Intrinsic self-initiating thermal ring-opening polymerization of 1,3-benzoxazines without the influence of impurities using very high purity crystals

2017 ◽  
Vol 55 (20) ◽  
pp. 3434-3445 ◽  
Author(s):  
Lu Han ◽  
María Laura Salum ◽  
Kan Zhang ◽  
Pablo Froimowicz ◽  
Hatsuo Ishida
Keyword(s):  
High Purity ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Influence Of Impurities ◽  
Very High

scholarly journals Activity and stereoselectivity of Ru-based catalyst bearing a fluorinated imidazolinium ligand

2011 ◽  
Vol 9 (4) ◽  
pp. 605-609 ◽  
Author(s):  
Vincenzo Siano ◽  
Ilaria D’Auria ◽  
Fabia Grisi ◽  
Chiara Costabile ◽  
Pasquale Longo
Keyword(s):  
High Activity ◽  
Solvent Effects ◽  
Ring Opening ◽  
Methylene Chloride ◽  
Kinetic Studies ◽  
Ring Opening Polymerization ◽  
Catalyst Stability ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Very High

AbstractGrubbs II generation catalyst (3), bearing a fluorinated imidazolinium ligand, was investigated in cross metathesis (CM), ring closing metathesis (RCM) and ring opening polymerization metathesis (ROMP) for a variety of substrates. Kinetic studies showed reduced stability of the catalyst in methylene chloride following the first 15 minutes of reaction preventing a higher efficiency despite the very high activity. Beneficial solvent effects on the catalyst stability were observed by performing RCM in C6F6.

Radical Ring-Opening Polymerization of Phosphorus Heterocycles: Computational Design of Suitable Phosphetane Monomers

2007 ◽  
Vol 60 (10) ◽  
pp. 744 ◽  
Author(s):  
Michelle L. Coote ◽  
Jennifer L. Hodgson ◽  
Elizabeth H. Krenske ◽  
Mansoor Namazian ◽  
S. Bruce Wild
Keyword(s):  
Rate Constants ◽  
Ring Opening ◽  
Computational Design ◽  
Propagation Rate ◽  
Ring Opening Polymerization ◽  
Radical Ring ◽  
Ring Opening Reaction ◽  
High Level ◽  
Very High ◽  
Homolytic Substitution

High-level ab initio calculations have been used to determine the propensities of various phosphetanes towards radical ring-opening polymerization. At the G3(MP2)-RAD level of theory, the propagation rate constants of 1-methylphosphetane (7.5 × 104 L mol–1 s–1), 1-phenylphosphetane (4.6 × 105 L mol–1 s–1), cis,cis-2,4-dichloro-1-phenylphosphetane (3.8 × 107 L mol–1 s–1), cis,cis-2,4-difluoro-1-phenylphosphetane (3.0 × 107 L mol–1 s–1), and 1-phenyl-3-oxaphosphetane (4.0 × 106 L mol–1 s–1) are very high, rendering them unsuitable for copolymerization with common alkenes. In contrast, the propagation rate constants of 1-tert-butylphosphetane (1.7 × 103 L mol–1 s–1) and cis,cis-2,4-dimethyl-1-phenylphosphetane (9.2 × 102 L mol–1 s–1) indicate that either incorporation of a t-butyl substituent at phosphorus or alkylation at the 2- and/or 4-positions will produce monomers with more compatible reactivities for copolymerization with alkenes. In the case of 1-tert-butylphosphetane, however, homolytic substitution of the propagating radical with the t-butyl substituent at P will be competitive with the propagation step and could affect the microstructure of the polymer. The borane adduct and the oxide of 1-phenylphosphetane were both found to be unreactive towards radical ring-opening. The calculations suggest that, for chiral phosphetanes, the ring-opening reaction is enantioselective at phosphorus and the resulting polymer will be isotactic.

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>

Very-high-purity InP l.p.e. layers

1977 ◽  
Vol 13 (22) ◽  
pp. 682 ◽  
Author(s):  
K.T. Ip ◽  
L.F. Eastman ◽  
V.L. Wrick
Keyword(s):  
High Purity ◽  
Very High

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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