Stereoselective Ring-Opening Polymerization of Racemic Lactide Using Aluminum-Achiral Ligand Complexes:  Exploration of a Chain-End Control Mechanism

2002 ◽  
Vol 124 (21) ◽  
pp. 5938-5939 ◽  
Author(s):  
Nobuyoshi Nomura ◽  
Ryohei Ishii ◽  
Matsujiro Akakura ◽  
Keigo Aoi
Keyword(s):  
Ring Opening ◽  
Control Mechanism ◽  
Ring Opening Polymerization ◽  
A Chain

Isoselective mechanism of the ring-opening polymerization of rac-lactide catalyzed by chiral potassium binolates

2017 ◽  
Vol 4 (2) ◽  
pp. 261-269 ◽  
Author(s):  
Yaqin Cui ◽  
Changjuan Chen ◽  
Yangyang Sun ◽  
Jincai Wu ◽  
Xiaobo Pan
Keyword(s):  
Ring Opening ◽  
Control Mechanism ◽  
Ring Opening Polymerization ◽  
A Chain

A chain end control mechanism for the isoselective ring-opening polymerization of rac-lactide catalyzed by potassium complexes was proven via three different methods.

scholarly journals Chiral 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)-Catalyzed Stereoselective Ring-Opening Polymerization of rac-Lactide: High Reactivity for Isotactic Enriched Polylactides (PLAs)

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2365 ◽  
Author(s):  
Qaiser Mahmood ◽  
Guangqiang Xu ◽  
Li Zhou ◽  
Xuanhua Guo ◽  
Qinggang Wang
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Kinetic Studies ◽  
Monomer Conversion ◽  
Ring Opening Polymerization ◽  
High Reactivity ◽  
Chiral Hplc ◽  
Nmr Spectrum ◽  
Molecular Weight Distributions ◽  
A Chain

Chiral 4,8-diphenyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (DiPh-TBD) was synthesized and applied to a ring-opening polymerization of rac-lactide (rac-LA). The chiral DiPh-TBD promoted the synthesis of isotactic enriched polylactides (PLAs) with controlled molecular weight and narrow molecular weight distributions under mild, metal-free conditions. When the [rac-LA]/[Cat.] ratio was 100/1, full monomer conversion was achieved within only 1 min and a moderate probability of 0.67 meso dyads (Pm) was obtained at room temperature. A chain-end control mechanism (CEC) was found to be responsible for the isoselectivity based on the homodecoupled 1H NMR spectrum, the chiral HPLC measurement, and kinetic studies.

scholarly journals Sol-Gel Chemistry by Ring-Opening Polymerization

1999 ◽  
Vol 576 ◽  
Author(s):  
Kamyar Rahimian ◽  
Douglas A. Loy
Keyword(s):  
Growth Mechanism ◽  
Ring Opening ◽  
Sol Gel ◽  
Ring Opening Polymerization ◽  
Inorganic Materials ◽  
Ring Closure ◽  
Chain Growth ◽  
Alcohol Solvent ◽  
Phenylene Group ◽  
A Chain

ABSTRACTSol-gel processing of materials is plagued by shrinkage during polymerization of the alkoxide monomers and processing (aging and drying) of the resulting gels. We have developed a new class of hybrid organic-inorganic materials based on the solventless ring-opening polymerization (ROP) of monomers bearing the 2,2,5,5-tetramethyl-2,5-disilaoxacyclopentyl group, which permits us to drastically reduce shrinkage in sol-gel processed materials. Because the monomers are polymerized through a chain growth mechanism catalyzed by base rather than the step growth mechanism normally used in sol-gel systems, hydrolysis and condensation products are entirely eliminated. Furthermore, since water is not required for hydrolysis, an alcohol solvent is not necessary. Monomers with two disilaoxacyclopentyl groups, separated by a rigid phenylene group or a more flexible alkylene group, were prepared through disilylation of the corresponding diacetylenes, followed by ring closure and hydrogenation. Anionic polymerization of these materials, either neat or with 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane as a copolymer, affords thermally stable transparent gels with no visible shrinkage. These materials provide an easy route to the introduction of sol-gel type materials in encapsulation of microelectronics, which we have successfully demonstrated.

A Recommender System for Inverse Design of Polycarbonates and Polyesters

2020 ◽  
Author(s):  
Nathaniel Park ◽  
Dmitry Yu. Zubarev ◽  
James L. Hedrick ◽  
Vivien Kiyek ◽  
Christiaan Corbet ◽  
...  
Keyword(s):  
Ring Opening ◽  
High Performance ◽  
Recommendation System ◽  
Polymeric Materials ◽  
Monomer Conversion ◽  
Design Strategy ◽  
Ring Opening Polymerization ◽  
Inverse Design ◽  
False Negatives ◽  
Accelerate Development

The convergence of artificial intelligence and machine learning with material science holds significant promise to rapidly accelerate development timelines of new high-performance polymeric materials. Within this context, we report an inverse design strategy for polycarbonate and polyester discovery based on a recommendation system that proposes polymerization experiments that are likely to produce materials with targeted properties. Following recommendations of the system driven by the historical ring-opening polymerization results, we carried out experiments targeting specific ranges of monomer conversion and dispersity of the polymers obtained from cyclic lactones and carbonates. The results of the experiments were in close agreement with the recommendation targets with few false negatives or positives obtained for each class.<br>

Bisurea and Bisthiourea H-Bonding Organocatalysts for Ring-Opening Polymerization: Cues for the Catalyst Design

2019 ◽  
Vol 52 (23) ◽  
pp. 9232-9237 ◽  
Author(s):  
Rukshika S. Hewawasam ◽  
U. L. D. Inush Kalana ◽  
Nayanthara U. Dharmaratne ◽  
Thomas J. Wright ◽  
Timothy J. Bannin ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Catalyst Design
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