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Excessive electric field strength causes the droplets to contact but not coalesce, severely deteriorating the oil–water separation efficiency. The investigation of the non‐coalescence of nonidentical droplets in oil under a DC electric field is conducted using high‐speed photography. The effects of droplet volume ratio and interfacial tension ratio on the characteristics and critical parameters for droplet non‐coalescence are systematically explored. The results show the critical electrocapillary number for the non‐coalescence of nonidentical droplets and critical contact cone angle decreases as the volume sum increases or the interfacial tension ratio decreases, which is related to the competition between the resultant electric field force and the interfacial tension force. These results contribute to optimizing the operating parameters of the electric coalescer and improving the oil–water separation efficiency. [ABSTRACT FROM AUTHOR]

The ring opening copolymerization (ROCOP) of epoxides and cyclic anhydrides is one of the most important ways to synthesize polyesters both in industrial and academic fields. Herein, the zeolitic imidazolate framework‐67 (ZIF‐67) was used as a heterogeneous catalyst for the ROCOP of epoxides and cyclic anhydrides without co‐catalyst and initiator. Notably, the obtained polyesters with alternate structures were proved by the 1H NMR spectrum and FTIR spectrum, which indicate the ROCOP is alternatively copolymerized. Kinetic study of the ROCOP of cyclohexene oxide (CHO) and phthalic anhydride (PA) shows that the polymerization reaction is first‐order kinetics. The apparent activation energy (Ea) of the ROCOP of CHO and PA catalyzed by ZIF‐67 was found to be about 104.4 KJ/mol. A possible mechanism of ROCOP of CHO and PA is that the metal Co coordinates with the oxygen atom on the monomer to weaken the C‐O bond thereby opening the ring structure and initiating the copolymerization reaction. In this study, a new system for the copolymerization of epoxide and anhydride catalyzed by heterogeneous catalysts was discovered, which has important guiding significance. [ABSTRACT FROM AUTHOR]

Photo‐induced reversible complexation‐mediated polymerization (RCMP) is a green and economical method to prepare polymers with precise molecular weights, narrow molecular weight distributions and functionally active chain ends. Covalent organic frameworks (COFs) are a promising heterogeneous photocatalyst for mediating RCMP due to their adjustable structure, band gap, and porosity. In this work, 1,3,5‐triformylphloroglucinol (Tp) and p‐azoaniline (Azo) were selected to construct 2D β‐ketoenamine linked Tp‐Azo‐COF as a heterogeneous photocatalyst to trigger RCMP under white light irradiation. A series of polymers with controllable molecular weight and narrow molecular weight distribution were successfully prepared by using Tp‐Azo‐COF as photocatalysis. On/off light experiments confirmed the good spatiotemporal control feature, and chain expansion experiments demonstrated the high "activity" of polymer chain ends. Furthermore, the mechanistic research elucidated that electron transfer between Tp‐Azo‐COF and initiator occurred, allowing the formation of reactive radicals to mediate RCMP. Density functional theory calculations revealed that the coordination of iodine on the initiator to catalyst obviously reduced the bond dissociation energy, leading to enhance in the polymerization rate. This work provides a platform for constructing heterogeneous photocatalysts with more efficient and stable to mediate RCMP. [ABSTRACT FROM AUTHOR]

Surfactants play an important role in the domain of metal anticorrosion. Gemini surfactants, as corrosion inhibitors, have the advantages of strong practicality, high safety, convenient operation and fast response. In this study, a new Schiff‐base cationic Gemini surfactant (named TMPA) was designed, synthesized and characterized. The mechanism of metal anticorrosion of surfactant was studied by electrochemistry and static weightlessness method. And the adsorption isotherm of TMPA shows that the behavior follows Langmuir adsorption isotherm. The anticorrosion efficiency of printed circuit board (PCB) was 92.88% and Q235 carbon steel (Q235 CS) was 97.78% with the addition of only 5 mM TMPA. The surface appearance of the PCB and Q235 CS was scrutinized by x‐ray photoelectron spectroscopy and scanning electron microscopy, proving that samples have few corrosion marks in the presence of TMPA and oxidants. These results show that TMPA provides an attractive application in terms of metal corrosion inhibition. [ABSTRACT FROM AUTHOR]

Control over polymer architecture and composition is essential for disclosing structure‐property relationships and developing high‐performance materials. Herein, a new method is successfully developed to synthesize bottlebrush polymer (BP) with controllable graft density and side chain composition by "grafting‐from" strategy using in situ halogen exchange and reversible chain transfer catalyzed polymerization (RTCP). The main chain of the BP is first synthesized by the polymerization of methacrylates containing alkyl bromide as a side group. Then, the alkyl bromine is quantitatively converted to alkyl iodide with sodium iodide (NaI) via in situ halogen exchange to efficiently initiate the RTCP of methacrylates. By adjusting the input amount of NaI and monomers in sequence, BP named PBPEMA‐g‐PMMA/PBzMA/PPEGMEMA which contains three different kinds of polymer side chains including hydrophilic PPEGMEMA, hydrophobic PMMA, and PBzMA is synthesized with narrow molecular weight distribution (Mw/Mn ≤ 1.36). The grafting density and the chain length of each polymer side chain are well controlled by the addition of NaI in batches and following RTCP. Moreover, the obtained BP self‐assembled into spherical vesicles in aqueous with hydrophilic coronal structure, core region, and the hydrophobic wall between the former two, which enables to wrap hydrophobic pyrene and hydrophilic Rhodamine 6G separately or simultaneously. [ABSTRACT FROM AUTHOR]

Developing low‐cost and highly efficient hydrophobic absorbents via simple and environmentally friendly method is demanded for oil‐water separation. This paper reports the preparation of hydrophobic absorbents of porous poly(4‐tert‐butylstyrene‐co‐divinylbenzene) (poly(tBS‐co‐DVB)) via high internal phase emulsion (HIPE) template method. The effects of crosslinking degree and internal phase volume fraction on the porous structure and adsorption performance of the absorbents are investigated. As the tBS/DVB molar ratio increases from 1:1 to 4:1, the adsorption performance of poly(tBS‐co‐DVB) toward hexane first increases to a maximum at a molar ratio of 3:1 and then decreases. As the internal phase volume fraction increases, the specific surface area (SSA) and porosity of the poly(tBS‐co‐DVB)s notably increase from 33.06 m2/g and 84.07% to 102.89 m2/g and 92.94%, respectively. When the internal phase fraction is 95 vol%, the obtained poly(tBS‐co‐DVB) foam with a water contact angle of 140° shows an absorbing capacity as high as 70.21 g/g for dichloromethane. After 10 consecutive adsorption‐desorption cycles, the adsorption performance of the poly(tBS‐co‐DVB) foam shows only a slight decrease, indicating an excellent recycling ability. The obtained poly(tBS‐co‐DVB) foams exhibit the advantages of facile preparation, high oil absorption capacity and satisfactory recoverability, which enable them potential as sustainable oil adsorbents. [ABSTRACT FROM AUTHOR]

The generation of cyclic carbonates by the cycloaddition of CO2 with epoxides is attractive in the industry, by which CO2 is efficiently used as C1 source. Herein, a series of catalysts were developed to efficient mediate the cycloaddition of CO2 with epoxides to generate carbonates. The catalysts were easily synthesized via the amine‐formaldehyde condensation of ethidium bromide with a variety of linkers. The newly prepared heterogeneous catalysts have high thermal stability and degradation temperatures. The surface of the catalysts is smooth and spherical in shape. The effect of temperature, pressure, reaction time and catalyst dosage on the cycloaddition of CO2 with epoxide were investigated. The results show that the catalyst with 1,3,5‐tris(4‐formylphenyl)benzene as the linker can achieve 97.4 % conversion efficiency at the conditions of 100 °C, reaction time of 12 h, and the reaction pressure of 1.2 MPa in a solvent‐free environment. Notably, the polymers serve as homogeneous catalysts during the reaction (reaction temperature above Tg) and can be separated and recovered easily as homogeneous catalysts at room temperature. In addition, the catalyst is not only suitable for a wide range of epoxide substrates, but also can be recycled many times. Furthermore, DFT calculations show that the coordination between the electrophilic center of the catalyst and the epoxide reduces the energy barrier, and the reaction mechanism is proposed based on the reaction kinetic studies and DFT calculations. [ABSTRACT FROM AUTHOR]

Two imine‐based covalent organic framework photocatalysts with different building units, TPB‐DMTA‐COF and TAT‐DMTA‐COF, for photo‐induced energy transfer reversible complexation‐mediated radical polymerization (PET‐RCMP) were developed and investigated, producing ideal polymers with accurate molecular weight and moderate dispersity under visible light irradiation. The chain extension and spatiotemporal control experiments revealed the high chain‐end fidelity of polymers and the compatibility of RCMP processes in both bulk and aqueous system. Moreover, density functional theory (DFT) calculations verified that heteroatom‐doped TAT‐DMTA‐COF exhibits higher activities for weakening C−I bond energy barrier, which promotes PET‐RCMP polymerization performance. This work demonstrates that rational adjustment of building block for constructing COF heterogeneous photocatalyst can enhance the catalytic performance of PET‐RCMP, providing a design methodology for the development of polymeric organic photoelectric semiconductor catalysts to mediate RCMP. [ABSTRACT FROM AUTHOR]

Heteroatom doped carbonaceous material with high specific surface area (SSA) is vital for assembling advanced supercapacitor. Here, a moderate and valid strategy is proposed to synthesize N, S co‐doped porous carbons (NSPCs) which are derived from porous resorcinol‐melamine‐formaldehyde‐thiourea (RMFT) resins via high internal phase emulsion (HIPE) template. The morphology, structure, porous characteristics and chemical ingredients of the prepared NSPCs are investigated by SEM, XRD, Raman spectra, and XPS systematically. The obtained NSPCs show typical open‐cell morphology. As the molar ratio of thiourea to melamine (T/M) increased from 0:1 to 2:1, the SSA of NSPC increases gradually from 927 to 1721 m2 g−1. Electrochemical tests show that when T/M is 2:1, the specific capacity of NSPC reaches 213.5 F g−1 at 1 A g−1. After 10,000 charge–discharge cycles at 10 A g−1, the retention ratio of specific capacitance is 99.6%, indicating an excellent cycling stability. Excellent performances together with facile preparation make NSPC via HIPE template a potential candidate as electrode of advanced supercapacitors. [ABSTRACT FROM AUTHOR]

0.5 mol% of the amidinato disilyne [LSi:]2 (1, L=PhC(NtBu)2) and 1 mol% of B(C6F5)3 cooperatively polymerized methyl methacrylate (MMA) to form poly(MMA) with the H and CH2C(=CH2)COMe end groups (P1, Mn=3.1×103 gmol−1; repeating unit, n=31; polydispersity index, Đ: 1.55). The catalytic mechanism is proposed, where compound 1 could react with MMA and B(C6F5)3 to form a zwitterionic active species [LSi{CH2C(Me)=C(OMe)O}B(C6F5)3]2. The latter could activate MMA molecules affording poly(MMA) chains on the silicon centers. The methyl group of the last enolate of a poly(MMA) chain on a silicon center could then react with the Si−C bond of the adjacent poly(MMA) chain to form P1, as well as regenerate compound 1 and B(C6F5)3. When compound 1 was replaced by the amidinato amidosilylene [LSiN(SiMe3)2] (2), 1 mol% of compound 2 and 1 mol% of B(C6F5)3 mediated living MMA polymerization in toluene to form the poly(MMA) P2 (Mn=1.04×104 gmol−1; Đ: 1.97). [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a class of promising photocatalysts for conversing light energy into chemical energy. Based on the tunable building blocks, COFs can be well‐designed as photocatalyst for mediating reversible addition‐fragmentation chain‐transfer (RAFT) polymerization. Herein, 1,3,6,8‐tetrakis(4‐formylphenyl)pyrene (TFPPy) and 2,2″‐bipyridine‐5,5″‐diamine (Bpy) are chosen to construct imine‐based TFPPy‐Bpy‐COFs for catalyzing RAFT polymerization of methacrylates under white light irradiation. The well‐defined polymers with precise molecular weight and narrow molecular weight distribution are obtained. The switch on/off light experiments suggest excellent temporal control toward RAFT polymerization system and the chain‐extension reaction indicates high chain‐end fidelity of macro‐initiators. Mechanism study clarifies that the electron transfer between excited state of TFPPy‐Bpy‐COFs and RAFT agent can form living radicals to mediate polymerization. This methodology provides a novel platform for reversible‐deactivation radical polymerization using COFs as heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Carbon‐supported metal nanoparticles (NPs) play important roles in heterogeneous catalysis. In particular, supported bimetallic catalytic systems can be promising multifunctional catalysts for one‐pot tandem/cascade reactions, in which two or more successive independent reactions are realized in one pot. In this manuscript, we report the preparation of a carbon‐supported bimetallic CoCu catalytic system (Co−C@Cu−C), with Co NPs wrapped by carbon‐supported Cu NPs, from the pyrolysis of a core‐shell structured Co−MOF‐74@Cu−MOF‐74. The as‐obtained Co−C@Cu−C acts as a bifunctional catalyst for the transformation of phenylacetylene to 1, 4‐diphenyl‐1, 3‐butadiene in one pot, in which supported metallic Cu NPs and Co NPs are active for the coupling and hydrogenation reaction respectively. By tuning the reaction rates of the coupling and the hydrogenation in this tandem reaction over the Co−C@Cu−C via changing the reaction medium and the reducing agent, an efficient direct transformation of phenylacetylene to 1, 4‐diphenyl‐1, 3‐butadiene was realized. This work not only highlights the important role of MOFs in the preparation of multifunctional carbon supported metal NPs for heterogeneous catalysis, but also demonstrates the possibility of tuning the reaction rates of different catalytic steps in a tandem reaction to realize an efficient overall reaction. [ABSTRACT FROM AUTHOR]

A series of dimolybdenum metal catalysts with different ligand have been successfully synthesized and used to catalyze the epoxidation of alkenes to generate epoxides by using tert‐butyl‐hydroperoxide (TBHP) as oxidant. The reaction condition was optimized by the adjustment of some key parameters, such as, temperature, to target high catalytic performance. The oxidation of cyclooctene gave 95.00% conversion and almost 100.00% selectivity. Kinetic study of the oxidation of cyclooctene under different temperature was taken out, indicating the reaction have good catalytic performance. Furthermore, it is calculated from the Arrhenius equation that different functional groups affect the activation energy of the reaction. The electron donor group substituent on the liagnd increases the catalytic activity by reducing the activation energy, and vice versa. Finally, a possible catalytic mechanism has been proposed by measuring the electronic absorption spectrum of the reaction. [ABSTRACT FROM AUTHOR]

The present contribution describes an innovation in the copolymerization of cyclic monomers, ε-caprolactam ( ε- CL) and 2,2-dimethyltrimethylene carbonate ( DTC), with ethyl diazoacetate ( EDA). The characterizations of the obtained copolymers, poly( EA- ran- EDA- ran-ε- CL) and poly( EA- ran- EDA- ran- DTC) (where EA refers to the ethyl acetate group from EDA after nitrogen release), were performed using 1H NMR and 13C NMR spectroscopies and size exclusion chromatography. Under optimized conditions, the copolymer of ε- CL with EDA possessing a number-average molar mass ( Mn) of 1300 g mol−1 and dispersity of 2.12 as well as that of DTC with EDA with Mn of 8000 g mol−1 and dispersity of 1.47 were obtained. The incorporation of the azo group in the obtained copolymers was determined from the results of elemental analysis (3.30-10.22% nitrogen) and Fourier transform infrared spectroscopy. Furthermore, the thermal properties of the obtained copolymers were examined using differential scanning calorimetry. X-ray diffraction results showed that the synthesized copolymers were amorphous. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The ring-opening polymerization (ROP) of a cyclic ester using alkyl acetate carbene (ROCOCH:) is generated from diazoacetate as organocatalyst under microwave irradiation, which enables the one-pot preparation of copolymers of polyester and polyolefin. The chemical structure of the polymerized product is characterized by NMR, Fourier transformed infrared (FTIR), and UV-vis spectroscopy. The incorporation of the azo group into the obtained copolymer is determined by elemental analysis, which indicates that 1.38-6.21% nitrogen is contained in the obtained copolymers. The influences of catalyst and microwave irradiation parameters on the polymerization are investigated. Both the microwave power and irradiation time have great influences on the copolymerization. Moreover, the molar mass of the obtained polymers is calculated with polystyrene standards, which gradually increases from 600 to 36 100 g mol−1 as the reaction temperature increases from 60 to 120 °C. Poly­mer with [ABSTRACT FROM AUTHOR]