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
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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
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ε-Caprolactone: Activated monomer polymerization; controversy over the mechanism of polymerization catalyzed by phosphorus acids (diarylhydrogen phosphates). Do acids also act as initiators?
TL;DR: In this paper, the role of catalysts in the bulk polymerization of e-caprolactone (CL) with Mn up to 140,000 was investigated and it was shown that protonic catalysts are not initiators.
Journal ArticleDOI
Tuning Biocompatible Block Copolymer Micelles by Varying Solvent Composition: Core/Corona Structure and Solvent Uptake
Tyler J. Cooksey,Avantika Singh,Kim Mai Le,Shu Wang,Elizabeth G. Kelley,Lilin He,Sameer Vajjala Kesava,Enrique D. Gomez,Bryce E. Kidd,Louis A. Madsen,Megan L. Robertson +10 more
TL;DR: In this article, the structural properties and solvent uptake of poly(ethylene oxide-b-e-caprolactone) (PEO-PCL) diblock copolymers in deuterated water (D2O)/tetrahydrofuran (THF-d8) mixtures were investigated with a combination of small-angle neutron scattering, nuclear magnetic resonance, and transmission electron microscopy.
Journal ArticleDOI
Synthesis and trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate with diamines: a non-isocyanate route (NIR) to polyureas
TL;DR: In this paper, a nonisocyanate route (NIR) of making polyureas of high molecular weight has been found through transureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate (4 4′-DP-MDC) with a variety of diamines and mixed diamines.
Journal ArticleDOI
Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration.
Sora Park,Jeung Gon Kim +1 more
TL;DR: The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution, and liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.
Journal ArticleDOI
Maintaining the Hydrophilic–Hydrophobic Balance of Polyesters with Adjustable Crystallinity for Tailor-Made Nanoparticles
Damiano Bandelli,Christian Helbing,Christine Weber,Michael Seifert,Irina Muljajew,Klaus D. Jandt,Ulrich S. Schubert +6 more
TL;DR: In this paper, a block copolyester and a gradient copolymer were tailor-made via the triazabicyclodecene catalyzed ring-opening Copolymerization of δ-valerolactone (δVL) and δdecalactone(δDL) to match the hydrophobicity of poly(e-caprolactone) (PeCL) to explore the relationship between thermal properties of a polymer and the biological performance of the resulting nanoparticle.
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.
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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.
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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
TL;DR: A review of the uses of biodegradable polymers in terms of their relevance within current plastic waste management of packaging materials, biomedical applications and other uses is presented in this paper.
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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.