scholarly journals Combining alkali metals and zinc to harness heterometallic cooperativity in cyclic ester ring-opening polymerisation

2020 ◽  
Vol 11 (43) ◽  
pp. 11785-11790
Author(s):  
Weronika Gruszka ◽  
Anna Lykkeberg ◽  
Gary S. Nichol ◽  
Michael P. Shaver ◽  
Antoine Buchard ◽  
...  
Keyword(s):  
Ring Opening ◽  
Alkali Metals ◽  
Cyclic Ester ◽  
And Control

Cooperative heterotrimetallic Na/Zn2 and K/Zn2 complexes combine the excellent activities and control of the homometallic analogues, giving “best of both” in cyclic ester ring-opening polymerisation.

Chirality-Induced Catalyst Aggregation: Insights into Catalyst Speciation and Activity Using Chiral Aluminum Catalysts in Cyclic Ester Ring-Opening Polymerization

ACS Catalysis ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4084-4093
Author(s):  
Sami Gesslbauer ◽  
George Hutchinson ◽  
Andrew J. P. White ◽  
Jordi Burés ◽  
Charles Romain
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Cyclic Ester

scholarly journals Morphology and Degradation of Multicompartment Microparticles Based on Semi-Crystalline Polystyrene-block-Polybutadiene-block-Poly(L-lactide) Triblock Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4358
Author(s):  
Nicole Janoszka ◽  
Suna Azhdari ◽  
Christian Hils ◽  
Deniz Coban ◽  
Holger Schmalz ◽  
...  
Keyword(s):  
Cross Sections ◽  
Ring Opening ◽  
Particle Diameter ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Selective Degradation ◽  
The Core ◽  
Transmission Electron ◽  
And Control ◽  
Triblock Terpolymers

The confinement assembly of block copolymers shows great potential regarding the formation of functional microparticles with compartmentalized structure. Although a large variety of block chemistries have already been used, less is known about microdomain degradation, which could lead to mesoporous microparticles with particularly complex morphologies for ABC triblock terpolymers. Here, we report on the formation of triblock terpolymer-based, multicompartment microparticles (MMs) and the selective degradation of domains into mesoporous microparticles. A series of polystyrene-block-polybutadiene-block-poly(L-lactide) (PS-b-PB-b-PLLA, SBL) triblock terpolymers was synthesized by a combination of anionic vinyl and ring-opening polymerization, which were transformed into microparticles through evaporation-induced confinement assembly. Despite different block compositions and the presence of a crystallizable PLLA block, we mainly identified hexagonally packed cylinders with a PLLA core and PB shell embedded in a PS matrix. Emulsions were prepared with Shirasu Porous Glass (SPG) membranes leading to a narrow size distribution of the microparticles and control of the average particle diameter, d ≈ 0.4 µm–1.8 µm. The core–shell cylinders lie parallel to the surface for particle diameters d < 0.5 µm and progressively more perpendicular for larger particles d > 0.8 µm as verified with scanning and transmission electron microscopy and particle cross-sections. Finally, the selective degradation of the PLLA cylinders under basic conditions resulted in mesoporous microparticles with a pronounced surface roughness.

Ring-Opening Polymerization of Cyclic Ester Monomers by Poly(propylene glycol) in the Presence of Monomer Activator and Examination of Triblock Copolymer Solution Properties

2011 ◽  
Vol 7 (6) ◽  
pp. 955-960 ◽  
Author(s):  
Jae Il Kim ◽  
Hwi Ju Kang ◽  
Doo Yeon Kwon ◽  
Bong Lee ◽  
Heung Jae Chun ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Ring Opening ◽  
Triblock Copolymer ◽  
Ring Opening Polymerization ◽  
Cyclic Ester ◽  
Solution Properties ◽  
Copolymer Solution ◽  
Poly Propylene

Ring-Opening Polymerization of L-lactide Initiated by Samarium(III) Acetate

2019 ◽  
Vol 3 (2) ◽  
pp. 112-119
Author(s):  
Jesús Miguel Contreras Ramírez ◽  
Dimas Medina ◽  
Francisco López-Carrasquero ◽  
Ricardo Rafael Contreras
Keyword(s):  
1H Nmr ◽  
Ring Opening ◽  
Alkali Metals ◽  
Molar Mass ◽  
Ring Opening Polymerization ◽  
Solvent Free ◽  
Size Exclusion ◽  
Polymerization Process ◽  
Molar Ratio ◽  
Aliphatic Polyesters

Background: The synthesis of the aliphatic polyesters obtained by the ring opening polymerization has been achieved using as initiators a large amount of organometallic compounds derivative from: Alkali metals, alkaline earth metals, transition metals and lanthanide metals. Of all these compounds, the lanthanide derivatives have acquired great importance in the synthesis of aliphatic polyesters, since these show a greater catalytic activity and also can provide polymer with characteristics that will be very useful in the design of biomaterials. Objective: It was proposed the synthesis of poly(L-lactida) (PL-LA) through a ring opening polymerization process of L-lactide initiated with samarium(III) acetate (Sm(OAc)3) under solvent-free melt conditions. The influence of different parameters of reaction, such as temperature, time, molar ratio monomer to initiator, on typical variables of polymers, e.g., conversion, dispersity, and molar mass, were analyzed. Methods: All polymerizations were carried out under solvent-free melt conditions in ampoules-like flasks, equipped with a magnetic stirrer. The obtained polyesters were characterized by size exclusion chromatography (SEC) and 1H-NMR. Results: The Sm(OAc)3 induces the polymerization of L-LA at high conversion, and produce polyesters with number-average molecular weights of 1.00 x 103 to 30.00 x 103 Dalton. The 1H-NMR analysis indicates a typical polymerization mechanism of coordination-insertion, with a breakdown of the acyl-oxygen bond of the L-LA. Conclusion: Sm(OAc)3 was an effective initiator for the ring-opening polymerization of L-LA. SEC chromatography showed that, at high temperatures and prolonged reaction times, the molar mass of the polyester decreases, which is associated with the transesterification collateral reactions that occur during the polymerization process.

scholarly journals Investigation of the K-Mg-Ca Sulfate System as Part of Monitoring Problematic Phase Formations in Renewable-Energy Power Plants

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5366
Author(s):  
Fiseha Tesfaye ◽  
Daniel Lindberg ◽  
Mykola Moroz ◽  
Leena Hupa
Keyword(s):  
Renewable Energy ◽  
Power Plants ◽  
Alkali Metals ◽  
Wind Farms ◽  
Biomass Combustion ◽  
Term Operation ◽  
Binary Phase Diagrams ◽  
Combustion Processes ◽  
And Control

Besides the widely applied hydropower, wind farms and solar energy, biomass and municipal and industrial waste are increasingly becoming important sources of renewable energy. Nevertheless, fouling, slagging and corrosion associated with the combustion processes of these renewable sources are costly and threaten the long-term operation of power plants. During a high-temperature biomass combustion, alkali metals in the biomass fuel and the ash fusion behavior are the two major contributors to slagging. Ash deposits on superheater tubes that reduce thermal efficiency are often composed of complex combinations of sulfates and chlorides of Ca, Mg, Na, and K. However, thermodynamic databases involving all the sulfates and chlorides that would favor a better understanding and control of the problems in combustion processes related to fouling, slagging and corrosion are not complete. In the present work, thermodynamic properties including solubility limits of some phases and phase mixtures in the K2SO4-(Mg,Ca)SO4 system were reviewed and experimentally investigated. Based on the new and revised thermochemical data, binary phase diagrams of the K2SO4-CaSO4 and K2SO4-MgSO4 systems above 400 °C, which are of interest in the combustion processes of renewable-energy power plants, were optimized.

Organophosphate-catalyzed bulk ring-opening polymerization as an environmentally benign route leading to block copolyesters, end-functionalized polyesters, and polyester-based polyurethane

2015 ◽  
Vol 6 (24) ◽  
pp. 4374-4384 ◽  
Author(s):  
Tatsuya Saito ◽  
Yusuke Aizawa ◽  
Kenji Tajima ◽  
Takuya Isono ◽  
Toshifumi Satoh
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Cyclic Carbonate ◽  
Environmentally Benign ◽  
Cyclic Ester ◽  
Cyclic Esters

To expand the potential of an organophosphate catalyst, ring-opening polymerization of cyclic esters, cyclic ester-ether, and cyclic carbonate was demonstrated under bulk conditions.

The preparation of the mixed alkali metal silanolate K4Li4(OSiMe3)x(OCMe3)8−x (8⩾x⩾5.7) and the effects of mixed alkali metals on the anion induced ring opening polymerization of octamethylcyclotetrasiloxane

1996 ◽  
Vol 244 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Kenton B. Renkema ◽  
Ronald J. Matthews ◽  
Tammy L. Bush ◽  
Susan K. Hendges ◽  
Robin N. Redding ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Ring Opening ◽  
Alkali Metals ◽  
Ring Opening Polymerization ◽  
Mixed Alkali

Tripodal hydrogen bond donor binding with sulfonic acid enables ring-opening polymerization

2016 ◽  
Vol 7 (7) ◽  
pp. 1368-1374 ◽  
Author(s):  
Xiaopei Li ◽  
Qiguo Zhang ◽  
Zhenjiang Li ◽  
Songquan Xu ◽  
Chengxu Zhao ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Ring Opening ◽  
Sulfonic Acid ◽  
Ring Opening Polymerization ◽  
Cyclic Ester ◽  
Cyclic Carbonates ◽  
Hydrogen Bond Donor ◽  
Acidic Catalysis

The first Brønsted acidic catalysis platform workable in all of the three major types of cyclic ester monomers including lactides, cyclic carbonates, and lactones, is described in this paper.

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