovitt,Geoffrey W. Coates +1 more
TL;DR: A polymer exchange mechanism is proposed to account for the PLA microstructures resulting from rac-4, which polymerizes meso-lactide to syndiotactic poly(lactic acid) (PLA) and heterotactic and isotactic stereoblock PLA, respectively.