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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Preparation of porous PCL-PEG-PCL scaffolds using supercritical carbon dioxide.
Farzin Hadizadeh,Elham Khodaverdi,Fatemeh Oroojalian,Pouria Rahmanian-Devin,S. Hassan M. Hashemi,Negar Omidkhah,Kofi Asare-Addo,Ali Nokhodchi,Hossein Kamali +8 more
TL;DR: In this article , the Supercritical Carbon Dioxide (scCO2) gas foaming procedure was used in the preparation of scaffolds containing the model drug dexamethasone (DXMT).
Journal ArticleDOI
Breaking the Paradox between Grafting-Through and Depolymerization to Access Recyclable Graft Polymers
Recent advances in the synthesis of aliphatic polye sters by ring-opening polymerization *
TL;DR: The first sect ions of this review aim at reporting on the evoluti on of the initiators/catalytic systems and of the synthesis c onditions in order to produce aliphatic polyesters with controlled macromolecular parameters by still "greener" ways.
Patent
Method for preparing glycolide polyester by ring opening polymerization
Jun Shan,Mika Härkönen,Jarmo Ropponen,Ali Harlin,Harri Heikkinen,Virpi Rämö,Thomas Gädda,Leena Nurmi,Pia Willberg-Keyriläinen +8 more
TL;DR: In this article, a method for preparation a glycolide polyester by ring opening polymerization characterized in that glycolides with optional co-monomer(s) of cyclic ester(s), are/are subjected to ring-opening polymerization in the presence of a dispersion stabilizer and a catalyst.
Journal ArticleDOI
Concentration-Driven Self-Assembly of PS-b-PLA Bottlebrush Diblock Copolymers in Solution
Bijal B. Patel,Tian-Tian Pan,Yilong Chang,Dylan J. Walsh,Justin J. Kwok,Kyung Sun Park,Kush Patel,Damien Guironnet,Charles E. Sing,Ying Yan Diao +9 more
TL;DR: In this article , a set of large, nearly symmetric PS-b-PLA bottlebrush diblock copolymers in toluene were synthesized, with side chains of number-averaged molecular weights of 4500 (PS) and 4200 g/mol (PLA) and total backbone degrees of polymerization of 100, 255, and 400 repeat units.
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.
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.