Impact of dynamic covalent chemistry and precise linker length on crystallization kinetics and morphology in ethylene vitrimers

Vitrimers, dynamic polymer networks with topology conserving exchange reactions, can lead to unusual evolution of the melting temperature and crystal structure of ethylene networks.

Synthesis, structural and photophysical properties of dimethyl-phosphino(perfluoro-)phenylene-based gold(I) dimers

Starting with 1,2 dibromobenzene and 1,2,3,4 tetrafluorobenzene, dimethyl(2-(trimethylstannyl)phenyl)phosphane, Me2P(o-C6H4)SnMe2, and dimethyl-[2,3,4,5-tetrafluoro 6 (trimethylstannyl)phenyl]phosphane, Me3P(o-C6F4)SnMe3, were synthesized and used in tin-gold exchange reactions to prepare two gold(I) dimers, bis[(2 dimethylphosphino)phenyl]di-gold(I), [Au2(μ2-C6H4PMe2)2],...

The crystal and defect structures of polar KBiNb2O7

KBiNb2O7 was prepared from RbBiNb2O7 by a sequence of cation exchange reactions which first convert RbBiNb2O7 to LiBiNb2O7, before KBiNb2O7 is formed by a further K-for-Li cation exchange. A combination...

Investigations on Reactivity, Stability and Biological Activity of Halido (NHC)gold(I) Complexes

The significance of the halido ligand (Cl-, Br-, I-) in halido[3-ethyl-4-phenyl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) complexes (2, 3, 4) in terms of ligand exchange reactions, including the ligand scrambling to the bis[3-ethyl-4-phenyl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) complex (5)...

Insights into Sorption–Mineralization Mechanism for Sustainable Granular Composite of MgO-CaO-Al2O3-SiO2-CO2 Based on Nanosized Adsorption Centers and Its Effect on Aqueous Cu(II) Removal

Although copper is needed for living organisms at low concentrations, it is one of the pollutants that should be monitored along with other heavy metals. A novel and sustainable composite mineralizing sorbent based on MgO-CaO-Al2O3-SiO2-CO2 with nanosized adsorption centers was synthesized using natural calcium–magnesium carbonates and clay aluminosilicates for copper sorption. An organometallic modifier was added as a temporary binder and a source of inovalent ions participating in the reactions of defect formation and activated sintering. The sorbent-mineralizer samples of specified composition and properties showed irreversible sorption of Cu2+ ions by the ion exchange reactions Ca2+ ↔ Cu2+ and Mg2+ ↔ Cu2+. The topochemical reactions of the ion exchange 2OH− → CO32−, 2OH− → SO42− and CO32− → SO42− occurred at the surface with formation of the mixed calcium–copper carbonates and sulfates structurally connected with aluminosilicate matrix. The reverse migration of ions to the environment is blocked by the subsequent mineralization of the newly formed interconnected aluminosilicate and carbonate structures.

TENSILE AND STRETCH OF PAPER FILLED WITH BACTERICIDAL ZEOLITES

The purpose of present work was to study tensile and stretch of paper prepared with the use of bactericide zeolite fillers containing up to 130 mg/g of silver, 72 mg/g of copper, and 58 mg/g of zinc, prepared by ion exchange reactions using heulandite-clinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia. Filled papers with zeolite content up to 4 g/m2 and bactericidal activity confirmed by the colony forming unit assay were manufactured on the production lines of the GPM enterprise (Tbilisi, Georgia). The measured tensile strength and percentage elongation of filled paper depend on the nature of the filler and its metal content; the introduction of pure zeolite filler reduces the tensile and stretch of the paper, but fillers containing silver and copper increase the tensile strength. Accelerated aging results in lower tensile and stretch, but zeolite fillers generally make the paper more resistant to aging.

Geochemical Modeling of Hybrid Surfactant and Engineered Water Injections in Carbonate Reservoirs under Harsh Conditions

Engineered water injection (EWI) has gained popularity as an effective technique for enhancing oil recovery. Surfactant flooding is also a well-established and commercially-available technique in the petroleum industry. In this study, a numerical simulation model is developed and used to investigate the hybrid effect of surfactant-EWI in carbonates. This developed model was validated by history-matching a recently conducted surfactant coreflood in the secondary mode of injection. Oil recovery, pressure drop, and surfactant concentration data were utilized. The surfactant flooding model was then coupled with a geochemical model that captures different reactions during engineered water injection. The geochemical reactions considered include: aqueous, dissolution/precipitation, and ion- exchange reactions. Also, different simulation scenarios were considered including waterflooding, surfactant flooding, engineered water injection, and the hybrid surfactant-EWI technique. For the case of EWI, wettability alteration was considered as the main mechanism underlying incremental oil recovery. However, both wettability alteration and interfacial tension reduction mechanisms were considered for surfactant flooding depending on the type of surfactant used. The results showed that for the hybrid surfactant-EWI, wettability alteration is considered as the controlling mechanism where surfactant boosts oil recovery rate through increasing oil relative permeability while EWI reduces residual oil. Moreover, the simulation runs showed that the hybrid surfactant-EWI is a promising technique for enhancing oil recovery from carbonates under harsh conditions. The hybrid surfactant-EWI outperformed other injection techniques followed by EWI, then surfactant flooding, and least waterflooding. This work gives more insight into the application of hybrid surfactant-EWI on enhancing oil recovery from carbonates.

Conversion of Electrochemically Deposited Aragonite Crystallites to Perovskite through In Situ Ion Exchange

The unique and broadly applicable optoelectronic properties of metal-halide perovskite materials are determined by structural dimensionality. Conversion of scaffold supported carbonate salts to perovskite with microstructure retention has previously been shown to act as a gateway to unique morphologies. In the present work, calcium carbonate microstructures are electrochemically deposited on a transparent conducting oxide substrate. Through a series of ion-exchange reactions the microstructures are decorated with a layer of surface localized perovskite nanocrystals, indicating that this ion exchange process occurs at the microstructure surface. Throughout the conversion process, electron microscopy confirms that the microstructures retain their overall morphology while cubic perovskite nanocrystals exhibiting characteristic photoluminescence and photoblinking are formed at the interface. This work confirms a synthetic pathway in which perovskites can be made in shapes previously inaccessible, which may lead to enhanced optoelectronic properties.