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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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
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Journal ArticleDOI
Dilute solution structure of bottlebrush polymers.
TL;DR: It is demonstrated that intrinsic viscosity and hydrodynamic radius are experimental observations sensitive to molecular architecture, exhibiting distinct differences with different choices of branches and backbone lengths.
Journal ArticleDOI
New titanium and zirconium initiators for the production of polylactide
TL;DR: Two new group 4 initiators based on N,N′-Bis(2-hydroxybenzyl)ethylenediamine have been prepared and fully characterised via multi-nuclear NMR spectroscopy and single crystal X-ray diffraction studies.
Journal ArticleDOI
H-Bonding Organocatalysts for the Living, Solvent-Free Ring-Opening Polymerization of Lactones: Toward an All-Lactones, All-Conditions Approach
Jinal U. Pothupitiya,Nayanthara U. Dharmaratne,Terra Marie M. Jouaneh,Kurt V. Fastnacht,Danielle N. Coderre,Matthew K. Kiesewetter +5 more
TL;DR: The triclocarban (TCC) plus base systems are particularly attractive in the context of solvent-free organocatalytic ROPs as discussed by the authors, and one-pot block copolymerizations of lactide and valerolactone can be achieved under these reaction conditions, and onepot triblock copolymers are also synthesized.
Journal ArticleDOI
Controlled ROP of β‐Butyrolactone Simply Mediated by Amidine, Guanidine, and Phosphazene Organocatalysts
TL;DR: Poly(3-hydroxybutyrate)s (PHBs) with controlled molecular features are formed at 60 °C from bulk monomer, mechanistically suggests the formation of N-acyl-α,β-unsaturated propagating species that originate from 1:1 guanidine/amidine/phosphazene:BL adducts.
Journal ArticleDOI
Synthesis of biodegradable macroporous poly(l-lactide)/poly(ε-caprolactone) blend using oil-in-eutectic-mixture high-internal-phase emulsions as template
María G. Pérez-García,María G. Pérez-García,María C. Gutiérrez,Josué D. Mota-Morales,Gabriel Luna-Bárcenas,Francisco del Monte +5 more
TL;DR: These materials proved effective as oil absorbents for oil/water separation with not only a noticeable performance, similar to that of conventional sorbents, but also unprecedented safe disposability, certainly of interest for applications in the cleanup of industrial oily wastewaters and oil spills.
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.
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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.