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
More filters
Journal ArticleDOI
Organocatalysis by N-Heterocyclic Carbenes
TL;DR: The inversion of the classical reactivity (Umpolung) opens up new synthetic pathways in biochemical processes as nucleophilic acylations and in nature, the coenzyme thiamine (vitamin B1), a natural thiazolium salt, utilizes a catalytic variant of this concept in biochemical process as nucleophile acylation.
Journal ArticleDOI
Synthesis of polycaprolactone: a review
Marianne Labet,Wim Thielemans +1 more
TL;DR: This critical review summarises the different conditions which have been described to synthesise PCL, and gives a broad overview of the different catalytic systems that were used (enzymatic, organic and metal catalyst systems).
Journal ArticleDOI
Organocatalytic ring-opening polymerization.
Nahrain E. Kamber,and Wonhee Jeong,Robert M. Waymouth,Russell C. Pratt,and Bas G. G. Lohmeijer,James L. Hedrick +5 more
TL;DR: This paper presents the design of highly efficient families of “living” polymerization strategies for the synthesis of block, graft, and star polymers through controlled methods for the controlled synthesis of dendritic macromolecules.
Journal ArticleDOI
Organocatalysis: Opportunities and Challenges for Polymer Synthesis
TL;DR: In this article, the ring-opening polymerization of cyclic monomers is used as a representative polymerization process to illustrate some of the features of organic catalysts and initiators and compare them to metal-based approaches.
Journal ArticleDOI
Biocompatible Initiators for Lactide Polymerization
TL;DR: A review of recent developments in the preparation and use of new initiators for the ring opening polymerization of lactide is presented in this article, where the authors compare different classes of initiators including metal complexes, classed according to their group in the periodic table, and carbon-based initiators/organocatalysts.
References
More filters
Journal ArticleDOI
Triazabicyclodecene: A Simple Bifunctional Organocatalyst for Acyl Transfer and Ring-Opening Polymerization of Cyclic Esters
Russell C. Pratt,Bas G. G. Lohmeijer,David A. Long,Robert M. Waymouth, ,§ and,James L. Hedrick +4 more
TL;DR: The simplicity of the reaction conditions, the ready commercial availability of the catalyst, and its high activity provide an accessible methodology to allow future studies of tailor-made polyesters.
Journal ArticleDOI
New Paradigms for Organic Catalysts: The First Organocatalytic Living Polymerization
TL;DR: A metal-free approach to the living ring-opening polymerization (ROP) of lactide has been developed using strongly basic amines such as 4-(dimethylamino)pyridine as transesterification catalysts.
Journal ArticleDOI
Single-Site β-Diiminate Zinc Catalysts for the Ring-Opening Polymerization of β-Butyrolactone and β-Valerolactone to Poly(3-hydroxyalkanoates)
TL;DR: In this article, the zinc alkoxide initiator (BDI-1)ZnOiPr was used to polymerize β-butyrolactone and β-valerolactone.
Journal ArticleDOI
H-bonding additives act like Lewis acid catalysts.
TL;DR: A combination of NMR, IR, and ab initio techniques reveals the striking structural similarities of an exemplary H-bonded complex of an N-acyloxazolidinone with an N,N'-disubstituted electron-poor thiourea and the corresponding Lewis acid complex.
Journal ArticleDOI
A modular approach toward functionalized three-dimensional macromolecules: from synthetic concepts to practical applications.
TL;DR: A new strategy for the preparation of functional, multiarm star polymers via nitroxide-mediated "living" radical polymerization has been explored, which allows for the construction of nanoscopically defined materials from a wide range of different homo, block, and random copolymers combining both apolar and polar vinylic repeat units.