Humidity sensitivity of polypyrrole and polypyrrole/SBA‐15 host–guest composite materials

Polypyrrole (PPY) and PPY/SBA‐15 host–guest composite materials have been prepared using chemical synthesis route and characterized by XRD, IR, N₂ adsorption–desorption isotherms, and SEM. The humidity sensitive properties (HSP) of this kind of materials have been studied by analyzing the variation curve of impedance as a function of relative humidity. It was found that the PPY/SBA‐15 host–guest composites materials exhibit better HSP than that of the corresponding pure PPY. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3301–3305, 2006     

离子束加速电压对真空电弧沉积Ti(C,N)涂层性能的影响

利用等离子辅助真空电孤沉积技术分别在高速钢片和单晶硅片制备了Ti(C,N）涂层，通过X-射线衍射和扫描电镜研究了不同离子加速电压对单晶硅片上涂层结构和组织形貌的影响，并测定了高速钢片上涂层的显微硬度，同时进行了耐磨性实验。结果表明：涂层主要由TiN和Ti(C,N）组成，随着离子束加速电压的增大，涂层的沉积速度增大，Ti(C,N）的衍射峰不断宽化，晶格尺寸发生变化，但其表面形貌不受影响；当离子束加速电压为1500V时，涂层有较高的耐磨性和显微硬度，当离子束加速电压为2500V时，涂层的耐磨性和显微硬度都有所下降：     

N,N′-乙撑双[N(乙磺酸钠)-十二酰胺]的合成与性能评价

以乙二胺、2-氯乙基磺酸钠、月桂酸等为原料合成了N,N′-乙撑双[N(乙磺酸钠)-十二酰胺](简记为DTM-12)。以IR和1HNMR对其结构进行了初步表征。该目标产物水溶液的CMC(0.5 mmol/L)分别是十二烷基硫酸钠和十二烷基磺酸钠的1/16和1/20,γCMC(29.7 mN/m)低8~9 mN/m。DTM-12分别与十二烷基三甲基溴化铵(DTAB)和辛基酚聚乙氧基醚9-10EO(Triton X-100)组成的复配体系在摩尔比为3∶7时,CMC达到0.106和0.049 mmol/L,γCMC达到25.4和31.7 mN/m,优于十二烷基磺酸钠组成的复配体系。DTM-12还具有良好的起泡性和稳泡性。     

介孔分子筛SBA-15的改性研究进展

从金属改性、酸改性和氧化物改性三方面综述了介孔分子筛SBA-15的改性研究进展,重点介绍了SBA-15表面功能化后引入金属改性的方法。评述了金属纳米粒子的制备对改性的SBA-15催化剂催化性能的影响。     

Si加入量对Si_3N_4-SiC复合材料性能的影响

固定其他组分配比不变,仅改变配方中Si粉加入量即Si粉从10％增加到60％,经过准静态氮化法反应烧结制得Si3N4——SiC复合材料,并对其进行力学性能、XRD和SEM检测,实验结果显示:随着Si加入量的增加,复合材料的强度逐渐增大,而密度却呈现减小趋势,生成的Si3N4-中β-Si3N4含量增加,形成的网络结构的致密度也相应增大,但β-Si3N4晶粒减小。     

硫代磷酸/伯胺N1923协同萃取锌和镉的机理

有机硫代磷酸/伯胺N1923协同萃取锌、镉的萃取率随pH的变化较为反常，可能因伯胺N1923与硫酸作用进而聚为反向胶束. 实验表明，如以(N1923)n.H2SO4表示反向胶束的实验式，N1923与H2SO4比值n多为3左右，可能与空间效应相关. 萃取机理为: M2+(a) +2BHA(o) + (2/n)SO42–(a) = MA2(o) + (2/n)(Bn.H2SO4)(o) + 2(1–2/n)H+(a)， n=3, 4, 5.     

Predicting N mineralized in a Georgia Coastal Plain field

The N mineralized from soil organic matter provides an important portion of N available for crop production. The objective of this study was to determine the amount of spatial variability in N mineralization potential in a field and to evaluate three different methods that might be used to estimate this variability. The three methods tested included predicting the N mineralized from surface soil properties as well as from a biological and a chemical procedure. Three soils varying in N mineralization potential were selected for the study from a field in the Georgia Coastal Plain. The N mineralized from these soils was determined by an N balance of unfertilized and cropped plots. The amount of N mineralized could not be reliably predicted from surface soil organic C, although surface soil clay concentration was positively correlated with the N mineralized. The N mineralized that was predicted using mineralization parameters determined by aerobic incubation, adjusted daily for soil water content and temperature, was approximately 50% of the field measurements of N mineralized. The values of NH₄-N extracted with hot 2 M KCl were related significantly to N mineralized in the field (r²= 0.60) and also to the zero order rate constant of mineralization, k₀ (r²= 0.77), determined from the N mineralized in the aerobic laboratory incubation.     

New N,O-containing ligands for the biomimetic copper-catalyzed polymerization of 2,6-dimethylphenol

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE), which is widely used in high-performance engineering plastics, is obtained by the copper-catalyzed oxidative coupling of 2,6-dimethylphenol. The oxidative polymerizations have been carried out in acetonitrile with structurally related [copper-(N,O-containing ligand)] complexes as the catalyst precursor compounds, which appeared to be of great interest for a better understanding of the factors influencing the catalytic activities. Steric effects (influence of a methyl group close to the metal center; ligands 4–7) or electronic effects (imino versus amino group; ligands 4, 5, 8 and 6, 7, 9, respectively) on the polymerization rates have been demonstrated. The use of mono- or dinucleating ligands has strengthened the proposed mechanism of the reaction involving dinuclear active species.     

表面处理对氮化硅陶瓷力学性能的影响

采用X射线衍射应力分析的sin2ψ法计算了Si3N4陶瓷试样的残余应力，并分别测量了表面处理前后Si3N4试样的力学性能。结果表明，经平面磨削后的Si3N4试样表面残余应力为拉应力，而抛光处理可适当降低残余应力。两种方法都使试样抗弯强度降低。     

Photophysical studies of copolymers of N‐vinylcarbazole

The absorption, fluorescence excitation and emission spectroscopy, and time‐dependent spectrofluorimetry have been used to study the photophysics of copolymers of N‐vinylcarbazole with different monomers like vinyl acetate, methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate in dichloromethane. In all the copolymers and at different N‐vinylcarbazole content, the absorption spectra reflect only the monomer carbazole units. The two kinds of excited monomer species of N‐vinylcarbazole are present in S₁ state. Short‐lived (～3 ns) excited monomer decays forming low energy excimer obtained by the complete overlap of the excited carbazole monomer. The long‐lived excited monomer (～8 ns) decays to ground state without formation of any excimer. The high energy excimer is relatively short‐lived and is formed by the partial overlap of the carbazole units. The presence of bulky group in the copolymer chain hinders the formation of excimers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 372–380, 2006