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
Dual Catalysis for Selective Ring-Opening Polymerization of Lactones: Evolution toward Simplicity.
TL;DR: This study demonstrates that the combination of N-heterocyclic carbenes, 1,8-diazabicycloundec-7-ene (DBU) and 4-dimethylaminopyridine (DMAP) with simple Lewis acids enables the ROP of the macrolactone pentadecalactone in a rapid and efficient manner.
Journal ArticleDOI
Synthesis and Functionalization of Thiol-Reactive Biodegradable Polymers
Sebla Onbulak,Sarah Tempelaar,Ryan J. Pounder,Ozgul Gok,Rana Sanyal,Andrew P. Dove,Amitav Sanyal +6 more
TL;DR: A novel strategy to synthesize and functionalize biodegradable poly(ester)s that can be efficiently postfunctionalized with thiolcontaining molecules using the thermally initiated thiol−ene reaction in the presence of azobis(isobutyronitrile), and vinyl−sulfone functionalized polymers were obtained by ROP.
Journal ArticleDOI
Organocatalysis paradigm revisited: are metal-free catalysts really harmless?
Amandine Nachtergael,Olivier Coulembier,Philippe Dubois,Maxime Helvenstein,Pierre Duez,Bertrand Blankert,Laetitia Mespouille +6 more
TL;DR: Among the investigated organocatalysts, only functionalized thiourea shows an important cytotoxicity on both cell models, and 4-Dimethylaminopyridine, 1,5,7-triazabicyclo, and meta-(trimethylammonio)phenolate betaine (m-BE) show cytot toxicity against HepaRG cell line only at a high concentration.
Journal ArticleDOI
Monomer versus alcohol activation in the 4-dimethylaminopyridine-catalyzed ring-opening polymerization of lactide and lactic O-carboxylic anhydride.
TL;DR: The concerted pathway for the ring-opening of lactide and lacOCA was shown to compete with the traditional stepwise mechanism involving tetrahedral intermediates and DMAP is proposed to act as a bifunctional catalyst through its basic nitrogen center and an acidic ortho-hydrogen atom.
Journal ArticleDOI
Hydrogen-bonding catalysts based on fluorinated alcohol derivatives for living polymerization.
Olivier Coulembier,Daniel P. Sanders,Alshakim Nelson,Andrew N. Hollenbeck,Hans W. Horn,Julia E. Rice,Masaki Fujiwara,Philippe Dubois,James L. Hedrick +8 more
TL;DR: The catalytic activity of the hydrogen-bonded systems was demonstrated for the ring-opening polymerization of a variety of strained heterocycles and narrowly dispersed polymers with predictable molecular weights were obtained with end-group fidelity.
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
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.
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.
Journal ArticleDOI
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.