Article
Environmental Sciences
Mercedes Tajuelo, Ana Rodriguez, Alfonso Aranda, Yolanda Diaz-de-Mera, Maria E. Tucceri, Diana Rodriguez
Summary: The formation of secondary organic aerosol (SOA) generated by OH-photooxidation of gamma-butyrolactone (GBL) and gamma-valerolactone (GVL) in the presence of OH, NO, H2O vapor and aerosol seeds ((NH4)(2)SO4 and CaCl2) has been investigated. The results show that the formation of SOA is influenced by the initial concentration of GVL, while it is minor for GBL. The presence of NO decreases the number concentration, mass and yield of particles, while higher humidity and seed surface area increase them. The results suggest that humidity and seed aerosols play a role in the formation of SOA.
ATMOSPHERIC ENVIRONMENT
(2022)
Review
Polymer Science
Jiaxi Xu, Xin Wang, Jingjing Liu, Xiaoshuang Feng, Yves Gnanou, Nikos Hadjichristidis
Summary: Ring-opening polymerization (ROP) is a prevalent and convenient method for synthesizing well-defined polymers with initiators/catalysts. One of the challenges faced by ROP catalysts is the selective activation of functional groups or linkages of the monomer without those carried out in the polymer chains, especially at high conversion. H-bonding organocatalysts can offer precise selectivity for ROP in a wide range of monomers.
PROGRESS IN POLYMER SCIENCE
(2022)
Article
Chemistry, Physical
Krzysztof Kaluzynski, Julia Pretula, Slawomir Kazmierski, Piotr Lewinski, Marek Cypryk, Stanislaw Penczek
Summary: Trimethylene carbonate, a monomer prepared from CO2 and 1,3-propanediol, was polymerized cationically, providing a biocompatible and degradable polymer. Unlike traditional protonic acid catalysis, this polymerization method uses an initiator and catalyst in one molecule, preventing the catalyst from diffusing to the surface of the polymer.
JOURNAL OF CATALYSIS
(2022)
Article
Chemistry, Inorganic & Nuclear
Shijie Deng, Paula L. Diaconescu
Summary: A dimeric yttrium phenoxide complex supported by a ferrocene Schiff base ligand was synthesized and studied for its catalytic activity in ring opening polymerization. Oxidation was found to affect the catalytic activity differently in cyclic esters and epoxides polymerization. Block copolymer syntheses using a redox switch were also performed.
INORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Multidisciplinary
Rajesh K. Jena, Dhiraj Das
Summary: The design and synthesis of a new chiral aminophosphinite-ligated ruthenium complex has been described, which catalyzes the nucleophilic addition of phenol and carboxylic acid to allyl chloride in a highly regioselective fashion with enantiomeric excess ranging from 12 to 90.
Article
Chemistry, Organic
Haruna Araki, Shohei Furuya, Kazuya Kanemoto, Shin-ichi Fukuzawa
Summary: The conjugated addition reaction of 1-pyrroline-5-carbonitrile to alpha-enones was effectively catalyzed by AgF/ThioClickFerrophos (TCF) in diethyl ether in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and nearly single diastereomers of adducts with good enantiomeric excesses (up to 97% ee) were obtained in high yields. The reduction of the nitrile group with H2/Raney Ni in ethanol successfully transformed the conjugate adduct to the corresponding spirocyclic piperidine (60% yield) as a single stereoisomer.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Polymer Science
Zengping Peng, Hassan Ahmed, Guangqiang Xu, Xuanhua Guo, Rulin Yang, Hongguang Sun, Qinggang Wang
Summary: A series of unreported aluminium complexes with chiral cyclohexylsalen ligands were synthesized and used for the asymmetric kinetic resolution polymerization (AKRP) of rac-lactide (LA). These chiral complexes exhibited an interesting stereoselectivity-switch behavior in rac-LA polymerization. Among them, (R,R)-Salen[6-Cl] showed the highest activity for the ROP of rac-LA, while (R,R)-salen[4,6-Br,Bu-t] demonstrated excellent stereoselectivity with enriched isotactic PLA (P-m = 0.88, CEC; P-m = 0.93, ESC). Kinetic study using (R,R)-salen[4,6-Br,Bu-t] as an initiator indicated first-order dependence on monomer concentration with a rate constant ratio k(L)/k(D) = 30. Asymmetric kinetic resolution polymerization provided evidence that the enantiomorphic site control mechanism plays a major role in rac-LA ROP mediated by aluminium catalysts with a bulkier electron donor near the metal center, while the ROP of rac-LA mediated by Al(salen) catalysts with electron-withdrawing groups primarily occurs via the chain end control mechanism.
Article
Chemistry, Multidisciplinary
Jayeeta Bhattacharjee, Alok Sarkar, Tarun K. Panda
Summary: This review highlights the progress of alkali metal-based catalysis for the ring opening polymerization of rac-lactide, critically assesses futuristic research, spotlights major developments achieved in the past few years, and provides an overview of the challenges and opportunities.
CURRENT OPINION IN GREEN AND SUSTAINABLE CHEMISTRY
(2021)
Review
Chemistry, Applied
Farah Naz, Rahaman M. Abdur, Fatima Mumtaz, Mirella Elkadi, Francis Verpoort
Summary: This study reviews the application of heterogeneous catalysts in the ring-opening polymerization of cyclic esters, with a focus on metal-organic frameworks (MOFs) and supported catalysts. The importance of precise design and catalyst stability is emphasized in controlling polymerizations.
APPLIED ORGANOMETALLIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Chi Shing Cheung, Zonglin Qiu, Donghui Li, Huiyun Deng, Handou Zheng, Haiyang Gao
Summary: This study presents experimental and theoretical insights into the polymerization of para-N,N-disubstituted aminostyrene monomers using cationic alpha-diimine palladium complexes. The effects of catalyst structure and monomer substituent were systematically studied. The results show that the monomer substituents have a significant impact on the polymerization turnover frequency and molecular weight of the produced polymers. The study also revealed the mechanism of carbocation generation during the polymerization process.
DALTON TRANSACTIONS
(2023)
Article
Polymer Science
Chi Shing Cheung, Zonglin Qiu, Yinwu Li, Handou Zheng, Heng Gao, Huiyun Deng, Haiyang Gao
Summary: In this study, three different initiating systems were used to polymerize DMAS, and BF3·OEt2 showed the highest efficiency for high-molecular-weight polymer production. However, copolymerization of DMAS and MOS was unsuccessful.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Polymer Science
Soren Schumacher, Sanwardhini Pantawane, Stephan Gekle, Seema Agarwal
Summary: The synthesis and polymerization behavior of four different monofunctional vinyl cyclopropane (VCP) derivatives were investigated. The study found that different VCPs have varying abilities to form hydrogen bonds in their side chains, leading to preorganization and potentially faster polymerization. Although VCPs capable of hydrogen bonding did not show significant differences, a general effect of hydrogen bonds on polymerization behavior was observed.
Review
Energy & Fuels
Ning Li, Heping Xie, Jianjun Hu, Cunbao Li
Summary: This article comprehensively reviews the latest research progress on cyclic hydraulic fracturing (CHF), clarifies six CHF cyclic loading schemes, and discusses the stimulation results. It is difficult to evaluate the advantages and disadvantages of different loading schemes, but confining pressure and fracturing fluid viscosity are key factors affecting the stimulation results of CHF. In addition, through the review and discussion of existing theoretical and numerical models, some aspects for further understanding the failure mechanism of CHF are proposed.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Chemistry, Analytical
Dragoslav Sumarac, Petar Knezevic, Cemal Dolicanin, Maosen Cao
Summary: The study successfully applied the Preisach model to model the plateau problem of mild steel, discussing heat dissipation and locked-in energy of plastic deformation, verifying theoretical results through experiments, and demonstrating the model's capability in predicting the behavior of structures in the elastoplastic region under cyclic loading.
Article
Engineering, Chemical
Yang Ye, Yawu Zeng, Hanqing Sun, Xi Chen, Shufan Cheng, Wenjun Ma
Summary: Improved knowledge of cyclic contact behaviour of brittle particle can be obtained through cyclic compression tests and elastoplastic contact theory. The study reveals significant differences in cyclic contact behaviour between the first cycle and subsequent cycles, and proposes modified contact models to accurately reproduce experimental results. The semi-theoretical cyclic contact model shows good agreement with the main characteristics of cyclic contact behaviour.