SYNTHESIS AND PROPERTIES OF NOVEL POLY(IMINO KETONE)S AS HIGH-PERFORMANCE POLYMERS

Di(4-bromophenyl)ketone and various aromatic diamines as the monomers,a series of novel poly(imino ketone)s (PIKs)have been synthesized via palladium-catalyzed aryl amination,which is Hartwig-Buchwald polycondensation reaction.The structures of PIKs are characterized by means of elemental analysis,FT-IR,~1H-NMR and UV-Vis spectroscopy. The results show a good agreement with the proposed structure.The general properties of PIKs are studied by DSC,TG and wide-angle X-ray diffraction,the solubility behavior...     

CaO solubility and activity coefficient in molten salts CaCl2–x (x = 0, NaCl, KCl, SrCl2, BaCl2 and LiCl)

CaO solubility in equimolar molten salts CaCl₂–x (x = 0, NaCl, KCl, SrCl₂, BaCl₂ and LiCl) was determined at 873–1223 K and activity coefficient calculated. CaO solubility in the binary salts is less than in CaCl₂, and the activity coefficient is greater than one. With increasing temperature CaO solubility increases and the activity coefficient decreases. The dependency of CaO activity coefficient on temperature in equimolar molten salts CaCl₂–x is

CaCl2	RTln γCaO = 6961 + 5.06 T (K)	1123–1223 K
CaCl2–NaCl	RTln γCaO = 3985 + 17.67 T (K)	923–1123 K
CaCl2–KCl	RTln γCaO = 2384 + 22.72 T (K)	1073–1223 K
CaCl2–SrCl2	RTln γCaO = 27245–1.13 T (K)	1073–1223 K
CaCl2–BaCl2	RTln γCaO = 17068 + 10.19 T (K)	1223–1273 K
CaCl2–LiCl	RTln γCaO = 14724 + 0.72 T (K)	923–1073 K

Full-size table

     

Enolic schiff base aluminum complexes and their catalytic stereoselective polymerization of racemic lactide

A series of enolic Schiff base aluminum(III) complexes LAlR (where L=NNOO-tetradentate enolic Schiff base ligand) containing ligands that differ in their steric and electronic properties were synthesized. Their single crystals showed that these complexes are five-coordinated around the aluminum center. Their coordination geometries are between square pyramidal and trigonal bipyramidal. Their catalytic properties in the solution polymerization of racemic lactide (rac-LA) were examined. The modifications in the auxiliary ligand exhibited a dramatic influence on the catalytic performance. Lengthening the backbone from C(2) alkylene to C(3) alkylene resulted in remarkable enhancement of both the stereoselectivity and the polymerization rate because of the increasing flexibility of the diimine backbone. Electron-withdrawing substituents in the diketone also highly improved the activity and the stereoselectivity. Among these complexes, 4 b had the highest activity and the stereoselectivity owing to the C(3) alkylene backbone and the two gem-methyl groups on the middle carbon atom. The value of the polymerization rate constant (k(p)) catalyzed by 4 b in 70 degrees C was 1.90 L mol(-1) min(-1), the activation energy of the polymerization (35.4 kJ mol(-1)) was calculated according to the Arrhenius equation. Other factors that influenced the polymerization, such as the polymerization time, the temperature, and the monomer concentration, are also discussed in detail.     

BaCe0.5Zr0.4Y0.1O3-δ粉体的溶胶-凝胶法和高温固相法制备及性能表征

分别通过溶胶-凝胶法和高温固相反应法制备了BaCe0.5Zr0.4Y0.1O3-δ粉体.采用热重-差热分析(TG-DTA),粉末X射线衍射(XRD),扫描电子显微镜(SEM),傅立叶红外衍射(FT-IR),N2吸附-脱附等方法对所制备的粉体进行了表征.结果表明:用溶胶-凝胶法在1200 ℃×10 h可以合成纯的BaCe0.5Zr0.4Y0.1O3-δ粉体,合成温度比传统的高温固相反应法降低400 ℃左右;溶胶-凝胶法合成粉体具有多孔结构特征,与固相法合成粉体相比具有较高的比表面积.但致密化试验表明:溶胶-凝胶法合成粉体与固相法合成粉体相比具有较低的烧结活性.溶胶-凝胶法合成粉体颗粒表面残余的有机基团和颗粒内部的大量微孔将在致密化过程中产生空间位阻,从而影响高温下原子的迁移,阻碍材料的致密化过程.     

Efficient and green tetrahydropyranylation and deprotection of alcohols and phenols by using activated carbon supported sulfuric acid

A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.     

Inter versus intra-molecular photoinduced charge separation in solid films of donor-acceptor molecules

We report on photoinduced charge separation in solid films of two perylene diimides; intramolecular charge separation and recombination is correlated with a reduction in the yield of long-lived, intermolecular charge-separated species.     

Self-assembly of star ABC triblock copolymer thin films: self-consistent field theory

Microphase separation and morphology of star ABC triblock copolymers confined between two identical parallel walls (symmetric wetting or dewetting) are investigated with self-consistent field theory (SCFT) combined with the "masking" technique to describe the geometric confinement of the films. In particular, we examine the morphology of confined near-symmetric star triblock copolymers under symmetric and asymmetric interactions as a function of the film thickness and the surface field. Under the interplay between the degree of spatial confinement, characterized by the ratio of the film thickness to bulk period, and surface field, the confined star ABC triblock copolymers are found to exhibit a rich phase behavior. In the parameter space we have explored, the thin film morphologies are described by four primary classes including cylinders, perforated lamellae, lamellae, and other complex hybrid structures. Some of them involve novel structures, such as spheres in a continuous matrix and cylinders with alternating helices structure, which are observed to be stable with suitable film thickness and surface field. In particular, complex hybrid network structures in thin films of bulk cylinder-forming star triblock copolymers are found when the natural domain period is not commensurate with the film thickness. Furthermore, a strong surface field is found to be more significant than the spatial confinement on changing the morphology of star triblock copolymers in bulk. These findings provide a guide to designing novel microstructures involving star triblock copolymers via geometric confinement and surface fields.     

Recent advances in multimode microfluidic separation of particles and cells

Microfluidic separation of particles and cells is crucial to lab-on-a-chip applications in the fields of science, engineering, and industry. The continuous-flow separation methods can be classified as active or passive depending on whether the force involved in the process is externally imposed or internally induced. The majority of current separations have been realized using only one of the active or passive methods. Such a single-mode process is usually limited to one-parameter separation, which often becomes less effective or even ineffective when dealing with real samples because of their inherent heterogeneity. Integrating two or more separation methods of either type has been demonstrated to offer several advantages like improved specificity, resolution, and throughput. This article reviews the recent advances of such multimode particle and cell separations in microfluidic devices, including the serial-mode prefocused separation, serial-mode multistage separation, and parallel-mode force-tuned separation.     

一种水中稳定的锌(Ⅱ)金属有机骨架用于检测四环素

采用溶剂热法合成1个锌(Ⅱ)金属有机骨架（Zn-MOF）：[Zn (H₂L)(4,4''-bpy)]_n (1),其中H₄L=1,1''-乙烷基联苯-3,3'',5,5''-四羧酸,4,4''-bpy=4,4''-联吡啶。通过单晶X射线衍射、元素分析和热重分析等方法对其结构进行表征。单晶结构分析表明,1属于单斜晶系C2/c空间群,H₂L^2-配体采取单齿配位模式连接Zn (Ⅱ)形成一维链,4,4''-bpy连接一维链构筑成二维波浪状网。该化合物在水中表现出良好的稳定性,并且可作为高灵敏度、高选择性荧光探针检测四环素(TET),其检出限为0.17 μmol·L^-1。1可成功用于延河水中TET的测定。此外,还研究了1对TET的荧光猝灭机理。     

Reversible Zn Metal Anodes Enabled by Trace Amounts of Underpotential Deposition Initiators

Routine electrolyte additives are not effective enough for uniform zinc (Zn) deposition, because they are hard to proactively guide atomic-level Zn deposition. Here, based on underpotential deposition (UPD), we propose an “escort effect” of electrolyte additives for uniform Zn deposition at the atomic level. With nickel ion (Ni²⁺) additives, we found that metallic Ni deposits preferentially and triggers the UPD of Zn on Ni. This facilitates firm nucleation and uniform growth of Zn while suppressing side reactions. Besides, Ni dissolves back into the electrolyte after Zn stripping with no influence on interfacial charge transfer resistance. Consequently, the optimized cell operates for over 900 h at 1 mA cm⁻² (more than 4 times longer than the blank one). Moreover, the universality of “escort effect” is identified by using Cr³⁺ and Co²⁺ additives. This work would inspire a wide range of atomic-level principles by controlling interfacial electrochemistry for various metal batteries.