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
Order and Disorder in High χ/Low N, Broad Dispersity ABA Triblock Polymers
TL;DR: In this article, a combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) was used to document the composition-dependent morphologies of 39 new poly(lactide-block-1,4-butadiene-block lactide) (LBL) block polymers, comprising a broad dispersity B segment (Mn = 4.5-17.7 kg/mol; Đ = Mw/Mn= 1.72-1.88) and narrow dispersity L end blocks
Journal ArticleDOI
Synthesis and one-dimensional assembly of cylindrical polymer nanoparticles prepared from tricomponent bottlebrush copolymers
Sebla Onbulak,Javid Rzayev +1 more
TL;DR: In this paper, the synthesis of well-defined nanostructured building blocks, cylindrical polymeric nanoparticles with controlled dimensions and inner surface chemistry, and their dynamic anisotropic organization into one-dimensional assemblies were reported.
Journal ArticleDOI
Heterogeneous catalysts for the controlled ring-opening polymerisation of rac-lactide and homogeneous silsesquioxane model complexes.
Matthew D. Jones,Matthew G. Davidson,Callum G. Keir,Ashley J. Wooles,Mary F. Mahon,David C. Apperley +5 more
TL;DR: This communication reports, for the first time, the ring-opening polymerisation in the melt of rac-lactide with heterogeneous catalysts with Homogeneous model systems based on silsesquioxanes.
Journal ArticleDOI
TBD-Catalyzed Ring-Opening Polymerization of Alkyl-Substituted Morpholine-2,5-Dione Derivatives.
Michael Dirauf,Damiano Bandelli,Christine Weber,Helmar Görls,Michael Gottschaldt,Ulrich S. Schubert +5 more
TL;DR: Kinetic studies of the ROP reveal that the molar masses and dispersities could be well controlled, and Matrix-assisted laser desorption time-of-flight mass spectrometry indicates the presence of polymer chains with α-end groups derived from the initiator.
Journal ArticleDOI
Theoretical and experimental studies of 1,5,7-triazabicyclo[4.4.0]dec-5-ene-catalyzed ring opening/ring closure reaction mechanism for 5-, 6- and 7-membered cyclic esters and carbonates
Ilya E. Nifant'ev,Andrey V. Shlyakhtin,Vladimir V. Bagrov,Boris A. Lozhkin,Gladis G. Zakirova,Pavel V. Ivchenko,Olga Legon’kova +6 more
TL;DR: In this article, the authors investigated the ring-opening polymerization (ROP) of cyclic substrates, as well as the transesterification of acyclic esters, with 1,5,7-triazabicyclo[4.0]dec-5-ene (TBD) as a catalyst precursor in the presence of methanol as an initiator.
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.
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.