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
Reads0
Chats0
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
More filters
Journal ArticleDOI
Phase-switching Homogeneous Catalysis for Clean Production of Biodiesel and Glycerol from Soybean and Microbial Lipids
TL;DR: In this paper, an efficient and facile process for the integrated clean production of biodiesel and glycerol from soybean and microbial lipids, and the catalyst DBU can be recycled by an easy extraction process.
Journal ArticleDOI
Selective or living organopolymerization of a six-five bicyclic lactone to produce fully recyclable polyesters
TL;DR: In this article, a screening of (thio)urea [(T)U] and organic base pairs revealed unique trends in reactivity for this monomer as well as the most active catalyst pairs, which were employed as received commercially to produce relatively high molecular weight (Mn up to 106 kDa), low dispersity (Đ = 1.04), and their reactions can be performed in air.
Journal ArticleDOI
Cocatalyst Binding Effects in Organocatalytic Ring-Opening Polymerization of l-Lactide
TL;DR: In this paper, several alkylamine bases are shown to be weakly associated with a thiourea cocatalyst in solution, and the nature of cocatalytic interactions vary with the identity of the alklamine.
Journal ArticleDOI
Ambient temperature catalyst-free light-induced preparation of macrocyclic aliphatic polyesters
Thomas Josse,Ozcan Altintas,Kim K. Oehlenschlaeger,Philippe Dubois,Pascal Gerbaux,Olivier Coulembier,Christopher Barner-Kowollik +6 more
TL;DR: The light induced, catalyst-free ambient temperature preparation of macrocyclic aliphatic polyesters is pioneered and can be easily transferred to a large range of polymers, complex topologies (tadpole, sun-shaped, jellyfish, etc.) and applications.
Journal ArticleDOI
External and Reversible CO2 Regulation of Ring-Opening Polymerizations Based on a Primary Alcohol Propagating Species
TL;DR: In this article, the use of an organic catalyst system capable of switching between active and dormant propagating states during the ROP of cyclic monomers was reported. But the system was not shown to be suitable for cyclic polymers with high molecular weights and it was shown that cycling between atmospheres provides the ability to regulate the molecular weights of the resulting polymers without appreciable loss of catalytic activity for several “on/off” cycles.
References
More filters
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.