Liquid-liquid phase behavior of toluene/polyethylene oxide/poly(ethyleneoxide-b-dimethylsiloxane) polymer-containing ternary mixtures

The experimental data of phase diagrams for both polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) binary and toluene/polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) ternary polymer-containing systems was obtained at atmosphere pressure by light scattering method. The critical points for some pre-selected compositions and the pressure effect on the phase transition behavior of ternary system were investigated by turbidity measurements. The chosen system is a mixture of ternary which is one of the very few abnormal polymer-containing systems exhibiting pressure-induced both miscibility and immiscibility. This unusual behavior is related to the toluene concentration in the mixtures. The effect of toluene on the phase transition behavior of the ternary polymer-containing mixture was traced. Such behavior can make it possible to process composite materials from incompatible polymers.

Abnormal pressure dependence of the phase boundaries in TL/PEO/P(EO-b-DMS) ternary mixtures

The cloud-point temperatures (T-cl's) of both binary poly(ethylene oxide) (PEO)-poly(ethylene oxide-b-dimethylsiloxane) [P(EO-b-DMS)] and ternary[toluene/PEO/P(EO-b-DMS)] systems were determined by light scattering measurements at atmospheric pressure. The phase separation behavior upon cooling in the ternary system has been investigated at atmospheric pressure and under high pressure and compared to the phase behavior in the binary system. The phase transition temperatures have been obtained for all of the samples. As a result, the pressure induces compatibility in the binary mixtures, but for the ternary system, pressure not only can induce mixing but also can induce phase separation.

Thermodynamics of phase behavior in PEO/P(EO-b-DMS) homopolymer and block co-oligomer mixtures under pressure

The cloud-point temperatures (T-cl's) of poly(ethylene oxide) (PEO) and poly(ethylene oxide)-block-polydimethylsiloxane (P(EO-b-DMS)) homopolymer and block-oligomer mixtures were determined by turbidity measurements over a range of temperatures (105 to 130degrees), pressures (1 to 800 bar), and compositions (10-40 wt.-% PEO). The system phase separates upon cooling and T-cl was found to decrease with an increase in pressure for a constant composition. In the absence of special effects, this finding indicates negative excess volumes. Special attention was paid to the demixing temperatures as a function of the pressure for the different polymer mixtures and the plots in the T-phi plane (where phi signifies volume fractions). The cloud-point curves of the polymer mixture under pressures were observed for different compositions. The Sanchez-Lacombe (SL) lattice fluid theory was used to calculate the spinodals, the binodals, the Flory-Huggins (FH) interaction parameter, the enthalphy of mixing, and the volume changes of mixing. The calculated results show that modified P(EO-b-DMS) scaling parameters with the new combining rules can describe the thermodynamics of the PEO/P(EO-b-DMS) system well with the SL theory.

A two-dimensional molybdenum (V) phosphate with covalently bonded transition metal coordination complexes: hydrothermal synthesis and structure characterization of Na-2[{Mn(phen)(2)(H2O)}{Mn(phen)(2)}(3){Mn (Mo12O24)-O-V (HPO4)(6)(PO4)(2)(OH)(6)}] center dot 4H(2)O (phen=1,10-phenanthroline)

An organic-inorganic hybrid molybdenum phosphate, Na-2[{Mn(phen)(2)(H2O)} {Mn(phen)(2)}(3){(MnMo12O24)-O-v (HPO4)(6)(PO4)(2) (OH)(6)}] . 4H(2)O (phen=1,10-phenanthroline), involving molybdenum present in V oxidation state and covalently bonded transition metal coordination complexes, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a=16.581(l)Angstrom, b=18.354(1)Angstrom, c=24.485(2)Angstrom, alpha=80.589(l)degrees, beta=71.279(1)degrees, gamma=67.084(1)degrees, V=6493.8(8)Angstrom(3), Z=2, lambda(MoKalpha)=0.71073Angstrom (R(F)=0.0686 for 29,053 reflections). Data were collected on a Bruker Smart Apex CCD diffractometer at 293 K in the range of 1.76 < theta < 28.06degrees using omega-2theta scans technique. The structure of the title compound may be considered to be based on {Mo6O12(HPO4)(3)(PO4)(OH)(3)} units bonded together with {Mn(phen)(2)} subunits into a two-dimensional network. Two types of tunnels are observed in the solid of the title compound.

Synthesis of poly(epsilon-caprolactone)-b-poly(gamma-benzyl-L-glutamic acid) block copolymer using amino organic calcium catalyst

A biodegradable two block copolymer, poly(epsilon-caprolactone)-b- poly(gamma-benzyl-L-glutamic acid) (PCL-PBLG) was synthesized successfully by ring-opening polymerization of N-carboxyanhydride of gamma-benzyl-L-glutamate (BLG-NCA) with aminophenyl-terminated PCL as a macroinitiator. The aminophenethoxyl-terminated PCL was prepared via hydrogenation of a 4-nitrophenethoxyl-teminated PCL, which was novelly obtained from the polymerization of c-caprolactone (CL) initiated by amino calcium 4-nitrobenzoxide. The structures of the block copolymer and its precursors from the initial step of PCL were confirmed and investigated by H-1 NMR, FT-IR, GPC, and FT-ICRMS analyses and DSC measurements.

采用新萃取方法的PP-b-PE的研究

采用独特的二次溶解和沉淀的萃取方法,将PP b PE中的不可溶物与可溶物分离,并通过1 3C NMR,DSC,FT IR进行结构与性能的研究

Ion channel behavior of amphotericin B in sterol-free and cholesterol- or ergosterol-containing supported phosphatidylcholine bilayer model membranes investigated by electrochemistry and spectroscopy

Amphotericin B (AmB) is a popular drug frequently applied in the treatment of systemic fungal infections. In the presence of ruthenium (II) as the maker ion, the behavior of AmB to form ion channels in sterol-free and cholesterol- or ergosterol-containing supported phosphatidylcholine bilayer model membranes were studied by cyclic votammetry, AC impedance spectroscopy, and UV/visible absorbance spectroscopy. Different concentrations of AmB ranging from a molecularly dispersed to a highly aggregated state of the drug were investigated. In a fixed cholesterol or ergosterol content (5 mol %) in glassy carbon electrode-supported model membranes, our results showed that no matter what form of AmB, monomeric or aggregated, AmB could form ion channels in supported ergosterol-containing phosphatidylcholine bilayer model membranes. However, AmB could not form ion channels in its monomeric form in sterol-free and cholesterol-containing supported model membranes. On the one hand, when AmB is present as an aggregated state, it can form ion channels in cholesterol-containing supported model membranes; on the other hand, only when AmB is present as a relatively highly aggregated state can it form ion channels in sterol-free supported phosphatidylcholine bilayer model membranes. The results showed that the state of AmB played an important role in forming ion channels in sterol-free and cholesterol-containing supported phosphatidylcholine bilayer model membranes.

Preparation and characterization of PSt-b-PHEMA metal hybrids

The block copolymer polystyrene-b-poly[2-(trimethylsilyloxy)ethylene methacrylate] (PSt-b-PTMSEMA) was synthesized using atom-transfer radical polymerization (ATRP). The hydrolysis of PSt-b-PTMSEMA led to the formation of an amphiphilic block copolymer, polystyrene-b-poly(2-hydroxylethyl methacrylate) (PSt-b-PHEMA), which was characterized by GPC and H-1-NMR. TEM showed that the PSt-b-PHEMA formed a micelle, which is PSt as the core and PHEMA as the shell. Under appropriate conditions, the nickel or cobalt ion cause chemical reactions in these micelles and could be reduced easily. ESCA analysis showed that before reduction the metal existed as a hydroxide; after reduction, the metal existed as an oxide, and the metal content of these materials on the surface is more than that on the surface of the copolymer metal ion. XRD analysis showed that the metal existed as a hydroxide before reduction and existed as a metal after reduction.

杂质离子对Y_2O_3∶Eu~(3+)发光性能的影响

研究了碱金属及碱土金属离子掺杂的荧光体Y2 O3∶Eu3+ 0 .0 5,A+ 0 .0 2 (A =Li、Na、K)和Y2 O3∶Eu3+ 0 .0 5,B2 + 0 .0 2 (B =Mg、Ca、Sr、Ba)的荧光、余辉发光及热释光特性。余辉光谱数据表明 :杂质离子掺杂的荧光体Y2 O3∶Eu3+ 的余辉发射主峰与未掺杂荧光体Y2 O3∶Eu3+ 的荧光发射主峰 (611nm)一致 ,为经典Eu3+ 的5D0 7F2 电偶极跃迁 ;杂质离子的引入明显地延缓了Y2 O3∶Eu3+ 的余辉衰减 ,其中Y2 O3∶Eu3+ ,A+ (A =Li、Na、K)的余辉衰减趋势几乎完全一致 ,而Y2 O3∶Eu3+ 、B2 + (B =Mg、Ca、Sr、Ba)的余辉衰减趋势由慢到快依次为Ca、Sr、Ba、Mg。热释光谱数据显示 ,杂质离子的掺杂导致基质中电子陷阱能级的生成 ,这是导致余辉衰减减慢的直接原因。Y2 O3∶Eu3+ ,A+ 的热释峰都位于 175℃左右 ,相应电子陷阱能级深度为 0 .966eV左右 ;而Y2 O3∶Eu3+ ,B2 + 的热释峰由高到低分别位于 192℃ (Ca)、164℃ (Sr)、1...

Observation of inverted phases in poly(styrene-b-butadiene-b-styrene) triblock copolymer by solvent-induced order-disorder phase transition

We report observation of inverted phases consisting of spheres and/or cylinders of the majority fraction block in a poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer by solvent-induced order-disorder phase transition (ODT). The SBS sample has a molecular weight of 140K Da and a polystyrene (PS) weight fraction of 30%. Tapping mode atomic force microscopy (AFM) and transmission electron microscopy (TEM) were utilized to study the copolymer microstructure of a set of solution-cast SBS films dried with different solvent evaporation rates, R. The control with different R leads to kinetic frozen-in of microstructures corresponding to a different combination parameter chi (eff)Z of the drying films (where chi (eff) is the effective interaction parameter of the polymer solution in the cast film and Z the number of "blobs" of size equal to the correlation length one block copolymer chain contains), for which faster evaporation rates result in microstructures of smaller chi (eff)Z. As R was decreased from rapid evaporations (similar to0.1 mL/h), the microstructure evolved from a totally disordered one sequentially to inverted phases consisting of spheres and then cylinders of polybutadiene (PB) in a PS matrix and finally reached the equilibrium phase, namely cylinders of PS in a PB matrix. We interpret the formation of inverted phases as due to the increased relative importance of entropy as chi (eff)Z is decreased, which may dominate the energy penalty for having a bigger interfacial area between the immiscible blocks in the inverted phases.

VUV excitation properties of LnAl(3)B(4)O(12): Re (Ln = Y, Gd; Re=Eu, Tb)

Vacuum ultraviolet excitation spectra of LnAl(3)B(4)O(12):Re (Ln = Y, Gd; Re = Eu, To), along with X-ray photoelectron spectra, were measured. The spectra are tentatively interpreted in terms of the optical properties of the rare earth ions and the band structure. It was found that there is an energy transfer from the hosts to the rare earth ions. It was also found that the top of the valence band in the Gd compound is mainly formed by the 2p levels of O2- and the 4f levels of Gd3+, and in the Y compound mainly by the 2p levels of O2-. (C) 2000 Elsevier Science Ltd. All rights reserved.

一些含半夹心结构ⅥB族金属的1,1’-二硫(硒)二茂铁化合物的合成

CpCr(NO)(CO)_2与Fe(C_5H_4S)_2S反应,形成氧化-还原产物CpCr(NO)(SC_5H_4)_2Fe(1)。双杂核二茂铁化合物CpM(NO)(EC_5H_4)_2Fe[M=Mo,E=S(2a),Se(2b);M=W,E=S(4a),Se(4b)]、CpMo(NO)(SC_5H_4)_2Fe(3)、Cp_2Mo(SeC_5H_4)_2Fe(6)和Cp_2W(SC_5H_4)_2Fe(7)可通过Fe(C_5H_4ELi)_2·2THF(E=S,Se)与CpM(NO)I_2(M=Mo,W)、[CpMo(NO)I_2]_2或Cp_2MCl_2(M=Mo,W)反应制得。三核杂原子二茂铁化合物[CpCr(NO)_2]_2(EC_5H_4)_2Fe[E=S(8a),Se(8b)],由Fe(C_5H_4ELi)_2·2THF(E=S,Se)与二倍摩尔量的CpCr(NO)_2I反应制备。通过AgBF_4氧化2a得到二茂铁离子型化合物[CpMo(NO)(SC_5H_4)_2Fe]~+BF_4~-(5)。采用元素分析、红外光谱、~1H和~(13)C NMR谱以及EI-MS表征了所合成的新型化合物。

ABF_3:Eu,Gd(A:K,Li;B:Ba,Mg)中Gd~(3+)→Eu~(2+)的能量传递

通过高温固相反应法,在高纯N_2气氛中合成了BaLiF_3,KMgF_3中单掺和双掺Eu,Gd的ABF_3型复合氟化物。研究了各类掺杂体系的光谱特性,观察到了Gd~(3+)→Eu~(2+)的能量传递,分析了能量传递过程,探讨了能量传递机理,并讨论了Gd~(3+)和Eu~(2+)的取代格位。

Hydrothermal synthesis and structure of [{Mo8V4O36(VO4)(VO)(2)}(n)](7n-) bi-capped alpha-Keggin fragments linked to a chain

The title compound, (H(2)en)(3)H3O {MO8V4O36 (VO4) (VO)(2)} . 4H(2)O, was hydrothermally synthesized and structurally characterized by means of IR, ESR spectrum and single crystal X-ray diffraction. It crystallized in a monoclinic system with space group P2(1)/c, a=1. 980 4(4) nm, b=2. 063 4(4) nm, c=1. 192 0(2) nm, (beta =94. 76(3)degrees and deep black colour. The compound contains V-centered bi-capped alpha -Keggin fragments {Mo8V7O42} that are linked together by edge-shared units (VO5)-O-N via V-O-V bonds, forming a chain.