Thermal Behaviour of Transition Metal-Containing Zirconium Phosphate

The thermal behaviour of Co(II), Ni(II) and Zn(II)-containing zirconium phosphate of α type was investigated. XRPD analysis revealed that, for the samples containing Co(II) or Ni(II), the first reflection of the solid phase is split into a doublet. In contrast, when Zn(II) is present, a single solid phase system is formed. The thermal behaviour of the materials followed this sequence. For the samples containing Co(II) or Ni(II), phase-transition processes were found and there was also a loss of crystal water, but for the sample containing Zn(II) there was only one endothermic effect, which corresponded to the decomposition of phosphate groups. This revised version was published online in July 2006 with corrections to the Cover Date.     

多孔二氧化硅对聚环氧乙烷结晶行为的影响

高分子化合物由于具有很长的分子链,不易进行规整排列,结晶速度通常很慢,为提高结晶速度,有时需要加入成核剂．多孔二氧化硅（ＳｉＯ２）具有较大的比表面积,故吸附作用较强,有可能作为成核剂影响部分结晶高聚物的结晶过程．聚环氧乙烷（ＰＥＯ）为部分结晶高聚物,其结晶行为对杂质较为敏感．本文目的在于通过结晶动力学及结晶与熔融行为的研究,探索多孔二氧化硅对ＰＥＯ结晶行为的影响．１　实验部分　　聚环氧乙烷（ＰＥＯ,Ｍｗ＝１×１０５）．两种多孔二氧化硅（ＳｉＯ２）按文献［１］方法制备,平均粒度为０．３μｍ,平均孔…     

TiO~2光催化降解苯乙酸苄酯的研究

研究了苯乙酸苄酯在各种不同条件下的光化学反应和苯乙酸苄酯在TiO~2的悬浮体系中的光化学反应,比较了这两种条件下光降解的效果。并对反应机理进行了初步探讨。     

Mathematical modeling of TE CO2 laser with SF6 as a saturable absorber

A mathematical model describing the dynamic emission of a single mode TE CO₂ laser with saturable absorber has been adapted. A six-temperature model has been used to describe the amplifying medium, while a four-coupled energy level is used to describe the selective absorbing medium. The suggested mathematical model allows the investigation of the effects of the intracavity absorber on the mode characteristics of the TE CO₂ laser and, moreover, the study of the effect of the laser input parameters on the output laser pulse. The model simulates the passive Q-switch in both low- and high-pressure cases in the absorbing medium.

In addition, numerical solutions of a non-linear rate equation system of the suggested model are quantitatively discussed. The solutions describe the photon number density, the population inversion and the energy transfer processes of amplifying and absorbing media.     

基于CaCO3/SiO2复合粒子的超疏水表面制备

通过表面化学修饰,制备了超疏水CaCO3/SiO2复合粒子,并用接触角测量仪检测疏水性能,当CaCO3与纳米SiO2质量比小于10：1时,可以制得超疏水复合粒子.基于表面修饰的CaCO3/SiO2复合粒子,对亲水涂料进行改性,当CaCO3与纳米SiO2质量比小于6：1时,可以制得超疏水涂层,且涂层疏水性随复合粒子加入量的增加而增大.同时,采用扫描电镜、红外光谱和热重分析等对复合粒子进行结构表征,探讨了基于CaCO3/SiO2复合粒子制备超疏水表面的机理.     

DMAP/Cr(III) Catalyst Ratio: The Decisive Factor for Poly(propylene carbonate) Formation in the Coupling of CO2 and Propylene Oxide

Highly efficient formation of poly(propylene carbonate) can be achieved in the coupling of CO₂ and propylene oxide assisted by 4‐(N,N‐dimethylamino)pyridine (DMAP) and catalyzed with salen chromium(III) chloride by using DMAP/Cr ratios of less than 2. Under these conditions a possible backbiting mechanism is suppressed, leading to only minor amounts of cyclic carbonate as a side product.

     

气体扩散耦合顺序注射光度分析法测定葡萄酒中的二氧化硫*

依据在微碱性条件下,亚硫酸根离子可与孔雀绿溶液发生加成反应并使其褪色的原理,建立了气体扩散耦合顺序注射分光光度法测定葡萄酒中二氧化硫的新方法。当接收液流速为1.2mL/min和4.2mL/min时,方法的线性响应范围分别为1.0-5.0μg/mL和5.0-50.0μg/mL,方法的检出限为0.33μg/mL,相对标准偏差（RSD）≤0.43%,对葡萄酒样中二氧化硫测定的加标回收率为98.7%-104.7%。     

TiO2微图纹结构的制作

The representative soft lithographic techniques are used,which are micromolding and microtransfer molding methods to fabricate the micro array patterned titanium dioxide on glass substrates. Firstly titanium dioxide sol was synthesized by sol-gel method using tetrabutyl titanate as the precursor,then the pre-patterned poly（dimethylsiloxane） elastomeric stamp was used to mold the TiO2 sol on glass substrate by micromolding and microtransfer molding methods,micro patterned TiO2 sol was gelled at 70℃ with 0. 5 N pressure applied on the PDMS stamp,further heat treatment of TiO2 gel by annealing at 550℃ for 2 h produced the TiO2 microstructure. The TiO2 microstructure was observed by the optical microscope and the optical micrographs demonstrated the satisfactory yield and fidelity of pattern transfer by micromolding method and microtransfer method. The effect of gel temperature,the pressure applied on the PDMS stamp and the silicone mold on the fidelity and yield of TiO2 microstructure are discussed.     

Solubility of vinylidene fluoride polymers in supercritical CO2 and halogenated solvents

The cloud‐point behaviors of poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐co‐22 mol % hexafluoropropylene) (VDF–HFP₂₂) are reported at temperatures up to 250 °C and pressures up to 3000 bar in supercritical CO₂, CHF₃, CH₂F₂, CHClF₂, CClF₃, CH₃CHF₂, CH₂FCF₃, CHF₂CF₃, and CH₃CClF₂. The molecular weight of PVDF has a smaller effect on the cloud point than the solvent quality. Cloud‐point pressures for both fluoropolymers decrease as the solvent polarizability, polar moment per molar volume, and density increases. However, it is extremely difficult to dissolve either fluoropolymer in CClF₃, which has a large polarizability and a small dipole moment. CO₂ is an effective solvent because it complexes with the C F dipole at low temperatures where energetic interactions fix the phase behavior. In addition, polymer architecture has a strong impact on the cloud‐point pressure. VDF–HFP₂₂ has lower cloud‐point pressures than PVDF in all solvents because it has a larger free volume that promotes facile interactions between the solvent and the polymer segments. Cloud‐point data are also reported for amorphous poly(tetrafluoroethylene‐co‐x mol % 2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole) (TFE–PDD_x ; x = 65 and 85) in CO₂. These data provide an interesting comparison to the PVDF–CO₂ and VDF–HFP₂₂–CO₂ systems because TFE–PDD₆₅ and TFE–PDD₈₇ have very high glass‐transition temperatures of 160 and 240 °C, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2832–2840, 2000     

Dispersion polymerization of 2‐hydroxyethyl methacrylate in supercritical carbon dioxide

Herein we report a successful dispersion polymerization of 2‐hydroxyethyl methacrylate (HEMA) in a carbon dioxide continuous phase with a block copolymer consisting of polystyrene and poly(1,1‐dihydroperfluorooctyl acrylate) as a stabilizer. Poly(2‐hydroxyethyl methacrylate) was effectively emulsified in carbon dioxide with the amphiphilic diblock copolymer surfactant, and the successful stabilization of the polymerization simultaneously gave spherical particles in the submicrometer range with relatively narrow particle size distributions. The initial concentrations of HEMA and the stabilizer and the pressure had substantial effects on the size of the colloidal particles. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3783–3790, 2000